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

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

- 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)