db: modify mysql/pg/sqlite interface for pool working (#24780)

Author: kbkpbot

examples/database/mysql.v

@@ -13,5 +13,5 @@ fn main() {
 	for row in res.rows() {
 		println(row.vals.join(', '))
 	}
-	conn.close()
+	conn.close()!
 }

examples/database/mysql_pool.v

@@ -0,0 +1,159 @@
+// vtest build: !(macos || windows)
+import db.mysql
+import pool
+import time
+
+// Define your connection factory function
+fn create_conn() !&pool.ConnectionPoolable {
+	config := mysql.Config{
+		host:     '127.0.0.1'
+		port:     3306
+		username: 'root'
+		password: '12345678'
+		dbname:   'mysql'
+	}
+	db := mysql.connect(config)!
+	return &db
+}
+
+fn main() {
+	// Configure pool parameters
+	config := pool.ConnectionPoolConfig{
+		max_conns:      50
+		min_idle_conns: 5
+		max_lifetime:   2 * time.hour
+		idle_timeout:   30 * time.minute
+		get_timeout:    5 * time.second
+	}
+
+	// Create connection pool
+	mut my_pool := pool.new_connection_pool(create_conn, config)!
+	defer {
+		// When application exits
+		my_pool.close()
+	}
+
+	// Acquire connection
+	mut conn := my_pool.get()!
+	defer {
+		// Return connection to pool
+		my_pool.put(conn) or { println(err) }
+	}
+
+	// Convert `conn` to a `mysql.DB` object
+	mut db := conn as mysql.DB
+
+	assert db.validate()!
+
+	mut response := db.exec('drop table if exists users')!
+	assert response == []mysql.Row{}
+
+	response = db.exec('create table if not exists users (
+                        id INT PRIMARY KEY AUTO_INCREMENT,
+                        username TEXT,
+						last_name TEXT NULL DEFAULT NULL
+                      )')!
+	assert response == []mysql.Row{}
+
+	mut result_code := db.exec_none('insert into users (username) values ("jackson")')
+	assert result_code == 0
+	result_code = db.exec_none('insert into users (username) values ("shannon")')
+	assert result_code == 0
+	result_code = db.exec_none('insert into users (username) values ("bailey")')
+	assert result_code == 0
+	result_code = db.exec_none('insert into users (username) values ("blaze")')
+	assert result_code == 0
+	rows := db.exec_param('insert into users (username) values (?)', 'Hi')!
+	assert rows == []mysql.Row{}
+
+	// Regression testing to ensure the query and exec return the same values
+	res := db.query('select * from users')!
+	response = res.rows()
+	assert response[0].vals[1] == 'jackson'
+	response = db.exec('select * from users')!
+	assert response[0].vals[1] == 'jackson'
+
+	response = db.exec('select * from users where id = 400')!
+	assert response.len == 0
+
+	single_row := db.exec_one('select * from users')!
+	assert single_row.vals[1] == 'jackson'
+
+	response = db.exec_param_many('select * from users where username = ?', [
+		'jackson',
+	])!
+	assert response[0] == mysql.Row{
+		vals: ['1', 'jackson', '']
+	}
+
+	response = db.exec_param_many('select * from users where username = ? and id = ?',
+		['bailey', '3'])!
+	assert response[0] == mysql.Row{
+		vals: ['3', 'bailey', '']
+	}
+
+	response = db.exec_param_many('select * from users', [''])!
+	assert response == [
+		mysql.Row{
+			vals: ['1', 'jackson', '']
+		},
+		mysql.Row{
+			vals: ['2', 'shannon', '']
+		},
+		mysql.Row{
+			vals: ['3', 'bailey', '']
+		},
+		mysql.Row{
+			vals: ['4', 'blaze', '']
+		},
+		mysql.Row{
+			vals: ['5', 'Hi', '']
+		},
+	]
+
+	response = db.exec_param('select * from users where username = ?', 'blaze')!
+	assert response[0] == mysql.Row{
+		vals: ['4', 'blaze', '']
+	}
+
+	// transaction test
+	// turn off `autocommit` first
+	db.autocommit(false)!
+	// begin a new transaction
+	db.begin()!
+	result_code = db.exec_none('insert into users (username) values ("tom")')
+	assert result_code == 0
+	// make a savepoint
+	db.savepoint('savepoint1')!
+	result_code = db.exec_none('insert into users (username) values ("kitty")')
+	assert result_code == 0
+	// rollback to `savepoint1`
+	db.rollback_to('savepoint1')!
+	result_code = db.exec_none('insert into users (username) values ("mars")')
+	assert result_code == 0
+	db.commit()!
+	response = db.exec_param_many('select * from users', [''])!
+	assert response == [
+		mysql.Row{
+			vals: ['1', 'jackson', '']
+		},
+		mysql.Row{
+			vals: ['2', 'shannon', '']
+		},
+		mysql.Row{
+			vals: ['3', 'bailey', '']
+		},
+		mysql.Row{
+			vals: ['4', 'blaze', '']
+		},
+		mysql.Row{
+			vals: ['5', 'Hi', '']
+		},
+		mysql.Row{
+			vals: ['6', 'tom', '']
+		},
+		mysql.Row{
+			vals: ['8', 'mars', '']
+		},
+	]
+}

