134 lines
3.8 KiB
PHP
134 lines
3.8 KiB
PHP
<?php
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/**
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* FileLock.php
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*
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* -Description-
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* @package LibreNMS
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* @link http://librenms.org
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* @copyright 2017 Tony Murray
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* @author Tony Murray <murraytony@gmail.com>
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*/
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namespace LibreNMS\Util;
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use LibreNMS\Exceptions\LockException;
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use LibreNMS\Interfaces\Lock;
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class FileLock implements Lock
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{
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private $name;
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private $file;
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/**
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* @var resource | false
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*/
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private $handle;
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private $acquired = false;
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private function __construct($lock_name)
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{
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global $config;
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$this->name = $lock_name;
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$this->file = "$config[install_dir]/.$lock_name.lock";
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$this->handle = fopen($this->file, "w+");
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}
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public function __destruct()
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{
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$this->release();
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}
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/**
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* Release the lock.
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*/
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public function release()
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{
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if (!$this->acquired) {
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return;
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}
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if (is_resource($this->handle)) {
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flock($this->handle, LOCK_UN);
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fclose($this->handle);
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}
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if (file_exists($this->file)) {
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unlink($this->file);
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}
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}
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/**
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* Given a lock name, try to acquire the lock.
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* On success return a Lock object, or on failure return false.
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* @param string $lock_name Name of lock
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* @param int $wait Try for this many seconds to see if we can acquire the lock. Default is no wait. A negative timeout will wait forever.
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* @param int $expire Expire is unsupported for file lock at this time.
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* @return Lock
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* @throws LockException
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*/
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public static function lock($lock_name, $wait = 0, $expire = 0)
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{
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$lock = new self($lock_name);
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if ($lock->handle === false) {
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throw new LockException("Failed to acquire lock $lock_name");
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}
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// try to acquire the lock each second until we reach the timeout, once if timeout is 0, forever if timeout < 0
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for ($i = 0; $i <= $wait || $wait < 0; $i++) {
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if (flock($lock->handle, $wait < 0 ? LOCK_EX : LOCK_EX | LOCK_NB)) {
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$lock->acquired = true;
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return $lock;
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}
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if ($wait) {
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sleep(1);
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}
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}
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throw new LockException("Failed to acquire lock $lock_name");
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}
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/**
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* Given a lock name, try to acquire the lock, exiting on failure.
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* On success return a Lock object.
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* @param string $lock_name Name of lock
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* @param int $timeout Try for this many seconds to see if we can acquire the lock. Default is no wait. A negative timeout will wait forever.
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* @return \LibreNMS\Interfaces\Lock|false
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*/
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public static function lockOrDie($lock_name, $timeout = 0)
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{
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try {
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return self::lock($lock_name, $timeout);
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} catch (LockException $e) {
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echo $e->getMessage() . PHP_EOL;
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exit(1);
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}
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}
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/**
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* Renew an expiring lock
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*
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* @param int $expiration number of seconds to hold lock for (null to cancel expiration)
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*/
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public function renew($expiration)
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{
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echo "Unsupported";
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// TODO: Implement renew() method.
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}
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}
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