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PhabricatorWorker.php
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Wed, Jun 4, 07:46

PhabricatorWorker.php
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<?php
/**
* @task config Configuring Retries and Failures
*/
abstract class PhabricatorWorker extends Phobject {
private $data;
private static $runAllTasksInProcess = false;
private $queuedTasks = array();
private $currentWorkerTask;
// NOTE: Lower priority numbers execute first. The priority numbers have to
// have the same ordering that IDs do (lowest first) so MySQL can use a
// multipart key across both of them efficiently.
const PRIORITY_ALERTS = 1000;
const PRIORITY_DEFAULT = 2000;
const PRIORITY_BULK = 3000;
const PRIORITY_IMPORT = 4000;
/**
* Special owner indicating that the task has yielded.
*/
const YIELD_OWNER = '(yield)';
/* -( Configuring Retries and Failures )----------------------------------- */
/**
* Return the number of seconds this worker needs hold a lease on the task for
* while it performs work. For most tasks you can leave this at `null`, which
* will give you a default lease (currently 2 hours).
*
* For tasks which may take a very long time to complete, you should return
* an upper bound on the amount of time the task may require.
*
* @return int|null Number of seconds this task needs to remain leased for,
* or null for a default lease.
*
* @task config
*/
public function getRequiredLeaseTime() {
return null;
}
/**
* Return the maximum number of times this task may be retried before it is
* considered permanently failed. By default, tasks retry indefinitely. You
* can throw a @{class:PhabricatorWorkerPermanentFailureException} to cause an
* immediate permanent failure.
*
* @return int|null Number of times the task will retry before permanent
* failure. Return `null` to retry indefinitely.
*
* @task config
*/
public function getMaximumRetryCount() {
return null;
}
/**
* Return the number of seconds a task should wait after a failure before
* retrying. For most tasks you can leave this at `null`, which will give you
* a short default retry period (currently 60 seconds).
*
* @param PhabricatorWorkerTask The task itself. This object is probably
* useful mostly to examine the failure count
* if you want to implement staggered retries,
* or to examine the execution exception if
* you want to react to different failures in
* different ways.
* @return int|null Number of seconds to wait between retries,
* or null for a default retry period
* (currently 60 seconds).
*
* @task config
*/
public function getWaitBeforeRetry(PhabricatorWorkerTask $task) {
return null;
}
public function setCurrentWorkerTask(PhabricatorWorkerTask $task) {
$this->currentWorkerTask = $task;
return $this;
}
public function getCurrentWorkerTask() {
return $this->currentWorkerTask;
}
public function getCurrentWorkerTaskID() {
$task = $this->getCurrentWorkerTask();
if (!$task) {
return null;
}
return $task->getID();
}
abstract protected function doWork();
final public function __construct($data) {
$this->data = $data;
}
final protected function getTaskData() {
return $this->data;
}
final protected function getTaskDataValue($key, $default = null) {
$data = $this->getTaskData();
if (!is_array($data)) {
throw new PhabricatorWorkerPermanentFailureException(
pht('Expected task data to be a dictionary.'));
}
return idx($data, $key, $default);
}
final public function executeTask() {
$this->doWork();
}
final public static function scheduleTask(
$task_class,
$data,
$options = array()) {
PhutilTypeSpec::checkMap(
$options,
array(
'priority' => 'optional int|null',
'objectPHID' => 'optional string|null',
'delayUntil' => 'optional int|null',
));
$priority = idx($options, 'priority');
if ($priority === null) {
$priority = self::PRIORITY_DEFAULT;
}
$object_phid = idx($options, 'objectPHID');
$task = id(new PhabricatorWorkerActiveTask())
->setTaskClass($task_class)
->setData($data)
->setPriority($priority)
->setObjectPHID($object_phid);
$delay = idx($options, 'delayUntil');
if ($delay) {
$task->setLeaseExpires($delay);
}
if (self::$runAllTasksInProcess) {
// Do the work in-process.
$worker = newv($task_class, array($data));
while (true) {
try {
$worker->executeTask();
$worker->flushTaskQueue();
break;
} catch (PhabricatorWorkerYieldException $ex) {
phlog(
pht(
'In-process task "%s" yielded for %s seconds, sleeping...',
$task_class,
$ex->getDuration()));
sleep($ex->getDuration());
}
}
// Now, save a task row and immediately archive it so we can return an
// object with a valid ID.
$task->openTransaction();
$task->save();
$archived = $task->archiveTask(
PhabricatorWorkerArchiveTask::RESULT_SUCCESS,
0);
$task->saveTransaction();
return $archived;
} else {
$task->save();
return $task;
}
}
public function renderForDisplay(PhabricatorUser $viewer) {
return null;
}
/**
* Set this flag to execute scheduled tasks synchronously, in the same
* process. This is useful for debugging, and otherwise dramatically worse
* in every way imaginable.
*/
public static function setRunAllTasksInProcess($all) {
self::$runAllTasksInProcess = $all;
}
final protected function log($pattern /* , ... */) {
$console = PhutilConsole::getConsole();
$argv = func_get_args();
call_user_func_array(array($console, 'writeLog'), $argv);
return $this;
}
/**
* Queue a task to be executed after this one succeeds.
*
* The followup task will be queued only if this task completes cleanly.
*
* @param string Task class to queue.
* @param array Data for the followup task.
* @param array Options for the followup task.
* @return this
*/
final protected function queueTask(
$class,
array $data,
array $options = array()) {
$this->queuedTasks[] = array($class, $data, $options);
return $this;
}
/**
* Get tasks queued as followups by @{method:queueTask}.
*
* @return list<tuple<string, wild, int|null>> Queued task specifications.
*/
final protected function getQueuedTasks() {
return $this->queuedTasks;
}
/**
* Schedule any queued tasks, then empty the task queue.
*
* By default, the queue is flushed only if a task succeeds. You can call
* this method to force the queue to flush before failing (for example, if
* you are using queues to improve locking behavior).
*
* @param map<string, wild> Optional default options.
* @return this
*/
final public function flushTaskQueue($defaults = array()) {
foreach ($this->getQueuedTasks() as $task) {
list($class, $data, $options) = $task;
$options = $options + $defaults;
self::scheduleTask($class, $data, $options);
}
$this->queuedTasks = array();
}
/**
* Awaken tasks that have yielded.
*
* Reschedules the specified tasks if they are currently queued in a yielded,
* unleased, unretried state so they'll execute sooner. This can let the
* queue avoid unnecessary waits.
*
* This method does not provide any assurances about when these tasks will
* execute, or even guarantee that it will have any effect at all.
*
* @param list<id> List of task IDs to try to awaken.
* @return void
*/
final public static function awakenTaskIDs(array $ids) {
if (!$ids) {
return;
}
$table = new PhabricatorWorkerActiveTask();
$conn_w = $table->establishConnection('w');
// NOTE: At least for now, we're keeping these tasks yielded, just
// pretending that they threw a shorter yield than they really did.
// Overlap the windows here to handle minor client/server time differences
// and because it's likely correct to push these tasks to the head of their
// respective priorities. There is a good chance they are ready to execute.
$window = phutil_units('1 hour in seconds');
$epoch_ago = (PhabricatorTime::getNow() - $window);
queryfx(
$conn_w,
'UPDATE %T SET leaseExpires = %d
WHERE id IN (%Ld)
AND leaseOwner = %s
AND leaseExpires > %d
AND failureCount = 0',
$table->getTableName(),
$epoch_ago,
$ids,
self::YIELD_OWNER,
$epoch_ago);
}
}

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