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

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

[Chris Sosnin]

Currently if a user wants to change session setting with sql, he has
to execute non-obvious query, thus, we introduce a more native way to
do this.

Part of #4711
---
This patch is a follow-up for session settings patchset.

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

 src/box/sql/build.c                           | 31 ++++++++++++
 src/box/sql/parse.y                           |  5 ++
 src/box/sql/sqlInt.h                          | 11 +++++
 src/box/sql/vdbe.c                            | 45 +++++++++++++++++
 ...1-access-settings-from-any-frontend.result | 49 +++++++++++++++++++
 ...access-settings-from-any-frontend.test.lua | 13 +++++
 6 files changed, 154 insertions(+)

diff --git a/src/box/sql/build.c b/src/box/sql/build.c
index 7dcf7b858..cb7733cfc 100644
--- a/src/box/sql/build.c
+++ b/src/box/sql/build.c
@@ -3474,3 +3474,34 @@ sql_session_settings_init()
 		setting->set = sql_session_setting_set;
 	}
 }
+
+void
+sql_set_setting(struct Parse *parse_context, struct Token *name,
+		struct Expr *value)
+{
+	struct Vdbe *vdbe = sqlGetVdbe(parse_context);
+	assert(vdbe != NULL);
+	sqlVdbeCountChanges(vdbe);
+	char *key = sql_name_from_token(sql_get(), name);
+	if (key == NULL)
+		goto abort;
+	int low = 0, high = session_setting_MAX - 1;
+	while (low <= high) {
+		int index = (high + low) / 2;
+		int cmp = strcasecmp(session_settings[index].name, key);
+		if (cmp == 0) {
+			sqlVdbeAddOp4(vdbe, OP_Set, index, 0, 0,
+				      (const char *)value, P4_PTR);
+			return;
+		}
+		if (cmp < 0)
+			low = index + 1;
+		else
+			high = index - 1;
+	}
+	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 cfe1c0012..9d9b498a7 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 SET command ////////////////////////////////
+cmd ::= SET nm(X) EQ term(Y).  {
+    sql_set_setting(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 d1fcf4761..5e192a7bb 100644
--- a/src/box/sql/sqlInt.h
+++ b/src/box/sql/sqlInt.h
@@ -4510,4 +4510,15 @@ int
 sql_fieldno_by_name(struct Parse *parse_context, struct Expr *field_name,
 		    uint32_t *fieldno);
 
+/**
+ * Create VDBE instructions to set new value of session setting.
+ *
+ * @param parse_context Parsing context.
+ * @param name Name of the session setting.
+ * @param value New value of the session setting.
+ */
+void
+sql_set_setting(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 eab74db4a..0ee90de47 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
@@ -5261,6 +5262,50 @@ case OP_IncMaxid: {
 	break;
 }
 
+/* Opcode: Set P1 * * P4 *
+ *
+ * Set new value to session setting. P1 is ID of the setting.
+ * P4 is actually of type "struct Expr *" and contains value
+ * of the setting.
+ */
+case OP_Set: {
+	assert(pOp->p4type == P4_PTR);
+	struct Expr *expr = (struct Expr *)pOp->p4.p;
+	int sid = pOp->p1;
+	assert(sid >= 0 && sid < session_setting_MAX);
+	struct session_setting *setting = &session_settings[sid];
+	switch (expr->type) {
+		case FIELD_TYPE_BOOLEAN: {
+			bool value = expr->op == TK_TRUE;
+			size_t size = mp_sizeof_bool(value);
+			char *mp_value = (char *)region_alloc(&fiber()->gc,
+							      size);
+			mp_encode_bool(mp_value, value);
+			if (setting->set(sid, mp_value) != 0)
+				goto abort_due_to_error;
+			break;
+		}
+		case FIELD_TYPE_STRING: {
+			const char *str = expr->u.zToken;
+			size_t len = strlen(str);
+			uint32_t size = mp_sizeof_str(len);
+			char *mp_value = (char *)region_alloc(&fiber()->gc,
+							      size);
+			mp_encode_str(mp_value, str, len);
+			if (setting->set(sid, mp_value) != 0)
+				goto abort_due_to_error;
+			break;
+		}
+		default:
+			diag_set(ClientError, ER_SESSION_SETTING_INVALID_VALUE,
+				 setting->name,
+				 field_type_strs[setting->metadata.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/gh-4511-access-settings-from-any-frontend.result b/test/box/gh-4511-access-settings-from-any-frontend.result
index 1c3ca7661..0597365a1 100644
--- a/test/box/gh-4511-access-settings-from-any-frontend.result
+++ b/test/box/gh-4511-access-settings-from-any-frontend.result
@@ -343,6 +343,39 @@ settings.sql_defer_foreign_keys
  | - false
  | ...
 
