/// <summary>
/// Get a response from the storage
/// </summary>
/// <param name="callback">the response callback, the async result should be the BrokerQueueItem</param>
/// <param name="callbackState">the state object for the callback</param>
public void GetResponseAsync(PersistCallback callback, object callbackState)
{
if (this.isClosedField)
{
BrokerTracing.TraceWarning("[MemoryPersist] .GetResponseAsync: the queue is closed.");
return;
}
BrokerQueueItem responseItem = null;
try
{
lock (this.lockResponseQueueField)
{
responseItem = this.responseQueueField.Dequeue();
}
}
catch (InvalidOperationException)
{
BrokerTracing.TraceError("[MemoryPersist] .GetResponseAsync: no response available. sessionId = {0}, clientId = {1}", this.sessionIdField, this.clientIdField);
}
if (callback == null)
{
return;
}
ThreadPool.QueueUserWorkItem(this.GetOperationComplete, new GetCallbackContext(callback, callbackState, responseItem));
}
/// <summary>
/// Initializes a new instance of the GetMessageState class.
/// </summary>
/// <param name="messageCallback">the callback that get the message</param>
/// <param name="callbackState">the callback state object.</param>
public GetMessageState(PersistCallback messageCallback, object callbackState)
{
if (messageCallback == null)
{
throw new ArgumentNullException("messageCallback");
}
this.messageCallbackField = messageCallback;
this.callbackStateField = callbackState;
}
public void Persist()
{
Log.Instance.LogFineDebug(string.Format("TaskListGroup.Persist"));
if (PersistCallback != null)
{
PersistCallback.OnPersist();
}
else
{
Log.Instance.LogInfo(string.Format("TaskListGroup.Persist - PersistCallback is null, skipping"));
}
}
/// <summary>
/// Fetch the requests one by one from the storage but not remove the original message in the storage.
/// </summary>
/// <param name="callback">the callback to get the async result</param>
/// <param name="state">the state object for the callback</param>
public void GetRequestAsync(PersistCallback callback, object state)
{
if (this.isClosedField)
{
BrokerTracing.TraceWarning("[MemoryPersist] .GetRequestAsync: the queue is closed.");
return;
}
BrokerQueueItem requestItem = null;
if (!this.requestQueueField.TryDequeue(out requestItem))
{
BrokerTracing.TraceError("[MemoryPersist] .GetRequestAsync: no request available. sessionId={0}, clientId={1}", this.sessionIdField, this.clientIdField);
}
if (callback == null)
{
return;
}
ThreadPool.QueueUserWorkItem(this.GetOperationComplete, new GetCallbackContext(callback, state, requestItem));
}
public void GetMessageAsync(PersistCallback callback, object state)
{
if (this.isDisposedField)
{
BrokerTracing.TraceWarning(
"[AzureQueueMessageFetcher] .GetMessageAsync: fetcherId={0} the instance is disposed.",
this.fetcherId);
return;
}
BrokerTracing.TraceVerbose(
"[AzureQueueMessageFetcher] .GetMessageAsync: fetcherId={0} Get message come in.",
this.fetcherId);
// GetMessageAsync:
// step 1, try to get message from prefetch cache. If succeeded, invoke the callback directly; or else,
// step 2, save context of this GetMessageAsync call, including callback and callback state into this.currentGetMessageState, which will be handled when a message is retrieved back from MSMQ.
// step 3, check if need to get more messages. If so, initiate more BeginPeek calls into MSMQ
GetMessageState getMessageState = new GetMessageState(callback, state);
MessageResult result = null;
Queue <MessageResult> messageQueue = new Queue <MessageResult>();
#if DEBUG
bool getResponse = false;
#endif
long getMessageCount = 1;
ResponseCallbackItem responseCallbackItem = state as ResponseCallbackItem;
if (responseCallbackItem != null)
{
#if DEBUG
getResponse = true;
#endif
getMessageCount = responseCallbackItem.ExpectedResponseCount;
Debug.WriteLine(
$"[AzureQueueMessageFetcher] .GetMessageAsync: working to get response. getMessageCount={getMessageCount}.");
}
else
{
Debug.WriteLine(
$"[AzureQueueMessageFetcher] .GetMessageAsync: working to get request. getMessageCount={getMessageCount}.");
}
this.lockPrefetchCache.EnterReadLock();
try
{
if (this.prefetchCache == null)
{
// this instance is disposed
BrokerTracing.TraceWarning(
"[AzureQueueMessageFetcher] .GetMessageAsync: the instance is disposed.");
return;
}
while (getMessageCount > 0)
{
if (!(this.prefetchCache.Count > 0 && this.prefetchCache.TryDequeue(out result)))
{
BrokerTracing.TraceVerbose("[AzureQueueMessageFetcher] .GetMessageAsync: cache miss");
result = null;
this.currentGetMessageQueue.Enqueue(getMessageState);
break;
}
BrokerTracing.TraceVerbose("[AzureQueueMessageFetcher] .GetMessageAsync: hit cache");
messageQueue.Enqueue(result);
getMessageCount--;
}
}
finally
{
this.lockPrefetchCache.ExitReadLock();
}
Debug.WriteLine(
$"[AzureQueueMessageFetcher] .GetMessageAsync: getMessageCount={getMessageCount} after dequeue.");
while (messageQueue.Any())
{
var message = messageQueue.Dequeue();
if (message != null)
{
// There is one more space available in prefetch cache
lock (this.lockFetchCount)
{
this.prefetchCredit++;
}
// GetMessageAsync is a light-weight call and is supposed to return very soon. While in its callback,
// there may be time-consuming operations. So here we always invoke the callback in another thread.
ThreadPool.QueueUserWorkItem(
this.GetMessageAsyncCallback,
new object[] { getMessageState, message });
}
else
{
BrokerTracing.TraceWarning(
"[AzureQueueMessageFetcher] .GetMessageAsync: fetcherId={0} encountered null message result.",
this.fetcherId);
}
}
this.CheckAndGetMoreMessages();
}
/// <summary>
/// Instantiate a new instance of class GetCallbackContext
/// </summary>
/// <param name="callback">the callback</param>
/// <param name="callbackState">the callback context</param>
/// <param name="callbackMsg">the retrieved back message</param>
public GetCallbackContext(PersistCallback callback, object callbackState, BrokerQueueItem callbackMsg)
{
this.callbackField = callback;
this.callbackStateField = callbackState;
this.callbackMsgField = callbackMsg;
}
