<?php

/** DomFramework
  * @package domframework
  * @author Dominique Fournier <dominique@fournier38.fr>
  * @license BSD
  */

namespace Domframework;

/** The lock management of files
  */
class Lockfile
{
    /** The Exclusive lock file */
    public $storagelock = "./data/lockfile.lock";
    /** The Read-Only lock file */
    private $storagelockRO = false;

    /** This function lock the storage file until all is written.
        If an other processus want to lock, it hang until the lock is released */
    public function lockRW()
    {
        if (!is_dir(dirname($this->storagelock))) {
            @mkdir(dirname($this->storagelock));
        }
        if (!is_dir(dirname($this->storagelock))) {
            throw new \Exception(
                "Can't create '" . dirname($this->storagelock) .
                           "' directory for lockfile",
                500
            );
        }
        $lockid = uniqid() . '_' . md5(mt_rand());
        $startTime = microtime(true);
        // Stale lock : 60s old min
        if (
            file_exists($this->storagelock) &&
            filemtime($this->storagelock) < time() - 60
        ) {
            // TODO : Log the Stale lock removing
            unlink($this->storagelock);
        }

        // Wait RW Lock
        while (1) {
            while (file_exists($this->storagelock)) {
                usleep(100000);
                clearstatcache(true, $this->storagelock);
                if (microtime(true) > $startTime + 10) {
                    throw new \Exception(
                        "Can't have the authorization lock RW in 10s",
                        500
                    );
                }
            }

            file_put_contents($this->storagelock, $lockid, FILE_APPEND);
            clearstatcache(true, $this->storagelock);
            $cnt = file_get_contents($this->storagelock);
            if (substr($cnt, 0, strlen($lockid)) === $lockid) {
                break;
            }
        }

        // Wait all the RO lock to go away
        $startTime = microtime(true);
        while (count(glob($this->storagelock . "-*")) > 0) {
            usleep(100000);
            if (microtime(true) > $startTime + 10) {
                throw new \Exception(
                    "Can't have the authorization lock RO in 10s",
                    500
                );
            }
        }

        // I have the lock and no RO lock !
        return true;
    }

    /** This function lock the storage in share mode (to read the file without
        modification at the same time) */
    public function lockRO()
    {
        if (!is_dir(dirname($this->storagelock))) {
            @mkdir(dirname($this->storagelock));
        }
        if (!is_dir(dirname($this->storagelock))) {
            throw new \Exception(
                "Can't create '" . dirname($this->storagelock) . "'",
                500
            );
        }
        $lockid = uniqid() . '_' . md5(mt_rand());
        // Stale lock : 60s old min
        if (
            file_exists($this->storagelock) &&
            filemtime($this->storagelock) < time() - 60
        ) {
            // TODO : Log the Stale lock removing
            unlink($this->storagelock);
        }

        // wait the removing of lockRW
        $startTime = microtime(true);
        while (file_exists($this->storagelock)) {
            usleep(100000);
            clearstatcache(true, $this->storagelock);
            if (microtime(true) > $startTime + 10) {
                throw new \Exception("Can't have the authorization lock in 10s", 500);
            }
        }

        touch($this->storagelock . "-" . $lockid);
        $this->storagelockRO = $this->storagelock . "-" . $lockid;
    }

    /** This function unlock RW the storage file */
    public function unlockRW()
    {
        if (file_exists($this->storagelock)) {
            unlink($this->storagelock);
        }
    }

    /** This function unlock RO the storage file */
    public function unlockRO()
    {
        if ($this->storagelockRO !== false && file_exists($this->storagelockRO)) {
            unlink($this->storagelockRO);
        }
    }
}