Initial commit

src/Lock/FileLock.php

@@ -0,0 +1,88 @@
+<?php
+
+namespace NoccyLabs\Ipc\Lock;
+
+/**
+ * Simple filesystem-based lock
+ * 
+ * 
+ */
+class FileLock
+{
+    const DEFAULT_TIMEOUT = 5;
+
+    protected $pathname;
+
+    protected $resource;
+
+    protected $locked = false;
+
+    /**
+     * Constructor
+     *
+     * @param string $pathname
+     */
+    public function __construct(string $pathname)
+    {
+        if (!file_exists($pathname)) {
+            throw new \RuntimeException(sprintf(
+                "The file %s does not exist",
+                $pathname
+            ));
+        }
+
+        $this->pathname = $pathname;
+        $this->resource = fopen($pathname, "r");
+    }
+
+    public function __destruct()
+    {
+        $this->release();
+        fclose($this->resource);
+    }
+
+    /**
+     * Acquire an exclusive lock
+     *
+     * @param float $timeout
+     * @return boolean
+     */
+    public function acquire(float $timeout = self::DEFAULT_TIMEOUT):bool
+    {
+        if ($this->locked) {
+            return true;
+        }
+
+        $expire = microtime(true) + $timeout;
+        while (!flock($this->resource, LOCK_EX|LOCK_NB)) {
+            if (microtime(true)>$expire) {
+                return false;
+            }
+            usleep(1000);
+        }
+
+        $this->locked = true;
+        return true;
+    }
+
+    /**
+     * Release an acquired lock
+     *
+     * @return void
+     */
+    public function release()
+    {
+        flock($this->resource, LOCK_UN);
+        $this->locked = false;
+    }
+
+    /**
+     * Check if the lock is acquired
+     *
+     * @return boolean
+     */
+    public function isLocked():bool
+    {
+        return $this->locked;
+    }
+}