+box.execute([[set sql_default_engine = 'vinyl']])
+ | ---
+ | - row_count: 1
+ | ...
+assert(s:get('sql_default_engine').value == 'vinyl')
+ | ---
+ | - true
+ | ...
+box.execute([[set sql_default_engine = 'memtx']])
+ | ---
+ | - row_count: 1
+ | ...
+assert(s:get('sql_default_engine').value == 'memtx')
+ | ---
+ | - true
+ | ...
+box.execute([[set sql_defer_foreign_keys = true]])
+ | ---
+ | - row_count: 1
+ | ...
+assert(s:get('sql_defer_foreign_keys').value == true)
+ | ---
+ | - true
+ | ...
+box.execute([[set sql_defer_foreign_keys = false]])
+ | ---
+ | - row_count: 1
+ | ...
+assert(s:get('sql_defer_foreign_keys').value == false)
+ | ---
+ | - true
+ | ...
+
 settings.sql_default_engine:set(true)
  | ---
  | - error: Session setting sql_default_engine expected a value of type string
@@ -355,3 +388,19 @@ settings.sql_parser_debug:set('string')
  | ---
  | - error: Session setting sql_parser_debug expected a value of type boolean
  | ...
+
+box.execute([[set sql_def_engine = true]])
+ | ---
+ | - null
+ | - Session setting SQL_DEF_ENGINE doesn't exist
+ | ...
+box.execute([[set sql_default_engine = true]])
+ | ---
+ | - null
+ | - Session setting sql_default_engine expected a value of type string
+ | ...
+box.execute([[set sql_defer_foreign_keys = 'true']])
+ | ---
+ | - null
+ | - Session setting sql_defer_foreign_keys expected a value of type boolean
+ | ...
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 53f03450d..e93edaf98 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
@@ -132,6 +132,19 @@ assert(s:get('sql_defer_foreign_keys').value == true)
 s:update('sql_defer_foreign_keys', {{'=', 2, false}})
 settings.sql_defer_foreign_keys
 
+box.execute([[set sql_default_engine = 'vinyl']])
+assert(s:get('sql_default_engine').value == 'vinyl')
+box.execute([[set sql_default_engine = 'memtx']])
+assert(s:get('sql_default_engine').value == 'memtx')
+box.execute([[set sql_defer_foreign_keys = true]])
+assert(s:get('sql_defer_foreign_keys').value == true)
+box.execute([[set sql_defer_foreign_keys = false]])
+assert(s:get('sql_defer_foreign_keys').value == false)
+
 settings.sql_default_engine:set(true)
 settings.sql_defer_foreign_keys:set(false, 1, 2, 3)
 settings.sql_parser_debug:set('string')
+
+box.execute([[set sql_def_engine = true]])
+box.execute([[set sql_default_engine = true]])
+box.execute([[set sql_defer_foreign_keys = 'true']])
-- 
2.21.1 (Apple Git-122.3)

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

[Vladislav Shpilevoy]

Thanks for the patch!

See 4 comments below.

