[Tarantool-patches] [PATCH 0/4] session settings fixes

[Tarantool-patches] [PATCH 0/4] session settings fixes

[Chris Sosnin]

issue #1:https://github.com/tarantool/tarantool/issues/4711
issue #2:https://github.com/tarantool/tarantool/issues/4712
branch:https://github.com/tarantool/tarantool/tree/ksosnin/gh-4712-session-settings-v2

Chris Sosnin (4):
  box: replace session_settings modules with a single array
  box: add binary search for _session_settings space
  box: provide a user friendly frontend for accessing session settings
  sql: provide a user friendly frontend for accessing session settings

 extra/mkkeywordhash.c                         |   1 +
 src/box/lua/session.c                         | 111 +++++++++
 src/box/session.cc                            |   1 +
 src/box/session.h                             |   2 +
 src/box/session_settings.c                    | 214 +++++++++++-------
 src/box/session_settings.h                    |  53 +++--
 src/box/sql.c                                 |   5 -
 src/box/sql/build.c                           | 104 ++++-----
 src/box/sql/parse.y                           |   5 +
 src/box/sql/sqlInt.h                          |  11 +
 src/box/sql/vdbe.c                            |  50 ++++
 ...rontend.result => session_settings.result} | 147 ++++++++++--
 ...end.test.lua => session_settings.test.lua} |  61 ++++-
 13 files changed, 589 insertions(+), 176 deletions(-)
 rename test/box/{gh-4511-access-settings-from-any-frontend.result => session_settings.result} (71%)
 rename test/box/{gh-4511-access-settings-from-any-frontend.test.lua => session_settings.test.lua} (64%)

-- 
2.21.1 (Apple Git-122.3)

[Tarantool-patches] [PATCH 1/4] box: replace session_settings modules with a single array

[Chris Sosnin]

Currently we have an array of modules and each module has
its own array of session_settings. This patch merges these
into one array, as long as it turned out, that we cannot
represent every setting as a part of some module. This
change is also needed for implementing binary search for
_session_settings space.

Part of #4711, #4712
---
 src/box/session_settings.c | 121 ++++++++++++++-----------------------
 src/box/session_settings.h |  50 +++++++++------
 src/box/sql/build.c        |  79 +++++++-----------------
 3 files changed, 101 insertions(+), 149 deletions(-)

diff --git a/src/box/session_settings.c b/src/box/session_settings.c
index 37d2a3e85..2ecf71f2d 100644
--- a/src/box/session_settings.c
+++ b/src/box/session_settings.c
@@ -38,8 +38,20 @@
 #include "xrow.h"
 #include "sql.h"
 
-struct session_setting_module
-	session_setting_modules[session_setting_type_MAX] = {};
+struct session_setting session_settings[SESSION_SETTING_COUNT] = {};
+
+/** Corresponding names of session settings. */
+const char *session_setting_strs[SESSION_SETTING_COUNT] = {
+	"sql_default_engine",
+	"sql_defer_foreign_keys",
+	"sql_full_column_names",
+	"sql_full_metadata",
+	"sql_parser_debug",
+	"sql_recursive_triggers",
+	"sql_reverse_unordered_selects",
+	"sql_select_debug",
+	"sql_vdbe_debug",
+};
 
 struct session_settings_index {
 	/** Base index. Must be the first member. */
@@ -61,12 +73,7 @@ struct session_settings_iterator {
 	 * a format for selected tuples.
 	 */
 	struct tuple_format *format;
-	/**
-	 * ID of the current session settings module in the global
-	 * list of the modules.
-	 */
-	int module_id;
-	/** ID of the setting in current module. */
+	/** ID of the setting. */
 	int setting_id;
 	/** Decoded key. */
 	char *key;
@@ -86,46 +93,40 @@ session_settings_iterator_free(struct iterator *ptr)
 }
 
 static int
-session_settings_next_in_module(const struct session_setting_module *module,
-				int *sid, const char *key, bool is_eq,
-				bool is_including)
+session_settings_next(int *sid, const char *key, bool is_eq, bool is_including)
 {
 	int i = *sid;
-	int count = module->setting_count;
-	if (i >= count)
+	if (i >= SESSION_SETTING_COUNT)
 		return -1;
 	if (key == NULL)
 		return 0;
 	assert(i >= 0);
-	const char **name = &module->settings[i];
-	for (; i < count; ++i, ++name) {
-		int cmp = strcmp(*name, key);
+	for (; i < SESSION_SETTING_COUNT; ++i) {
+		const char *name = session_setting_strs[i];
+		int cmp = strcmp(name, key);
 		if ((cmp == 0 && is_including) ||
 		    (cmp > 0 && !is_eq)) {
 			*sid = i;
 			return 0;
 		}
 	}
-	*sid = count;
+	*sid = SESSION_SETTING_COUNT;
 	return -1;
 }
 
 static int
-session_settings_prev_in_module(const struct session_setting_module *module,
-				int *sid, const char *key, bool is_eq,
-				bool is_including)
+session_settings_prev(int *sid, const char *key, bool is_eq, bool is_including)
 {
 	int i = *sid;
-	int count = module->setting_count;
 	if (i < 0)
 		return -1;
 	if (key == NULL)
 		return 0;
-	if (i >= count)
-		i = count - 1;
-	const char **name = &module->settings[i];
-	for (; i >= 0; --i, --name) {
-		int cmp = strcmp(*name, key);
+	if (i >= SESSION_SETTING_COUNT)
+		i = SESSION_SETTING_COUNT - 1;
+	for (; i >= 0; --i) {
+		const char *name = session_setting_strs[i];
+		int cmp = strcmp(name, key);
 		if ((cmp == 0 && is_including) ||
 		    (cmp < 0 && !is_eq)) {
 			*sid = i;
@@ -141,27 +142,19 @@ session_settings_iterator_next(struct iterator *iterator, struct tuple **result)
 {
 	struct session_settings_iterator *it =
 		(struct session_settings_iterator *)iterator;
-	int mid = it->module_id, sid = it->setting_id;
-	struct session_setting_module *module;
+	int sid = it->setting_id;
 	const char *key = it->key;
 	bool is_including = it->is_including, is_eq = it->is_eq;
 	bool is_found = false;
-	for (; mid < session_setting_type_MAX; ++mid, sid = 0) {
-		module = &session_setting_modules[mid];
-		if (session_settings_next_in_module(module, &sid, key, is_eq,
-						    is_including) == 0) {
-			is_found = true;
-			break;
-		}
-	}
-	it->module_id = mid;
+	if (session_settings_next(&sid, key, is_eq, is_including) == 0)
+		is_found = true;
 	it->setting_id = sid + 1;
 	if (!is_found) {
 		*result = NULL;
 		return 0;
 	}
 	const char *mp_pair, *mp_pair_end;
-	module->get(sid, &mp_pair, &mp_pair_end);
+	session_settings[sid].get(sid, &mp_pair, &mp_pair_end);
 	*result = box_tuple_new(it->format, mp_pair, mp_pair_end);
 	return *result != NULL ? 0 : -1;
 }
@@ -171,27 +164,19 @@ session_settings_iterator_prev(struct iterator *iterator, struct tuple **result)
 {
 	struct session_settings_iterator *it =
 		(struct session_settings_iterator *)iterator;
-	int mid = it->module_id, sid = it->setting_id;
-	struct session_setting_module *module;
+	int sid = it->setting_id;
 	const char *key = it->key;
 	bool is_including = it->is_including, is_eq = it->is_eq;
 	bool is_found = false;
-	for (; mid >= 0; --mid, sid = INT_MAX) {
-		module = &session_setting_modules[mid];
-		if (session_settings_prev_in_module(module, &sid, key, is_eq,
-						    is_including) == 0) {
-			is_found = true;
-			break;
-		}
-	}
-	it->module_id = mid;
+	if (session_settings_prev(&sid, key, is_eq, is_including) == 0)
+		is_found = true;
 	it->setting_id = sid - 1;
 	if (!is_found) {
 		*result = NULL;
 		return 0;
 	}
 	const char *mp_pair, *mp_pair_end;
-	module->get(sid, &mp_pair, &mp_pair_end);
+	session_settings[sid].get(sid, &mp_pair, &mp_pair_end);
 	*result = box_tuple_new(it->format, mp_pair, mp_pair_end);
 	return *result != NULL ? 0 : -1;
 }
@@ -239,14 +224,10 @@ session_settings_index_create_iterator(struct index *base,
 	it->format = index->format;
 	if (!iterator_type_is_reverse(type)) {
 		it->base.next = session_settings_iterator_next;
-		it->module_id = 0;
 		it->setting_id = 0;
 	} else {
 		it->base.next = session_settings_iterator_prev;
-		it->module_id = session_setting_type_MAX - 1;
-		struct session_setting_module *module =
-			&session_setting_modules[it->module_id];
-		it->setting_id = module->setting_count - 1;
+		it->setting_id = SESSION_SETTING_COUNT - 1;
 	}
 	return (struct iterator *)it;
 }
@@ -262,20 +243,14 @@ session_settings_index_get(struct index *base, const char *key,
 	uint32_t len;
 	key = mp_decode_str(&key, &len);
 	key = tt_cstr(key, len);
-	struct session_setting_module *module = &session_setting_modules[0];
-	struct session_setting_module *end = module + session_setting_type_MAX;
 	int sid = 0;
-	for (; module < end; ++module, sid = 0) {
-		if (session_settings_next_in_module(module, &sid, key, true,
-						    true) == 0)
-			goto found;
+	if (session_settings_next(&sid, key, true, true) != 0) {
+		*result = NULL;
+		return 0;
 	}
-	*result = NULL;
-	return 0;
-found:;
 	const char *mp_pair;
 	const char *mp_pair_end;
-	module->get(sid, &mp_pair, &mp_pair_end);
+	session_settings[sid].get(sid, &mp_pair, &mp_pair_end);
 	*result = box_tuple_new(index->format, mp_pair, mp_pair_end);
 	return *result != NULL ? 0 : -1;
 }
@@ -370,17 +345,11 @@ session_settings_space_execute_update(struct space *space, struct txn *txn,
 	}
 	key = mp_decode_str(&key, &key_len);
 	key = tt_cstr(key, key_len);
-	struct session_setting_module *module = &session_setting_modules[0];
-	struct session_setting_module *end = module + session_setting_type_MAX;
-	for (; module < end; ++module, sid = 0) {
-		if (session_settings_next_in_module(module, &sid, key, true,
-						    true) == 0)
-			goto found;
+	if (session_settings_next(&sid, key, true, true) != 0) {
+		*result = NULL;
+		return 0;
 	}
-	*result = NULL;
-	return 0;
-found:
-	module->get(sid, &old_data, &old_data_end);
+	session_settings[sid].get(sid, &old_data, &old_data_end);
 	new_data = xrow_update_execute(request->tuple, request->tuple_end,
 				       old_data, old_data_end, format,
 				       &new_size, request->index_base,
@@ -402,7 +371,7 @@ found:
 			goto finish;
 		}
 	}
-	if (module->set(sid, new_data) != 0)
+	if (session_settings[sid].set(sid, new_data) != 0)
 		goto finish;
 	rc = 0;
 finish:
diff --git a/src/box/session_settings.h b/src/box/session_settings.h
index 25490a7e3..de24e3c6f 100644
--- a/src/box/session_settings.h
+++ b/src/box/session_settings.h
@@ -30,29 +30,44 @@
  * SUCH DAMAGE.
  */
 
+#include "field_def.h"
+
 /**
- * Session has settings. Settings belong to different subsystems,
- * such as SQL. Each subsystem registers here its session setting
- * type and a set of settings with getter and setter functions.
- * The self-registration of modules allows session setting code
- * not to depend on all the subsystems.
+ * Identifiers of all session settings. The identifier of the
+ * option is equal to its place in the sorted list of session
+ * options.
  *
- * The types should be ordered in alphabetical order, because the
- * type list is used by setting iterators.
+ * It is IMPORTANT that these options are sorted by name. If this
+ * is not the case, the result returned by the _session_settings
+ * space iterator will not be sorted properly.
  */
-enum session_setting_type {
-	SESSION_SETTING_SQL,
-	session_setting_type_MAX,
+enum {
+	SESSION_SETTING_SQL_BEGIN,
+	SESSION_SETTING_SQL_DEFAULT_ENGINE = SESSION_SETTING_SQL_BEGIN,
+	SESSION_SETTING_SQL_DEFER_FOREIGN_KEYS,
+	SESSION_SETTING_SQL_FULL_COLUMN_NAMES,
+	SESSION_SETTING_SQL_FULL_METADATA,
+	SESSION_SETTING_SQL_PARSER_DEBUG,
+	SESSION_SETTING_SQL_RECURSIVE_TRIGGERS,
+	SESSION_SETTING_SQL_REVERSE_UNORDERED_SELECTS,
+	SESSION_SETTING_SQL_SELECT_DEBUG,
+	SESSION_SETTING_SQL_VDBE_DEBUG,
+	SESSION_SETTING_SQL_END,
+	/**
+	 * Follow the pattern for groups of settings:
+	 * SESSION_SETTING_<N>_BEGIN = SESSION_SETTING_<N-1>_END,
+	 * ...
+	 * SESSION_SETTING_<N>_END,
+	 */
+	SESSION_SETTING_COUNT = SESSION_SETTING_SQL_END,
 };
 
-struct session_setting_module {
+struct session_setting {
 	/**
-	 * An array of setting names. All of them should have the
-	 * same prefix.
+	 * Setting's value type. Used for error checking and
+	 * reporting only.
 	 */
-	const char **settings;
-	/** Count of settings. */
-	int setting_count;
+	enum field_type field_type;
 	/**
 	 * Get a MessagePack encoded pair [name, value] for a
 	 * setting having index @a id. Index is from the settings
@@ -67,4 +82,5 @@ struct session_setting_module {
 	int (*set)(int id, const char *mp_value);
 };
 
-extern struct session_setting_module session_setting_modules[];
+extern struct session_setting session_settings[SESSION_SETTING_COUNT];
+extern const char *session_setting_strs[SESSION_SETTING_COUNT];
diff --git a/src/box/sql/build.c b/src/box/sql/build.c
index 7511fad37..a00da31f9 100644
--- a/src/box/sql/build.c
+++ b/src/box/sql/build.c
@@ -3322,40 +3322,6 @@ sql_fieldno_by_name(struct Parse *parse_context, struct Expr *field_name,
 	return 0;
 }
 
