Update documentation and conn:reset()

README.md

@@ -27,6 +27,21 @@ make
 make install
 ```
 
+#### Run tests
+
+To run the tests, the following preparatory steps must be completed:
+* Run mysql instance.
+* Connect a client to the instance and execute the commands:
+  * `CREATE USER 'test_user' IDENTIFIED WITH mysql_native_password BY 'pass';`
+  * `CREATE DATABASE tarantool_mysql_test;`
+  * `GRANT ALL PRIVILEGES ON *.* TO 'test_user';`
+* Define MYSQL environment variable using the following format:<br/>
+`ip:port:user:user_pass:db_name:`<br/>
+Example:<br/>
+`export MYSQL=127.0.0.1:3306:test_user:pass:tarantool_mysql_test:`
+
+The tests can now be run by `make check`.
+
 #### tarantoolctl rocks
 
 You can also use tarantoolctl rocks:
@@ -77,18 +92,20 @@ Connect to a database.
  - `use_numeric_result` - provide result of the "conn:execute" as ordered list
    (true/false); default value: false
 
+Throws an error on failure.
+
 *Returns*:
 
  - `connection ~= nil` on success
- - `error(reason)` on error
 
 ### `conn:execute(statement, ...)`
 
 Execute a statement with arguments in the current transaction.
 
+Throws an error on failure.
+
 *Returns*:
 
- - `error(reason)` on error
  - `results, true` on success, where `results` is in the following form:
 
 (when `use_numeric_result = false` or is not set on a pool/connection creation)
@@ -165,10 +182,23 @@ Execute a dummy statement to check that connection is alive.
 
 Quote a query string.
 
+Throws an error on failure.
+
 *Returns*:
 
  - `quoted_string` on success
- - `error(reason)` on error
+
+### `conn:reset(user, pass, db)`
+
+Update the connection authentication settings.
+
+*Options*:
+
+ - `user` - username
+ - `pass` - password
+ - `db` - database name
+
+Throws an error on failure.
 
 ### `pool = mysql.pool_create(opts)`
 
@@ -185,10 +215,11 @@ Create a connection pool with count of size established connections.
  - `use_numeric_result` - provide result of the "conn:execute" as ordered list
    (true/false); default value: false
 
+Throws an error on failure.
+
 *Returns*
 
  - `pool ~= nil` on success
- - `error(reason)` on error
 
 ### `conn = pool:get(opts)`
 

mysql/driver.c

@@ -663,9 +663,14 @@ lua_mysql_reset(lua_State *L)
 	const char *user = lua_tostring(L, 2);
 	const char *pass = lua_tostring(L, 3);
 	const char *db = lua_tostring(L, 4);
-	mysql_change_user(raw_conn, user, pass, db);
 
-	return 0;
+	if (mysql_change_user(raw_conn, user, pass, db) == 0) {
+		lua_pushboolean(L, 1);
+	} else {
+		lua_pushboolean(L, 0);
+	}
+
+	return 1;
 }
 
 LUA_API int

mysql/init.lua

@@ -41,7 +41,7 @@ local function conn_get(pool, timeout)
                                             pool.user, pool.pass,
                                             pool.db, pool.use_numeric_result)
         if status < 0 then
-            return error(mysql_conn)
+            error(mysql_conn)
         end
     end
 
@@ -70,11 +70,11 @@ conn_mt = {
     __index = {
         execute = function(self, sql, ...)