On 30/01/2020 12:10, Chris Sosnin wrote:
> Currently if a user wants to change session setting with sql, he has
> to execute non-obvious query, thus, we introduce a more native way to
> do this.
> 
> Part of #4711
> ---
> This patch is a follow-up for session settings patchset.
> 
> issue:https://github.com/tarantool/tarantool/issues/4711
> branch:https://github.com/tarantool/tarantool/tree/ksosnin/gh-4712-search-settings
> 
>  src/box/sql/build.c                           | 31 ++++++++++++
>  src/box/sql/parse.y                           |  5 ++
>  src/box/sql/sqlInt.h                          | 11 +++++
>  src/box/sql/vdbe.c                            | 45 +++++++++++++++++
>  ...1-access-settings-from-any-frontend.result | 49 +++++++++++++++++++
>  ...access-settings-from-any-frontend.test.lua | 13 +++++
>  6 files changed, 154 insertions(+)
> 
> diff --git a/src/box/sql/build.c b/src/box/sql/build.c
> index 7dcf7b858..cb7733cfc 100644
> --- a/src/box/sql/build.c
> +++ b/src/box/sql/build.c
> @@ -3474,3 +3474,34 @@ sql_session_settings_init()
>  		setting->set = sql_session_setting_set;
>  	}
>  }
> +
> +void
> +sql_set_setting(struct Parse *parse_context, struct Token *name,
> +		struct Expr *value)
> +{
> +	struct Vdbe *vdbe = sqlGetVdbe(parse_context);
> +	assert(vdbe != NULL);
> +	sqlVdbeCountChanges(vdbe);
> +	char *key = sql_name_from_token(sql_get(), name);
> +	if (key == NULL)
> +		goto abort;
> +	int low = 0, high = session_setting_MAX - 1;
> +	while (low <= high) {
> +		int index = (high + low) / 2;
> +		int cmp = strcasecmp(session_settings[index].name, key);

1. All other places in SQL are case sensitive. I don't think this
place should be an exception.

> +		if (cmp == 0) {
> +			sqlVdbeAddOp4(vdbe, OP_Set, index, 0, 0,
> +				      (const char *)value, P4_PTR);

2. 1) struct Expr is a parsing stage object, it should not exist during
execution, 2) it is generally a bad practice to save an object by a
pointer, because that makes VDBE harder to serialize in future, when we
will expropriate VDBE generation into a library. You should encode
the expression as a set of VDBE operations storing result into a register,
from where SET would read it. Ideally, it would support '?' parameters.
See sqlExprCode().

> +			return;
> +		}
> +		if (cmp < 0)
> +			low = index + 1;
> +		else
> +			high = index - 1;
> +	}

3. Well, why not to expose session_settings_set_forward() into
session_settings.h header and use it here?

> +	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/test/box/gh-4511-access-settings-from-any-frontend.result b/test/box/gh-4511-access-settings-from-any-frontend.result
> index 1c3ca7661..0597365a1 100644
> --- a/test/box/gh-4511-access-settings-from-any-frontend.result
> +++ b/test/box/gh-4511-access-settings-from-any-frontend.result
> @@ -343,6 +343,39 @@ settings.sql_defer_foreign_keys
>   | - false
>   | ...
>  
> +box.execute([[set sql_default_engine = 'vinyl']])
> + | ---
> + | - row_count: 1
> + | ...
> +assert(s:get('sql_default_engine').value == 'vinyl')

4. Please, avoid calling assert. Because in case it will fail,
you won't get the real value, and it will be harder to debug.
Especially if that test will become flaky some day. Assert is ok,
if you know for sure what the other value is, or when there is a
function/cycle, which can't print directly to the output.

> + | ---
> + | - true
> + | ...
> +box.execute([[set sql_default_engine = 'memtx']])
> + | ---
> + | - row_count: 1
> + | ...
> +assert(s:get('sql_default_engine').value == 'memtx')
> + | ---
> + | - true
> + | ...
> +box.execute([[set sql_defer_foreign_keys = true]])
> + | ---
> + | - row_count: 1
> + | ...
> +assert(s:get('sql_defer_foreign_keys').value == true)
> + | ---
> + | - true
> + | ...
> +box.execute([[set sql_defer_foreign_keys = false]])
> + | ---
> + | - row_count: 1
> + | ...
> +assert(s:get('sql_defer_foreign_keys').value == false)
> + | ---
> + | - true
> + | ...
> +

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

[Chris Sosnin]

Thank you for the review!
See my answers to your comments below:

> 1. All other places in SQL are case sensitive. I don't think this
> place should be an exception.

I thought it is convenient for users to omit quotes. Well, we can keep
it for consistency.