examples/database/orm.v

@@ -110,7 +110,7 @@ fn msql_array() ! {
 		sql db {
 			drop table Parent
 		} or {}
-		db.close()
+		db.close() or {}
 	}
 
 	db.query('drop table if exists Parent')!
@@ -144,7 +144,7 @@ fn psql_array() ! {
 	mut db := pg.connect(host: pg_host, user: pg_user, password: pg_pass, dbname: pg_db)!
 	defer {
 		db.exec_one('drop table if exists "Parent", "Child"') or { eprintln(err) }
-		db.close()
+		db.close() or {}
 	}
 	db.exec_one('drop table if exists "Parent", "Child"') or { eprintln(err) }
 
@@ -219,7 +219,7 @@ fn msql() ! {
 	defer {
 		conn.query('DROP TABLE IF EXISTS Module') or { eprintln(err) }
 		conn.query('DROP TABLE IF EXISTS User') or { eprintln(err) }
-		conn.close()
+		conn.close() or {}
 	}
 	conn.query('DROP TABLE IF EXISTS Module') or { eprintln(err) }
 	conn.query('DROP TABLE IF EXISTS User') or { eprintln(err) }
@@ -253,7 +253,7 @@ fn psql() ! {
 	mut db := pg.connect(host: pg_host, user: pg_user, password: pg_pass, dbname: pg_db)!
 	defer {
 		db.exec_one('drop table if exists "modules", "User"') or { eprintln(err) }
-		db.close()
+		db.close() or {}
 	}
 	db.exec_one('drop table if exists "modules", "User"') or { eprintln(err) }
 	sql db {

vlib/db/mysql/mysql.c.v

@@ -330,12 +330,10 @@ pub fn (mut db DB) refresh(options u32) !bool {
 }
 
 // reset resets the connection, and clear the session state.
-pub fn (mut db DB) reset() !bool {
+pub fn (mut db DB) reset() ! {
 	if C.mysql_reset_connection(db.conn) != 0 {
 		db.throw_mysql_error()!
 	}
-
-	return true
 }
 
 // ping pings a server connection, or tries to reconnect if the connection
@@ -348,8 +346,14 @@ pub fn (mut db DB) ping() !bool {
 	return true
 }
 
+// validate pings a server connection, or tries to reconnect if the connection
+// has gone down.
+pub fn (mut db DB) validate() !bool {
+	return db.ping()!
+}
+
 // close closes the connection.
-pub fn (mut db DB) close() {
+pub fn (mut db DB) close() ! {
 	C.mysql_close(db.conn)
 }
 

vlib/db/mysql/mysql_orm_test.v

@@ -58,7 +58,7 @@ fn test_mysql_orm() {
 		dbname:   'mysql'
 	)!
 	defer {
-		db.close()
+		db.close() or {}
 	}
 	table := orm.Table{
 		name: 'Test'

vlib/db/mysql/mysql_test.v

@@ -16,6 +16,11 @@ fn test_mysql() {
 	}
 
 	mut db := mysql.connect(config)!
+	defer {
+		db.close() or {}
+	}
+
+	assert db.validate()!
 
 	mut response := db.exec('drop table if exists users')!
 	assert response == []mysql.Row{}

vlib/db/mysql/pool.v

@@ -33,6 +33,6 @@ pub fn (mut pool ConnectionPool) release(conn DB) {
 pub fn (mut pool ConnectionPool) close() {
 	for _ in 0 .. pool.connections.len {
 		mut conn := <-pool.connections or { break }
-		conn.close()
+		conn.close() or { break }
 	}
 }

vlib/db/pg/pg.c.v

@@ -224,7 +224,7 @@ fn res_to_rows(res voidptr) []Row {
 }
 
 // close frees the underlying resource allocated by the database connection
-pub fn (db &DB) close() {
+pub fn (db &DB) close() ! {
 	C.PQfinish(db.conn)
 }
 
@@ -510,3 +510,13 @@ pub fn (db &DB) savepoint(savepoint string) ! {
 		return error('pg exec error: "${e}"')
 	}
 }
+
+// validate checks if the connection is still usable
+pub fn (db &DB) validate() !bool {
+	db.exec_one('SELECT 1')!
+	return true
+}
+
+// reset returns the connection to initial state for reuse
+pub fn (db &DB) reset() ! {
+}

vlib/db/pg/pg_double_test.v

@@ -19,7 +19,7 @@ fn test_float_field() {
 	conn := 'host=localhost user=postgres password=12345678' // insert own connection string
 	db := pg.connect_with_conninfo(conn)!
 	defer {
-		db.close()
+		db.close() or {}
 	}
 
 	sql db {

vlib/db/pg/pg_orm_test.v

@@ -57,7 +57,7 @@ fn test_pg_orm() {
 	) or { panic(err) }
 
 	defer {
-		db.close()
+		db.close() or {}
 	}
 	table := orm.Table{
 		name: 'Test'