-/**
- * Identifiers of all SQL session setings. The identifier of the
- * option is equal to its place in the sorted list of session
- * options of current module.
- *
- * It is IMPORTANT that these options are sorted by name. If this
- * is not the case, the result returned by the _session_settings
- * space iterator will not be sorted properly.
- */
-enum {
-	SQL_SESSION_SETTING_DEFAULT_ENGINE = 0,
-	SQL_SESSION_SETTING_DEFER_FOREIGN_KEYS,
-	SQL_SESSION_SETTING_FULL_COLUMN_NAMES,
-	SQL_SESSION_SETTING_FULL_METADATA,
-	SQL_SESSION_SETTING_PARSER_DEBUG,
-	SQL_SESSION_SETTING_RECURSIVE_TRIGGERS,
-	SQL_SESSION_SETTING_REVERSE_UNORDERED_SELECTS,
-	SQL_SESSION_SETTING_SELECT_DEBUG,
-	SQL_SESSION_SETTING_VDBE_DEBUG,
-	sql_session_setting_MAX,
-};
-
-static const char *sql_session_setting_strs[sql_session_setting_MAX] = {
-	"sql_default_engine",
-	"sql_defer_foreign_keys",
-	"sql_full_column_names",
-	"sql_full_metadata",
-	"sql_parser_debug",
-	"sql_recursive_triggers",
-	"sql_reverse_unordered_selects",
-	"sql_select_debug",
-	"sql_vdbe_debug",
-};
-
 /**
  * A local structure that allows to establish a connection between
  * parameter and its field type and mask, if it has one.
@@ -3373,24 +3339,24 @@ struct sql_option_metadata
  * It is IMPORTANT that these options sorted by name.
  */
 static struct sql_option_metadata sql_session_opts[] = {
-	/** SQL_SESSION_SETTING_DEFAULT_ENGINE */
+	/** SESSION_SETTING_SQL_DEFAULT_ENGINE */
 	{FIELD_TYPE_STRING, 0},
-	/** SQL_SESSION_SETTING_DEFER_FOREIGN_KEYS */
+	/** SESSION_SETTING_SQL_DEFER_FOREIGN_KEYS */
 	{FIELD_TYPE_BOOLEAN, SQL_DeferFKs},
-	/** SQL_SESSION_SETTING_FULL_COLUMN_NAMES */
+	/** SESSION_SETTING_SQL_FULL_COLUMN_NAMES */
 	{FIELD_TYPE_BOOLEAN, SQL_FullColNames},
-	/** SQL_SESSION_SETTING_FULL_METADATA */
+	/** SESSION_SETTING_SQL_FULL_METADATA */
 	{FIELD_TYPE_BOOLEAN, SQL_FullMetadata},
-	/** SQL_SESSION_SETTING_PARSER_DEBUG */
+	/** SESSION_SETTING_SQL_PARSER_DEBUG */
 	{FIELD_TYPE_BOOLEAN, SQL_SqlTrace | PARSER_TRACE_FLAG},
-	/** SQL_SESSION_SETTING_RECURSIVE_TRIGGERS */
+	/** SESSION_SETTING_SQL_RECURSIVE_TRIGGERS */
 	{FIELD_TYPE_BOOLEAN, SQL_RecTriggers},
-	/** SQL_SESSION_SETTING_REVERSE_UNORDERED_SELECTS */
+	/** SESSION_SETTING_SQL_REVERSE_UNORDERED_SELECTS */
 	{FIELD_TYPE_BOOLEAN, SQL_ReverseOrder},
-	/** SQL_SESSION_SETTING_SELECT_DEBUG */
+	/** SESSION_SETTING_SQL_SELECT_DEBUG */
 	{FIELD_TYPE_BOOLEAN,
 	 SQL_SqlTrace | SQL_SelectTrace | SQL_WhereTrace},
-	/** SQL_SESSION_SETTING_VDBE_DEBUG */
+	/** SESSION_SETTING_SQL_VDBE_DEBUG */
 	{FIELD_TYPE_BOOLEAN,
 	 SQL_SqlTrace | SQL_VdbeListing | SQL_VdbeTrace},
 };
@@ -3398,12 +3364,12 @@ static struct sql_option_metadata sql_session_opts[] = {
 static void
 sql_session_setting_get(int id, const char **mp_pair, const char **mp_pair_end)
 {
-	assert(id >= 0 && id < sql_session_setting_MAX);
+	assert(id >= SESSION_SETTING_SQL_BEGIN && id < SESSION_SETTING_SQL_END);
 	struct session *session = current_session();
 	uint32_t flags = session->sql_flags;
 	struct sql_option_metadata *opt = &sql_session_opts[id];
 	uint32_t mask = opt->mask;
-	const char *name = sql_session_setting_strs[id];
+	const char *name = session_setting_strs[id];
 	size_t name_len = strlen(name);
 	size_t engine_len;
 	const char *engine;
@@ -3416,7 +3382,7 @@ sql_session_setting_get(int id, const char **mp_pair, const char **mp_pair_end)
 	if (is_bool) {
 		size += mp_sizeof_bool(true);
 	} else {
-		assert(id == SQL_SESSION_SETTING_DEFAULT_ENGINE);
+		assert(id == SESSION_SETTING_SQL_DEFAULT_ENGINE);
 		engine = sql_storage_engine_strs[session->sql_default_engine];
 		engine_len = strlen(engine);
 		size += mp_sizeof_str(engine_len);
@@ -3452,7 +3418,7 @@ sql_set_boolean_option(int id, bool value)
 		session->sql_flags |= option->mask;
 	else
 		session->sql_flags &= ~option->mask;
-	if (id == SQL_SESSION_SETTING_PARSER_DEBUG) {
+	if (id == SESSION_SETTING_SQL_PARSER_DEBUG) {
 		if (value)
 			sqlParserTrace(stdout, "parser: ");
 		else
@@ -3466,7 +3432,7 @@ static int
 sql_set_string_option(int id, const char *value)
 {
 	assert(sql_session_opts[id].field_type = FIELD_TYPE_STRING);
-	assert(id == SQL_SESSION_SETTING_DEFAULT_ENGINE);
+	assert(id == SESSION_SETTING_SQL_DEFAULT_ENGINE);
 	(void)id;
 	enum sql_storage_engine engine = STR2ENUM(sql_storage_engine, value);
 	if (engine == sql_storage_engine_MAX) {
@@ -3480,7 +3446,7 @@ sql_set_string_option(int id, const char *value)
 static int
 sql_session_setting_set(int id, const char *mp_value)
 {
-	assert(id >= 0 && id < sql_session_setting_MAX);
+	assert(id >= SESSION_SETTING_SQL_BEGIN && id < SESSION_SETTING_SQL_END);
 	enum mp_type mtype = mp_typeof(*mp_value);
 	enum field_type stype = sql_session_opts[id].field_type;
 	uint32_t len;
@@ -3500,17 +3466,18 @@ sql_session_setting_set(int id, const char *mp_value)
 		unreachable();
 	}
 	diag_set(ClientError, ER_SESSION_SETTING_INVALID_VALUE,
-		 sql_session_setting_strs[id], field_type_strs[stype]);
+		 session_setting_strs[id], field_type_strs[stype]);
 	return -1;
 }
 
 void
 sql_session_settings_init()
 {
-	struct session_setting_module *module =
-		&session_setting_modules[SESSION_SETTING_SQL];
-	module->settings = sql_session_setting_strs;
-	module->setting_count = sql_session_setting_MAX;
-	module->get = sql_session_setting_get;
-	module->set = sql_session_setting_set;
+	for (int id = SESSION_SETTING_SQL_BEGIN; id < SESSION_SETTING_SQL_END;
+	     ++id) {
+		struct session_setting *setting = &session_settings[id];
+		setting->field_type = sql_session_opts[id].field_type;
+		setting->get = sql_session_setting_get;
+		setting->set = sql_session_setting_set;
+	}
 }
-- 
2.21.1 (Apple Git-122.3)

[Tarantool-patches] [PATCH 2/4] box: add binary search for _session_settings space

[Chris Sosnin]

As it is mentioned in implementation, it is important
that _session_settings options are sorted by name, so
there is no need in linear lookup and we can replace it
with binary search.

Closes #4712
---
 src/box/session_settings.c                    | 97 +++++++++++++++++--
 ...1-access-settings-from-any-frontend.result | 37 ++++---
 ...access-settings-from-any-frontend.test.lua | 28 ++++--
 3 files changed, 133 insertions(+), 29 deletions(-)

diff --git a/src/box/session_settings.c b/src/box/session_settings.c
index 2ecf71f2d..5e4a50427 100644
--- a/src/box/session_settings.c
+++ b/src/box/session_settings.c
@@ -81,6 +81,8 @@ struct session_settings_iterator {
 	bool is_eq;
 	/** True if the iterator should include equal keys. */
 	bool is_including;
+	/** True if the iterator is pointing to an existing setting */
+	bool is_set;
 };
 
 static void
@@ -92,6 +94,72 @@ session_settings_iterator_free(struct iterator *ptr)
 	free(it);
 }
 
+static int
+session_settings_set_forward(int *sid, const char *key, bool is_eq,
+			     bool is_including)
+{
+	int low = 0, high = SESSION_SETTING_COUNT - 1;
+	if (key == NULL)
+		return 0;
+	while (low <= high) {
+		int index = (high + low) / 2;
+		const char *name = session_setting_strs[index];
+		int cmp = strcmp(name, key);
+		if (cmp == 0) {
+			if (is_including) {
+				*sid = index;
+				return 0;
+			}
+			*sid = ++index;
+			return index < SESSION_SETTING_COUNT ? 0 : -1;
+		}
+		if (cmp < 0)
+			low = index + 1;
+		else
+			high = index - 1;
+	}
+	if (is_eq) {
+		*sid = SESSION_SETTING_COUNT;
+		return -1;
+	}
+	assert(low > high);
+	*sid = low;
+	return low < SESSION_SETTING_COUNT ? 0 : -1;
+}
+
+static int
+session_settings_set_reverse(int *sid, const char *key, bool is_eq,
+			     bool is_including)
+{
+	int low = 0, high = SESSION_SETTING_COUNT - 1;
+	if (key == NULL)
+		return 0;
+	while (low <= high) {
+		int index = (high + low) / 2;
+		const char *name = session_setting_strs[index];
+		int cmp = strcmp(name, key);
+		if (cmp == 0) {
+			if (is_including) {
+				*sid = index;
+				return 0;
+			}
+			*sid = --index;
+			return index >= 0 ? 0 : -1;
+		}
+		if (cmp < 0)
+			low = index + 1;
+		else
+			high = index - 1;
+	}
+	if (is_eq) {
+		*sid = SESSION_SETTING_COUNT;
+		return -1;
+	}
+	assert(low > high);
+	*sid = high;
+	return high >= 0 ? 0 : -1;
+}
+
 static int
 session_settings_next(int *sid, const char *key, bool is_eq, bool is_including)
 {
@@ -145,9 +213,15 @@ session_settings_iterator_next(struct iterator *iterator, struct tuple **result)
 	int sid = it->setting_id;
 	const char *key = it->key;
 	bool is_including = it->is_including, is_eq = it->is_eq;
-	bool is_found = false;
-	if (session_settings_next(&sid, key, is_eq, is_including) == 0)
-		is_found = true;
+	bool is_found;
+	if (!it->is_set) {
+		it->is_set = true;
+		is_found = session_settings_set_forward(&sid, key, is_eq,
+							is_including) == 0;
+	} else {
+		is_found = session_settings_next(&sid, key, is_eq,
+						 is_including) == 0;
+	}
 	it->setting_id = sid + 1;
 	if (!is_found) {
 		*result = NULL;
@@ -167,9 +241,15 @@ session_settings_iterator_prev(struct iterator *iterator, struct tuple **result)
 	int sid = it->setting_id;
 	const char *key = it->key;
 	bool is_including = it->is_including, is_eq = it->is_eq;
-	bool is_found = false;
-	if (session_settings_prev(&sid, key, is_eq, is_including) == 0)
-		is_found = true;
+	bool is_found;
+	if (!it->is_set) {
+		it->is_set = true;
+		is_found = session_settings_set_reverse(&sid, key, is_eq,
+							is_including) == 0;
+	} else {
+		is_found = session_settings_prev(&sid, key, is_eq,
+						 is_including) == 0;
+	}
 	it->setting_id = sid - 1;
 	if (!is_found) {
 		*result = NULL;
@@ -221,6 +301,7 @@ session_settings_index_create_iterator(struct index *base,
 	it->is_eq = type == ITER_EQ || type == ITER_REQ;
 	it->is_including = it->is_eq || type == ITER_GE || type == ITER_ALL ||
 			   type == ITER_LE;
+	it->is_set = false;
 	it->format = index->format;
 	if (!iterator_type_is_reverse(type)) {
 		it->base.next = session_settings_iterator_next;
@@ -244,7 +325,7 @@ session_settings_index_get(struct index *base, const char *key,
 	key = mp_decode_str(&key, &len);
 	key = tt_cstr(key, len);
 	int sid = 0;
-	if (session_settings_next(&sid, key, true, true) != 0) {
+	if (session_settings_set_forward(&sid, key, true, true) != 0) {
 		*result = NULL;
 		return 0;
 	}
@@ -345,7 +426,7 @@ session_settings_space_execute_update(struct space *space, struct txn *txn,
 	}
 	key = mp_decode_str(&key, &key_len);
 	key = tt_cstr(key, key_len);
-	if (session_settings_next(&sid, key, true, true) != 0) {
+	if (session_settings_set_forward(&sid, key, true, true) != 0) {
 		*result = NULL;
 		return 0;
 	}
diff --git a/test/box/gh-4511-access-settings-from-any-frontend.result b/test/box/gh-4511-access-settings-from-any-frontend.result
index ed340d053..bae77192e 100644
--- a/test/box/gh-4511-access-settings-from-any-frontend.result
+++ b/test/box/gh-4511-access-settings-from-any-frontend.result
@@ -82,6 +82,12 @@ function check_sorting(ss, ts, key)
     for _, it in pairs(iterators_list) do
         local view_space = ss:select({key}, {iterator = it})
         local test_space = ts:select({key}, {iterator = it})
+        if #view_space ~= #test_space then
+            return {
+                err = 'bad sorting', type = it, exp = test_space,
+                got = view_space
+            }
+        end
         for key, value in pairs(view_space) do
             if test_space[key].name ~= value.name then
                 return {
@@ -111,32 +117,37 @@ check_sorting(s, t, 'sql_d')
 check_sorting(s, t, 'sql_v')
  | ---
  | ...
-check_sorting(s, t, 'sql_defer_foreign_keys')
+check_sorting(s, t, 'z')
  | ---
  | ...
-
-t:drop()
+check_sorting(s, t, 'sql_parser_debuf')
+ | ---
+ | ...
+check_sorting(s, t, 'sql_parser_debuh')
  | ---
  | ...
 
--- Check get() method of session_settings space.
-s:get({'sql_defer_foreign_keys'})
+name = nil
  | ---
- | - ['sql_defer_foreign_keys', false]
  | ...
-s:get({'sql_recursive_triggers'})
+err = nil
  | ---
- | - ['sql_recursive_triggers', true]
  | ...
-s:get({'sql_reverse_unordered_selects'})
+for _, tuple in t:pairs() do                    \
+    name = tuple.name                           \
+    err = check_sorting(s, t, name)             \
+    if err then                                 \
+        break                                   \
+    end                                         \
+end
  | ---
- | - ['sql_reverse_unordered_selects', false]
  | ...
-s:get({'sql_default_engine'})
+err and {err, name}
  | ---
- | - ['sql_default_engine', 'memtx']
+ | - null
  | ...
-s:get({'abcd'})
+
+t:drop()
  | ---
  | ...
 
diff --git a/test/box/gh-4511-access-settings-from-any-frontend.test.lua b/test/box/gh-4511-access-settings-from-any-frontend.test.lua
index 366874998..b243be15e 100644
--- a/test/box/gh-4511-access-settings-from-any-frontend.test.lua
+++ b/test/box/gh-4511-access-settings-from-any-frontend.test.lua
@@ -36,6 +36,12 @@ function check_sorting(ss, ts, key)
     for _, it in pairs(iterators_list) do
         local view_space = ss:select({key}, {iterator = it})
         local test_space = ts:select({key}, {iterator = it})
+        if #view_space ~= #test_space then
+            return {
+                err = 'bad sorting', type = it, exp = test_space,
+                got = view_space
+            }
+        end
         for key, value in pairs(view_space) do
             if test_space[key].name ~= value.name then
                 return {
@@ -52,17 +58,23 @@ check_sorting(s, t)
 check_sorting(s, t, 'abcde')
 check_sorting(s, t, 'sql_d')
 check_sorting(s, t, 'sql_v')
-check_sorting(s, t, 'sql_defer_foreign_keys')
+check_sorting(s, t, 'z')
+check_sorting(s, t, 'sql_parser_debuf')
+check_sorting(s, t, 'sql_parser_debuh')
+
+name = nil
+err = nil
+for _, tuple in t:pairs() do                    \
+    name = tuple.name                           \
+    err = check_sorting(s, t, name)             \
+    if err then                                 \
+        break                                   \
+    end                                         \
+end
+err and {err, name}
 
 t:drop()
 
--- Check get() method of session_settings space.
-s:get({'sql_defer_foreign_keys'})
-s:get({'sql_recursive_triggers'})
-s:get({'sql_reverse_unordered_selects'})
-s:get({'sql_default_engine'})
-s:get({'abcd'})
-
 -- Check pairs() method of session_settings space.
 t = {}
 for key, value in s:pairs() do table.insert(t, {key, value}) end
-- 
2.21.1 (Apple Git-122.3)

[Tarantool-patches] [PATCH 3/4] box: provide a user friendly frontend for accessing session settings

[Chris Sosnin]

- space_object:update() is hard to use for configuring session settings,
so we provide box.session.settings table, which can be used in a much more
native way.

- Prior to this patch sql settings were not accessible before box.cfg()
call, even though these flags can be set right after session creation.

