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Locks now work - ready to be used in the wild

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Michael 2017-06-04 08:36:08 +00:00
parent 32f61016d3
commit 5de03c1b27
1 changed files with 35 additions and 18 deletions
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51
src/Util/Lock.php
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@ -16,11 +16,16 @@ use dbm;
*/ */
class Lock { class Lock {
/**
// Provide some ability to lock a PHP function so that multiple processes * @brief Sets a lock for a given name
// can't run the function concurrently *
* @param string $fn_name Name of the lock
public static function set($fn_name, $wait_sec = 2, $timeout = 30) { * @param integer $timeout Seconds until we give up
* @param integer $wait_sec Time between to lock attempts
*
* @return boolean Was the lock successful?
*/
public static function set($fn_name, $timeout = 30, $wait_sec = 2) {
if ($wait_sec == 0) { if ($wait_sec == 0) {
$wait_sec = 2; $wait_sec = 2;
} }
@ -29,34 +34,46 @@ class Lock {
$start = time(); $start = time();
do { do {
dba:p("LOCK TABLE `locks` WRITE"); dba::p("LOCK TABLE `locks` WRITE");
$lock = dba::select('locks', array('locked'), array('name' => $fn_name), array('limit' => 1)); $lock = dba::select('locks', array('locked', 'pid'), array('name' => $fn_name), array('limit' => 1));
if ((dbm::is_result($lock)) AND !$lock['locked']) { if (dbm::is_result($lock)) {
dba::update('locks', array('locked' => true), array('name' => $fn_name)); if ($lock['locked']) {
// When the process id isn't used anymore, we can safely claim the lock for us.
if (!posix_kill($lock['pid'], 0)) {
$lock['locked'] = false;
}
// We want to lock something that was already locked by us? So we got the lock.
if ($lock['pid'] == getmypid()) {
$got_lock = true; $got_lock = true;
}
}
if (!$lock['locked']) {
dba::update('locks', array('locked' => true, 'pid' => getmypid()), array('name' => $fn_name));
$got_lock = true;
}
} elseif (!dbm::is_result($lock)) { } elseif (!dbm::is_result($lock)) {
dbm::insert('locks', array('name' => $fn_name, 'locked' => true)); dba::insert('locks', array('name' => $fn_name, 'locked' => true, 'pid' => getmypid()));
$got_lock = true; $got_lock = true;
} }
dbm::p("UNLOCK TABLES"); dba::p("UNLOCK TABLES");
if (!$got_lock) { if (!$got_lock) {
sleep($wait_sec); sleep($wait_sec);
} }
} while (!$got_lock AND ((time() - $start) < $timeout)); } while (!$got_lock AND ((time() - $start) < $timeout));
logger('lock_function: function ' . $fn_name . ' with blocking = ' . $block . ' got_lock = ' . $got_lock . ' time = ' . (time() - $start), LOGGER_DEBUG);
return $got_lock; return $got_lock;
} }
/**
* @brief Removes a lock if it was set by us
*
* @param string $fn_name Name of the lock
*/
public static function remove($fn_name) { public static function remove($fn_name) {
dba::update('locks', array('locked' => false), array('name' => $fn_name)); dba::update('locks', array('locked' => false, 'pid' => 0), array('name' => $fn_name, 'pid' => getmypid()));
logger('unlock_function: released lock for function ' . $fn_name, LOGGER_DEBUG);
return; return;
} }
} }