> 2. 1) struct Expr is a parsing stage object, it should not exist during
> execution, 2) it is generally a bad practice to save an object by a
> pointer, because that makes VDBE harder to serialize in future, when we
> will expropriate VDBE generation into a library. You should encode
> the expression as a set of VDBE operations storing result into a register,
> from where SET would read it. Ideally, it would support '?' parameters.
> See sqlExprCode().

> 3. Well, why not to expose session_settings_set_forward() into
> session_settings.h header and use it here?

Fixed:

+int
+session_setting_find(const char *name) {
+	int sid;
+	if (session_settings_set_forward(&sid, name, true, true) == 0)
+		return sid;
+	else
+		return -1;
+}
...
+	int index = session_setting_find(key);
+	if (index >= 0) {
+		int target = ++parse_context->nMem;
+		sqlExprCode(parse_context, expr, target);
+		sqlVdbeAddOp3(vdbe, OP_Set, index, target, expr->type);
+		return;
+	}

> 4. Please, avoid calling assert. Because in case it will fail,
> you won't get the real value, and it will be harder to debug.
> Especially if that test will become flaky some day. Assert is ok,
> if you know for sure what the other value is, or when there is a
> function/cycle, which can't print directly to the output.

Got it, tests fixed.

See new version below:
================================================================================

Currently if a user wants to change session setting with sql, he has
to execute non-obvious query, thus, we introduce a more native way to
do this.

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/session_settings.c         |  9 ++++++
 src/box/session_settings.h         |  3 ++
 src/box/sql/build.c                | 24 +++++++++++++++
 src/box/sql/parse.y                |  5 +++
 src/box/sql/sqlInt.h               | 11 +++++++
 src/box/sql/vdbe.c                 | 44 +++++++++++++++++++++++++++
 test/box/session_settings.result   | 49 ++++++++++++++++++++++++++++++
 test/box/session_settings.test.lua | 13 ++++++++
 8 files changed, 158 insertions(+)

diff --git a/src/box/session_settings.c b/src/box/session_settings.c
index 874fc304a..c7cb4f6d4 100644
--- a/src/box/session_settings.c
+++ b/src/box/session_settings.c
@@ -520,3 +520,12 @@ 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 1f18f147b..34f4aeb7f 100644
--- a/src/box/session_settings.h
+++ b/src/box/session_settings.h
@@ -92,3 +92,6 @@ 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/build.c b/src/box/sql/build.c
index 3da60df86..f0e7df96f 100644
--- a/src/box/sql/build.c
+++ b/src/box/sql/build.c
@@ -3459,3 +3459,27 @@ sql_session_settings_init()
 		setting->set = sql_session_setting_set;
 	}
 }
+
+void
+sql_set_setting(struct Parse *parse_context, struct Token *name,
+		struct Expr *expr)
+{
+	struct Vdbe *vdbe = sqlGetVdbe(parse_context);
+	assert(vdbe != NULL);
+	sqlVdbeCountChanges(vdbe);
+	char *key = sql_name_from_token(sql_get(), 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);
+		sqlVdbeAddOp3(vdbe, OP_Set, index, target, expr->type);
+		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 cfe1c0012..9d9b498a7 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 SET command ////////////////////////////////
+cmd ::= SET nm(X) EQ term(Y).  {
+    sql_set_setting(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 d1fcf4761..5e192a7bb 100644
--- a/src/box/sql/sqlInt.h
+++ b/src/box/sql/sqlInt.h
@@ -4510,4 +4510,15 @@ int
 sql_fieldno_by_name(struct Parse *parse_context, struct Expr *field_name,
 		    uint32_t *fieldno);
 
+/**
+ * Create VDBE instructions to set new value of session setting.
+ *
+ * @param parse_context Parsing context.
+ * @param name Name of the session setting.
+ * @param value New value of the session setting.
+ */
+void
+sql_set_setting(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 eab74db4a..aa6e758c6 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
@@ -5261,6 +5262,49 @@ case OP_IncMaxid: {
 	break;
 }
 