Part of #4711
---
 src/box/lua/session.c                         | 111 ++++++++++++++++++
 src/box/session.cc                            |   1 +
 src/box/session.h                             |   2 +
 src/box/session_settings.c                    |  16 ++-
 src/box/session_settings.h                    |   3 +
 src/box/sql.c                                 |   5 -
 ...rontend.result => session_settings.result} |  61 ++++++++++
 ...end.test.lua => session_settings.test.lua} |  20 ++++
 8 files changed, 211 insertions(+), 8 deletions(-)
 rename test/box/{gh-4511-access-settings-from-any-frontend.result => session_settings.result} (86%)
 rename test/box/{gh-4511-access-settings-from-any-frontend.test.lua => session_settings.test.lua} (86%)

diff --git a/src/box/lua/session.c b/src/box/lua/session.c
index c6a600f6f..103bf22fd 100644
--- a/src/box/lua/session.c
+++ b/src/box/lua/session.c
@@ -42,6 +42,8 @@
 #include "box/user.h"
 #include "box/schema.h"
 #include "box/port.h"
+#include "box/session_settings.h"
+#include "tt_static.h"
 
 static const char *sessionlib_name = "box.session";
 
@@ -411,6 +413,114 @@ lbox_session_on_access_denied(struct lua_State *L)
 				  lbox_push_on_access_denied_event, NULL);
 }
 
+static int
+lbox_session_setting_get_by_id(struct lua_State *L, int sid)
+{
+	assert(sid >= 0 && sid < SESSION_SETTING_COUNT);
+	const char *mp_pair, *mp_pair_end;
+	session_settings[sid].get(sid, &mp_pair, &mp_pair_end);
+	uint32_t len;
+	mp_decode_array(&mp_pair);
+	mp_decode_str(&mp_pair, &len);
+	enum field_type field_type = session_settings[sid].field_type;
+	if (field_type == FIELD_TYPE_BOOLEAN) {
+		bool value = mp_decode_bool(&mp_pair);
+		lua_pushboolean(L, value);
+	} else {
+		assert(field_type == FIELD_TYPE_STRING);
+		const char *str = mp_decode_str(&mp_pair, &len);
+		lua_pushlstring(L, str, len);
+	}
+	return 1;
+}
+
+static int
+lbox_session_setting_get(struct lua_State *L)
+{
+	assert(lua_gettop(L) == 2);
+	const char *setting_name = lua_tostring(L, -1);
+	int sid = session_setting_find(setting_name);
+	if (sid < 0) {
+		diag_set(ClientError, ER_PROC_LUA, tt_sprintf("Session "\
+			 "setting %s doesn't exist", setting_name));
+		return luaT_error(L);
+	}
+	return lbox_session_setting_get_by_id(L, sid);
+}
+
+static int
+lbox_session_setting_set(struct lua_State *L)
+{
+	assert(lua_gettop(L) == 3);
+	int arg_type = lua_type(L, -1);
+	const char *setting_name = lua_tostring(L, -2);
+	int sid = session_setting_find(setting_name);
+	if (sid < 0) {
+		diag_set(ClientError, ER_PROC_LUA, tt_sprintf("Session "\
+			 "setting %s doesn't exist", setting_name));
+		return luaT_error(L);
+	}
+	struct session_setting *setting = &session_settings[sid];
+	switch (arg_type) {
+	case LUA_TBOOLEAN: {
+		bool value = lua_toboolean(L, -1);
+		size_t size = mp_sizeof_bool(value);
+		char *mp_value = (char *) static_alloc(size);
+		mp_encode_bool(mp_value, value);
+		if (setting->set(sid, mp_value) != 0)
+			return luaT_error(L);
+		break;
+	}
+	case LUA_TSTRING: {
+		const char *str = lua_tostring(L, -1);
+		size_t len = strlen(str);
+		uint32_t size = mp_sizeof_str(len);
+		char *mp_value = (char *) static_alloc(size);
+		if (mp_value == NULL) {
+			diag_set(OutOfMemory, size, "static_alloc",
+				 "mp_value");
+			return luaT_error(L);
+		}
+		mp_encode_str(mp_value, str, len);
+		if (setting->set(sid, mp_value) != 0)
+			return luaT_error(L);
+		break;
+	}
+	default:
+		diag_set(ClientError, ER_SESSION_SETTING_INVALID_VALUE,
+			 session_setting_strs[sid],
+			 field_type_strs[setting->field_type]);
+		return luaT_error(L);
+	}
+	return 0;
+}
+
+static int
+lbox_session_settings_serialize(struct lua_State *L)
+{
+	lua_newtable(L);
+	for (int id = 0; id < SESSION_SETTING_COUNT; ++id) {
+		lbox_session_setting_get_by_id(L, id);
+		lua_setfield(L, -2, session_setting_strs[id]);
+	}
+	return 1;
+}
+
+static void
+lbox_session_settings_init(struct lua_State *L)
+{
+	lua_newtable(L);
+	lua_createtable(L, 0, 3);
+	lua_pushcfunction(L, lbox_session_settings_serialize);
+	lua_setfield(L, -2, "__serialize");
+	lua_pushcfunction(L, lbox_session_setting_get);
+	lua_setfield(L, -2, "__index");
+	lua_pushcfunction(L, lbox_session_setting_set);
+	lua_setfield(L, -2, "__newindex");
+	lua_setmetatable(L, -2);
+	lua_setfield(L, -2, "settings");
+}
+
 void
 session_storage_cleanup(int sid)
 {
@@ -478,5 +588,6 @@ box_lua_session_init(struct lua_State *L)
 		{NULL, NULL}
 	};
 	luaL_register_module(L, sessionlib_name, sessionlib);
+	lbox_session_settings_init(L);
 	lua_pop(L, 1);
 }
diff --git a/src/box/session.cc b/src/box/session.cc
index 881318252..b557eed62 100644
--- a/src/box/session.cc
+++ b/src/box/session.cc
@@ -283,6 +283,7 @@ session_init()
 		panic("out of memory");
 	mempool_create(&session_pool, &cord()->slabc, sizeof(struct session));
 	credentials_create(&admin_credentials, admin_user);
+	sql_session_settings_init();
 }
 
 void
diff --git a/src/box/session.h b/src/box/session.h
index 6dfc7cba5..1c47b8986 100644
--- a/src/box/session.h
+++ b/src/box/session.h
@@ -41,6 +41,8 @@
 extern "C" {
 #endif /* defined(__cplusplus) */
 
+extern void sql_session_settings_init();
+
 struct port;
 struct session_vtab;
 
diff --git a/src/box/session_settings.c b/src/box/session_settings.c
index 5e4a50427..15ab65a97 100644
--- a/src/box/session_settings.c
+++ b/src/box/session_settings.c
@@ -324,8 +324,8 @@ session_settings_index_get(struct index *base, const char *key,
 	uint32_t len;
 	key = mp_decode_str(&key, &len);
 	key = tt_cstr(key, len);
-	int sid = 0;
-	if (session_settings_set_forward(&sid, key, true, true) != 0) {
+	int sid = session_setting_find(key);
+	if (sid < 0) {
 		*result = NULL;
 		return 0;
 	}
@@ -426,7 +426,8 @@ session_settings_space_execute_update(struct space *space, struct txn *txn,
 	}
 	key = mp_decode_str(&key, &key_len);
 	key = tt_cstr(key, key_len);
-	if (session_settings_set_forward(&sid, key, true, true) != 0) {
+	sid = session_setting_find(key);
+	if (sid < 0) {
 		*result = NULL;
 		return 0;
 	}
@@ -520,3 +521,12 @@ const struct space_vtab session_settings_space_vtab = {
 	/* .prepare_alter = */ generic_space_prepare_alter,
 	/* .invalidate = */ generic_space_invalidate,
 };
+
+int
+session_setting_find(const char *name) {
+	int sid;
+	if (session_settings_set_forward(&sid, name, true, true) == 0)
+		return sid;
+	else
+		return -1;
+}
diff --git a/src/box/session_settings.h b/src/box/session_settings.h
index de24e3c6f..e2adc5289 100644
--- a/src/box/session_settings.h
+++ b/src/box/session_settings.h
@@ -84,3 +84,6 @@ struct session_setting {
 
 extern struct session_setting session_settings[SESSION_SETTING_COUNT];
 extern const char *session_setting_strs[SESSION_SETTING_COUNT];
+
+int
+session_setting_find(const char *name);
diff --git a/src/box/sql.c b/src/box/sql.c
index 1256df856..ba98ce5df 100644
--- a/src/box/sql.c
+++ b/src/box/sql.c
@@ -64,14 +64,9 @@ static const uint32_t default_sql_flags = SQL_EnableTrigger
 					  | SQL_AutoIndex
 					  | SQL_RecTriggers;
 
-extern void
-sql_session_settings_init();
-
 void
 sql_init()
 {
-	sql_session_settings_init();
-
 	default_flags |= default_sql_flags;
 
 	current_session()->sql_flags |= default_sql_flags;
diff --git a/test/box/gh-4511-access-settings-from-any-frontend.result b/test/box/session_settings.result
similarity index 86%
rename from test/box/gh-4511-access-settings-from-any-frontend.result
rename to test/box/session_settings.result
index bae77192e..b32a0becb 100644
--- a/test/box/gh-4511-access-settings-from-any-frontend.result
+++ b/test/box/session_settings.result
@@ -298,3 +298,64 @@ s:update('sql_defer_foreign_keys', {{'=', 'value', '1'}})
  | ---
  | - error: Session setting sql_defer_foreign_keys expected a value of type boolean
  | ...
+
+-- gh-4711: Provide a user-friendly frontend for accessing session settings.
+settings = box.session.settings
+ | ---
+ | ...
+assert(settings ~= nil)
+ | ---
+ | - true
+ | ...
+
+s:update('sql_default_engine', {{'=', 2, 'vinyl'}})
+ | ---
+ | - ['sql_default_engine', 'vinyl']
+ | ...
+settings.sql_default_engine
+ | ---
+ | - vinyl
+ | ...
+settings.sql_default_engine = 'memtx'
+ | ---
+ | ...
+s:get('sql_default_engine').value
+ | ---
+ | - memtx
+ | ...
+settings.sql_defer_foreign_keys = true
+ | ---
+ | ...
+s:get('sql_defer_foreign_keys').value
+ | ---
+ | - true
+ | ...
+s:update('sql_defer_foreign_keys', {{'=', 2, false}})
+ | ---
+ | - ['sql_defer_foreign_keys', false]
+ | ...
+settings.sql_defer_foreign_keys
+ | ---
+ | - false
+ | ...
+
+settings.sql_default_engine = true
+ | ---
+ | - error: Session setting sql_default_engine expected a value of type string
+ | ...
+settings.sql_defer_foreign_keys = 'false'
+ | ---
+ | - error: Session setting sql_defer_foreign_keys expected a value of type boolean
+ | ...
+settings.sql_parser_debug = 'string'
+ | ---
+ | - error: Session setting sql_parser_debug expected a value of type boolean
+ | ...
+
+str = string.rep('a', 20 * 1024)
+ | ---
+ | ...
+box.session.settings.sql_default_engine = str
+ | ---
+ | - error: Failed to allocate 20483 bytes in static_alloc for mp_value
+ | ...
diff --git a/test/box/gh-4511-access-settings-from-any-frontend.test.lua b/test/box/session_settings.test.lua
similarity index 86%
rename from test/box/gh-4511-access-settings-from-any-frontend.test.lua
rename to test/box/session_settings.test.lua
index b243be15e..440bef7ce 100644
--- a/test/box/gh-4511-access-settings-from-any-frontend.test.lua
+++ b/test/box/session_settings.test.lua
@@ -118,3 +118,23 @@ s:update('sql_defer_foreign_keys', {{'=', 'some text', true}})
 s:update('sql_defer_foreign_keys', {{'=', 'value', 1}})
 s:update('sql_defer_foreign_keys', {{'=', 'value', {1}}})
 s:update('sql_defer_foreign_keys', {{'=', 'value', '1'}})
+
+-- gh-4711: Provide a user-friendly frontend for accessing session settings.
+settings = box.session.settings
+assert(settings ~= nil)
+
+s:update('sql_default_engine', {{'=', 2, 'vinyl'}})
+settings.sql_default_engine
+settings.sql_default_engine = 'memtx'
+s:get('sql_default_engine').value
+settings.sql_defer_foreign_keys = true
+s:get('sql_defer_foreign_keys').value
+s:update('sql_defer_foreign_keys', {{'=', 2, false}})
+settings.sql_defer_foreign_keys
+
+settings.sql_default_engine = true
+settings.sql_defer_foreign_keys = 'false'
+settings.sql_parser_debug = 'string'
+
+str = string.rep('a', 20 * 1024)
+box.session.settings.sql_default_engine = str
-- 
2.21.1 (Apple Git-122.3)

[Tarantool-patches] [PATCH 4/4] sql: provide a user friendly frontend for accessing session settings

[Chris Sosnin]

Currently if a user wants to change session setting with SQL, one has
to execute UPDATE query like:
[[UPDATE "_session_settings" SET "value" = true WHERE "name" = 'name']]
However, direct access to system spaces isn't considered to be a good practice.
To avoid that and a bit simplify user's life, we introduce SQL shortcut command
SETTING SET.

Closes #4711

@TarantoolBot document
Title: API for accessing _session_settings space.
There are two ways of updating values of session settings:
via Lua and SQL.

Lua:
box.session.settings is a table, which is always accessible
to user. The syntax is the following:
`box.session.settings.<setting_name> = <new_value>`.

Example of usage:
```
tarantool> box.session.settings.sql_default_engine
---
- memtx
...

tarantool> box.session.settings.sql_default_engine = 'vinyl'
---
...

```

The table itself represents the (unordered) result of select
from _session_settings space.

SQL:
Instead of typing long UPDATE query one can use the SETTING SET command:
`box.execute([[SETTING SET "<setting_name>" = <new_value>]])`.
Note, that this query is case sensitive so the name must be quoted.
Also, SETTING SET doesn't prove any implicit casts, so <new_value> must
be of the type corresponding to the setting being updated.

Example:
```
tarantool> box.execute([[setting set "sql_default_engine" = 'memtx']])
---
- row_count: 1
...

tarantool> box.execute([[setting set "sql_defer_foreign_keys" = true]])
---
- row_count: 1
...

```
---
 extra/mkkeywordhash.c              |  1 +
 src/box/sql/build.c                | 25 +++++++++++++++
 src/box/sql/parse.y                |  5 +++
 src/box/sql/sqlInt.h               | 11 +++++++
 src/box/sql/vdbe.c                 | 50 ++++++++++++++++++++++++++++++
 test/box/session_settings.result   | 49 +++++++++++++++++++++++++++++
 test/box/session_settings.test.lua | 13 ++++++++
 7 files changed, 154 insertions(+)

diff --git a/extra/mkkeywordhash.c b/extra/mkkeywordhash.c
index 006285622..887853529 100644
--- a/extra/mkkeywordhash.c
+++ b/extra/mkkeywordhash.c
@@ -159,6 +159,7 @@ static Keyword aKeywordTable[] = {
   { "SCALAR",                 "TK_SCALAR",      true  },
   { "SELECT",                 "TK_SELECT",      true  },
   { "SET",                    "TK_SET",         true  },
+  { "SETTING",                "TK_SETTING",     false },
   { "SIMPLE",                 "TK_SIMPLE",      true  },
   { "START",                  "TK_START",       true  },
   { "STRING",                 "TK_STRING_KW",   true  },
diff --git a/src/box/sql/build.c b/src/box/sql/build.c
index a00da31f9..cdcf8b6d8 100644
--- a/src/box/sql/build.c
+++ b/src/box/sql/build.c
@@ -3481,3 +3481,28 @@ sql_session_settings_init()
 		setting->set = sql_session_setting_set;
 	}
 }
+
+void
+sql_setting_set(struct Parse *parse_context, struct Token *name,
+		struct Expr *expr)
+{
+	struct Vdbe *vdbe = sqlGetVdbe(parse_context);
+	if (vdbe == NULL)
+		goto abort;
+	sqlVdbeCountChanges(vdbe);
+	char *key = sql_name_from_token(parse_context->db, name);
+	if (key == NULL)
+		goto abort;
+	int index = session_setting_find(key);
+	if (index >= 0) {
+		int target = ++parse_context->nMem;
+		sqlExprCode(parse_context, expr, target);
+		sqlVdbeAddOp2(vdbe, OP_SetSetting, index, target);
+		return;
+	}
+	diag_set(ClientError, ER_SQL_PARSER_GENERIC,
+		 tt_sprintf("Session setting %s doesn't exist", key));
+abort:
+	parse_context->is_aborted = true;
+	return;
+}
diff --git a/src/box/sql/parse.y b/src/box/sql/parse.y
index 1a0e89703..56977b003 100644
--- a/src/box/sql/parse.y
+++ b/src/box/sql/parse.y
@@ -1541,6 +1541,11 @@ cmd ::= DROP INDEX ifexists(E) nm(X) ON fullname(Y).   {
   sql_drop_index(pParse);
 }
 
+///////////////////////////// The SETTING SET command ////////////////////////
+cmd ::= SETTING SET nm(X) EQ expr(Y).  {
+    sql_setting_set(pParse,&X,Y.pExpr);
+}
+
 ///////////////////////////// The PRAGMA command /////////////////////////////
 //
 cmd ::= PRAGMA nm(X).                        {
diff --git a/src/box/sql/sqlInt.h b/src/box/sql/sqlInt.h
index 1579cc92e..a700dd9c9 100644
--- a/src/box/sql/sqlInt.h
+++ b/src/box/sql/sqlInt.h
@@ -4513,4 +4513,15 @@ int
 sql_fieldno_by_name(struct Parse *parse_context, struct Expr *field_name,
 		    uint32_t *fieldno);
 
+/**
+ * Create VDBE instructions to set the new value of the session setting.
+ *
+ * @param parse_context Parsing context.
+ * @param name Name of the session setting.
+ * @param value New value of the session setting.
+ */
+void
+sql_setting_set(struct Parse *parse_context, struct Token *name,
+		struct Expr *value);
+
 #endif				/* sqlINT_H */
diff --git a/src/box/sql/vdbe.c b/src/box/sql/vdbe.c
index e8a029a8a..d6b753a51 100644
--- a/src/box/sql/vdbe.c
+++ b/src/box/sql/vdbe.c
@@ -55,6 +55,7 @@
 #include "box/schema.h"
 #include "box/space.h"
 #include "box/sequence.h"
+#include "box/session_settings.h"
 
 /*
  * Invoke this macro on memory cells just prior to changing the
@@ -5252,6 +5253,55 @@ case OP_IncMaxid: {
 	break;
 }
 
+/* Opcode: SetSetting P1 P2 * * *
+ *
+ * Set the new value of the session setting. P1 is the id of the
+ * setting in the session_settings array, P2 is the register
+ * holding a value.
+ */
+case OP_SetSetting: {
+	int sid = pOp->p1;
+	pIn1 = &aMem[pOp->p2];
+	assert(sid >= 0 && sid < SESSION_SETTING_COUNT);
+	struct session_setting *setting = &session_settings[sid];
+	switch (setting->field_type) {
+	case FIELD_TYPE_BOOLEAN: {
+		if ((pIn1->flags & MEM_Bool) == 0)
+			goto invalid_type;
+		bool value = pIn1->u.b;
+		size_t size = mp_sizeof_bool(value);
+		char *mp_value = (char *) static_alloc(size);
+		mp_encode_bool(mp_value, value);
+		if (setting->set(sid, mp_value) != 0)
+			goto abort_due_to_error;
+		break;
+	}
+	case FIELD_TYPE_STRING: {
+		if ((pIn1->flags & MEM_Str) == 0)
+			goto invalid_type;
+		const char *str = pIn1->z;
+		uint32_t size = mp_sizeof_str(pIn1->n);
+		char *mp_value = (char *) static_alloc(size);
+		if (mp_value == NULL) {
+			diag_set(OutOfMemory, size, "static_alloc", "mp_value");
+			goto abort_due_to_error;
+		}
+		mp_encode_str(mp_value, str, pIn1->n);
+		if (setting->set(sid, mp_value) != 0)
+			goto abort_due_to_error;
+		break;
+	}
+	default:
+	invalid_type:
+		diag_set(ClientError, ER_SESSION_SETTING_INVALID_VALUE,
+			 session_setting_strs[sid],
+			 field_type_strs[setting->field_type]);
+		goto abort_due_to_error;
+	}
+	p->nChange++;
+	break;
+}
+
 /* Opcode: Noop * * * * *
  *
  * Do nothing.  This instruction is often useful as a jump
diff --git a/test/box/session_settings.result b/test/box/session_settings.result
index b32a0becb..28c79379b 100644
--- a/test/box/session_settings.result
+++ b/test/box/session_settings.result
@@ -339,6 +339,39 @@ settings.sql_defer_foreign_keys
  | - false
  | ...
 
