From bab3f23189efa6820d26b4db291b14641cc7cb39 Mon Sep 17 00:00:00 2001
From: Hitalo Souza <enghitalo@gmail.com>
Date: Thu, 10 Apr 2025 01:17:32 +0100
Subject: [PATCH] db: connection pool (#24161)

---
 vlib/db/mysql/pool.v  | 38 ++++++++++++++++++++++++++++++++++++++
 vlib/db/pg/pool.v     | 38 ++++++++++++++++++++++++++++++++++++++
 vlib/db/sqlite/pool.v | 38 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 114 insertions(+)
 create mode 100644 vlib/db/mysql/pool.v
 create mode 100644 vlib/db/pg/pool.v
 create mode 100644 vlib/db/sqlite/pool.v

diff --git a/vlib/db/mysql/pool.v b/vlib/db/mysql/pool.v
new file mode 100644
index 0000000000..648921fb8f
--- /dev/null
+++ b/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()
+	}
+}
diff --git a/vlib/db/pg/pool.v b/vlib/db/pg/pool.v
new file mode 100644
index 0000000000..e8a32591d2
--- /dev/null
+++ b/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()
+	}
+}
diff --git a/vlib/db/sqlite/pool.v b/vlib/db/sqlite/pool.v
new file mode 100644
index 0000000000..a37b6c26c2
--- /dev/null
+++ b/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}') }
+	}
+}