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vendor/yiisoft/yii2/mutex/Mutex.php

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+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\mutex;
+
+use yii\base\Component;
+
+/**
+ * The Mutex component allows mutual execution of concurrent processes in order to prevent "race conditions".
+ *
+ * This is achieved by using a "lock" mechanism. Each possibly concurrent thread cooperates by acquiring
+ * a lock before accessing the corresponding data.
+ *
+ * Usage example:
+ *
+ * ```
+ * if ($mutex->acquire($mutexName)) {
+ *     // business logic execution
+ * } else {
+ *     // execution is blocked!
+ * }
+ * ```
+ *
+ * This is a base class, which should be extended in order to implement the actual lock mechanism.
+ *
+ * @author resurtm <resurtm@gmail.com>
+ * @since 2.0
+ */
+abstract class Mutex extends Component
+{
+    /**
+     * @var bool whether all locks acquired in this process (i.e. local locks) must be released automatically
+     * before finishing script execution. Defaults to true. Setting this property to true means that all locks
+     * acquired in this process must be released (regardless of errors or exceptions).
+     */
+    public $autoRelease = true;
+
+    /**
+     * @var string[] names of the locks acquired by the current PHP process.
+     */
+    private $_locks = [];
+
+
+    /**
+     * Initializes the Mutex component.
+     */
+    public function init()
+    {
+        if ($this->autoRelease) {
+            $locks = &$this->_locks;
+            register_shutdown_function(function () use (&$locks) {
+                foreach ($locks as $lock) {
+                    $this->release($lock);
+                }
+            });
+        }
+    }
+
+    /**
+     * Acquires a lock by name.
+     * @param string $name of the lock to be acquired. Must be unique.
+     * @param int $timeout time (in seconds) to wait for lock to be released. Defaults to zero meaning that method will return
+     * false immediately in case lock was already acquired.
+     * @return bool lock acquiring result.
+     */
+    public function acquire($name, $timeout = 0)
+    {
+        if ($this->acquireLock($name, $timeout)) {
+            $this->_locks[] = $name;
+
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * Releases acquired lock. This method will return false in case the lock was not found.
+     * @param string $name of the lock to be released. This lock must already exist.
+     * @return bool lock release result: false in case named lock was not found..
+     */
+    public function release($name)
+    {
+        if ($this->releaseLock($name)) {
+            $index = array_search($name, $this->_locks);
+            if ($index !== false) {
+                unset($this->_locks[$index]);
+            }
+
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * This method should be extended by a concrete Mutex implementations. Acquires lock by name.
+     * @param string $name of the lock to be acquired.
+     * @param int $timeout time (in seconds) to wait for the lock to be released.
+     * @return bool acquiring result.
+     */
+    abstract protected function acquireLock($name, $timeout = 0);
+
+    /**
+     * This method should be extended by a concrete Mutex implementations. Releases lock by given name.
+     * @param string $name of the lock to be released.
+     * @return bool release result.
+     */
+    abstract protected function releaseLock($name);
+}