+box.execute([[setting set "sql_default_engine" = 'vinyl']])
+ | ---
+ | - row_count: 1
+ | ...
+s:get('sql_default_engine').value
+ | ---
+ | - vinyl
+ | ...
+box.execute([[setting set "sql_default_engine" = 'memtx']])
+ | ---
+ | - row_count: 1
+ | ...
+s:get('sql_default_engine').value
+ | ---
+ | - memtx
+ | ...
+box.execute([[setting set "sql_defer_foreign_keys" = true]])
+ | ---
+ | - row_count: 1
+ | ...
+s:get('sql_defer_foreign_keys').value
+ | ---
+ | - true
+ | ...
+box.execute([[setting set "sql_defer_foreign_keys" = ?]], {false})
+ | ---
+ | - row_count: 1
+ | ...
+s:get('sql_defer_foreign_keys').value
+ | ---
+ | - false
+ | ...
+
 settings.sql_default_engine = true
  | ---
  | - error: Session setting sql_default_engine expected a value of type string
@@ -359,3 +392,19 @@ box.session.settings.sql_default_engine = str
  | ---
  | - error: Failed to allocate 20483 bytes in static_alloc for mp_value
  | ...
+
+box.execute([[setting set "sql_def_engine" = true]])
+ | ---
+ | - null
+ | - Session setting sql_def_engine doesn't exist
+ | ...
+box.execute([[setting set "sql_default_engine" = true]])
+ | ---
+ | - null
+ | - Session setting sql_default_engine expected a value of type string
+ | ...
+box.execute([[setting set "sql_defer_foreign_keys" = 'true']])
+ | ---
+ | - null
+ | - Session setting sql_defer_foreign_keys expected a value of type boolean
+ | ...
diff --git a/test/box/session_settings.test.lua b/test/box/session_settings.test.lua
index 440bef7ce..c477139f9 100644
--- a/test/box/session_settings.test.lua
+++ b/test/box/session_settings.test.lua
@@ -132,9 +132,22 @@ s:get('sql_defer_foreign_keys').value
 s:update('sql_defer_foreign_keys', {{'=', 2, false}})
 settings.sql_defer_foreign_keys
 
+box.execute([[setting set "sql_default_engine" = 'vinyl']])
+s:get('sql_default_engine').value
+box.execute([[setting set "sql_default_engine" = 'memtx']])
+s:get('sql_default_engine').value
+box.execute([[setting set "sql_defer_foreign_keys" = true]])
+s:get('sql_defer_foreign_keys').value
+box.execute([[setting set "sql_defer_foreign_keys" = ?]], {false})
+s:get('sql_defer_foreign_keys').value
+
 settings.sql_default_engine = true
 settings.sql_defer_foreign_keys = 'false'
 settings.sql_parser_debug = 'string'
 
 str = string.rep('a', 20 * 1024)
 box.session.settings.sql_default_engine = str
+
+box.execute([[setting set "sql_def_engine" = true]])
+box.execute([[setting set "sql_default_engine" = true]])
+box.execute([[setting set "sql_defer_foreign_keys" = 'true']])
-- 
2.21.1 (Apple Git-122.3)

Re: [Tarantool-patches] [PATCH 0/4] session settings fixes

[Timur Safin]

I'm late here on this party, but I very much dislike proposed syntax of

	SETTING SET configuration_name = value;

It feels not SQL-ish, and I see no much value introducing new statement 
while there is still SET statement available. 

Why we could not simply use something like:
	SET box.session.settings.name = value;
?

Thanks,
Timur


: -----Original Message-----
: From: Tarantool-patches <tarantool-patches-bounces@dev.tarantool.org> On
: Behalf Of Chris Sosnin
: Sent: Monday, March 30, 2020 12:14 PM
: To: v.shpilevoy@tarantool.org; korablev@tarantool.org; tarantool-
: patches@dev.tarantool.org
: Subject: [Tarantool-patches] [PATCH 0/4] session settings fixes
: 
: issue #1:https://github.com/tarantool/tarantool/issues/4711
: issue #2:https://github.com/tarantool/tarantool/issues/4712
: branch:https://github.com/tarantool/tarantool/tree/ksosnin/gh-4712-
: session-settings-v2
: 
: Chris Sosnin (4):
:   box: replace session_settings modules with a single array
:   box: add binary search for _session_settings space
:   box: provide a user friendly frontend for accessing session settings
:   sql: provide a user friendly frontend for accessing session settings
: 
:  extra/mkkeywordhash.c                         |   1 +
:  src/box/lua/session.c                         | 111 +++++++++
:  src/box/session.cc                            |   1 +
:  src/box/session.h                             |   2 +
:  src/box/session_settings.c                    | 214 +++++++++++-------
:  src/box/session_settings.h                    |  53 +++--
:  src/box/sql.c                                 |   5 -
:  src/box/sql/build.c                           | 104 ++++-----
:  src/box/sql/parse.y                           |   5 +
:  src/box/sql/sqlInt.h                          |  11 +
:  src/box/sql/vdbe.c                            |  50 ++++
:  ...rontend.result => session_settings.result} | 147 ++++++++++--
:  ...end.test.lua => session_settings.test.lua} |  61 ++++-
:  13 files changed, 589 insertions(+), 176 deletions(-)
:  rename test/box/{gh-4511-access-settings-from-any-frontend.result =>
: session_settings.result} (71%)
:  rename test/box/{gh-4511-access-settings-from-any-frontend.test.lua =>
: session_settings.test.lua} (64%)
: 
: --
: 2.21.1 (Apple Git-122.3)

Re: [Tarantool-patches] [PATCH 0/4] session settings fixes

[Chris Sosnin]

> On 2 Apr 2020, at 12:14, Timur Safin <tsafin@tarantool.org> wrote:
> 
> I'm late here on this party, but I very much dislike proposed syntax of
> 
> 	SETTING SET configuration_name = value;
> 
> It feels not SQL-ish, and I see no much value introducing new statement 
> while there is still SET statement available. 
> 
> Why we could not simply use something like:
> 	SET box.session.settings.name = value;
> ?
> 
> Thanks,
> Timur

It was SET <setting_name> = <new_value> in the first version.

However, we agreed on this syntax being too generic for configuring
session settings, so I added SETTING keyword.

> 
> 
> : -----Original Message-----
> : From: Tarantool-patches <tarantool-patches-bounces@dev.tarantool.org> On
> : Behalf Of Chris Sosnin
> : Sent: Monday, March 30, 2020 12:14 PM
> : To: v.shpilevoy@tarantool.org; korablev@tarantool.org; tarantool-
> : patches@dev.tarantool.org
> : Subject: [Tarantool-patches] [PATCH 0/4] session settings fixes
> : 
> : issue #1:https://github.com/tarantool/tarantool/issues/4711
> : issue #2:https://github.com/tarantool/tarantool/issues/4712
> : branch:https://github.com/tarantool/tarantool/tree/ksosnin/gh-4712-
> : session-settings-v2
> : 
> : Chris Sosnin (4):
> :   box: replace session_settings modules with a single array
> :   box: add binary search for _session_settings space
> :   box: provide a user friendly frontend for accessing session settings
> :   sql: provide a user friendly frontend for accessing session settings
> : 
> :  extra/mkkeywordhash.c                         |   1 +
> :  src/box/lua/session.c                         | 111 +++++++++
> :  src/box/session.cc                            |   1 +
> :  src/box/session.h                             |   2 +
> :  src/box/session_settings.c                    | 214 +++++++++++-------
> :  src/box/session_settings.h                    |  53 +++--
> :  src/box/sql.c                                 |   5 -
> :  src/box/sql/build.c                           | 104 ++++-----
> :  src/box/sql/parse.y                           |   5 +
> :  src/box/sql/sqlInt.h                          |  11 +
> :  src/box/sql/vdbe.c                            |  50 ++++
> :  ...rontend.result => session_settings.result} | 147 ++++++++++--
> :  ...end.test.lua => session_settings.test.lua} |  61 ++++-
> :  13 files changed, 589 insertions(+), 176 deletions(-)
> :  rename test/box/{gh-4511-access-settings-from-any-frontend.result =>
> : session_settings.result} (71%)
> :  rename test/box/{gh-4511-access-settings-from-any-frontend.test.lua =>
> : session_settings.test.lua} (64%)
> : 
> : --
> : 2.21.1 (Apple Git-122.3)
> 
> 

Re: [Tarantool-patches] [PATCH 0/4] session settings fixes

[Nikita Pettik]

On 02 Apr 12:14, Timur Safin wrote:
> I'm late here on this party, but I very much dislike proposed syntax of

Patch is not merged, so it's still okay to suggest changes.

> 	SETTING SET configuration_name = value;
> 
> It feels not SQL-ish, and I see no much value introducing new statement 
> while there is still SET statement available. 

SET is not available as a separated statements; it's only a part
of UPDATE statements syntax. Rolling it back (SETTING SET -> SET)
is not a big deal - only one line of parse.y requires patching.

As I already said, I'm okay with all variations, whether it is
SET, SET SETTING or SETTING SET.
 
> Why we could not simply use something like:
> 	SET box.session.settings.name = value;

box.session.settings -- too long prefix. Originally, SET was
suggested as a shortcat for normal UPDATE "_session_settings" ...
SQL statement. Since it is shortcat, let's keep it short.

> ?
> 
> Thanks,
> Timur
> 

Re: [Tarantool-patches] [PATCH 0/4] session settings fixes

[Nikita Pettik]

On 30 Mar 12:13, Chris Sosnin wrote:
> issue #1:https://github.com/tarantool/tarantool/issues/4711
> issue #2:https://github.com/tarantool/tarantool/issues/4712
> branch:https://github.com/tarantool/tarantool/tree/ksosnin/gh-4712-session-settings-v2

Nit: while sending next version of patch-set please specify it
explicitly with --subject-prefix='PATCH v2' and attach changelog
between versions. For example: https://lists.tarantool.org/pipermail/tarantool-patches/2020-March/015103.html
 
> Chris Sosnin (4):
>   box: replace session_settings modules with a single array
>   box: add binary search for _session_settings space
>   box: provide a user friendly frontend for accessing session settings
>   sql: provide a user friendly frontend for accessing session settings
> 
>  extra/mkkeywordhash.c                         |   1 +
>  src/box/lua/session.c                         | 111 +++++++++
>  src/box/session.cc                            |   1 +
>  src/box/session.h                             |   2 +
>  src/box/session_settings.c                    | 214 +++++++++++-------
>  src/box/session_settings.h                    |  53 +++--
>  src/box/sql.c                                 |   5 -
>  src/box/sql/build.c                           | 104 ++++-----
>  src/box/sql/parse.y                           |   5 +
>  src/box/sql/sqlInt.h                          |  11 +
>  src/box/sql/vdbe.c                            |  50 ++++
>  ...rontend.result => session_settings.result} | 147 ++++++++++--
>  ...end.test.lua => session_settings.test.lua} |  61 ++++-
>  13 files changed, 589 insertions(+), 176 deletions(-)
>  rename test/box/{gh-4511-access-settings-from-any-frontend.result => session_settings.result} (71%)
>  rename test/box/{gh-4511-access-settings-from-any-frontend.test.lua => session_settings.test.lua} (64%)
> 
> -- 
> 2.21.1 (Apple Git-122.3)
> 

Re: [Tarantool-patches] [PATCH 1/4] box: replace session_settings modules with a single array

[Nikita Pettik]

On 30 Mar 12:13, Chris Sosnin wrote:
> Currently we have an array of modules and each module has
> its own array of session_settings. This patch merges these
> into one array, as long as it turned out, that we cannot
> represent every setting as a part of some module. This
> change is also needed for implementing binary search for
> _session_settings space.
> 
> Part of #4711, #4712

LGTM

Re: [Tarantool-patches] [PATCH 2/4] box: add binary search for _session_settings space

[Nikita Pettik]

On 30 Mar 12:13, Chris Sosnin wrote:
> As it is mentioned in implementation, it is important
> that _session_settings options are sorted by name, so
> there is no need in linear lookup and we can replace it
> with binary search.
> 
> Closes #4712
> ---

Still I see no need for this patch. It is unclear which improvements
it introduces except for code complication.
 
