public static void Create(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 (Exists(database, name))
throw new ArgumentException(string.Format("Workflow with the name \"{0}\" already exists.", name), "name");
var workflow = new Workflow(name);
database.WorkflowsLock.EnterWriteLock();
try
{
workflow.WorkflowLock.EnterWriteLock();
try
{
database.WorkflowNames.Add(workflow.Name, workflow.Id);
database.Workflows.Add(workflow.Id, workflow);
}
finally
{
workflow.WorkflowLock.ExitWriteLock();
}
}
finally
{
database.WorkflowsLock.ExitWriteLock();
}
}
public static bool Exists(Database database, string name)
{
if (database == null)
throw new ArgumentNullException("database", "database is null.");
if (name == null)
throw new ArgumentNullException("name", "name is null.");
database.WorkflowsLock.EnterReadLock();
try
{
return database.WorkflowNames.ContainsKey(name);
}
finally
{
database.WorkflowsLock.ExitReadLock();
}
}
public static bool IsEmpty(Database database, string name)
{
if (database == null)
throw new ArgumentNullException("database", "database is null.");
if (name == null)
throw new ArgumentNullException("name", "name is null.");
database.QueuesLock.EnterReadLock();
try
{
if (!database.QueueNames.ContainsKey(name))
throw new ArgumentException(string.Format("Queue with the name \"{0}\" not found.", name), "name");
var queue = database.Queues[database.QueueNames[name]];
queue.QueueLock.EnterReadLock();
try
{
return !queue.QueuedTasks.Any();
}
finally
{
queue.QueueLock.ExitReadLock();
}
}
finally
{
database.QueuesLock.ExitReadLock();
}
}
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 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 void Create(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 (Exists(database, name))
throw new ArgumentException(string.Format("Queue with the name \"{0}\" already exists.", name), "name");
var queue = new Queue(name);
queue.QueueLock.EnterWriteLock();
try
{
database.QueuesLock.EnterWriteLock();
try
{
database.QueueNames.Add(queue.Name, queue.Id);
database.Queues.Add(queue.Id, queue);
}
finally
{
database.QueuesLock.ExitWriteLock();
}
}
finally
{
queue.QueueLock.ExitWriteLock();
}
}
public static void Resume(Database database, string name)
{
if (database == null)
throw new ArgumentNullException("database", "database is null.");
if (name == null)
throw new ArgumentNullException("name", "name is null.");
var workflow = Get(database, name);
workflow.WorkflowLock.EnterWriteLock();
try
{
if (!workflow.Suspended)
return;
database.QueuesLock.EnterReadLock();
try
{
var tasksToQueue = workflow.Tasks.Values.Where(task => task.State == TaskState.Queued).ToList();
var queues = tasksToQueue.Select(task => task.QueueId).OrderBy(id => id).Distinct().Select(id => database.Queues[id]).ToList();
int queueLocksHeld = 0;
try
{
foreach (var queue in queues)
{
queue.QueueLock.EnterWriteLock();
queueLocksHeld++;
}
foreach (var task in tasksToQueue)
{
database.Queues[task.QueueId].QueuedTasks.AddLast(new LinkedListNode<Tuple<Guid, Guid>>(new Tuple<Guid, Guid>(workflow.Id, task.Id)));
}
workflow.Suspended = false;
}
finally
{
// Release write locks for any that were taken.
