public async Task CloudQueueGetMessagesAsync()
{
CloudQueueClient client = GenerateCloudQueueClient();
string name = GenerateNewQueueName();
CloudQueue queue = client.GetQueueReference(name);
await queue.CreateAsync();
int messageCount = 30;
List <CloudQueueMessage> emptyMessages = (await queue.GetMessagesAsync(messageCount)).ToList();
Assert.AreEqual(0, emptyMessages.Count);
List <string> messageContentList = new List <string>();
for (int i = 0; i < messageCount; i++)
{
string messageContent = i.ToString();
CloudQueueMessage message = new CloudQueueMessage(messageContent);
await queue.AddMessageAsync(message);
messageContentList.Add(messageContent);
}
List <CloudQueueMessage> receivedMessages = (await queue.GetMessagesAsync(messageCount)).ToList();
Assert.AreEqual(messageCount, receivedMessages.Count);
for (int i = 0; i < messageCount; i++)
{
Assert.IsTrue(messageContentList.Contains(receivedMessages[i].AsString));
}
await queue.DeleteAsync();
}
protected override async Task StartAsync()
{
InfoLogging(string.Format("{0} - Processing", QueueName));
_queue = await _clientFactory.CreateStorageQueueClientAsync(QueueName).ConfigureAwait(false);
var stopWatch = new Stopwatch();
while (!Token.IsCancellationRequested)
{
await _queue.FetchAttributesAsync().ConfigureAwait(false);
if (_queue.ApproximateMessageCount.GetValueOrDefault() <= 0)
{
await Task.Delay(LoopWaitTime).ConfigureAwait(false);
continue;
}
var messages = await _queue
.GetMessagesAsync(MessageCount, TimeSpan.FromSeconds(10), null, null, Token)
.ConfigureAwait(false);
var cloudQueueMessages = messages as IList<CloudQueueMessage> ?? messages.ToList();
if (!cloudQueueMessages.Any()) continue;
var correlationId = Guid.NewGuid().ToString();
DebugLogging(string.Format("{0} - Received {1} new messages", QueueName, cloudQueueMessages.Count),
correlationId);
stopWatch.Restart();
await Do(cloudQueueMessages).ConfigureAwait(false);
stopWatch.Stop();
var timeSpan = stopWatch.Elapsed;
DebugLogging(string.Format("{0} - Processed messages", QueueName), correlationId,
timeSpan.TotalSeconds);
}
}
/// <summary>
/// Demonstrate adding a number of messages, checking the message count and batch retrieval of messages. During retrieval we
/// also set the visibility timeout to 5 minutes. Visibility timeout is the amount of time message is not visible to other
/// clients after a GetMessageOperation assuming DeleteMessage is not called.
/// </summary>
/// <param name="queue">The sample queue</param>
private static async Task ProcessBatchOfMessagesAsync(CloudQueue queue)
{
// Enqueue 20 messages by which to demonstrate batch retrieval
Console.WriteLine("7. Enqueue 20 messages.");
for (int i = 0; i < 20; i++)
{
await queue.AddMessageAsync(new CloudQueueMessage(string.Format("{0} - {1}", i, "Hello World")));
}
// The FetchAttributes method asks the Queue service to retrieve the queue attributes, including an approximation of message count
Console.WriteLine("8. Get the queue length");
queue.FetchAttributes();
int? cachedMessageCount = queue.ApproximateMessageCount;
Console.WriteLine("Number of messages in queue: {0}", cachedMessageCount);
// Dequeue a batch of 21 messages (up to 32) and set visibility timeout to 5 minutes. Note we are dequeuing 21 messages because the earlier
// UpdateEnqueuedMessage method left a message on the queue hence we are retrieving that as well.
Console.WriteLine("9. Dequeue 21 messages, allowing 5 minutes for the clients to process.");
foreach (CloudQueueMessage msg in await queue.GetMessagesAsync(21, TimeSpan.FromMinutes(5), null, null))
{
Console.WriteLine("Processing & deleting message with content: {0}", msg.AsString);
// Process all messages in less than 5 minutes, deleting each message after processing.
await queue.DeleteMessageAsync(msg);
}
}
/// <inheritdoc />
public async Task<IEnumerable<CloudQueueMessage>> GetMessagesAsync(CloudQueue queue, int messageCount, TimeSpan timeout)
{
if (queue == null)
{
throw new ArgumentNullException(nameof(queue));
}
try
{
IEnumerable<CloudQueueMessage> messages = await queue.GetMessagesAsync(messageCount, timeout, options: null, operationContext: null);
return messages;
}
catch (Exception ex)
{
string errorMessage = GetStorageErrorMessage(ex);
int statusCode = GetStorageStatusCode(ex);
string msg = string.Format(CultureInfo.CurrentCulture, AzureStorageResources.StorageManager_OperationFailed, statusCode, errorMessage);
_logger.Error(msg, ex);
return Enumerable.Empty<CloudQueueMessage>();
}
}
private static async Task ProcessBatchOfMessagesAsync(CloudQueue queue)
{
Console.WriteLine("7. Enqueue 20 messages.");
for (int i = 0; i < 20; i++)
{
await queue.AddMessageAsync(new CloudQueueMessage(string.Format("{0} - {1}", i, "Hello World")));
}
Console.WriteLine("8. Get the queue length");
queue.FetchAttributes();
int? cachedMessageCount = queue.ApproximateMessageCount;
Console.WriteLine("Number of messages in queue: {0}", cachedMessageCount);
Console.WriteLine("9. Dequeue 21 messages, allowing 5 minutes for the clients to process.");
foreach (CloudQueueMessage msg in await queue.GetMessagesAsync(21, TimeSpan.FromMinutes(5), null, null))
{
Console.WriteLine("Processing & deleting message with content: {0}", msg.AsString);
await queue.DeleteMessageAsync(msg);
}
}