+/* Opcode: Set P1 P2 P3 * *
+ *
+ * Set the new value of the session setting. P1 is the id of the setting
+ * in the session_settings array, P2 is the memory location of the
+ * new value, P3 is its field_type.
+ */
+case OP_Set: {
+	int sid = pOp->p1;
+	pIn1 = &aMem[pOp->p2];
+	assert(sid >= 0 && sid < SESSION_SETTING_COUNT);
+	struct session_setting *setting = &session_settings[sid];
+	switch (pOp->p3) {
+		case FIELD_TYPE_BOOLEAN: {
+			bool value = pIn1->u.b;
+			size_t size = mp_sizeof_bool(value);
+			char *mp_value = (char *)region_alloc(&fiber()->gc,
+							      size);
+			mp_encode_bool(mp_value, value);
+			if (setting->set(sid, mp_value) != 0)
+				goto abort_due_to_error;
+			break;
+		}
+		case FIELD_TYPE_STRING: {
+			const char *str = pIn1->z;
+			size_t len = strlen(str);
+			uint32_t size = mp_sizeof_str(len);
+			char *mp_value = (char *)region_alloc(&fiber()->gc,
+							      size);
+			mp_encode_str(mp_value, str, len);
+			if (setting->set(sid, mp_value) != 0)
+				goto abort_due_to_error;
+			break;
+		}
+		default:
+			diag_set(ClientError, ER_SESSION_SETTING_INVALID_VALUE,
+				 session_setting_strs[sid],
+				 field_type_strs[setting->metadata.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 403a4506c..42cc123a4 100644
--- a/test/box/session_settings.result
+++ b/test/box/session_settings.result
@@ -343,6 +343,39 @@ settings.sql_defer_foreign_keys
  | - false
  | ...
 
+box.execute([[set "sql_default_engine" = 'vinyl']])
+ | ---
+ | - row_count: 1
+ | ...
+s:get('sql_default_engine').value
+ | ---
+ | - vinyl
+ | ...
+box.execute([[set "sql_default_engine" = 'memtx']])
+ | ---
+ | - row_count: 1
+ | ...
+s:get('sql_default_engine').value
+ | ---
+ | - memtx
+ | ...
+box.execute([[set "sql_defer_foreign_keys" = true]])
+ | ---
+ | - row_count: 1
+ | ...
+s:get('sql_defer_foreign_keys').value
+ | ---
+ | - true
+ | ...
+box.execute([[set "sql_defer_foreign_keys" = false]])
+ | ---
+ | - row_count: 1
+ | ...
+s:get('sql_defer_foreign_keys').value
+ | ---
+ | - false
+ | ...
+
 settings.sql_default_engine:set(true)
  | ---
  | - null
@@ -357,3 +390,19 @@ settings.sql_parser_debug:set('string')
  | - null
  | - Session setting sql_parser_debug expected a value of type boolean
  | ...
+
+box.execute([[set "sql_def_engine" = true]])
+ | ---
+ | - null
+ | - Session setting sql_def_engine doesn't exist
+ | ...
+box.execute([[set "sql_default_engine" = true]])
+ | ---
+ | - null
+ | - Session setting sql_default_engine expected a value of type string
+ | ...
+box.execute([[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 99559100d..2dfb201e5 100644
--- a/test/box/session_settings.test.lua
+++ b/test/box/session_settings.test.lua
@@ -132,6 +132,19 @@ s:get('sql_defer_foreign_keys').value
 s:update('sql_defer_foreign_keys', {{'=', 2, false}})
 settings.sql_defer_foreign_keys
 
+box.execute([[set "sql_default_engine" = 'vinyl']])
+s:get('sql_default_engine').value
+box.execute([[set "sql_default_engine" = 'memtx']])
+s:get('sql_default_engine').value
+box.execute([[set "sql_defer_foreign_keys" = true]])
+s:get('sql_defer_foreign_keys').value
+box.execute([[set "sql_defer_foreign_keys" = false]])
+s:get('sql_defer_foreign_keys').value
+
 settings.sql_default_engine:set(true)
 settings.sql_defer_foreign_keys:set(false, 1, 2, 3)
 settings.sql_parser_debug:set('string')
+
+box.execute([[set "sql_def_engine" = true]])
+box.execute([[set "sql_default_engine" = true]])
+box.execute([[set "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]

Thanks for the patch!

