public IProcessedEntity GetNext(List <ProcessedEntityType> types)
{
if (types == null)
{
throw new ArgumentNullException("types");
}
// Filter free projects
IOrderedEnumerable <IProcessedEntity> entities = _taskKeeper
.GetTasks()
.Where(p => types.Contains(p.EntityType) && _validStates.Contains(p.State))
.OrderByDescending(p => p.Created);
IProcessedEntity entity;
// It should be atomic to prevent reservation of the same task
lock (_lockObject)
{
entity = SelectNextTask(entities.ToList());
if (entity != null)
{
try
{
entity.SetState(new ReservedState());
}
catch (Exception e)
{
Trace.TraceError("Failed to change task state: {0}", e);
}
}
}
return(entity);
}
/// <summary>
/// Checks current tasks.
/// </summary>
public void CheckTasks()
{
// Check hanged tasks
List <IProcessedEntity> hangedTasks = _taskKeeper
.GetTasks()
.Where(p => !_completedStates.Contains(p.State) &&
_processingStates.Contains(p.State) &&
DateTime.UtcNow.Subtract(p.Modified) > TaskProcessingTimeout)
.ToList();
foreach (IProcessedEntity entity in hangedTasks)
{
Trace.TraceInformation("Task {0} hanged up while video {1} processing. Current state: {2}, Attempts: {3}, DestinationFileId: {4}.",
entity.TaskId,
entity.SourceFileId,
entity.State,
entity.AttemptsCount,
entity.DestinationFileId ?? "null");
entity.AttemptsCount++;
try
{
if (entity.State == TaskState.Reserved)
{
// Nobody wants to process this entity
entity.SetState(new WaitingState());
}
else
{
// Somebody hanged up while entity processing
entity.SetState(new FailedState());
}
}
catch (Exception e)
{
Trace.TraceError("Failed to change task state: {0}", e);
}
}
// Check failed tasks
List <IProcessedEntity> corruptedTasks = _taskKeeper
.GetTasks()
.Where(p => (p.AttemptsCount >= MaxAttemptsCount && !_completedStates.Contains(p.State))).ToList();
foreach (IProcessedEntity corruptedTask in corruptedTasks)
{
try
{
corruptedTask.SetState(new CorruptedState());
}
catch (Exception e)
{
Trace.TraceError("Failed to change task state: {0}", e);
}
}
}
