<?php
/****************************************************************************
	 For license information see doc/license.txt

	 Unicode Reminder メモ

	 synchronization of processes which must not run concurrently

 ****************************************************************************/

	class ProcessSync
	{
		var $pidfile_path;


		function __construct($name)
		{
			global $opt;
			$this->pidfile_path = $opt['rootpath'] . "cache2/$name.pid";
		}


		// Enter code section which must not run concurrently

		function Enter()
		{
			if (!$this->CheckDaemon())
				return false;

			if (file_exists($this->pidfile_path))
			{
				echo "Error: Pidfile (".$this->pidfile_path.") already present\n";
				return false;
			}
			else
			{
				if ($pidfile = @fopen($this->pidfile_path, "w"))
				{
					fputs($pidfile, posix_getpid());
					fclose($pidfile);
					return true;
				}
				else
				{
					echo "can't create Pidfile ".$this->pidfile_path."\n";
					return false;
				}
			}
		}


		// checks if other instance of process is running

		private function CheckDaemon()
		{
			if ($pidfile = @fopen($this->pidfile_path, "r"))
			{
				$pid_daemon = fgets($pidfile, 20);
				fclose($pidfile);

				$pid_daemon = (int)$pid_daemon;

				// process running?
				if (posix_kill($pid_daemon, 0))
				{
					// yes, good bye
					echo "Error: process for ".$this->pidfile_path. " is already running with pid=$pid_daemon\n";
					false;
				}
				else
				{
					// no, remove pid_file
					echo "process not running, removing old pid_file (".$this->pidfile_path.")\n";
					unlink($this->pidfile_path);
					return true;
				}
			}
			else
			{
				return true;
			}
		}


		// Leave code section which must not run concurrently

		function Leave($message = false)
		{
			if ($pidfile = @fopen($this->pidfile_path, "r"))
			{
				$pid = fgets($pidfile, 20);
				fclose($pidfile);
				if ($pid == posix_getpid())
					unlink($this->pidfile_path);
			}
			else
			{
				echo "Error: can't delete own pidfile (".$this->pidfile_path.")\n";
			}

			if ($message)
			{
				echo $message . "\n";
			}
		}

	}

?>