> diff --git a/src/box/session_settings.c b/src/box/session_settings.c
> index 2ecf71f2d..5e4a50427 100644
> --- a/src/box/session_settings.c
> +++ b/src/box/session_settings.c
> @@ -81,6 +81,8 @@ struct session_settings_iterator {
>  	bool is_eq;
>  	/** True if the iterator should include equal keys. */
>  	bool is_including;
> +	/** True if the iterator is pointing to an existing setting */
> +	bool is_set;
>  };
>  
>  static void
> @@ -92,6 +94,72 @@ session_settings_iterator_free(struct iterator *ptr)
>  	free(it);
>  }
>  
> +static int
> +session_settings_set_forward(int *sid, const char *key, bool is_eq,
> +			     bool is_including)
> +{
> +	int low = 0, high = SESSION_SETTING_COUNT - 1;
> +	if (key == NULL)
> +		return 0;
> +	while (low <= high) {
> +		int index = (high + low) / 2;
> +		const char *name = session_setting_strs[index];
> +		int cmp = strcmp(name, key);
> +		if (cmp == 0) {
> +			if (is_including) {
> +				*sid = index;
> +				return 0;
> +			}
> +			*sid = ++index;
> +			return index < SESSION_SETTING_COUNT ? 0 : -1;
> +		}
> +		if (cmp < 0)
> +			low = index + 1;
> +		else
> +			high = index - 1;
> +	}
> +	if (is_eq) {
> +		*sid = SESSION_SETTING_COUNT;
> +		return -1;
> +	}
> +	assert(low > high);
> +	*sid = low;
> +	return low < SESSION_SETTING_COUNT ? 0 : -1;
> +}
> +
> +static int
> +session_settings_set_reverse(int *sid, const char *key, bool is_eq,
> +			     bool is_including)
> +{
> +	int low = 0, high = SESSION_SETTING_COUNT - 1;
> +	if (key == NULL)
> +		return 0;
> +	while (low <= high) {
> +		int index = (high + low) / 2;
> +		const char *name = session_setting_strs[index];
> +		int cmp = strcmp(name, key);
> +		if (cmp == 0) {
> +			if (is_including) {
> +				*sid = index;
> +				return 0;
> +			}
> +			*sid = --index;
> +			return index >= 0 ? 0 : -1;
> +		}
> +		if (cmp < 0)
> +			low = index + 1;
> +		else
> +			high = index - 1;
> +	}
> +	if (is_eq) {
> +		*sid = SESSION_SETTING_COUNT;
> +		return -1;
> +	}
> +	assert(low > high);
> +	*sid = high;
> +	return high >= 0 ? 0 : -1;
> +}
> +
>  static int
>  session_settings_next(int *sid, const char *key, bool is_eq, bool is_including)
>  {
> @@ -145,9 +213,15 @@ session_settings_iterator_next(struct iterator *iterator, struct tuple **result)
>  	int sid = it->setting_id;
>  	const char *key = it->key;
>  	bool is_including = it->is_including, is_eq = it->is_eq;
> -	bool is_found = false;
> -	if (session_settings_next(&sid, key, is_eq, is_including) == 0)
> -		is_found = true;
> +	bool is_found;
> +	if (!it->is_set) {
> +		it->is_set = true;
> +		is_found = session_settings_set_forward(&sid, key, is_eq,
> +							is_including) == 0;
> +	} else {
> +		is_found = session_settings_next(&sid, key, is_eq,
> +						 is_including) == 0;
> +	}
>  	it->setting_id = sid + 1;
>  	if (!is_found) {
>  		*result = NULL;
> @@ -167,9 +241,15 @@ session_settings_iterator_prev(struct iterator *iterator, struct tuple **result)
>  	int sid = it->setting_id;
>  	const char *key = it->key;
>  	bool is_including = it->is_including, is_eq = it->is_eq;
> -	bool is_found = false;
> -	if (session_settings_prev(&sid, key, is_eq, is_including) == 0)
> -		is_found = true;
> +	bool is_found;
> +	if (!it->is_set) {
> +		it->is_set = true;
> +		is_found = session_settings_set_reverse(&sid, key, is_eq,
> +							is_including) == 0;
> +	} else {
> +		is_found = session_settings_prev(&sid, key, is_eq,
> +						 is_including) == 0;
> +	}
>  	it->setting_id = sid - 1;
>  	if (!is_found) {
>  		*result = NULL;
> @@ -221,6 +301,7 @@ session_settings_index_create_iterator(struct index *base,
>  	it->is_eq = type == ITER_EQ || type == ITER_REQ;
>  	it->is_including = it->is_eq || type == ITER_GE || type == ITER_ALL ||
>  			   type == ITER_LE;
> +	it->is_set = false;
>  	it->format = index->format;
>  	if (!iterator_type_is_reverse(type)) {
>  		it->base.next = session_settings_iterator_next;
> @@ -244,7 +325,7 @@ session_settings_index_get(struct index *base, const char *key,
>  	key = mp_decode_str(&key, &len);
>  	key = tt_cstr(key, len);
>  	int sid = 0;
> -	if (session_settings_next(&sid, key, true, true) != 0) {
> +	if (session_settings_set_forward(&sid, key, true, true) != 0) {
>  		*result = NULL;
>  		return 0;
>  	}
> @@ -345,7 +426,7 @@ session_settings_space_execute_update(struct space *space, struct txn *txn,
>  	}
>  	key = mp_decode_str(&key, &key_len);
>  	key = tt_cstr(key, key_len);
> -	if (session_settings_next(&sid, key, true, true) != 0) {
> +	if (session_settings_set_forward(&sid, key, true, true) != 0) {
>  		*result = NULL;
>  		return 0;
>  	}
> diff --git a/test/box/gh-4511-access-settings-from-any-frontend.result b/test/box/gh-4511-access-settings-from-any-frontend.result
> index ed340d053..bae77192e 100644
> --- a/test/box/gh-4511-access-settings-from-any-frontend.result
> +++ b/test/box/gh-4511-access-settings-from-any-frontend.result
> @@ -82,6 +82,12 @@ function check_sorting(ss, ts, key)
>      for _, it in pairs(iterators_list) do
>          local view_space = ss:select({key}, {iterator = it})
>          local test_space = ts:select({key}, {iterator = it})
> +        if #view_space ~= #test_space then
> +            return {
> +                err = 'bad sorting', type = it, exp = test_space,
> +                got = view_space
> +            }
> +        end
>          for key, value in pairs(view_space) do
>              if test_space[key].name ~= value.name then
>                  return {
> @@ -111,32 +117,37 @@ check_sorting(s, t, 'sql_d')
>  check_sorting(s, t, 'sql_v')
>   | ---
>   | ...
> -check_sorting(s, t, 'sql_defer_foreign_keys')
> +check_sorting(s, t, 'z')
>   | ---
>   | ...
> -
> -t:drop()
> +check_sorting(s, t, 'sql_parser_debuf')
> + | ---
> + | ...
> +check_sorting(s, t, 'sql_parser_debuh')
>   | ---
>   | ...
>  
> --- Check get() method of session_settings space.
> -s:get({'sql_defer_foreign_keys'})
> +name = nil
>   | ---
> - | - ['sql_defer_foreign_keys', false]
>   | ...
> -s:get({'sql_recursive_triggers'})
> +err = nil
>   | ---
> - | - ['sql_recursive_triggers', true]
>   | ...
> -s:get({'sql_reverse_unordered_selects'})
> +for _, tuple in t:pairs() do                    \
> +    name = tuple.name                           \
> +    err = check_sorting(s, t, name)             \
> +    if err then                                 \
> +        break                                   \
> +    end                                         \
> +end
>   | ---
> - | - ['sql_reverse_unordered_selects', false]
>   | ...
> -s:get({'sql_default_engine'})
> +err and {err, name}
>   | ---
> - | - ['sql_default_engine', 'memtx']
> + | - null
>   | ...
> -s:get({'abcd'})
> +
> +t:drop()
>   | ---
>   | ...
>  
> diff --git a/test/box/gh-4511-access-settings-from-any-frontend.test.lua b/test/box/gh-4511-access-settings-from-any-frontend.test.lua
> index 366874998..b243be15e 100644
> --- a/test/box/gh-4511-access-settings-from-any-frontend.test.lua
> +++ b/test/box/gh-4511-access-settings-from-any-frontend.test.lua
> @@ -36,6 +36,12 @@ function check_sorting(ss, ts, key)
>      for _, it in pairs(iterators_list) do
>          local view_space = ss:select({key}, {iterator = it})
>          local test_space = ts:select({key}, {iterator = it})
> +        if #view_space ~= #test_space then
> +            return {
> +                err = 'bad sorting', type = it, exp = test_space,
> +                got = view_space
> +            }
> +        end
>          for key, value in pairs(view_space) do
>              if test_space[key].name ~= value.name then
>                  return {
> @@ -52,17 +58,23 @@ check_sorting(s, t)
>  check_sorting(s, t, 'abcde')
>  check_sorting(s, t, 'sql_d')
>  check_sorting(s, t, 'sql_v')
> -check_sorting(s, t, 'sql_defer_foreign_keys')
> +check_sorting(s, t, 'z')
> +check_sorting(s, t, 'sql_parser_debuf')
> +check_sorting(s, t, 'sql_parser_debuh')
> +
> +name = nil
> +err = nil
> +for _, tuple in t:pairs() do                    \
> +    name = tuple.name                           \
> +    err = check_sorting(s, t, name)             \
> +    if err then                                 \
> +        break                                   \
> +    end                                         \
> +end
> +err and {err, name}
>  
>  t:drop()
>  
> --- Check get() method of session_settings space.
> -s:get({'sql_defer_foreign_keys'})
> -s:get({'sql_recursive_triggers'})
> -s:get({'sql_reverse_unordered_selects'})
> -s:get({'sql_default_engine'})
> -s:get({'abcd'})
> -
>  -- Check pairs() method of session_settings space.
>  t = {}
>  for key, value in s:pairs() do table.insert(t, {key, value}) end
> -- 
> 2.21.1 (Apple Git-122.3)
> 

Re: [Tarantool-patches] [PATCH 0/4] session settings fixes

[Chris Sosnin]

It was v2, Vlad asked me to resend the whole patchset for 
convenience. Won’t forget to do this next time.

> On 3 Apr 2020, at 16:09, Nikita Pettik <korablev@tarantool.org> wrote:
> 
> On 30 Mar 12:13, Chris Sosnin wrote:
>> issue #1:https://github.com/tarantool/tarantool/issues/4711
>> issue #2:https://github.com/tarantool/tarantool/issues/4712
>> branch:https://github.com/tarantool/tarantool/tree/ksosnin/gh-4712-session-settings-v2
> 
> Nit: while sending next version of patch-set please specify it
> explicitly with --subject-prefix='PATCH v2' and attach changelog
> between versions. For example: https://lists.tarantool.org/pipermail/tarantool-patches/2020-March/015103.html
> 
>> Chris Sosnin (4):
>>  box: replace session_settings modules with a single array
>>  box: add binary search for _session_settings space
>>  box: provide a user friendly frontend for accessing session settings
>>  sql: provide a user friendly frontend for accessing session settings
>> 
>> extra/mkkeywordhash.c                         |   1 +
>> src/box/lua/session.c                         | 111 +++++++++
>> src/box/session.cc                            |   1 +
>> src/box/session.h                             |   2 +
>> src/box/session_settings.c                    | 214 +++++++++++-------
>> src/box/session_settings.h                    |  53 +++--
>> src/box/sql.c                                 |   5 -
>> src/box/sql/build.c                           | 104 ++++-----
>> src/box/sql/parse.y                           |   5 +
>> src/box/sql/sqlInt.h                          |  11 +
>> src/box/sql/vdbe.c                            |  50 ++++
>> ...rontend.result => session_settings.result} | 147 ++++++++++--
>> ...end.test.lua => session_settings.test.lua} |  61 ++++-
>> 13 files changed, 589 insertions(+), 176 deletions(-)
>> rename test/box/{gh-4511-access-settings-from-any-frontend.result => session_settings.result} (71%)
>> rename test/box/{gh-4511-access-settings-from-any-frontend.test.lua => session_settings.test.lua} (64%)
>> 
>> -- 
>> 2.21.1 (Apple Git-122.3)
>> 

Re: [Tarantool-patches] [PATCH 3/4] box: provide a user friendly frontend for accessing session settings

[Nikita Pettik]

On 30 Mar 12:13, Chris Sosnin wrote:
> - space_object:update() is hard to use for configuring session settings,
> so we provide box.session.settings table, which can be used in a much more
> native way.
> 
> - Prior to this patch sql settings were not accessible before box.cfg()
> call, even though these flags can be set right after session creation.
> 
> Part of #4711
> ---

LGTM

Re: [Tarantool-patches] [PATCH 4/4] sql: provide a user friendly frontend for accessing session settings

[Nikita Pettik]

On 30 Mar 12:13, Chris Sosnin wrote:
> diff --git a/src/box/sql/build.c b/src/box/sql/build.c
> index a00da31f9..cdcf8b6d8 100644
> --- a/src/box/sql/build.c
> +++ b/src/box/sql/build.c
> @@ -3481,3 +3481,28 @@ sql_session_settings_init()
>  		setting->set = sql_session_setting_set;
>  	}
>  }
> +
> +void
> +sql_setting_set(struct Parse *parse_context, struct Token *name,
> +		struct Expr *expr)
> +{
> +	struct Vdbe *vdbe = sqlGetVdbe(parse_context);
> +	if (vdbe == NULL)
> +		goto abort;
> +	sqlVdbeCountChanges(vdbe);
> +	char *key = sql_name_from_token(parse_context->db, name);
> +	if (key == NULL)
> +		goto abort;
> +	int index = session_setting_find(key);
> +	if (index >= 0) {
> +		int target = ++parse_context->nMem;
> +		sqlExprCode(parse_context, expr, target);
> +		sqlVdbeAddOp2(vdbe, OP_SetSetting, index, target);
> +		return;
> +	}
> +	diag_set(ClientError, ER_SQL_PARSER_GENERIC,
> +		 tt_sprintf("Session setting %s doesn't exist", key));

Mb it is worth moving this check to runtime? I.e. pass to OP_SetSetting
name of setting to be set. The less appeals to system spaces and
cache look ups are made, the better parsing process is organized.

The rest is ok.

Re: [Tarantool-patches] [PATCH 4/4] sql: provide a user friendly frontend for accessing session settings

[Vladislav Shpilevoy]

Hi! Thanks for the patch!

> diff --git a/src/box/sql/build.c b/src/box/sql/build.c
> index a00da31f9..cdcf8b6d8 100644
> --- a/src/box/sql/build.c
> +++ b/src/box/sql/build.c
> @@ -3481,3 +3481,28 @@ sql_session_settings_init()
>  		setting->set = sql_session_setting_set;
>  	}
>  }
> +
> +void
> +sql_setting_set(struct Parse *parse_context, struct Token *name,
> +		struct Expr *expr)
> +{
> +	struct Vdbe *vdbe = sqlGetVdbe(parse_context);
> +	if (vdbe == NULL)
> +		goto abort;
> +	sqlVdbeCountChanges(vdbe);
> +	char *key = sql_name_from_token(parse_context->db, name);
> +	if (key == NULL)
> +		goto abort;
> +	int index = session_setting_find(key);

I agree with Nikita. Better make this call part of OP_SetSetting.

> +	if (index >= 0) {
> +		int target = ++parse_context->nMem;
> +		sqlExprCode(parse_context, expr, target);
> +		sqlVdbeAddOp2(vdbe, OP_SetSetting, index, target);
> +		return;
> +	}
> +	diag_set(ClientError, ER_SQL_PARSER_GENERIC,
> +		 tt_sprintf("Session setting %s doesn't exist", key));
> +abort:
> +	parse_context->is_aborted = true;
> +	return;
> +}

Talking of the syntax, I don't have a strong opinion here
regarding any particular option. I only want the new statement
be short, and not involving _session_settings manipulations.

Re: [Tarantool-patches] [PATCH 4/4] sql: provide a user friendly frontend for accessing session settings

[Chris Sosnin]

> > diff --git a/src/box/sql/build.c b/src/box/sql/build.c
> > index a00da31f9..cdcf8b6d8 100644
> > --- a/src/box/sql/build.c
> > +++ b/src/box/sql/build.c
> > @@ -3481,3 +3481,28 @@ sql_session_settings_init()
> >  		setting->set = sql_session_setting_set;
> >  	}
> >  }
> > +
> > +void
> > +sql_setting_set(struct Parse *parse_context, struct Token *name,
> > +		struct Expr *expr)
> > +{
> > +	struct Vdbe *vdbe = sqlGetVdbe(parse_context);
> > +	if (vdbe == NULL)
> > +		goto abort;
> > +	sqlVdbeCountChanges(vdbe);
> > +	char *key = sql_name_from_token(parse_context->db, name);
> > +	if (key == NULL)
> > +		goto abort;
> > +	int index = session_setting_find(key);
> 
> I agree with Nikita. Better make this call part of OP_SetSetting.

I agree, fixed:

+
+void
+sql_setting_set(struct Parse *parse_context, struct Token *name,
+		struct Expr *expr)
+{
+	struct Vdbe *vdbe = sqlGetVdbe(parse_context);
+	if (vdbe == NULL)
+		goto abort;
+	sqlVdbeCountChanges(vdbe);
+	char *key = sql_name_from_token(parse_context->db, name);
+	if (key == NULL)
+		goto abort;
+	int target = ++parse_context->nMem;
+	sqlExprCode(parse_context, expr, target);
+	sqlVdbeAddOp4(vdbe, OP_SetSession, target, 0, 0, key, P4_DYNAMIC);
+	return;
+abort:
+	parse_context->is_aborted = true;
+	return;
+}


+/* Opcode: SetSession P1 * * P4 *
+ *
+ * Set new value of the session setting. P4 is the name of the
+ * setting being updated, P1 is the register holding a value.
+ */
+case OP_SetSession: {
+	assert(pOp->p4type == P4_DYNAMIC);
+	const char *setting_name = pOp->p4.z;
+	int sid = session_setting_find(setting_name);
+	if (sid < 0) {
+		diag_set(ClientError, ER_NO_SUCH_SESSION_SETTING, setting_name);
+		goto abort_due_to_error;
+	}
+	pIn1 = &aMem[pOp->p1];
...

> Talking of the syntax, I don't have a strong opinion here
> regarding any particular option. I only want the new statement
> be short, and not involving _session_settings manipulations.

I changed it to the following (the main problem with reserved word persists):

+///////////////////////////// The SET SESSION command ////////////////////////
+//
+cmd ::= SET SESSION nm(X) EQ term(Y).  {
+    sql_setting_set(pParse,&X,Y.pExpr);
+}
+

I also changed the 3rd commit (Lua frontend) in the series to introduce new error
code (it's present in the diff above):

+       /*213 */_(ER_NO_SUCH_SESSION_SETTING,   "Session setting %s doesn't exist") \

as long as searching is moved to vdbe.c and raising parsing error is not correct.

You can see the whole patch below:

===============================================================================

Currently if a user wants to change session setting with SQL, one has
to execute UPDATE query like:
[[UPDATE "_session_settings" SET "value" = true WHERE "name" = 'name']]
However, direct access to system spaces isn't considered to be a good practice.
To avoid that and a bit simplify user's life, we introduce SQL shortcut command
SET SESSION.

Closes #4711

@TarantoolBot document
Title: API for accessing _session_settings space.
There are two ways of updating values of session settings:
via Lua and SQL.

Lua:
box.session.settings is a table, which is always accessible
to user. The syntax is the following:
`box.session.settings.<setting_name> = <new_value>`.

Example of usage:
```
tarantool> box.session.settings.sql_default_engine
---
- memtx
...

tarantool> box.session.settings.sql_default_engine = 'vinyl'
---
...

```

The table itself represents the (unordered) result of select
from _session_settings space.

SQL:
Instead of typing long UPDATE query one can use the SET SESSION command:
`box.execute([[SET SESSION "<setting_name>" = <new_value>]])`.
Note, that this query is case sensitive so the name must be quoted.
Also, SET SESSION doesn't provide any implicit casts, so <new_value> must
be of the type corresponding to the setting being updated.

Example:
```
tarantool> box.execute([[set session "sql_default_engine" = 'memtx']])
---
- row_count: 1
...

tarantool> box.execute([[set session "sql_defer_foreign_keys" = true]])
---
- row_count: 1
...

