public override IFetchedJob FetchNextJob([NotNull] string[] queues, CancellationToken cancellationToken)
{
if (queues == null)
{
throw new ArgumentNullException(nameof(queues));
}
string jobId = null;
string queueName = null;
do
{
cancellationToken.ThrowIfCancellationRequested();
for (int i = 0; i < queues.Length; i++)
{
queueName = queues[i];
var queueKey = _storage.GetRedisKey($"queue:{queueName}");
var fetchedKey = _storage.GetRedisKey($"queue:{queueName}:dequeued");
jobId = Redis.ListRightPopLeftPush(queueKey, fetchedKey);
if (jobId != null)
{
break;
}
}
if (jobId == null)
{
_subscription.WaitForJob(_fetchTimeout, cancellationToken);
}
}while (jobId == null);
// The job was fetched by the server. To provide reliability,
// we should ensure, that the job will be performed and acquired
// resources will be disposed even if the server will crash
// while executing one of the subsequent lines of code.
// The job's processing is splitted into a couple of checkpoints.
// Each checkpoint occurs after successful update of the
// job information in the storage. And each checkpoint describes
// the way to perform the job when the server was crashed after
// reaching it.
// Checkpoint #1-1. The job was fetched into the fetched list,
// that is being inspected by the FetchedJobsWatcher instance.
// Job's has the implicit 'Fetched' state.
Redis.HashSet(
_storage.GetRedisKey($"job:{jobId}"),
"Fetched",
JobHelper.SerializeDateTime(DateTime.UtcNow));
// Checkpoint #2. The job is in the implicit 'Fetched' state now.
// This state stores information about fetched time. The job will
// be re-queued when the JobTimeout will be expired.
return(new RedisFetchedJob(_storage, Redis, jobId, queueName));
}
/// <summary>
/// 拉取下一个作业
/// </summary>
/// <param name="queues">队列数组</param>
/// <param name="cancellationToken">取消令牌</param>
public override IFetchedJob FetchNextJob([NotNull] string[] queues, CancellationToken cancellationToken)
{
if (queues == null)
{
throw new ArgumentNullException(nameof(queues));
}
string jobId = null;
string queueName = null;
do
{
cancellationToken.ThrowIfCancellationRequested();
foreach (var queue in queues)
{
queueName = queue;
var queueKey = _storage.GetRedisKey($"queue:{queueName}");
var fetchedKey = _storage.GetRedisKey($"queue:{queueName}:dequeued");
jobId = RedisClient.RPopLPush(queueKey, fetchedKey);
if (jobId != null)
{
break;
}
}
if (jobId == null)
{
_subscription.WaitForJob(_fetchTimeout, cancellationToken);
}
} while (jobId == null);
RedisClient.HSet(_storage.GetRedisKey($"job:{jobId}"), "Fetched", JobHelper.SerializeDateTime(DateTime.UtcNow));
return(new RedisFetchedJob(_storage, RedisClient, jobId, queueName));
}
