public static QueueTask Peek(Database database, string queueName)
{
if (database == null)
{
throw new ArgumentNullException("database", "database is null.");
}
if (queueName == null)
{
throw new ArgumentNullException("queueName", "queueName is null.");
}
Guid workflowId, taskId;
var 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();
}
database.WorkflowsLock.EnterReadLock();
try
{
if (!database.Workflows.ContainsKey(workflowId))
{
return(null);
}
var workflow = database.Workflows[workflowId];
workflow.WorkflowLock.EnterReadLock();
try
{
return(new QueueTask()
{
WorkflowName = workflow.Name,
TaskName = workflow.Tasks[taskId].Name,
});
}
finally
{
workflow.WorkflowLock.ExitReadLock();
}
}
finally
{
database.WorkflowsLock.ExitReadLock();
}
}
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);
}
public static void Create(Database database, string workflowName, string name, string queueName)
{
if (database == null)
{
throw new ArgumentNullException("database", "database is null.");
}
if (workflowName == null)
{
throw new ArgumentNullException("workflowName", "workflowName is null.");
}
if (name == null)
{
throw new ArgumentNullException("name", "name is null.");
}
if (queueName == null)
{
throw new ArgumentNullException("queueName", "queueName is null.");
}
Task task;
var workflow = Workflow.Get(database, workflowName);
var queue = Queue.Get(database, queueName);
queue.QueueLock.EnterReadLock();
try
{
task = new Task(name, queue.Id);
}
finally
{
queue.QueueLock.ExitReadLock();
}
database.WorkflowsLock.EnterReadLock();
try
{
if (!database.WorkflowNames.ContainsKey(workflowName))
{
throw new Exception(string.Format("Workflow with the name \"{0}\" not found.", workflowName));
}
workflow = database.Workflows[database.WorkflowNames[workflowName]];
if (workflow.Suspended)
{
workflow.WorkflowLock.EnterUpgradeableReadLock();
try
{
workflow.Tasks.Add(task.Id, task);
workflow.TaskNames.Add(task.Name, task.Id);
}
finally
{
workflow.WorkflowLock.ExitUpgradeableReadLock();
}
}
else
{
database.QueuesLock.EnterReadLock();
try
{
workflow.WorkflowLock.EnterUpgradeableReadLock();
try
{
queue.QueueLock.EnterWriteLock();
try
{
workflow.Tasks.Add(task.Id, task);
workflow.TaskNames.Add(task.Name, task.Id);
queue.QueuedTasks.AddLast(new LinkedListNode <Tuple <Guid, Guid> >(new Tuple <Guid, Guid>(workflow.Id, task.Id)));
}
finally
{
queue.QueueLock.ExitWriteLock();
}
}
finally
{
workflow.WorkflowLock.ExitUpgradeableReadLock();
}
}
finally
{
database.QueuesLock.ExitReadLock();
}
}
}
finally
{
database.WorkflowsLock.ExitReadLock();
}
}
public static void AddDependency(Database database, string workflowName, string nameDependantOn, string nameDependancyTo)
{
if (database == null)
{
throw new ArgumentNullException("database", "database is null.");
}
if (workflowName == null)
{
throw new ArgumentNullException("workflowName", "workflowName is null.");
}
if (nameDependantOn == null)
{
throw new ArgumentNullException("nameDependantOn", "nameDependantOn is null.");
}
if (workflowName == null)
{
throw new ArgumentNullException("nameDependancyTo", "nameDependancyTo is null.");
}
var workflow = Workflow.Get(database, workflowName);
var dependantOn = Task.Get(database, workflowName, nameDependantOn);
var dependancyTo = Task.Get(database, workflowName, nameDependancyTo);
var dependancyToQueue = Queue.Get(database, dependancyTo.QueueId);
workflow.WorkflowLock.EnterWriteLock();
try
{
switch (dependancyTo.State)
{
case TaskState.AwaitDependence:
break;
case TaskState.Queued:
if (!workflow.Suspended)
{
dependancyToQueue.QueueLock.EnterWriteLock();
try
{
dependancyToQueue.QueuedTasks.Remove(dependancyToQueue.QueuedTasks.First(t => t.Item2 == dependancyTo.Id));
}
finally
{
dependancyToQueue.QueueLock.ExitWriteLock();
}
}
break;
case TaskState.Running:
case TaskState.Completed:
case TaskState.Failed:
default:
throw new InvalidOperationException("Can only add dependancy to a task which has not yet been started.");
}
dependancyTo.State = TaskState.AwaitDependence;
dependantOn.DependencyTo.Add(dependancyTo.Id);
dependancyTo.DependantOn.Add(dependantOn.Id);
switch (dependantOn.State)
{
case TaskState.AwaitDependence:
case TaskState.Queued:
case TaskState.Running:
dependancyTo.OutstandingDependencies.Add(dependantOn.Id);
break;
}
}
finally
{
workflow.WorkflowLock.ExitWriteLock();
}
}
