Added lock for when checking and updating pids

src/Schedule/Event.php

@@ -569,6 +569,16 @@ public function pids(): array
 
         $pidsFile = $this->lockFile();
 
+        /**
+         * Lock this process but does not stop race if you call schedule:run twice at the same time
+         * which you should not.
+         */
+        $lock = new Lock('event-' . $this->id());
+
+        if (! $lock->acquire()) {
+            throw new RuntimeException('Error getting lock');
+        }
+
         if (file_exists($pidsFile)) {
             $contents = file_get_contents($pidsFile);
 

src/Schedule/Lock.php

@@ -0,0 +1,118 @@
+<?php
+/**
+ * OriginPHP Framework
+ * Copyright 2018 - 2021 Jamiel Sharief.
+ *
+ * Licensed under The MIT License
+ * The above copyright notice and this permission notice shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * @copyright   Copyright (c) Jamiel Sharief
+ * @link        https://www.originphp.com
+ * @license     https://opensource.org/licenses/mit-license.php MIT License
+ */
+declare(strict_types = 1);
+namespace Origin\Schedule;
+
+use Exception;
+use LogicException;
+use RuntimeException;
+
+/**
+ * New class, this might be eventually moved into own namespace or into filesystem, not
+ * sure yet.
+ */
+class Lock
+{
+    const BLOCKING = LOCK_EX;
+    const NON_BLOCKING = LOCK_EX | LOCK_NB;
+
+    /**
+     * Path to lock file
+     *
+     * @var string
+     */
+    private $path;
+
+    /**
+     * File pointer
+     *
+     * @var resource
+     */
+    private $fp = null;
+
+    /**
+     * @param string $path
+     */
+    public function __construct(string $name)
+    {
+        $this->path = sys_get_temp_dir() . "/{$name}.lock";
+    }
+
+    /**
+     * Acquires a lock, if it cannot get a lock it will return false.
+     *
+     * @param boolean $block
+     * @return boolean
+     */
+    public function acquire(bool $block = true): bool
+    {
+        if ($this->fp) {
+            throw new LogicException('Lock has already been acquired');
+        }
+
+        touch($this->path); // Ensure file exists
+
+        $this->fp = fopen($this->path, 'r+');
+        if (! $this->fp) {
+            throw new RuntimeException('Error opening file');
+        }
+
+        if (! flock($this->fp, $block ? self::BLOCKING : self::NON_BLOCKING)) {
+            $this->closeFile();
+
+            return false;
+        }
+
+        return ftruncate($this->fp, 0) && fwrite($this->fp, (string) getmypid()) && fflush($this->fp);
+    }
+
+    /**
+     * Releases the lock
+     *
+     * @return void
+     */
+    public function release(): void
+    {
+        if (! $this->fp) {
+            throw new LogicException('Lock was not acquired');
+        }
+
+        if (! flock($this->fp, LOCK_UN)) {
+            throw new RuntimeException('Error releasing lock');
+        }
+
+        $this->closeFile();
+    }
+
+    /**
+     * Close the file if its still open
+     */
+    public function __destruct()
+    {
+        $this->closeFile();
+    }
+
+    /**
+     * Closes the file and cleans up
+     *
+     * @return void
+     */
+    private function closeFile(): void
+    {
+        if ($this->fp && ! fclose($this->fp)) {
+            throw new Exception('Error closing file');
+        }
+        $this->fp = null;
+    }
+}

tests/TestCase/Schedule/LockTest.php

@@ -0,0 +1,74 @@
+<?php
+/**
+ * OriginPHP Framework
+ * Copyright 2018 - 2021 Jamiel Sharief.
+ *
+ * Licensed under The MIT License
+ * The above copyright notice and this permission notice shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * @copyright   Copyright (c) Jamiel Sharief
+ * @link        https://www.originphp.com
+ * @license     https://opensource.org/licenses/mit-license.php MIT License
+ */
+namespace Origin\Test\TestCase\Schedule;
+
+use LogicException;
+use Origin\Schedule\Lock;
+
+class LockTest extends \PHPUnit\Framework\TestCase
+{
+    public function testAcquire()
+    {
+        $lock = new Lock('test');
+        $file = sys_get_temp_dir() . '/test.lock';
+        $this->assertFileDoesNotExist($file);
+        $this->assertTrue($lock->acquire());
+        $this->assertFileExists($file);
+        $this->assertEquals((string) getmypid(), trim(file_get_contents($file)));
+    }
+
+    public function testAcquireAlreadyLocked()
+    {
+        $lock = new Lock('test');
+        $this->assertTrue($lock->acquire());
+
+        $this->expectException(LogicException::class);
+        $lock->acquire();
+    }
+
+    public function testAcquireUnableToGetLock()
+    {
+        $lock1 = new Lock('test');
+        $lock2 = new Lock('test');
+
+        $this->assertTrue($lock1->acquire());
+        $this->assertFalse($lock2->acquire(false));
+    }
+
+    public function testRelease()
+    {
+        $lock1 = new Lock('test');
+        $lock2 = new Lock('test');
+
+        $this->assertTrue($lock1->acquire());
+        $this->assertFalse($lock2->acquire(false));
+        $lock1->release();
+        $this->assertTrue($lock2->acquire(false));
+    }
+
+    public function testReleaseNotAcquired()
+    {
+        $lock = new Lock('test');
+        $this->expectException(LogicException::class);
+        $lock->release();
+    }
+
+    protected function setUp(): void
+    {
+        $file = sys_get_temp_dir() . '/test.lock';
+        if (file_exists($file)) {
+            unlink($file);
+        }
+    }
+}