public static void EnqueueTask(object state)
{
CancellationToken token = (CancellationToken)state;
using (DSTeckWebPushNotificationsContext db = new DSTeckWebPushNotificationsContext())
{
while (!token.IsCancellationRequested)
{
if (enqueueSignal.WaitOne())
{
int toEnqueue = 100 - deliveryQueue.Count;
if (toEnqueue > 0)
{
// fetch some records from db to be enqueued
NotificationDelivery[] deliveries = db.NotificationDeliveries
.Include("Subscription")
.Include("Notification")
.Include("Notification.NotificationLanguages")
.Include("Notification.NotificationLanguages.Language")
.Where(nd => nd.Status == NotificationDeliveryStatus.Pending && DateTime.Now >= nd.StartSendingAt)
.OrderBy(nd => nd.StartSendingAt)
.Take(toEnqueue)
.ToArray();
foreach (NotificationDelivery delivery in deliveries)
{
delivery.Status = NotificationDeliveryStatus.Queued;
deliveryQueue.Enqueue(delivery);
}
if (deliveries.Length > 0)
{
// save Queued state, so not fetched again the next loop
db.SaveChanges();
// signal the DequeueTask
dequeueSignal.Set();
}
else
{
// no more notifications, wait 5 seconds before try fetching again
enqueueSignal.Reset();
enqueueTimer.Start();
}
}
// save any changes made by the DequeueTask
// an event may be used here to know if any changes made
db.SaveChanges();
}
}
Task.WaitAll(dequeueTasks);
db.SaveChanges();
}
}
public static void StartSending(CancellationToken token)
{
PushService.InitServices();
using (DSTeckWebPushNotificationsContext db = new DSTeckWebPushNotificationsContext())
{
NotificationDelivery[] queuedDeliveries = db.NotificationDeliveries
.Where(nd => nd.Status == NotificationDeliveryStatus.Queued)
.ToArray();
foreach (NotificationDelivery delivery in queuedDeliveries)
{
delivery.Status = NotificationDeliveryStatus.Pending;
}
db.SaveChanges();
}
enqueueSignal = new ManualResetEvent(true);
dequeueSignal = new ManualResetEvent(false);
enqueueTimer = new System.Timers.Timer();
enqueueTimer.Elapsed += EnqueueTimerCallback;
enqueueTimer.Interval = 5000;
enqueueTimer.AutoReset = false;
enqueueTimer.Stop();
enqueueTask = new Task(EnqueueTask, token, TaskCreationOptions.LongRunning);
enqueueTask.Start();
deliveryQueue = new ConcurrentQueue <NotificationDelivery>();
int dequeueTasksCount = 10;
dequeueTasks = new Task[dequeueTasksCount];
for (int i = 0; i < dequeueTasksCount; i++)
{
dequeueTasks[i] = new Task(DequeueTask, token, TaskCreationOptions.LongRunning);
dequeueTasks[i].Start();
}
}