79 lines
1.9 KiB
PHP
79 lines
1.9 KiB
PHP
<?php
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namespace Friendica\Util;
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/**
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* @file src/Util/Lock.php
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* @brief Functions for preventing parallel execution of functions
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*
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*/
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use dba;
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use dbm;
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/**
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* @brief This class contain Functions for preventing parallel execution of functions
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*/
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class Lock {
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/**
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* @brief Sets a lock for a given name
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*
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* @param string $fn_name Name of the lock
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* @param integer $timeout Seconds until we give up
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* @param integer $wait_sec Time between to lock attempts
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*
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* @return boolean Was the lock successful?
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*/
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public static function set($fn_name, $timeout = 30, $wait_sec = 2) {
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if ($wait_sec == 0) {
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$wait_sec = 2;
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}
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$got_lock = false;
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$start = time();
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do {
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dba::p("LOCK TABLE `locks` WRITE");
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$lock = dba::select('locks', array('locked', 'pid'), array('name' => $fn_name), array('limit' => 1));
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if (dbm::is_result($lock)) {
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if ($lock['locked']) {
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// When the process id isn't used anymore, we can safely claim the lock for us.
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if (!posix_kill($lock['pid'], 0)) {
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$lock['locked'] = false;
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}
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// We want to lock something that was already locked by us? So we got the lock.
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if ($lock['pid'] == getmypid()) {
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$got_lock = true;
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}
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}
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if (!$lock['locked']) {
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dba::update('locks', array('locked' => true, 'pid' => getmypid()), array('name' => $fn_name));
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$got_lock = true;
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}
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} elseif (!dbm::is_result($lock)) {
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dba::insert('locks', array('name' => $fn_name, 'locked' => true, 'pid' => getmypid()));
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$got_lock = true;
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}
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dba::p("UNLOCK TABLES");
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if (!$got_lock) {
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sleep($wait_sec);
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}
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} while (!$got_lock AND ((time() - $start) < $timeout));
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return $got_lock;
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}
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/**
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* @brief Removes a lock if it was set by us
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*
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* @param string $fn_name Name of the lock
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*/
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public static function remove($fn_name) {
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dba::update('locks', array('locked' => false, 'pid' => 0), array('name' => $fn_name, 'pid' => getmypid()));
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return;
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}
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}
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