for (int i = 0; i < queueLocksHeld; i++)
{
queues[i].QueueLock.ExitWriteLock();
}
}
}
finally
{
database.QueuesLock.ExitReadLock();
}
}
finally
{
workflow.WorkflowLock.ExitWriteLock();
}
}
internal static Queue Get(Database database, string name)
{
if (database == null)
throw new ArgumentNullException("database", "database is null.");
if (name == null)
throw new ArgumentNullException("name", "name is null.");
database.QueuesLock.EnterReadLock();
try
{
if (!database.QueueNames.ContainsKey(name))
throw new Exception(string.Format("Queue named \"{0}\" not found.", name));
return database.Queues[database.QueueNames[name]];
}
finally
{
database.QueuesLock.ExitReadLock();
}
}
public static int RunningCount(Database database, string name)
{
if (database == null)
throw new ArgumentNullException("database", "database is null.");
if (name == null)
throw new ArgumentNullException("name", "name is null.");
var queue = Get(database, name);
queue.QueueLock.EnterReadLock();
try
{
return queue.RunningTasks.Count;
}
finally
{
queue.QueueLock.ExitReadLock();
}
}
public void Initialise()
{
this.database = new Database();
}
public static bool IsSuspended(Database database, string name)
{
if (database == null)
throw new ArgumentNullException("database", "database is null.");
if (name == null)
throw new ArgumentNullException("name", "name is null.");
var workflow = Get(database, name);
workflow.WorkflowLock.EnterReadLock();
try
{
return workflow.Suspended;
}
finally
{
workflow.WorkflowLock.ExitReadLock();
}
}
internal static Workflow Get(Database database, Guid id)
{
if (database == null)
throw new ArgumentNullException("database", "database is null.");
if (id == Guid.Empty)
throw new ArgumentException("id", "id is empty.");
database.WorkflowsLock.EnterReadLock();
try
{
if (!database.Workflows.ContainsKey(id))
return null;
return database.Workflows[id];
}
finally
{
database.WorkflowsLock.ExitReadLock();
}
}
public static void Suspend(Database database, string name)
{
throw new NotImplementedException();
}
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 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();
}
}
/// <summary>
/// Requeue a task if it was unable to be completed.
/// </summary>
/// <param name="database">Database instance.</param>
/// <param name="workflowName">Name of the workflow of the task to requeue.</param>
/// <param name="taskName">Name of the task to requeue.</param>
public static void Requeue(Database database, string workflowName, string taskName)
{
throw new NotImplementedException();
}
internal static Task Get(Database database, string workflowName, string name)
{
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.");
Workflow workflow = Workflow.Get(database, workflowName);
workflow.WorkflowLock.EnterReadLock();
try
{
if (!workflow.TaskNames.ContainsKey(name))
throw new Exception(string.Format("Task named \"{0}\" not found in the workflow named \"{1}\".", name, workflowName));
return workflow.Tasks[workflow.TaskNames[name]];
}
finally
{
workflow.WorkflowLock.ExitReadLock();
}
}
public static void Complete(Database database, string workflowName, string taskName)
{
if (database == null)
throw new ArgumentNullException("database", "database is null.");
if (workflowName == null)
throw new ArgumentNullException("workflowName", "workflowName is null.");
if (taskName == null)
throw new ArgumentNullException("taskName", "taskName is null.");
Workflow workflow;
Task task;
Queue queue;
bool workflowCompleted = false;
database.WorkflowsLock.EnterReadLock();
try
{
database.QueuesLock.EnterReadLock();
try
{
workflow = database.Workflows[database.WorkflowNames[workflowName]];
workflow.WorkflowLock.EnterWriteLock();
try
{
task = workflow.Tasks[workflow.TaskNames[taskName]];
queue = database.Queues[task.QueueId];
var queuesIdsToLock = task.DependencyTo.Select(taskId => workflow.Tasks[taskId].QueueId).ToList();
queuesIdsToLock.Add(task.QueueId);
queuesIdsToLock = queuesIdsToLock.OrderBy(id => id).Distinct().ToList();
int queueLockCount = 0;
try
{
foreach (var queueId in queuesIdsToLock)
{
database.Queues[queueId].QueueLock.EnterWriteLock();
queueLockCount++;
}
queue.RunningTasks.Remove(task.Id);
task.State = TaskState.Completed;
workflow.CompletedTasks.Add(task.Id);
foreach (var nextTaskId in task.DependencyTo)
{
var nextTask = workflow.Tasks[nextTaskId];
nextTask.OutstandingDependencies.Remove(task.Id);
if (nextTask.OutstandingDependencies.Count == 0)
{
nextTask.State = TaskState.Queued;
var nextQueue = database.Queues[nextTask.QueueId];
nextQueue.QueuedTasks.AddLast(new LinkedListNode<Tuple<Guid, Guid>>(new Tuple<Guid, Guid>(workflow.Id, nextTask.Id)));
}
}
if (workflow.CompletedTasks.Count == workflow.Tasks.Count)
{
workflowCompleted = true;
}
}
finally
{
// Release all taken locks in order taken.
