/// <summary>
/// Creates a new background operation. The background operations runs the given method at given intervals. Must be separately started.
/// </summary>
/// <param name="name">The name of the operation.</param>
/// <param name="method">The method to invoke at given intervals.</param>
/// <returns>A new background operation, that is not yet started.</returns>
public TaskQueueBackgroundOperation <TDirective> CreateBackgroundOperation <TDirective>
(
string name,
Action <TaskProcessorJob, TDirective> method
)
where TDirective : TaskQueueDirective
{
TaskQueueBackgroundOperation <TDirective> backgroundOperation;
lock (TaskQueueBackgroundOperationManager._lock)
{
if (this.BackgroundOperations.ContainsKey(name))
{
throw new ArgumentException(
$"A background operation with the name {name} in queue {this.QueueId} could not be found.",
nameof(name));
}
// Create the background operation.
backgroundOperation = new TaskQueueBackgroundOperation <TDirective>
(
this,
name,
method,
this.CancellationTokenSource
);
// Add it to the dictionary.
this.BackgroundOperations.Add(name, backgroundOperation);
}
// Return it.
return(backgroundOperation);
}
/// <summary>
/// Handles when a job from a task requires processing.
/// Note that all tasks/jobs in the queue use the same task type ID,
/// so the directive <see cref="BackgroundOperationTaskQueueDirective.BackgroundOperationName"/>
/// is used to identify which tasks should be executed by
/// which background operation.
/// </summary>
/// <param name="job">The job to process.</param>
protected virtual void ProcessJobHandler(TaskProcessorJob job)
{
// Sanity.
if (null == job)
{
return;
}
// Ensure cancellation has not been requested.
job.ThrowIfCancellationRequested();
// Update the progress of the task in the task queue.
this.TaskProcessor.UpdateTaskAsAssignedToProcessor(job);
// Sanity.
if (null == job.Data?.Value)
{
// This is an issue. We have no way to decide what background operation should run it. Die.
SysUtils.ReportErrorToEventLog
(
$"Job loaded with no application task (queue: {job.AppTaskQueueId}, task type: {job.AppTaskId})."
);
return;
}
// Deserialize the background directive.
var backgroundOperationDirective = job.GetTaskQueueDirective <BackgroundOperationTaskQueueDirective>();
if (null == backgroundOperationDirective)
{
// This is an issue. We have no way to decide what background operation should run it. Die.
SysUtils.ReportErrorToEventLog
(
$"Job loaded with no background operation name loaded (queue: {job.AppTaskQueueId}, task type: {job.AppTaskId})."
);
return;
}
// If we have a directive then extract it.
var dir = backgroundOperationDirective.GetParsedInternalDirective();
// If it is a broadcast directive, then was it generated on the same server?
// If so then ignore.
if (dir is BroadcastDirective broadcastDirective)
{
if (broadcastDirective.GeneratedFromGuid == TaskQueueBackgroundOperationManager.CurrentServer.ServerID)
{
return;
}
}
// Find the background operation to run.
TaskQueueBackgroundOperation bo = null;
lock (_lock)
{
if (false == this.BackgroundOperations.TryGetValue(backgroundOperationDirective.BackgroundOperationName, out bo))
{
// We have no registered background operation to handle the callback.
SysUtils.ReportErrorToEventLog
(
$"No background operation found with name {backgroundOperationDirective.BackgroundOperationName}(queue: {job.AppTaskQueueId}, task type: {job.AppTaskId})."
);
return;
}
}
// If it is recurring then use the ProcessingComplete event to schedule the next execution.
if (bo.Recurring && bo.Interval.HasValue)
{
// Bind to the completed event ( called always ) of the job.
// That way even if the job is canceled, fails, or finishes successfully
// ...we always schedule the next run.
job.ProcessingCompleted += (s, op)
=> this.RunOnce
(
bo.Name,
DateTime.UtcNow.Add(bo.Interval.Value),
dir
);
}
// Perform the action.
try
{
// Delegate to the background operation.
bo.RunJob(job, dir);
}
catch (Exception e)
{
// Exception.
this.TaskProcessor.UpdateTaskInfo
(
job.Data?.Value,
MFTaskState.MFTaskStateFailed,
e.Message,
false
);
// TODO: throw?
}
}