I used session_setting_find() in more places;
dropped P3 argument from OP_Set; replaced
region_alloc with static_alloc; added check that
vdbe is not NULL, because sql_set_setting may be the
first called function and may try to create a new
VDBE object; renamed sql_set_setting to sql_setting_set,
because in future we may add GET, and I want their C
emitters have the same prefix - sql_setting_*; made
SET argument expression instead of term, so I could use '?',
which is really useful when dealing with strings, against
SQL injections and to avoid string concatenations in
user's code.

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

commit 81182c89163581cb55fa40552bde779f0bbe025b
Author: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
Date:   Thu Feb 6 22:56:40 2020 +0100

    Review fixes

diff --git a/src/box/session_settings.c b/src/box/session_settings.c
index c7cb4f6d4..3d06a191a 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;
 	}
diff --git a/src/box/sql/build.c b/src/box/sql/build.c
index 259a16ab5..9cbe25443 100644
--- a/src/box/sql/build.c
+++ b/src/box/sql/build.c
@@ -3471,20 +3471,21 @@ sql_session_settings_init()
 }
 
 void
-sql_set_setting(struct Parse *parse_context, struct Token *name,
+sql_setting_set(struct Parse *parse_context, struct Token *name,
 		struct Expr *expr)
 {
 	struct Vdbe *vdbe = sqlGetVdbe(parse_context);
-	assert(vdbe != NULL);
+	if (vdbe == NULL)
+		goto abort;
 	sqlVdbeCountChanges(vdbe);
-	char *key = sql_name_from_token(sql_get(), name);
+	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);
-		sqlVdbeAddOp3(vdbe, OP_Set, index, target, expr->type);
+		sqlVdbeAddOp2(vdbe, OP_Set, index, target);
 		return;
 	}
 	diag_set(ClientError, ER_SQL_PARSER_GENERIC,
diff --git a/src/box/sql/parse.y b/src/box/sql/parse.y
index 9d9b498a7..a01c37e19 100644
--- a/src/box/sql/parse.y
+++ b/src/box/sql/parse.y
@@ -1542,8 +1542,8 @@ cmd ::= DROP INDEX ifexists(E) nm(X) ON fullname(Y).   {
 }
 
 ///////////////////////////// The SET command ////////////////////////////////
-cmd ::= SET nm(X) EQ term(Y).  {
-    sql_set_setting(pParse,&X,Y.pExpr);
+cmd ::= SET nm(X) EQ expr(Y).  {
+    sql_setting_set(pParse,&X,Y.pExpr);
 }
 
 ///////////////////////////// The PRAGMA command /////////////////////////////
diff --git a/src/box/sql/sqlInt.h b/src/box/sql/sqlInt.h
index 5e192a7bb..aabada4a2 100644
--- a/src/box/sql/sqlInt.h
+++ b/src/box/sql/sqlInt.h
@@ -4518,7 +4518,7 @@ sql_fieldno_by_name(struct Parse *parse_context, struct Expr *field_name,
  * @param value New value of the session setting.
  */
 void
-sql_set_setting(struct Parse *parse_context, struct Token *name,
+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 77dcfc57a..282a02b69 100644
--- a/src/box/sql/vdbe.c
+++ b/src/box/sql/vdbe.c
@@ -5262,44 +5262,51 @@ case OP_IncMaxid: {
 	break;
 }
 
