Pool::release

Release a resource back to the pool.

Pool::release ​

(PHP 8.6+, True Async 1.0)

php
public Pool::release(mixed $resource): void

Returns a previously acquired resource back to the pool. If a beforeRelease hook was set when creating the pool, it is called before the return. If the hook returns false, the resource is destroyed instead of being returned to the pool.

If there are coroutines waiting for a resource via acquire(), the resource is immediately handed to the first waiting coroutine.

Parameters ​

resource : A resource previously acquired via acquire() or tryAcquire().

Return Value ​

No value is returned.

Examples ​

Example #1 Safe return via finally ​

php
<?php

use Async\Pool;

$pool = new Pool(
    factory: fn() => new PDO('mysql:host=localhost;dbname=app', 'user', 'pass'),
    max: 10
);

$conn = $pool->acquire();

try {
    $conn->beginTransaction();
    $conn->exec("INSERT INTO logs (message) VALUES ('event')");
    $conn->commit();
} catch (\Throwable $e) {
    $conn->rollBack();
    throw $e;
} finally {
    $pool->release($conn);
}

Example #2 Automatic destruction via beforeRelease ​

php
<?php

use Async\Pool;

$pool = new Pool(
    factory: fn() => new TcpClient('api.example.com', 443),
    destructor: fn(TcpClient $c) => $c->disconnect(),
    beforeRelease: function(TcpClient $client): bool {
        // If the connection is broken — do not return to the pool
        return $client->isAlive();
    },
    max: 5
);

$client = $pool->acquire();

try {
    $client->send('PING');
} finally {
    // If isAlive() returns false, the client will be destroyed
    $pool->release($client);
}

See Also ​