From cef9d803cb2cef11d69d6b77fb1ba5c600ec50cc Mon Sep 17 00:00:00 2001
From: Ben Roberts <ben@sihnon.net>
Date: Sat, 31 Dec 2011 02:09:26 +0000
Subject: [PATCH] Add daemon for process locking

---
 source/lib/SihnonFramework/Daemon.class.php   | 50 +++++++++++++++++++
 .../lib/SihnonFramework/Exceptions.class.php  |  4 ++
 2 files changed, 54 insertions(+)
 create mode 100644 source/lib/SihnonFramework/Daemon.class.php

diff --git a/source/lib/SihnonFramework/Daemon.class.php b/source/lib/SihnonFramework/Daemon.class.php
new file mode 100644
index 0000000..0fc3d5b
--- /dev/null
+++ b/source/lib/SihnonFramework/Daemon.class.php
@@ -0,0 +1,50 @@
+<?php
+
+class SihnonFramework_Daemon {
+    
+    protected $config;
+    
+    protected $lock_file;
+    protected $lock;
+    protected $locked;
+    
+    public function __construct(SihnonFramework_Config $config) {
+        $this->config = $config;
+        $this->lock_file = $config->get('daemon.lock-file');
+        $this->lock = null;
+        $this->locked = false;
+        
+        $this->init();
+    }
+    
+    public function __destruct() {
+        $this->teardown();
+    }
+    
+    protected function init() {
+        $this->lock = fopen($this->lock_file, 'w');
+        $wouldBlock = false;
+        
+        $result = flock($this->lock, LOCK_EX|LOCK_NB, $wouldBlock);
+        if ($wouldBlock) {
+            // Another instance is already running
+            throw new SihnonFramework_Exception_AlreadyRunning();
+        } else if ( ! $result) {
+            throw new SihnonFramework_Exception_LockingFailed();
+        }
+        
+        
+    }
+    
+    protected function teardown() {
+        if ( ! $this->locked) {
+            return;
+        }
+        
+        flock($this->lock, LOCK_UN);
+        fclose($this->lock);
+        unlink($this->lock_file);
+    }
+}
+
+?>
\ No newline at end of file
diff --git a/source/lib/SihnonFramework/Exceptions.class.php b/source/lib/SihnonFramework/Exceptions.class.php
index bf0b0a0..c67f4d3 100644
--- a/source/lib/SihnonFramework/Exceptions.class.php
+++ b/source/lib/SihnonFramework/Exceptions.class.php
@@ -48,4 +48,8 @@ class SihnonFramework_Exception_ValidationException    extends SihnonFramework_E
 class SihnonFramework_Exception_InvalidContent         extends SihnonFramework_Exception_ValidationException {};
 class SihnonFramework_Exception_InvalidLength          extends SihnonFramework_Exception_ValidationException {};
 
+class SihnonFramework_Exception_DaemonException        extends SihnonFramework_Exception {};
+class SihnonFramework_Exception_AlreadyRunning         extends SihnonFramework_Exception_DaemonException {};
+class SihnonFramework_Exception_LockingFailed          extends SihnonFramework_Exception_DaemonException {};
+
 ?>