db: connection pool (#24161)

vlib/db/mysql/pool.v

@@ -0,0 +1,38 @@
+module mysql
+
+pub struct ConnectionPool {
+mut:
+	connections chan DB
+	config      Config
+}
+
+// new_connection_pool creates a new connection pool with the given size and configuration.
+pub fn new_connection_pool(config Config, size int) !ConnectionPool {
+	mut connections := chan DB{cap: size}
+	for _ in 0 .. size {
+		conn := connect(config)!
+		connections <- conn
+	}
+	return ConnectionPool{
+		connections: connections
+		config:      config
+	}
+}
+
+// acquire gets a connection from the pool
+pub fn (mut pool ConnectionPool) acquire() !DB {
+	return <-pool.connections or { return error('Failed to acquire a connection from the pool') }
+}
+
+// release returns a connection back to the pool.
+pub fn (mut pool ConnectionPool) release(conn DB) {
+	pool.connections <- conn
+}
+
+// close closes all connections in the pool.
+pub fn (mut pool ConnectionPool) close() {
+	for _ in 0 .. pool.connections.len {
+		mut conn := <-pool.connections or { break }
+		conn.close()
+	}
+}

vlib/db/pg/pool.v

@@ -0,0 +1,38 @@
+module pg
+
+pub struct ConnectionPool {
+mut:
+	connections chan DB
+	config      Config
+}
+
+// new_connection_pool creates a new connection pool with the given size and configuration.
+pub fn new_connection_pool(config Config, size int) !ConnectionPool {
+	mut connections := chan DB{cap: size}
+	for _ in 0 .. size {
+		conn := connect(config)!
+		connections <- conn
+	}
+	return ConnectionPool{
+		connections: connections
+		config:      config
+	}
+}
+
+// acquire gets a connection from the pool
+pub fn (mut pool ConnectionPool) acquire() !DB {
+	return <-pool.connections or { return error('Failed to acquire a connection from the pool') }
+}
+
+// release returns a connection back to the pool.
+pub fn (mut pool ConnectionPool) release(conn DB) {
+	pool.connections <- conn
+}
+
+// close closes all connections in the pool.
+pub fn (mut pool ConnectionPool) close() {
+	for _ in 0 .. pool.connections.len {
+		conn := <-pool.connections or { break }
+		conn.close()
+	}
+}

vlib/db/sqlite/pool.v

@@ -0,0 +1,38 @@
+module sqlite
+
+pub struct ConnectionPool {
+mut:
+	connections chan DB
+	config      string
+}
+
+// new_connection_pool creates a new connection pool with the given size and configuration.
+pub fn new_connection_pool(config string, size int) !ConnectionPool {
+	mut connections := chan DB{cap: size}
+	for _ in 0 .. size {
+		conn := connect(config)!
+		connections <- conn
+	}
+	return ConnectionPool{
+		connections: connections
+		config:      config
+	}
+}
+
+// acquire gets a connection from the pool
+pub fn (mut pool ConnectionPool) acquire() !DB {
+	return <-pool.connections or { return error('Failed to acquire a connection from the pool') }
+}
+
+// release returns a connection back to the pool.
+pub fn (mut pool ConnectionPool) release(conn DB) {
+	pool.connections <- conn
+}
+
+// close closes all connections in the pool.
+pub fn (mut pool ConnectionPool) close() {
+	for _ in 0 .. pool.connections.len {
+		mut conn := <-pool.connections or { break }
+		conn.close() or { panic('Failed to close connection: ${err}') }
+	}
+}