```
---
 extra/mkkeywordhash.c              |  1 +
 src/box/sql/build.c                | 20 +++++++++++
 src/box/sql/parse.y                |  6 ++++
 src/box/sql/sqlInt.h               | 11 ++++++
 src/box/sql/vdbe.c                 | 54 ++++++++++++++++++++++++++++++
 test/box/session_settings.result   | 49 +++++++++++++++++++++++++++
 test/box/session_settings.test.lua | 13 +++++++
 7 files changed, 154 insertions(+)

diff --git a/extra/mkkeywordhash.c b/extra/mkkeywordhash.c
index 006285622..dd42c8f5f 100644
--- a/extra/mkkeywordhash.c
+++ b/extra/mkkeywordhash.c
@@ -158,6 +158,7 @@ static Keyword aKeywordTable[] = {
   { "SAVEPOINT",              "TK_SAVEPOINT",   true  },
   { "SCALAR",                 "TK_SCALAR",      true  },
   { "SELECT",                 "TK_SELECT",      true  },
+  { "SESSION",                "TK_SESSION",     false },
   { "SET",                    "TK_SET",         true  },
   { "SIMPLE",                 "TK_SIMPLE",      true  },
   { "START",                  "TK_START",       true  },
diff --git a/src/box/sql/build.c b/src/box/sql/build.c
index a00da31f9..aecba4177 100644
--- a/src/box/sql/build.c
+++ b/src/box/sql/build.c
@@ -3481,3 +3481,23 @@ sql_session_settings_init()
 		setting->set = sql_session_setting_set;
 	}
 }
+
+void
+sql_setting_set(struct Parse *parse_context, struct Token *name,
+		struct Expr *expr)
+{
+	struct Vdbe *vdbe = sqlGetVdbe(parse_context);
+	if (vdbe == NULL)
+		goto abort;
+	sqlVdbeCountChanges(vdbe);
+	char *key = sql_name_from_token(parse_context->db, name);
+	if (key == NULL)
+		goto abort;
+	int target = ++parse_context->nMem;
+	sqlExprCode(parse_context, expr, target);
+	sqlVdbeAddOp4(vdbe, OP_SetSession, target, 0, 0, key, P4_DYNAMIC);
+	return;
+abort:
+	parse_context->is_aborted = true;
+	return;
+}
diff --git a/src/box/sql/parse.y b/src/box/sql/parse.y
index 1a0e89703..995875566 100644
--- a/src/box/sql/parse.y
+++ b/src/box/sql/parse.y
@@ -1541,6 +1541,12 @@ cmd ::= DROP INDEX ifexists(E) nm(X) ON fullname(Y).   {
   sql_drop_index(pParse);
 }
 
+///////////////////////////// The SET SESSION command ////////////////////////
+//
+cmd ::= SET SESSION nm(X) EQ term(Y).  {
+    sql_setting_set(pParse,&X,Y.pExpr);
+}
+
 ///////////////////////////// The PRAGMA command /////////////////////////////
 //
 cmd ::= PRAGMA nm(X).                        {
diff --git a/src/box/sql/sqlInt.h b/src/box/sql/sqlInt.h
index 2d6bad424..e45a7671d 100644
--- a/src/box/sql/sqlInt.h
+++ b/src/box/sql/sqlInt.h
@@ -4517,4 +4517,15 @@ int
 sql_fieldno_by_name(struct Parse *parse_context, struct Expr *field_name,
 		    uint32_t *fieldno);
 
+/**
+ * Create VDBE instructions to set the new value of the session setting.
+ *
+ * @param parse_context Parsing context.
+ * @param name Name of the session setting.
+ * @param value New value of the session setting.
+ */
+void
+sql_setting_set(struct Parse *parse_context, struct Token *name,
+		struct Expr *value);
+
 #endif				/* sqlINT_H */
diff --git a/src/box/sql/vdbe.c b/src/box/sql/vdbe.c
index e8a029a8a..c3256c15a 100644
--- a/src/box/sql/vdbe.c
+++ b/src/box/sql/vdbe.c
@@ -55,6 +55,7 @@
 #include "box/schema.h"
 #include "box/space.h"
 #include "box/sequence.h"
+#include "box/session_settings.h"
 
 /*
  * Invoke this macro on memory cells just prior to changing the
@@ -5252,6 +5253,59 @@ case OP_IncMaxid: {
 	break;
 }
 
+/* Opcode: SetSession P1 * * P4 *
+ *
+ * Set new value of the session setting. P4 is the name of the
+ * setting being updated, P1 is the register holding a value.
+ */
+case OP_SetSession: {
+	assert(pOp->p4type == P4_DYNAMIC);
+	const char *setting_name = pOp->p4.z;
+	int sid = session_setting_find(setting_name);
+	if (sid < 0) {
+		diag_set(ClientError, ER_NO_SUCH_SESSION_SETTING, setting_name);
+		goto abort_due_to_error;
+	}
+	pIn1 = &aMem[pOp->p1];
+	struct session_setting *setting = &session_settings[sid];
+	switch (setting->field_type) {
+	case FIELD_TYPE_BOOLEAN: {
+		if ((pIn1->flags & MEM_Bool) == 0)
+			goto invalid_type;
+		bool value = pIn1->u.b;
+		size_t size = mp_sizeof_bool(value);
+		char *mp_value = (char *) static_alloc(size);
+		mp_encode_bool(mp_value, value);
+		if (setting->set(sid, mp_value) != 0)
+			goto abort_due_to_error;
+		break;
+	}
+	case FIELD_TYPE_STRING: {
+		if ((pIn1->flags & MEM_Str) == 0)
+			goto invalid_type;
+		const char *str = pIn1->z;
+		uint32_t size = mp_sizeof_str(pIn1->n);
+		char *mp_value = (char *) static_alloc(size);
+		if (mp_value == NULL) {
+			diag_set(OutOfMemory, size, "static_alloc", "mp_value");
+			goto abort_due_to_error;
+		}
+		mp_encode_str(mp_value, str, pIn1->n);
+		if (setting->set(sid, mp_value) != 0)
+			goto abort_due_to_error;
+		break;
+	}
+	default:
+	invalid_type:
+		diag_set(ClientError, ER_SESSION_SETTING_INVALID_VALUE,
+			 session_setting_strs[sid],
+			 field_type_strs[setting->field_type]);
+		goto abort_due_to_error;
+	}
+	p->nChange++;
+	break;
+}
+
 /* Opcode: Noop * * * * *
  *
  * Do nothing.  This instruction is often useful as a jump
diff --git a/test/box/session_settings.result b/test/box/session_settings.result
index b32a0becb..b82bdda94 100644
--- a/test/box/session_settings.result
+++ b/test/box/session_settings.result
@@ -339,6 +339,39 @@ settings.sql_defer_foreign_keys
  | - false
  | ...
 
+box.execute([[set session "sql_default_engine" = 'vinyl']])
+ | ---
+ | - row_count: 1
+ | ...
+s:get('sql_default_engine').value
+ | ---
+ | - vinyl
+ | ...
+box.execute([[set session "sql_default_engine" = 'memtx']])
+ | ---
+ | - row_count: 1
+ | ...
+s:get('sql_default_engine').value
+ | ---
+ | - memtx
+ | ...
+box.execute([[set session "sql_defer_foreign_keys" = true]])
+ | ---
+ | - row_count: 1
+ | ...
+s:get('sql_defer_foreign_keys').value
+ | ---
+ | - true
+ | ...
+box.execute([[set session "sql_defer_foreign_keys" = false]])
+ | ---
+ | - row_count: 1
+ | ...
+s:get('sql_defer_foreign_keys').value
+ | ---
+ | - false
+ | ...
+
 settings.sql_default_engine = true
  | ---
  | - error: Session setting sql_default_engine expected a value of type string
@@ -359,3 +392,19 @@ box.session.settings.sql_default_engine = str
  | ---
  | - error: Failed to allocate 20483 bytes in static_alloc for mp_value
  | ...
+
+box.execute([[set session "sql_def_engine" = true]])
+ | ---
+ | - null
+ | - Session setting sql_def_engine doesn't exist
+ | ...
+box.execute([[set session "sql_default_engine" = true]])
+ | ---
+ | - null
+ | - Session setting sql_default_engine expected a value of type string
+ | ...
+box.execute([[set session "sql_defer_foreign_keys" = 'true']])
+ | ---
+ | - null
+ | - Session setting sql_defer_foreign_keys expected a value of type boolean
+ | ...
diff --git a/test/box/session_settings.test.lua b/test/box/session_settings.test.lua
index 440bef7ce..d4aac0286 100644
--- a/test/box/session_settings.test.lua
+++ b/test/box/session_settings.test.lua
@@ -132,9 +132,22 @@ s:get('sql_defer_foreign_keys').value
 s:update('sql_defer_foreign_keys', {{'=', 2, false}})
 settings.sql_defer_foreign_keys
 
+box.execute([[set session "sql_default_engine" = 'vinyl']])
+s:get('sql_default_engine').value
+box.execute([[set session "sql_default_engine" = 'memtx']])
+s:get('sql_default_engine').value
+box.execute([[set session "sql_defer_foreign_keys" = true]])
+s:get('sql_defer_foreign_keys').value
+box.execute([[set session "sql_defer_foreign_keys" = false]])
+s:get('sql_defer_foreign_keys').value
+
 settings.sql_default_engine = true
 settings.sql_defer_foreign_keys = 'false'
 settings.sql_parser_debug = 'string'
 
 str = string.rep('a', 20 * 1024)
 box.session.settings.sql_default_engine = str
+
+box.execute([[set session "sql_def_engine" = true]])
+box.execute([[set session "sql_default_engine" = true]])
+box.execute([[set session "sql_defer_foreign_keys" = 'true']])
-- 
2.21.1 (Apple Git-122.3)

Re: [Tarantool-patches] [PATCH 4/4] sql: provide a user friendly frontend for accessing session settings

[Vladislav Shpilevoy]

Hi! Thanks for the patchset!

I force pushed the style fix below.

LGTM now.

diff --git a/src/box/sql/parse.y b/src/box/sql/parse.y
index 995875566..380fb83d1 100644
--- a/src/box/sql/parse.y
+++ b/src/box/sql/parse.y
@@ -1544,7 +1544,7 @@ cmd ::= DROP INDEX ifexists(E) nm(X) ON fullname(Y).   {
 ///////////////////////////// The SET SESSION command ////////////////////////
 //
 cmd ::= SET SESSION nm(X) EQ term(Y).  {
-    sql_setting_set(pParse,&X,Y.pExpr);
+    sql_setting_set(pParse, &X, Y.pExpr);
 }
 
 ///////////////////////////// The PRAGMA command /////////////////////////////

Re: [Tarantool-patches] [PATCH 4/4] sql: provide a user friendly frontend for accessing session settings

[Timur Safin]

: 
: I changed it to the following (the main problem with reserved word
: persists):
: 
: +///////////////////////////// The SET SESSION command
: ////////////////////////
: +//
: +cmd ::= SET SESSION nm(X) EQ term(Y).  {
: +    sql_setting_set(pParse,&X,Y.pExpr);
: +}
: +
: 
..

: ==========================================================================
: =====
: 
: Currently if a user wants to change session setting with SQL, one has
: to execute UPDATE query like:
: [[UPDATE "_session_settings" SET "value" = true WHERE "name" = 'name']]
: However, direct access to system spaces isn't considered to be a good
: practice.
: To avoid that and a bit simplify user's life, we introduce SQL shortcut
: command
: SET SESSION.
: 
: Closes #4711
: 
: @TarantoolBot document
: Title: API for accessing _session_settings space.
: There are two ways of updating values of session settings:
: via Lua and SQL.
: 
...
: SQL:
: Instead of typing long UPDATE query one can use the SET SESSION command:
: `box.execute([[SET SESSION "<setting_name>" = <new_value>]])`.
: Note, that this query is case sensitive so the name must be quoted.
: Also, SET SESSION doesn't provide any implicit casts, so <new_value> must
: be of the type corresponding to the setting being updated.
: 
: Example:
: ```
: tarantool> box.execute([[set session "sql_default_engine" = 'memtx']])
: ---
: - row_count: 1
: ...
: 
: tarantool> box.execute([[set session "sql_defer_foreign_keys" = true]])
: ---
: - row_count: 1
: ...
: 

Like it! 
(The least intrusive way possible, but still is short for user to write)

Timur

Re: [Tarantool-patches] [PATCH 2/4] box: add binary search for _session_settings space

[Kirill Yukhin]

Hello,

On 03 Apr 14:00, Nikita Pettik wrote:
> On 30 Mar 12:13, Chris Sosnin wrote:
> > As it is mentioned in implementation, it is important
> > that _session_settings options are sorted by name, so
> > there is no need in linear lookup and we can replace it
> > with binary search.
> > 
> > Closes #4712
> > ---
> 
> Still I see no need for this patch. It is unclear which improvements
> it introduces except for code complication.

I agree, let's drop it.

--
Regards, Kirill Yukhin

Re: [Tarantool-patches] [PATCH 0/4] session settings fixes

[Kirill Yukhin]

Hello,

On 30 Mar 12:13, Chris Sosnin wrote:
> issue #1:https://github.com/tarantool/tarantool/issues/4711
> issue #2:https://github.com/tarantool/tarantool/issues/4712
> branch:https://github.com/tarantool/tarantool/tree/ksosnin/gh-4712-session-settings-v2
> 
> Chris Sosnin (4):
>   box: replace session_settings modules with a single array
>   box: add binary search for _session_settings space
>   box: provide a user friendly frontend for accessing session settings
>   sql: provide a user friendly frontend for accessing session settings
> 
>  extra/mkkeywordhash.c                         |   1 +
>  src/box/lua/session.c                         | 111 +++++++++
>  src/box/session.cc                            |   1 +
>  src/box/session.h                             |   2 +
>  src/box/session_settings.c                    | 214 +++++++++++-------
>  src/box/session_settings.h                    |  53 +++--
>  src/box/sql.c                                 |   5 -
>  src/box/sql/build.c                           | 104 ++++-----
>  src/box/sql/parse.y                           |   5 +
>  src/box/sql/sqlInt.h                          |  11 +
>  src/box/sql/vdbe.c                            |  50 ++++
>  ...rontend.result => session_settings.result} | 147 ++++++++++--
>  ...end.test.lua => session_settings.test.lua} |  61 ++++-
>  13 files changed, 589 insertions(+), 176 deletions(-)
>  rename test/box/{gh-4511-access-settings-from-any-frontend.result => session_settings.result} (71%)
>  rename test/box/{gh-4511-access-settings-from-any-frontend.test.lua => session_settings.test.lua} (64%)

I've checked 1, 3 and 4 patches into master.

--
Regards, Kirill Yukhin

Re: [Tarantool-patches] [PATCH 3/4] box: provide a user friendly frontend for accessing session settings

[Chris Sosnin]

[-- Attachment #1: Type: text/plain, Size: 2587 bytes --]



> On 17 Mar 2020, at 17:27, Nikita Pettik <korablev@tarantool.org> wrote:
> 
> On 16 Mar 23:53, Vladislav Shpilevoy wrote:
>> On 16/03/2020 17:08, Nikita Pettik wrote:
>>> On 17 Feb 15:12, Chris Sosnin wrote:
>>>> - space_object:update() is hard to use for configuring session settings,
>>>> so we provide box.session.setting table, which can be used in a much more
>>>> native way.
>>>> 
>>>> - Prior to this patch sql settings were not accessible before box.cfg()
>>>> call, even though these flags can be set right after session creation.
>>>> 
>>>> Part of #4711
>>>> ---
>>> 
>>> tarantool> box.session.settings.sql_vdbe_debug
>>> ---
>>> - false
>>> ...
>>> 
>>> tarantool> box.session.settings.sql_vdbe_debug = true
>>> ---
>>> ...
>>> 
>>> tarantool> box.session.settings.sql_vdbe_debug
>>> ---
>>> - true
>>> ...
>> 
>> Yeah, we can ban this. To avoid confusion.
>> 
>>> 
>>> tarantool> box.execute("select 1")
>>> ---
>>> - metadata:
>>>  - name: '1'
>>>    type: integer
>>>  rows:
>>>  - [1]
>>> ...
>>> 
>>> Looks inconsistent. Can we use instead of :set() method simple
>>> table value assignment? Otherwise accessing row table values
>> 
>> Assignment would require not to store settings in box.session.settings,
>> to be able to redefine __newindex metamethod. If we don't store them, we
>> kill autocompletion, which was asked explicitly by somebody.
>> 
>> But I am on your side here - I don't think autocompletion worth this
>> complication. Who wants to look at existing settings can just print
>> box.sessions.settings table.
>> 
>>> should be disallowed. Same concerns :get() method. Why ever
>>> anyone should bother with :get() when one can access table value
>>> via simple indexing?
>> 
>> Hm. But there is no :get() method. We didn't implement getting, because
>> no one asked for this.
> 
> As far as I remember no one either asked for :set() method (except for me) :)

This method is a workaround to allow console autocompletion, Lua doesn’t allow you to overload
indexing for the keys already present in the table. But here I agree that this implementation is rather
misleading. I will rework the patch to allow settings.<name> = <value> syntax.

> 
>> And indeed, usually you just set settings, without
>> checking if set really worked. I was thinking we could introduce get if
>> someone asks for that. But up to you. Can be added now as well.
> 
> I do not insist since do not consider this to be prio1 task (as well
> as any other issue connected with settings machinery).


[-- Attachment #2: Type: text/html, Size: 8115 bytes --]

Re: [Tarantool-patches] [PATCH 3/4] box: provide a user friendly frontend for accessing session settings

[Nikita Pettik]

On 16 Mar 23:53, Vladislav Shpilevoy wrote:
> On 16/03/2020 17:08, Nikita Pettik wrote:
> > On 17 Feb 15:12, Chris Sosnin wrote:
> >> - space_object:update() is hard to use for configuring session settings,
> >> so we provide box.session.setting table, which can be used in a much more
> >> native way.
> >>
> >> - Prior to this patch sql settings were not accessible before box.cfg()
> >> call, even though these flags can be set right after session creation.
> >>
> >> Part of #4711
> >> ---
> > 
> > tarantool> box.session.settings.sql_vdbe_debug
> > ---
> > - false
> > ...
> > 
> > tarantool> box.session.settings.sql_vdbe_debug = true
> > ---
> > ...
> > 
> > tarantool> box.session.settings.sql_vdbe_debug
> > ---
> > - true
> > ...
> 
> Yeah, we can ban this. To avoid confusion.
> 
> > 
> > tarantool> box.execute("select 1")
> > ---
> > - metadata:
> >   - name: '1'
> >     type: integer
> >   rows:
> >   - [1]
> > ...
> > 
> > Looks inconsistent. Can we use instead of :set() method simple
> > table value assignment? Otherwise accessing row table values
> 
> Assignment would require not to store settings in box.session.settings,
> to be able to redefine __newindex metamethod. If we don't store them, we
> kill autocompletion, which was asked explicitly by somebody.
> 
> But I am on your side here - I don't think autocompletion worth this
> complication. Who wants to look at existing settings can just print
> box.sessions.settings table.
> 
> > should be disallowed. Same concerns :get() method. Why ever
> > anyone should bother with :get() when one can access table value
> > via simple indexing?
> 
> Hm. But there is no :get() method. We didn't implement getting, because
> no one asked for this.