             if not self.usable then
-                return error('Connection is not usable')
+                error('Connection is not usable')
             end
             if not self.queue:get() then
                 self.queue:put(false)
-                return error('Connection is broken')
+                error('Connection is broken')
             end
             local status, datas
             if select('#', ...) > 0 then
@@ -84,7 +84,7 @@ conn_mt = {
             end
             if status ~= 0 then
                 self.queue:put(status > 0)
-                return error(datas)
+                error(datas)
             end
             self.queue:put(true)
             return datas, true
@@ -104,11 +104,11 @@ conn_mt = {
         end,
         close = function(self)
             if not self.usable then
-                return error('Connection is not usable')
+                error('Connection is not usable')
             end
             if not self.queue:get() then
                 self.queue:put(false)
-                return error('Connection is broken')
+                error('Connection is broken')
             end
             self.usable = false
             self.conn:close()
@@ -117,22 +117,28 @@ conn_mt = {
         end,
         reset = function(self, user, pass, db)
             if not self.usable then
-                return error('Connection is not usable')
+                error('Connection is not usable')
             end
             if not self.queue:get() then
                 self.queue:put(false)
-                return error('Connection is broken')
+                error('Connection is broken')
+            end
+            -- If the update of the connection settings fails, we must set
+            -- the connection to a "broken" state and throw an error.
+            local status = self.conn:reset(user, pass, db)
+            if not status then
+                self.queue:put(false)
+                error('Сonnection settings update failed.')
             end
-            self.conn:reset(user, pass, db)
             self.queue:put(true)
         end,
 	quote = function(self, value)
             if not self.usable then
-                return error('Connection is not usable')
+                error('Connection is not usable')
             end
             if not self.queue:get() then
                 self.queue:put(false)
-                return error('Connection is broken')
+                error('Connection is broken')
             end
             local ret = self.conn:quote(value)
             self.queue:put(true)
@@ -158,7 +164,7 @@ local function pool_create(opts)
                 mysql_conn:close()
             end
             if status < 0 then
-                return error(conn)
+                error(conn)
             end
         end
         queue:put(conn)
@@ -197,7 +203,7 @@ local function pool_get(self, opts)
     opts = opts or {}
 
     if not self.usable then
-        return error('Pool is not usable')
+        error('Pool is not usable')
     end
     local conn = conn_get(self, opts.timeout)
 
@@ -234,7 +240,7 @@ local function connect(opts)
                                               opts.user, opts.password,
                                               opts.db, opts.use_numeric_result)
     if status < 0 then
-        return error(mysql_conn)
+        error(mysql_conn)
     end
     return conn_create(mysql_conn)
 end

test/mysql.test.lua

@@ -431,8 +431,40 @@ local function test_connection_pool(test, pool)
     -- }}}
 end
 
+local function test_connection_reset(test, pool)
+    test:plan(2)
+
+    assert(pool.queue:is_full(), 'test case precondition fails')
+
+    -- Case: valid credentials were used to "reset" the connection
+    test:test('reset connection successfully', function(test)
+        test:plan(1)
+
+        assert(pool.size >= 1, 'test case precondition fails')
+
+        local conn = pool:get()
+        conn:reset(pool.user, pool.pass, pool.db)
+        test:ok(conn:ping(), 'connection "reset" successfully')
+        pool:put(conn)
+    end)
+
+    -- Case: invalid credentials were used to "reset" the connection
+    test:test('reset connection failed', function(test)
+        test:plan(1)
+
+        assert(pool.size >= 1, 'test case precondition fails')
+
+        local conn = pool:get()
+        local check = pcall(conn.reset, conn, "guinea pig", pool.pass, pool.db)
+        test:ok(not check, 'connection "reset" fails')
+        pool:put(conn)
+    end)
+
+    assert(pool.queue:is_full(), 'test case postcondition fails')
+end
+
 local test = tap.test('mysql connector')
-test:plan(6)
+test:plan(7)
 
 test:test('connection old api', test_old_api, conn)
 local pool_conn = p:get()
@@ -442,6 +474,7 @@ test:test('garbage collection', test_gc, p)
 test:test('concurrent connections', test_conn_concurrent, p)
 test:test('int64', test_mysql_int64, p)
 test:test('connection pool', test_connection_pool, p)
+test:test('connection reset', test_connection_reset, p)
 p:close()
 
 os.exit(test:check() and 0 or 1)