/// <summary>
/// Adds a task to the queue specified in the task itself and sends a message to
/// the associated channel, notifying any listeners.
/// </summary>
/// <param name="t"></param>
public void Enqueue(TaskMessage t)
{
if (string.IsNullOrEmpty(t.Queue))
throw new NoQueueSpecifiedException(
"TaskMessage.Queue is empty or null. Cannot append task to queue.");
var queue = new QueueName(t.Queue);
_taskMessageClient.Lists[queue.NameWhenPending].Add(t);
SendMessage(QueueSystemMessages.TaskAvailable.ToString(), queue);
_log.Info("New task in [" + queue.NameWhenPending + "]");
_log.DebugFormat("Task Parameters: {0}", t.Parameters);
}
/// <summary>
/// Obtains the first available task from the specified queue, and changes the client's
/// state into TaskReserved. In that state, no new tasks can be reserved until the
/// task's outcome is evident.
/// </summary>
/// <param name="queue"></param>
/// <returns></returns>
public TaskMessage Reserve(QueueName queue)
{
if (_state == RedisQueueState.TaskReserved)
throw new TaskAlreadyReservedException("Cannot reserve multiple tasks at once.");
if (string.IsNullOrEmpty(queue.ToString()))
throw new NoQueueSpecifiedException(
"Parameter <queue> is empty or null. Cannot retrieve task for no queue.");
if (_taskMessageClient.Lists[queue.NameWhenPending].Count == 0)
throw new QueueIsEmptyException("No tasks available in specified queue.");
CurrentTask = _taskMessageClient.Lists[queue.NameWhenPending].RemoveStart();
_state = RedisQueueState.TaskReserved;
_log.Info("Reserved task from [" + queue.NameWhenPending + "]");
_log.DebugFormat("Task Parameters: {0}", CurrentTask.Parameters);
return CurrentTask;
}
/// <summary>
/// Removes a task with a specific task identifier.
/// </summary>
/// <param name="task"></param>
public void RemoveTask(TaskMessage task)
{
var queueName = new QueueName(task.Queue);
removeTask(queueName.NameWhenPending, task);
removeTask(queueName.NameWhenFailed, task);
removeTask(queueName.NameWhenSucceeded, task);
}
private void removeTask(string queue, TaskMessage task)
{
var results = new List<TaskMessage>();
TaskMessage t;
while((t = _taskMessageClient.Lists[queue].RemoveStart()) != null)
{
if (t.Equals(task)) continue;
results.Add(t);
}
if (results.Count > 0)
_taskMessageClient.Lists[queue].AddRange(results);
}
public bool Equals(TaskMessage other)
{
if (ReferenceEquals(null, other)) return false;
if (ReferenceEquals(this, other)) return true;
return Equals(other._queue, _queue) && other.Identifier.Equals(Identifier) && Equals(other.Parameters, Parameters);
}