As far as I remember no one either asked for :set() method (except for me) :)

> And indeed, usually you just set settings, without
> checking if set really worked. I was thinking we could introduce get if
> someone asks for that. But up to you. Can be added now as well.

I do not insist since do not consider this to be prio1 task (as well
as any other issue connected with settings machinery).

Re: [Tarantool-patches] [PATCH 3/4] box: provide a user friendly frontend for accessing session settings

[Vladislav Shpilevoy]

On 16/03/2020 17:08, Nikita Pettik wrote:
> On 17 Feb 15:12, Chris Sosnin wrote:
>> - space_object:update() is hard to use for configuring session settings,
>> so we provide box.session.setting table, which can be used in a much more
>> native way.
>>
>> - Prior to this patch sql settings were not accessible before box.cfg()
>> call, even though these flags can be set right after session creation.
>>
>> Part of #4711
>> ---
> 
> tarantool> box.session.settings.sql_vdbe_debug
> ---
> - false
> ...
> 
> tarantool> box.session.settings.sql_vdbe_debug = true
> ---
> ...
> 
> tarantool> box.session.settings.sql_vdbe_debug
> ---
> - true
> ...

Yeah, we can ban this. To avoid confusion.

> 
> tarantool> box.execute("select 1")
> ---
> - metadata:
>   - name: '1'
>     type: integer
>   rows:
>   - [1]
> ...
> 
> Looks inconsistent. Can we use instead of :set() method simple
> table value assignment? Otherwise accessing row table values

Assignment would require not to store settings in box.session.settings,
to be able to redefine __newindex metamethod. If we don't store them, we
kill autocompletion, which was asked explicitly by somebody.

But I am on your side here - I don't think autocompletion worth this
complication. Who wants to look at existing settings can just print
box.sessions.settings table.

> should be disallowed. Same concerns :get() method. Why ever
> anyone should bother with :get() when one can access table value
> via simple indexing?

Hm. But there is no :get() method. We didn't implement getting, because
no one asked for this. And indeed, usually you just set settings, without
checking if set really worked. I was thinking we could introduce get if
someone asks for that. But up to you. Can be added now as well.

Re: [Tarantool-patches] [PATCH 3/4] box: provide a user friendly frontend for accessing session settings

[Nikita Pettik]

On 17 Feb 15:12, Chris Sosnin wrote:
> - space_object:update() is hard to use for configuring session settings,
> so we provide box.session.setting table, which can be used in a much more
> native way.
> 
> - Prior to this patch sql settings were not accessible before box.cfg()
> call, even though these flags can be set right after session creation.
> 
> Part of #4711
> ---

tarantool> box.session.settings.sql_vdbe_debug
---
- false
...

tarantool> box.session.settings.sql_vdbe_debug = true
---
...

tarantool> box.session.settings.sql_vdbe_debug
---
- true
...

tarantool> box.execute("select 1")
---
- metadata:
  - name: '1'
    type: integer
  rows:
  - [1]
...

Looks inconsistent. Can we use instead of :set() method simple
table value assignment? Otherwise accessing row table values
should be disallowed. Same concerns :get() method. Why ever
anyone should bother with :get() when one can access table value
via simple indexing?

[Tarantool-patches] [PATCH 3/4] box: provide a user friendly frontend for accessing session settings

[Chris Sosnin]

- space_object:update() is hard to use for configuring session settings,
so we provide box.session.setting table, which can be used in a much more
native way.

- Prior to this patch sql settings were not accessible before box.cfg()
call, even though these flags can be set right after session creation.

Part of #4711
---
 src/box/lua/session.c                         | 92 +++++++++++++++++++
 src/box/session.cc                            |  1 +
 src/box/session.h                             |  2 +
 src/box/sql.c                                 |  5 -
 ...rontend.result => session_settings.result} | 63 +++++++++++++
 ...end.test.lua => session_settings.test.lua} | 20 ++++
 6 files changed, 178 insertions(+), 5 deletions(-)
 rename test/box/{gh-4511-access-settings-from-any-frontend.result => session_settings.result} (86%)
 rename test/box/{gh-4511-access-settings-from-any-frontend.test.lua => session_settings.test.lua} (85%)

diff --git a/src/box/lua/session.c b/src/box/lua/session.c
index c6a600f6f..c0b4d6184 100644
--- a/src/box/lua/session.c
+++ b/src/box/lua/session.c
@@ -42,6 +42,8 @@
 #include "box/user.h"
 #include "box/schema.h"
 #include "box/port.h"
+#include "box/session_settings.h"
+#include "tt_static.h"
 
 static const char *sessionlib_name = "box.session";
 
@@ -411,6 +413,95 @@ lbox_session_on_access_denied(struct lua_State *L)
 				  lbox_push_on_access_denied_event, NULL);
 }
 
+static int
+lbox_session_setting_get(struct lua_State *L)
+{
+	lua_getfield(L, -1, "_id");
+	int sid = lua_tointeger(L, -1);
+	const char *mp_pair, *mp_pair_end;
+	session_settings[sid].get(sid, &mp_pair, &mp_pair_end);
+	uint32_t len;
+	mp_decode_array(&mp_pair);
+	mp_decode_str(&mp_pair, &len);
+	enum field_type field_type = session_settings[sid].field_type;
+	if (field_type == FIELD_TYPE_BOOLEAN) {
+		bool value = mp_decode_bool(&mp_pair);
+		lua_pushboolean(L, value);
+	} else {
+		const char *str = mp_decode_str(&mp_pair, &len);
+		lua_pushlstring(L, str, len);
+	}
+	return 1;
+}
+
+static int
+lbox_session_setting_set(struct lua_State *L)
+{
+	if (lua_gettop(L) != 2)
+		return luaL_error(L, "Usage: box.session.settings:set(value)");
+	int arg_type = lua_type(L, -1);
+	lua_getfield(L, -2, "_id");
+	int sid = lua_tointeger(L, -1);
+	struct session_setting *setting = &session_settings[sid];
+	lua_pop(L, 1);
+	switch (arg_type) {
+	case LUA_TBOOLEAN: {
+		bool value = lua_toboolean(L, -1);
+		size_t size = mp_sizeof_bool(value);
+		char *mp_value = (char *) static_alloc(size);
+		mp_encode_bool(mp_value, value);
+		if (setting->set(sid, mp_value) != 0)
+			return luaT_push_nil_and_error(L);
+		break;
+	}
+	case LUA_TSTRING: {
+		const char *str = lua_tostring(L, -1);
+		size_t len = strlen(str);
+		uint32_t size = mp_sizeof_str(len);
+		char *mp_value = (char *) static_alloc(size);
+		if (mp_value == NULL) {
+			diag_set(OutOfMemory, size, "static_alloc",
+				 "mp_value");
+			return luaT_error(L);
+		}
+		mp_encode_str(mp_value, str, len);
+		if (setting->set(sid, mp_value) != 0)
+			return luaT_push_nil_and_error(L);
+		break;
+	}
+	default:
+		diag_set(ClientError, ER_SESSION_SETTING_INVALID_VALUE,
+			 session_setting_strs[sid],
+			 field_type_strs[setting->field_type]);
+		return luaT_push_nil_and_error(L);
+	}
+	return 0;
+}
+
+static void
+lbox_session_settings_init(struct lua_State *L)
+{
+	lua_createtable(L, 0, 2);
+	lua_pushcfunction(L, lbox_session_setting_get);
+	lua_setfield(L, -2, "__serialize");
+	lua_createtable(L, 0, 1);
+	lua_pushcfunction(L, lbox_session_setting_set);
+	lua_setfield(L, -2, "set");
+	lua_setfield(L, -2, "__index");
+
+	lua_newtable(L);
+	for (int id = 0; id < SESSION_SETTING_COUNT; ++id) {
+		lua_newtable(L);
+		lua_pushinteger(L, id);
+		lua_setfield(L, -2, "_id");
+		lua_pushvalue(L, -3);
+		lua_setmetatable(L, -2);
+		lua_setfield(L, -2, session_setting_strs[id]);
+	}
+	lua_setfield(L, -3, "settings");
+	lua_pop(L, 1);
+}
+
 void
 session_storage_cleanup(int sid)
 {
@@ -478,5 +569,6 @@ box_lua_session_init(struct lua_State *L)
 		{NULL, NULL}
 	};
 	luaL_register_module(L, sessionlib_name, sessionlib);
+	lbox_session_settings_init(L);
 	lua_pop(L, 1);
 }
diff --git a/src/box/session.cc b/src/box/session.cc
index 881318252..b557eed62 100644
--- a/src/box/session.cc
+++ b/src/box/session.cc
@@ -283,6 +283,7 @@ session_init()
 		panic("out of memory");
 	mempool_create(&session_pool, &cord()->slabc, sizeof(struct session));
 	credentials_create(&admin_credentials, admin_user);
+	sql_session_settings_init();
 }
 
 void
diff --git a/src/box/session.h b/src/box/session.h
index 6dfc7cba5..1c47b8986 100644
--- a/src/box/session.h
+++ b/src/box/session.h
@@ -41,6 +41,8 @@
 extern "C" {
 #endif /* defined(__cplusplus) */
 
+extern void sql_session_settings_init();
+
 struct port;
 struct session_vtab;
 
diff --git a/src/box/sql.c b/src/box/sql.c
index 1256df856..ba98ce5df 100644
--- a/src/box/sql.c
+++ b/src/box/sql.c
@@ -64,14 +64,9 @@ static const uint32_t default_sql_flags = SQL_EnableTrigger
 					  | SQL_AutoIndex
 					  | SQL_RecTriggers;
 
-extern void
-sql_session_settings_init();
-
 void
 sql_init()
 {
-	sql_session_settings_init();
-
 	default_flags |= default_sql_flags;
 
 	current_session()->sql_flags |= default_sql_flags;
diff --git a/test/box/gh-4511-access-settings-from-any-frontend.result b/test/box/session_settings.result
similarity index 86%
rename from test/box/gh-4511-access-settings-from-any-frontend.result
rename to test/box/session_settings.result
index bae77192e..6d7074e8c 100644
--- a/test/box/gh-4511-access-settings-from-any-frontend.result
+++ b/test/box/session_settings.result
@@ -298,3 +298,66 @@ s:update('sql_defer_foreign_keys', {{'=', 'value', '1'}})
  | ---
  | - error: Session setting sql_defer_foreign_keys expected a value of type boolean
  | ...
+
+-- gh-4711: Provide a user-friendly frontend for accessing session settings.
+settings = box.session.settings
+ | ---
+ | ...
+assert(settings ~= nil)
+ | ---
+ | - true
+ | ...
+
+s:update('sql_default_engine', {{'=', 2, 'vinyl'}})
+ | ---
+ | - ['sql_default_engine', 'vinyl']
+ | ...
+settings.sql_default_engine
+ | ---
+ | - vinyl
+ | ...
+settings.sql_default_engine:set('memtx')
+ | ---
+ | ...
+s:get('sql_default_engine').value
+ | ---
+ | - memtx
+ | ...
+settings.sql_defer_foreign_keys:set(true)
+ | ---
+ | ...
+s:get('sql_defer_foreign_keys').value
+ | ---
+ | - true
+ | ...
+s:update('sql_defer_foreign_keys', {{'=', 2, false}})
+ | ---
+ | - ['sql_defer_foreign_keys', false]
+ | ...
+settings.sql_defer_foreign_keys
+ | ---
+ | - false
+ | ...
+
+settings.sql_default_engine:set(true)
+ | ---
+ | - null
+ | - Session setting sql_default_engine expected a value of type string
+ | ...
+settings.sql_defer_foreign_keys:set(false, 1, 2, 3)
+ | ---
+ | - error: 'Usage: box.session.settings:set(value)'
+ | ...
+settings.sql_parser_debug:set('string')
+ | ---
+ | - null
+ | - Session setting sql_parser_debug expected a value of type boolean
+ | ...
+
+str = string.rep('a', 20 * 1024)
+ | ---
+ | ...
+box.session.settings.sql_default_engine:set(str)
+ | ---
+ | - error: Failed to allocate 20483 bytes in static_alloc for mp_value
+ | ...
diff --git a/test/box/gh-4511-access-settings-from-any-frontend.test.lua b/test/box/session_settings.test.lua
similarity index 85%
rename from test/box/gh-4511-access-settings-from-any-frontend.test.lua
rename to test/box/session_settings.test.lua
index b243be15e..23799874a 100644
--- a/test/box/gh-4511-access-settings-from-any-frontend.test.lua
+++ b/test/box/session_settings.test.lua
@@ -118,3 +118,23 @@ s:update('sql_defer_foreign_keys', {{'=', 'some text', true}})
 s:update('sql_defer_foreign_keys', {{'=', 'value', 1}})
 s:update('sql_defer_foreign_keys', {{'=', 'value', {1}}})
 s:update('sql_defer_foreign_keys', {{'=', 'value', '1'}})
+
+-- gh-4711: Provide a user-friendly frontend for accessing session settings.
+settings = box.session.settings
+assert(settings ~= nil)
+
+s:update('sql_default_engine', {{'=', 2, 'vinyl'}})
+settings.sql_default_engine
+settings.sql_default_engine:set('memtx')
+s:get('sql_default_engine').value
+settings.sql_defer_foreign_keys:set(true)
+s:get('sql_defer_foreign_keys').value
+s:update('sql_defer_foreign_keys', {{'=', 2, false}})
+settings.sql_defer_foreign_keys
+
+settings.sql_default_engine:set(true)
+settings.sql_defer_foreign_keys:set(false, 1, 2, 3)
+settings.sql_parser_debug:set('string')
+
+str = string.rep('a', 20 * 1024)
+box.session.settings.sql_default_engine:set(str)
-- 
2.21.1 (Apple Git-122.3)

Re: [Tarantool-patches] [PATCH 3/4] box: provide a user friendly frontend for accessing session settings

[Vladislav Shpilevoy]

Thanks for the patch!

I fixed code style by adding lbox_ prefix to functions
related to Lua box.session.*; added 'struct' to lua_State
mentions; fixed a crash in setting set(); dropped global
type 'session_setting'; renamed session_setting_serialize
to session_setting_get, because in future we likely will
add setting:get() method, and we could use the same function
as __serialize for this.

Consider my fixes below and on the branch.

