Reduce loop wait time and make it configurable

Author: barclayadam

src/HangFire.Azure.ServiceBusQueue/ServiceBusManager.cs

@@ -35,13 +35,15 @@ public ServiceBusManager(ServiceBusQueueOptions options)
             }
         }
 
+        public ServiceBusQueueOptions Options { get { return _options; } }
+
         public QueueClient GetClient(string queue)
         {
             if (_clients.Count != _options.Queues.Length)
             {
                 CreateQueueClients();
             }
-            
+
             return _clients[queue];
         }
 
@@ -98,7 +100,7 @@ private static void CreateQueueIfNotExists(string prefixedQueue, NamespaceManage
             {
                 var errorMessage = string.Format(
                     "Queue '{0}' could not be checked / created, likely due to missing the 'Manage' permission. " +
-                    "You must either grant the 'Manage' permission, or setServiceBusQueueOptions.CheckAndCreateQueues to false", 
+                    "You must either grant the 'Manage' permission, or set ServiceBusQueueOptions.CheckAndCreateQueues to false",
                     prefixedQueue);
 
                 throw new UnauthorizedAccessException(errorMessage, ex);

src/HangFire.Azure.ServiceBusQueue/ServiceBusQueueJobQueue.cs

@@ -12,7 +12,6 @@ namespace Hangfire.Azure.ServiceBusQueue
     internal class ServiceBusQueueJobQueue : IPersistentJobQueue
     {
         private static readonly TimeSpan MinSyncReceiveTimeout = TimeSpan.FromTicks(1);
-        private static readonly TimeSpan SyncReceiveTimeout = TimeSpan.FromSeconds(5);
 
         private readonly ServiceBusManager _manager;
 
@@ -39,9 +38,10 @@ public IFetchedJob Dequeue(string[] queues, CancellationToken cancellationToken)
                 try
                 {
                     var client = clients[queueIndex];
+                    var isLastQueue = queueIndex == queues.Length - 1;
 
-                    message = queueIndex == queues.Length - 1
-                        ? client.Receive(SyncReceiveTimeout)
+                    message = isLastQueue
+                        ? client.Receive(_manager.Options.LoopReceiveTimeout) // Last queue
                         : client.Receive(MinSyncReceiveTimeout);
                 }
                 catch (TimeoutException)
@@ -51,7 +51,7 @@ public IFetchedJob Dequeue(string[] queues, CancellationToken cancellationToken)
                 {
                     var errorMessage = string.Format(
                         "Queue {0} could not be found. Either create the queue manually, " +
-                        "or grant the Manage permission and set ServiceBusQueueOptions.CheckAndCreateQueues to true", 
+                        "or grant the Manage permission and set ServiceBusQueueOptions.CheckAndCreateQueues to true",
 
                         clients[queueIndex].Path);
 

src/HangFire.Azure.ServiceBusQueue/ServiceBusQueueOptions.cs

@@ -8,6 +8,7 @@ public class ServiceBusQueueOptions
         public ServiceBusQueueOptions()
         {
             this.CheckAndCreateQueues = true;
+            this.LoopReceiveTimeout = TimeSpan.FromMilliseconds(500);
         }
 
         /// <summary>
@@ -19,7 +20,7 @@ public ServiceBusQueueOptions()
 
         /// <summary>
         /// Configures a queue on construction, for example setting maximum message
-        /// size of default TTL.
+        /// size or default TTL.
         /// </summary>
         public Action<QueueDescription> Configure { get; set; }
 
@@ -38,6 +39,17 @@ public ServiceBusQueueOptions()
 
         public string[] Queues { get; set; }
 
+        /// <summary>
+        /// Gets or sets a timeout that is used between loop runs of receiving messages from Azure Service Bus. This is the timeout
+        /// used when waiting on the last queue before looping around again (does not apply when only a single-queue exists).
+        /// </summary>
+        /// <remarks>
+        /// Typically a lower value is desired to keep the throughput of message processing high. A lower timeout means more calls to
+        /// Azure Service Bus which can increase costs, especially on an under-utilised server with few jobs.
+        /// </remarks>
+        /// <value>Defaults to <c>TimeSpan.FromMilliseconds(500)</c></value>
+        public TimeSpan LoopReceiveTimeout { get; set; }
+
         internal string GetQueueName(string name)
         {
             if (QueuePrefix != null)