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

[Chris Sosnin <k.sosnin@tarantool.org>]

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)