Initial Commit

dependencies/amphp/sync/src/LocalSemaphore.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace WP_Ultimo\Dependencies\Amp\Sync;
+
+use WP_Ultimo\Dependencies\Amp\CallableMaker;
+use WP_Ultimo\Dependencies\Amp\Deferred;
+use WP_Ultimo\Dependencies\Amp\Promise;
+use WP_Ultimo\Dependencies\Amp\Success;
+class LocalSemaphore implements Semaphore
+{
+    use CallableMaker;
+    // kept for BC only
+    /** @var int[] */
+    private $locks;
+    /** @var Deferred[] */
+    private $queue = [];
+    public function __construct(int $maxLocks)
+    {
+        if ($maxLocks < 1) {
+            throw new \Error('The number of locks must be greater than 0');
+        }
+        $this->locks = \range(0, $maxLocks - 1);
+    }
+    /** {@inheritdoc} */
+    public function acquire() : Promise
+    {
+        if (!empty($this->locks)) {
+            return new Success(new Lock(\array_shift($this->locks), \Closure::fromCallable([$this, 'release'])));
+        }
+        $this->queue[] = $deferred = new Deferred();
+        return $deferred->promise();
+    }
+    private function release(Lock $lock) : void
+    {
+        $id = $lock->getId();
+        if (!empty($this->queue)) {
+            $deferred = \array_shift($this->queue);
+            $deferred->resolve(new Lock($id, \Closure::fromCallable([$this, 'release'])));
+            return;
+        }
+        $this->locks[] = $id;
+    }
+}