for (int i = queueLockCount - 1; i >= 0; i--)
{
database.Queues[queuesIdsToLock[i]].QueueLock.ExitWriteLock();
}
}
}
finally
{
workflow.WorkflowLock.ExitWriteLock();
}
}
finally
{
database.QueuesLock.ExitReadLock();
}
}
finally
{
database.WorkflowsLock.ExitReadLock();
}
if (workflowCompleted)
{
database.WorkflowsLock.EnterWriteLock();
try
{
database.WorkflowNames.Remove(workflow.Name);
database.Workflows.Remove(workflow.Id);
}
finally
{
database.WorkflowsLock.ExitWriteLock();
}
}
}
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();
}
}
internal static Queue Get(Database database, Guid guid)
{
if (database == null)
throw new ArgumentNullException("database", "database is null.");
database.QueuesLock.EnterReadLock();
try
{
return database.Queues[guid];
}
finally
{
database.QueuesLock.ExitReadLock();
}
}
static void Main(string[] args)
{
queueNames = Enumerable.Range(1, QueueCount).Select(i => string.Format("Queue {0}", i)).ToList();
database = new Database();
foreach (var name in queueNames)
{
Queue.Create(database, name);
}
for (int i = 0; i < QueueProcessors; i++)
{
ThreadPool.QueueUserWorkItem(new WaitCallback(QueueProcessor), queueNames[i % QueueCount]);
}
for (int i = 0; i < WorkflowCreators; i++)
{
ThreadPool.QueueUserWorkItem(new WaitCallback(TaskCreator));
}
while (!stopping)
{
PrintOverview();
if (Console.KeyAvailable)
{
var keyPress = Console.ReadKey(true);
switch (keyPress.Key)
{
case ConsoleKey.DownArrow:
// Decrease process time.
if (TaskCompletionTime.TotalMilliseconds >= 1)
TaskCompletionTime = TaskCompletionTime.Add(TimeSpan.FromMilliseconds(-1));
break;
case ConsoleKey.UpArrow:
// Increase process time.
TaskCompletionTime = TaskCompletionTime.Add(TimeSpan.FromMilliseconds(1));
break;
case ConsoleKey.LeftArrow:
// Decrease rate of queuing.
WorkflowCreationFrequency = WorkflowCreationFrequency.Add(TimeSpan.FromMilliseconds(1));
break;
case ConsoleKey.RightArrow:
// Increase rate of queuing.
if (WorkflowCreationFrequency.TotalMilliseconds >= 1)
WorkflowCreationFrequency = WorkflowCreationFrequency.Add(TimeSpan.FromMilliseconds(-1));
break;
case ConsoleKey.OemComma:
// < - Decrease check frequency.
QueueCheckFrequency = QueueCheckFrequency.Add(TimeSpan.FromMilliseconds(1));
break;
case ConsoleKey.OemPeriod:
// > - Increase check frequency.
if (QueueCheckFrequency.TotalMilliseconds >= 1)
QueueCheckFrequency = QueueCheckFrequency.Add(TimeSpan.FromMilliseconds(-1));
break;
case ConsoleKey.X:
stopping = true;
break;
default:
break;
}
}
Thread.Sleep(200);
}
}