public static void Delete(Database database, string name)
{
if (database == null)
{
throw new ArgumentNullException("database", "database is null.");
}
if (name == null)
{
throw new ArgumentNullException("name", "name is null.");
}
if (!Queue.Exists(database, name))
{
throw new ArgumentException(string.Format("Queue with the name \"{0}\" not found.", name), "name");
}
if (!Queue.IsEmpty(database, name))
{
throw new InvalidOperationException(string.Format("Failed deleting queue with name \"{0}\", queue is not empty.", name));
}
var queue = Queue.Get(database, name);
queue.QueueLock.EnterWriteLock();
try
{
if (queue.QueuedTasks.Any())
{
throw new InvalidOperationException(string.Format("Failed deleting queue with name \"{0}\", queue is not empty.", name));
}
database.QueuesLock.EnterWriteLock();
try
{
queue.QueuedTasks = null;
database.Queues.Remove(queue.Id);
database.QueueNames.Remove(queue.Name);
}
finally
{
database.QueuesLock.ExitWriteLock();
}
}
finally
{
queue.QueueLock.ExitWriteLock();
}
}
public static QueueTask Dequeue(Database database, string queueName)
{
if (database == null)
{
throw new ArgumentNullException("database", "database is null.");
}
if (queueName == null)
{
throw new ArgumentNullException("queueName", "queueName is null.");
}
if (Queue.IsEmpty(database, queueName))
{
return(null);
}
Workflow workflow;
Task task;
Queue queue;
Guid workflowId, taskId;
for (int attemptNum = 0; attemptNum < MAX_DEQUEUE_ATTEMPTS; attemptNum++)
{
queue = Queue.Get(database, queueName);
queue.QueueLock.EnterReadLock();
try
{
if (queue.QueuedTasks.Count == 0)
{
return(null);
}
var first = queue.QueuedTasks.First.Value;
workflowId = first.Item1;
taskId = first.Item2;
}
finally
{
queue.QueueLock.ExitReadLock();
}
workflow = Workflow.Get(database, workflowId);
if (workflow == null)
{
continue;
}
workflow.WorkflowLock.EnterReadLock();
try
{
task = workflow.Tasks[taskId];
}
finally
{
workflow.WorkflowLock.ExitReadLock();
}
workflow.WorkflowLock.EnterWriteLock();
try
{
queue.QueueLock.EnterWriteLock();
try
{
// Validate state;
if (queue.QueuedTasks.Count == 0)
{
return(null);
}
if (queue.QueuedTasks.First().Item2 != taskId)
{
continue;
}
queue.QueuedTasks.RemoveFirst();
queue.RunningTasks.Add(taskId);
task.State = TaskState.Running;
return(new QueueTask()
{
WorkflowName = workflow.Name,
TaskName = task.Name,
});
}
finally
{
queue.QueueLock.ExitWriteLock();
}
}
finally
{
workflow.WorkflowLock.ExitWriteLock();
}
}
return(null);
}