================================================================================

commit ff63c003f7b7332f4b21c92cdcc8d85ac8f2e002
Author: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
Date:   Thu Feb 6 22:17:14 2020 +0100

    Review fixes

diff --git a/src/box/lua/session.c b/src/box/lua/session.c
index 9aaf9e8dd..a0bce2333 100644
--- a/src/box/lua/session.c
+++ b/src/box/lua/session.c
@@ -414,7 +414,7 @@ lbox_session_on_access_denied(struct lua_State *L)
 }
 
 static int
-session_setting_serialize(lua_State *L)
+lbox_session_setting_get(struct lua_State *L)
 {
 	lua_getfield(L, -1, "_id");
 	int sid = lua_tointeger(L, -1);
@@ -435,10 +435,10 @@ session_setting_serialize(lua_State *L)
 }
 
 static int
-session_setting_set(lua_State *L)
+lbox_session_setting_set(struct lua_State *L)
 {
 	if (lua_gettop(L) != 2)
-		goto error;
+		return luaL_error(L, "Usage: box.session.settings:set(value)");
 	int arg_type = lua_type(L, -1);
 	lua_getfield(L, -2, "_id");
 	int sid = lua_tointeger(L, -1);
@@ -459,43 +459,47 @@ session_setting_set(lua_State *L)
 			size_t len = strlen(str);
 			uint32_t size = mp_sizeof_str(len);
 			char *mp_value = static_alloc(size);
+			if (mp_value == NULL) {
+				diag_set(OutOfMemory, size, "static_alloc",
+					 "mp_value");
+				return luaT_error(L);
+			}
 			mp_encode_str(mp_value, str, len);
 			if (setting->set(sid, mp_value) != 0)
 				return luaT_push_nil_and_error(L);
 			break;
 		}
 		default:
-			goto error;
+			diag_set(ClientError, ER_SESSION_SETTING_INVALID_VALUE,
+				 session_setting_strs[sid],
+				 field_type_strs[setting->field_type]);
+			return luaT_push_nil_and_error(L);
 	}
-	lua_pushstring(L, session_setting_strs[sid]);
-	lua_pushvalue(L, -2);
-	return 2;
-error:
-	return luaL_error(L, "Usage: setting:set(value)");
+	return 0;
 }
 
 static void
-session_setting_create(struct lua_State *L, int id)
+lbox_session_settings_init(struct lua_State *L)
 {
-	lua_newtable(L);
-	lua_pushstring(L, "_id");
-	lua_pushinteger(L, id);
-	lua_settable(L, -3);
-	luaL_getmetatable(L, "session_setting");
-	lua_setmetatable(L, -2);
-}
+	lua_createtable(L, 0, 2);
+	lua_pushcfunction(L, lbox_session_setting_get);
+	lua_setfield(L, -2, "__serialize");
+	lua_createtable(L, 0, 1);
+	lua_pushcfunction(L, lbox_session_setting_set);
+	lua_setfield(L, -2, "set");
+	lua_setfield(L, -2, "__index");
 
-void
-session_settings_init(struct lua_State *L)
-{
-	lua_pushstring(L, "settings");
 	lua_newtable(L);
 	for (int id = 0; id < SESSION_SETTING_COUNT; ++id) {
-		lua_pushstring(L, session_setting_strs[id]);
-		session_setting_create(L, id);
-		lua_settable(L, -3);
+		lua_newtable(L);
+		lua_pushinteger(L, id);
+		lua_setfield(L, -2, "_id");
+		lua_pushvalue(L, -3);
+		lua_setmetatable(L, -2);
+		lua_setfield(L, -2, session_setting_strs[id]);
 	}
-	lua_settable(L, -3);
+	lua_setfield(L, -3, "settings");
+	lua_pop(L, 1);
 }
 
 void
@@ -545,13 +549,6 @@ box_lua_session_init(struct lua_State *L)
 	luaL_register(L, "box.internal.session", session_internal_lib);
 	lua_pop(L, 1);
 
-	static const struct luaL_Reg session_setting_meta[] = {
-		{"__serialize", session_setting_serialize},
-		{"set", session_setting_set},
-		{NULL, NULL}
-	};
-	luaL_register_type(L, "session_setting", session_setting_meta);
-	
 	static const struct luaL_Reg sessionlib[] = {
 		{"id", lbox_session_id},
 		{"type", lbox_session_type},
@@ -572,6 +569,6 @@ box_lua_session_init(struct lua_State *L)
 		{NULL, NULL}
 	};
 	luaL_register_module(L, sessionlib_name, sessionlib);
-	session_settings_init(L);
+	lbox_session_settings_init(L);
 	lua_pop(L, 1);
 }
diff --git a/test/box/session_settings.result b/test/box/session_settings.result
index 1bb3757ff..6d7074e8c 100644
--- a/test/box/session_settings.result
+++ b/test/box/session_settings.result
@@ -318,8 +318,6 @@ settings.sql_default_engine
  | ...
 settings.sql_default_engine:set('memtx')
  | ---
- | - sql_default_engine
- | - memtx
  | ...
 s:get('sql_default_engine').value
  | ---
@@ -327,8 +325,6 @@ s:get('sql_default_engine').value
  | ...
 settings.sql_defer_foreign_keys:set(true)
  | ---
- | - sql_defer_foreign_keys
- | - true
  | ...
 s:get('sql_defer_foreign_keys').value
  | ---
@@ -350,10 +346,18 @@ settings.sql_default_engine:set(true)
  | ...
 settings.sql_defer_foreign_keys:set(false, 1, 2, 3)
  | ---
- | - error: 'Usage: setting:set(value)'
+ | - error: 'Usage: box.session.settings:set(value)'
  | ...
 settings.sql_parser_debug:set('string')
  | ---
  | - null
  | - Session setting sql_parser_debug expected a value of type boolean
  | ...
+
+str = string.rep('a', 20 * 1024)
+ | ---
+ | ...
+box.session.settings.sql_default_engine:set(str)
+ | ---
+ | - error: Failed to allocate 20483 bytes in static_alloc for mp_value
+ | ...
diff --git a/test/box/session_settings.test.lua b/test/box/session_settings.test.lua
index 89b98dde2..23799874a 100644
--- a/test/box/session_settings.test.lua
+++ b/test/box/session_settings.test.lua
@@ -135,3 +135,6 @@ settings.sql_defer_foreign_keys
 settings.sql_default_engine:set(true)
 settings.sql_defer_foreign_keys:set(false, 1, 2, 3)
 settings.sql_parser_debug:set('string')
+
+str = string.rep('a', 20 * 1024)
+box.session.settings.sql_default_engine:set(str)

[Tarantool-patches] [PATCH 3/4] box: provide a user friendly frontend for accessing session settings

[Chris Sosnin]

Thank you for the review and your comments!
My answers below:

> 1. Please, don't mix SQL and Lua. At least here. Call it in
> session.cc in session_init(). This file should not initialize
> any session backends.

Done.

> 2. Avoid writing comments in the same line as the code, unless
> this is a special case like a structure inlined initialization.
> This has simple reasons: lines are shorter and therefore easier
> to read; diff is smaller when only the code or only the comment
> are changed.

Actually, I decided that comments are not essential here, so I
dropped them. Starting from here, everything about comments is
skipped.

> 3. Just use static_alloc. The same below.
+char *mp_value = static_alloc(size);

> 4. According to the new agreement, all new Lua functions should
> return nil, err when an error happens. Except OOM and invalid
> usage of API. So if set() returns != 0, then please, use
> luaT_push_nil_and_error().
+return luaT_push_nil_and_error(L);

> 6. You create lots of duplicate metatables here. I would
> try to create it only once and use that one object for
> all lua_setmetatable().

I did it the following way:
+	static const struct luaL_Reg session_setting_meta[] = {
+		{"__serialize", session_setting_serialize},
+		{"set", session_setting_set},
+		{NULL, NULL}
+	};
+	luaL_register_type(L, "session_setting", session_setting_meta);
...
+	luaL_getmetatable(L, "session_setting");
+	lua_setmetatable(L, -2);

> 9. If you start from SQL, you will need to change this code
> in case something will be added prior to SQL settings. Lets
> start from 0 and iterate to SESSION_SETTING_COUNT.

Well, I did it because SQL settings are available right after session
creation, if we add some settings that are not, then trying to access
them would lead to crash. However, currently it won't affect anything,
so ok.

+	for (int id = 0; id < SESSION_SETTING_COUNT; ++id) {
+		lua_pushstring(L, session_setting_strs[id]);
+		session_setting_create(L, id);
+		lua_settable(L, -3);
+	}

> 11. I propose you to move it to the end of this function. You
> initialize box.session.settings before box.session is
> created. If you move it to the end, you will be able to drop
> this dummy module registration, which you are doing above:

Done:
 	luaL_register_module(L, sessionlib_name, sessionlib);
+	session_settings_init(L);
 	lua_pop(L, 1);

+void
+session_settings_init(struct lua_State *L)
+{
+	lua_pushstring(L, "settings");
+	lua_newtable(L);
+	for (int id = 0; id < SESSION_SETTING_COUNT; ++id) {
+		lua_pushstring(L, session_setting_strs[id]);
+		session_setting_create(L, id);
+		lua_settable(L, -3);
+	}
+	lua_settable(L, -3);
+}

> 12. The file has name 'gh-4511-*', so you can't add issue 4711 tests
> here. Either add to a new file, or rename the test file to
> box/session_settings.

I renamed it.

See new version of the patch below:
================================================================================

- space_object:update() is hard to use for configuring session settings,
so we provide box.session.setting table, which can be used in a much more
native way.

- Prior to this patch sql settings were not accessible before box.cfg()
call, even though these flags can be set right after session creation.

Part of #4711
---
issue:https://github.com/tarantool/tarantool/issues/4711
branch:https://github.com/tarantool/tarantool/tree/ksosnin/gh-4712-search-settings

 src/box/lua/session.c                         | 95 +++++++++++++++++++
 src/box/session.cc                            |  1 +
 src/box/session.h                             |  2 +
 src/box/sql.c                                 |  5 -
 ...rontend.result => session_settings.result} | 59 ++++++++++++
 ...end.test.lua => session_settings.test.lua} | 17 ++++
 6 files changed, 174 insertions(+), 5 deletions(-)
 rename test/box/{gh-4511-access-settings-from-any-frontend.result => session_settings.result} (87%)
 rename test/box/{gh-4511-access-settings-from-any-frontend.test.lua => session_settings.test.lua} (87%)

diff --git a/src/box/lua/session.c b/src/box/lua/session.c
index c6a600f6f..b324cdab0 100644
--- a/src/box/lua/session.c
+++ b/src/box/lua/session.c
@@ -42,6 +42,8 @@
 #include "box/user.h"
 #include "box/schema.h"
 #include "box/port.h"
+#include "box/session_settings.h"
+#include "tt_static.h"
 
 static const char *sessionlib_name = "box.session";
 
@@ -411,6 +413,91 @@ lbox_session_on_access_denied(struct lua_State *L)
 				  lbox_push_on_access_denied_event, NULL);
 }
 
+static int
+session_setting_serialize(lua_State *L)
+{
+	lua_getfield(L, -1, "_id");
+	int sid = lua_tointeger(L, -1);
+	const char *mp_pair, *mp_pair_end;
+	session_settings[sid].get(sid, &mp_pair, &mp_pair_end);
+	uint32_t len;
+	mp_decode_array(&mp_pair);
+	mp_decode_str(&mp_pair, &len);
+	enum field_type field_type = session_settings[sid].metadata.field_type;
+	if (field_type == FIELD_TYPE_BOOLEAN) {
+		bool value = mp_decode_bool(&mp_pair);
+		lua_pushboolean(L, value);
+	} else {
+		const char *str = mp_decode_str(&mp_pair, &len);
+		lua_pushlstring(L, str, len);
+	}
+	return 1;
+}
+
+static int
+session_setting_set(lua_State *L)
+{
+	if (lua_gettop(L) != 2)
+		goto error;
+	int arg_type = lua_type(L, -1);
+	lua_getfield(L, -2, "_id");
+	int sid = lua_tointeger(L, -1);
+	struct session_setting *setting = &session_settings[sid];
+	lua_pop(L, 1);
+	switch (arg_type) {
+		case LUA_TBOOLEAN: {
+			bool value = lua_toboolean(L, -1);
+			size_t size = mp_sizeof_bool(value);
+			char *mp_value = static_alloc(size);
+			mp_encode_bool(mp_value, value);
+			if (setting->set(sid, mp_value) != 0)
+				return luaT_push_nil_and_error(L);
+			break;
+		}
+		case LUA_TSTRING: {
+			const char *str = lua_tostring(L, -1);
+			size_t len = strlen(str);
+			uint32_t size = mp_sizeof_str(len);
+			char *mp_value = static_alloc(size);
+			mp_encode_str(mp_value, str, len);
+			if (setting->set(sid, mp_value) != 0)
+				return luaT_push_nil_and_error(L);
+			break;
+		}
+		default:
+			goto error;
+	}
+	lua_pushstring(L, session_setting_strs[sid]);
+	lua_pushvalue(L, -2);
+	return 2;
+error:
+	return luaL_error(L, "Usage: setting:set(value)");
+}
+
+static void
+session_setting_create(struct lua_State *L, int id)
+{
+	lua_newtable(L);
+	lua_pushstring(L, "_id");
+	lua_pushinteger(L, id);
+	lua_settable(L, -3);
+	luaL_getmetatable(L, "session_setting");
+	lua_setmetatable(L, -2);
+}
+
+void
+session_settings_init(struct lua_State *L)
+{
+	lua_pushstring(L, "settings");
+	lua_newtable(L);
+	for (int id = 0; id < SESSION_SETTING_COUNT; ++id) {
+		lua_pushstring(L, session_setting_strs[id]);
+		session_setting_create(L, id);
+		lua_settable(L, -3);
+	}
+	lua_settable(L, -3);
+}
+
 void
 session_storage_cleanup(int sid)
 {
@@ -458,6 +545,13 @@ box_lua_session_init(struct lua_State *L)
 	luaL_register(L, "box.internal.session", session_internal_lib);
 	lua_pop(L, 1);
 
+	static const struct luaL_Reg session_setting_meta[] = {
+		{"__serialize", session_setting_serialize},
+		{"set", session_setting_set},
+		{NULL, NULL}
+	};
+	luaL_register_type(L, "session_setting", session_setting_meta);
+	
 	static const struct luaL_Reg sessionlib[] = {
 		{"id", lbox_session_id},
 		{"type", lbox_session_type},
@@ -478,5 +572,6 @@ box_lua_session_init(struct lua_State *L)
 		{NULL, NULL}
 	};
 	luaL_register_module(L, sessionlib_name, sessionlib);
+	session_settings_init(L);
 	lua_pop(L, 1);
 }
diff --git a/src/box/session.cc b/src/box/session.cc
index 881318252..b557eed62 100644
--- a/src/box/session.cc
+++ b/src/box/session.cc
@@ -283,6 +283,7 @@ session_init()
 		panic("out of memory");
 	mempool_create(&session_pool, &cord()->slabc, sizeof(struct session));
 	credentials_create(&admin_credentials, admin_user);
+	sql_session_settings_init();
 }
 
 void
diff --git a/src/box/session.h b/src/box/session.h
index 6dfc7cba5..1c47b8986 100644
--- a/src/box/session.h
+++ b/src/box/session.h
@@ -41,6 +41,8 @@
 extern "C" {
 #endif /* defined(__cplusplus) */
 
+extern void sql_session_settings_init();
+
 struct port;
 struct session_vtab;
 
diff --git a/src/box/sql.c b/src/box/sql.c
index 1256df856..ba98ce5df 100644
--- a/src/box/sql.c
+++ b/src/box/sql.c
@@ -64,14 +64,9 @@ static const uint32_t default_sql_flags = SQL_EnableTrigger
 					  | SQL_AutoIndex
 					  | SQL_RecTriggers;
 
-extern void
-sql_session_settings_init();
-
 void
 sql_init()
 {
-	sql_session_settings_init();
-
 	default_flags |= default_sql_flags;
 
 	current_session()->sql_flags |= default_sql_flags;
diff --git a/test/box/gh-4511-access-settings-from-any-frontend.result b/test/box/session_settings.result
similarity index 87%
rename from test/box/gh-4511-access-settings-from-any-frontend.result
rename to test/box/session_settings.result
index f072bafae..403a4506c 100644
--- a/test/box/gh-4511-access-settings-from-any-frontend.result
+++ b/test/box/session_settings.result
@@ -298,3 +298,62 @@ s:update('sql_defer_foreign_keys', {{'=', 'value', '1'}})
  | ---
  | - error: Session setting sql_defer_foreign_keys expected a value of type boolean
  | ...
+
+-- gh-4711: Provide a user-friendly frontend for accessing session settings.
+settings = box.session.settings
+ | ---
+ | ...
+assert(settings ~= nil)
+ | ---
+ | - true
+ | ...
+
+s:update('sql_default_engine', {{'=', 2, 'vinyl'}})
+ | ---
+ | - ['sql_default_engine', 'vinyl']
+ | ...
+settings.sql_default_engine
+ | ---
+ | - vinyl
+ | ...
+settings.sql_default_engine:set('memtx')
+ | ---
+ | - sql_default_engine
+ | - memtx
+ | ...
+s:get('sql_default_engine').value
+ | ---
+ | - memtx
+ | ...
+settings.sql_defer_foreign_keys:set(true)
+ | ---
+ | - sql_defer_foreign_keys
+ | - true
+ | ...
+s:get('sql_defer_foreign_keys').value
+ | ---
+ | - true
+ | ...
+s:update('sql_defer_foreign_keys', {{'=', 2, false}})
+ | ---
+ | - ['sql_defer_foreign_keys', false]
+ | ...
+settings.sql_defer_foreign_keys
+ | ---
+ | - false
+ | ...
+
+settings.sql_default_engine:set(true)
+ | ---
+ | - null
+ | - Session setting sql_default_engine expected a value of type string
+ | ...
+settings.sql_defer_foreign_keys:set(false, 1, 2, 3)
+ | ---
+ | - error: 'Usage: setting:set(value)'
+ | ...
+settings.sql_parser_debug:set('string')
+ | ---
+ | - null
+ | - Session setting sql_parser_debug expected a value of type boolean
+ | ...
diff --git a/test/box/gh-4511-access-settings-from-any-frontend.test.lua b/test/box/session_settings.test.lua
similarity index 87%
rename from test/box/gh-4511-access-settings-from-any-frontend.test.lua
rename to test/box/session_settings.test.lua
index 40a58ad04..99559100d 100644
--- a/test/box/gh-4511-access-settings-from-any-frontend.test.lua
+++ b/test/box/session_settings.test.lua
@@ -118,3 +118,20 @@ s:update('sql_defer_foreign_keys', {{'=', 'some text', true}})
 s:update('sql_defer_foreign_keys', {{'=', 'value', 1}})
 s:update('sql_defer_foreign_keys', {{'=', 'value', {1}}})
 s:update('sql_defer_foreign_keys', {{'=', 'value', '1'}})
+
+-- gh-4711: Provide a user-friendly frontend for accessing session settings.
+settings = box.session.settings
+assert(settings ~= nil)
+
+s:update('sql_default_engine', {{'=', 2, 'vinyl'}})
+settings.sql_default_engine
+settings.sql_default_engine:set('memtx')
+s:get('sql_default_engine').value
+settings.sql_defer_foreign_keys:set(true)
+s:get('sql_defer_foreign_keys').value
+s:update('sql_defer_foreign_keys', {{'=', 2, false}})
+settings.sql_defer_foreign_keys
+
+settings.sql_default_engine:set(true)
+settings.sql_defer_foreign_keys:set(false, 1, 2, 3)
+settings.sql_parser_debug:set('string')
-- 
2.21.1 (Apple Git-122.3)