-/* Opcode: Set P1 P2 P3 * *
+/* Opcode: Set 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 memory location of the
- * new value, P3 is its field_type.
+ * 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_Set: {
 	int sid = pOp->p1;
 	pIn1 = &aMem[pOp->p2];
 	assert(sid >= 0 && sid < SESSION_SETTING_COUNT);
 	struct session_setting *setting = &session_settings[sid];
-	switch (pOp->p3) {
-		case FIELD_TYPE_BOOLEAN: {
-			bool value = pIn1->u.b;
-			size_t size = mp_sizeof_bool(value);
-			char *mp_value = (char *)region_alloc(&fiber()->gc,
-							      size);
-			mp_encode_bool(mp_value, value);
-			if (setting->set(sid, mp_value) != 0)
-				goto abort_due_to_error;
-			break;
-		}
-		case FIELD_TYPE_STRING: {
-			const char *str = pIn1->z;
-			size_t len = strlen(str);
-			uint32_t size = mp_sizeof_str(len);
-			char *mp_value = (char *)region_alloc(&fiber()->gc,
-							      size);
-			mp_encode_str(mp_value, str, len);
-			if (setting->set(sid, mp_value) != 0)
-				goto abort_due_to_error;
-			break;
+	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;
+		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");
+			goto abort_due_to_error;
 		}
-		default:
-			diag_set(ClientError, ER_SESSION_SETTING_INVALID_VALUE,
-				 session_setting_strs[sid],
-				 field_type_strs[setting->field_type]);
+		mp_encode_str(mp_value, str, len);
+		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;
diff --git a/test/box/session_settings.result b/test/box/session_settings.result
index 9657ba58d..7c9802af6 100644
--- a/test/box/session_settings.result
+++ b/test/box/session_settings.result
@@ -363,7 +363,7 @@ s:get('sql_defer_foreign_keys').value
  | ---
  | - true
  | ...
-box.execute([[set "sql_defer_foreign_keys" = false]])
+box.execute([[set "sql_defer_foreign_keys" = ?]], {false})
  | ---
  | - row_count: 1
  | ...
diff --git a/test/box/session_settings.test.lua b/test/box/session_settings.test.lua
index d0f7ca0f7..f2d7e03f5 100644
--- a/test/box/session_settings.test.lua
+++ b/test/box/session_settings.test.lua
@@ -138,7 +138,7 @@ box.execute([[set "sql_default_engine" = 'memtx']])
 s:get('sql_default_engine').value
 box.execute([[set "sql_defer_foreign_keys" = true]])
 s:get('sql_defer_foreign_keys').value
-box.execute([[set "sql_defer_foreign_keys" = false]])
+box.execute([[set "sql_defer_foreign_keys" = ?]], {false})
 s:get('sql_defer_foreign_keys').value
 
 settings.sql_default_engine:set(true)

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

[Chris Sosnin]

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Hi! Thank you very much for your fixes!

I squashed all of your 4 commits and added some minor changes:
— Fixed indentation in session.c for switch statement
— Removed computation of string length from OP_Set since in struct Mem we have
int n;			/* size (in bytes) of string value, excluding trailing '\0' */

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

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

[Vladislav Shpilevoy]

Hi! Thanks for the fixes!

On the branch you said this commit is 'Part of #4711'. Why
not 'Closes #4711'? What else is left?

>     sql: provide a user friendly frontend for accessing session settings
>     
>     Currently if a user wants to change session setting with sql, he has
>     to execute non-obvious query, thus, we introduce a more native way to
>     do this.
>     
>     Part of #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 accessible right after
>     session creation. The syntax is the following:

Lets say it is available always. Because a user can't live without
a session anyway. It always exists for a user.

>     `box.session.settings.<setting_name>:set(<new_value>)`.
>     
>     Example of usage:
>     ```
>     tarantool> box.session.settings.sql_default_engine
>     ---
>     - memtx
>     ...
>     
>     tarantool> box.session.settings.sql_default_engine:set('vinyl')
>     ---
>     ...
>     
>     ```
>     
>     The table itself represents the (unordered) result of select
>     from _session_settings space. Every setting is implemented as
>     a table, so there is no way to retrieve an actual value and use
>     it until :get() method is introduced.
>     
>     SQL:
>     Instead of typing long UPDATE query one can use the SET statement:
>     `box.execute([[SET "<setting_name>" = <new_value>]])`.
>     Note, that this query is case sensitive so the name must be quoted.
>     
>     Example:
>     ```
>     tarantool> box.execute([[set "sql_default_engine" = 'memtx']])
>     ---
>     - row_count: 1
>     ...
>     
>     tarantool> box.execute([[set "sql_defer_foreign_keys" = true]])
>     ---
>     - row_count: 1
>     ...
>     
>     ```

I am not so sure about binary search anymore. I just found another
probably much faster way - perfect hash function. There is a GNU
tool 'gperf' to generate C code for a given keyset with hash
calculation and search functions.

I fed our settings to it and obtained not so scary result.

