private void ProcessQueue(string queue, RedisConnection connection)
{
// Allowing only one server at a time to process the timed out
// jobs from the specified queue.
Logger.DebugFormat(
"Acquiring the lock for the fetched list of the '{0}' queue...", queue);
using (connection.Redis.AcquireLock(
String.Format(RedisStorage.Prefix + "queue:{0}:dequeued:lock", queue),
_options.FetchedLockTimeout))
{
Logger.DebugFormat(
"Looking for timed out jobs in the '{0}' queue...", queue);
var jobIds = connection.Redis.GetAllItemsFromList(
String.Format(RedisStorage.Prefix + "queue:{0}:dequeued", queue));
var requeued = 0;
foreach (var jobId in jobIds)
{
if (RequeueJobIfTimedOut(connection, jobId, queue))
{
requeued++;
}
}
if (requeued == 0)
{
Logger.DebugFormat("No timed out jobs were found in the '{0}' queue", queue);
}
else
{
Logger.InfoFormat(
"{0} timed out jobs were found in the '{1}' queue and re-queued.",
requeued,
queue);
}
}
}
private bool RequeueJobIfTimedOut(RedisConnection connection, string jobId, string queue)
{
var flags = connection.Redis.HashGet(
string.Format(RedisStorage.Prefix + "job:{0}", jobId),
new RedisValue[]{"Fetched","Checked"});
var fetched = flags[0];
var @checked = flags[1];
if (string.IsNullOrEmpty(fetched) && string.IsNullOrEmpty(@checked))
{
// If the job does not have these flags set, then it is
// in the implicit 'Fetched' state. This state has no
// information about the time it was fetched. So we
// can not do anything with the job in this state, because
// there are two options:
// 1. It is going to move to the implicit 'Fetched' state
// in a short time.
// 2. It will stay in the 'Fetched' state forever due to
// its processing server is dead.
// To ensure its server is dead, we'll move the job to
// the implicit 'Checked' state with the current timestamp
// and will not do anything else at this pass of the watcher.
// If job's state will still be 'Checked' on the later passes
// and after the CheckedTimeout expired, then the server
// is dead, and we'll re-queue the job.
connection.Redis.HashSet(
string.Format(RedisStorage.Prefix + "job:{0}", jobId),
"Checked",
JobHelper.SerializeDateTime(DateTime.UtcNow));
// Checkpoint #1-2. The job is in the implicit 'Checked' state.
// It will be re-queued after the CheckedTimeout will be expired.
}
else
{
if (TimedOutByFetchedTime(fetched) || TimedOutByCheckedTime(fetched, @checked))
{
var fetchedJob = new RedisFetchedJob(connection.Redis, jobId, queue);
fetchedJob.Dispose();
return true;
}
}
return false;
}