File: test.gperf

    %%
    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
    %%

Command: gperf test.gperf > test.c

The test.c file is 122 lines long including some {}, useless
checks, macros, and comments. It could easily be compacted a lot.

This is probably overkill though. It needs to be completely
regenerated each time when the keyset is changed, consumes more
static memory.

The patchset LGTM. I propose to send it to Nikita on a second
review.

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

[Chris Sosnin]

[-- Attachment #1: Type: text/plain, Size: 3823 bytes --]



> 11 февр. 2020 г., в 01:09, Vladislav Shpilevoy <v.shpilevoy@tarantool.org> написал(а):
> 
> Hi! Thanks for the fixes!
> 
> On the branch you said this commit is 'Part of #4711'. Why
> not 'Closes #4711'? What else is left?
> 
Replaced with ‘Closes’.

>>    sql: provide a user friendly frontend for accessing session settings
>> 
>>    Currently if a user wants to change session setting with sql, he has
>>    to execute non-obvious query, thus, we introduce a more native way to
>>    do this.
>> 
>>    Part of #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 accessible right after
>>    session creation. The syntax is the following:
> 
> Lets say it is available always. Because a user can't live without
> a session anyway. It always exists for a user.
Commited the following change:

which is accessible right after session creation —> which is always accessible
to user


>>    `box.session.settings.<setting_name>:set(<new_value>)`.
>> 
>>    Example of usage:
>>    ```
>>    tarantool> box.session.settings.sql_default_engine
>>    ---
>>    - memtx
>>    ...
>> 
>>    tarantool> box.session.settings.sql_default_engine:set('vinyl')
>>    ---
>>    ...
>> 
>>    ```
>> 
>>    The table itself represents the (unordered) result of select
>>    from _session_settings space. Every setting is implemented as
>>    a table, so there is no way to retrieve an actual value and use
>>    it until :get() method is introduced.
>> 
>>    SQL:
>>    Instead of typing long UPDATE query one can use the SET statement:
>>    `box.execute([[SET "<setting_name>" = <new_value>]])`.
>>    Note, that this query is case sensitive so the name must be quoted.
>> 
>>    Example:
>>    ```
>>    tarantool> box.execute([[set "sql_default_engine" = 'memtx']])
>>    ---
>>    - row_count: 1
>>    ...
>> 
>>    tarantool> box.execute([[set "sql_defer_foreign_keys" = true]])
>>    ---
>>    - row_count: 1
>>    ...
>> 
>>    ```
> 
> I am not so sure about binary search anymore. I just found another
> probably much faster way - perfect hash function. There is a GNU
> tool 'gperf' to generate C code for a given keyset with hash
> calculation and search functions.
> 
> I fed our settings to it and obtained not so scary result.
> 
> File: test.gperf
> 
>    %%
>    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
>    %%
> 
> Command: gperf test.gperf > test.c
> 
> The test.c file is 122 lines long including some {}, useless
> checks, macros, and comments. It could easily be compacted a lot.
I like the idea of speeding search up, but it would make adding new settings
even more complicated (+regenerate file with gpref, +mannualy format it).

> 
> This is probably overkill though. It needs to be completely
> regenerated each time when the keyset is changed, consumes more
> static memory.
I agree.

> 
> The patchset LGTM. I propose to send it to Nikita on a second
> review.

Nikita, please do a second review.

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

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

[Nikita Pettik]

On 17 Feb 14:46, Chris Sosnin wrote:
> 
> 
> > 11 февр. 2020 г., в 01:09, Vladislav Shpilevoy <v.shpilevoy@tarantool.org> написал(а):
> > 
> > The patchset LGTM. I propose to send it to Nikita on a second
> > review.
> 
> Nikita, please do a second review.

Could you resend whole patch-set?
 
> branch: https://github.com/tarantool/tarantool/tree/ksosnin/gh-4712-search-settings <https://github.com/tarantool/tarantool/tree/ksosnin/gh-4712-search-settings>
> issue #1: https://github.com/tarantool/tarantool/issues/4711 <https://github.com/tarantool/tarantool/issues/4711>
> issue #2: https://github.com/tarantool/tarantool/issues/4712 <https://github.com/tarantool/tarantool/issues/4712>