private void DeactivateConnection(TrackedConnection connection)
        {
            lock (m_syncLock)
            {
                if (m_isActiveCompletionSource.Task.IsCompleted)
                {
                    if (m_isActiveCompletionSource.Task.Result)
                    {
                        m_isActiveCompletionSource = TaskSourceSlim.Create <bool>();
                    }
                }

                if (m_exceededInactivityTimeout)
                {
                    m_isActiveCompletionSource.TrySetResult(false);
                }
            }

            OnDeactivateConnection?.Invoke(this, EventArgs.Empty);

            // TODO: Do nothing to actual connection for now.
            // Consider recycling connection (ie create new BondTcpConnection) if
            // connection fails too many times or hasn't had a successful call for a significant
            // interval.
            // NOTE: connection may be null
            Analysis.IgnoreArgument(connection);
        }
        /// <summary>
        /// Class constructor
        /// </summary>
        /// <param name="client">the bond tcp client used to create the proxy</param>
        /// <param name="createProxyCallback">callback used to create a bond proxy</param>
        /// <param name="loggingContext">the logging context</param>
        /// <param name="services">shared services for distribution</param>
        /// <param name="maxConnectionConcurrency">the maximum number of connections</param>
        public BondProxyConnectionManager(
            BondTcpClient <TProxy> client,
            BondTcpClient <TProxy> .CreateProxyCallback createProxyCallback,
            LoggingContext loggingContext,
            DistributionServices services,
            int maxConnectionConcurrency = 1)
        {
            m_client = client;
            m_createProxyCallback      = createProxyCallback;
            m_loggingContext           = loggingContext;
            m_maxConnectionConcurrency = maxConnectionConcurrency;
            m_services      = services;
            m_bufferManager = services.BufferManager;

            m_proxySemaphore = new NullSemaphore();

            // m_proxySemaphore = new SemaphoreSlim(m_maxConnectionConcurrency);
            m_stopwatch      = Stopwatch.StartNew();
            m_heartbeatTimer = new Timer(HeartbeatTimerCallback);
            m_connections    = new TrackedConnection[m_maxConnectionConcurrency];
            for (int i = 0; i < m_maxConnectionConcurrency; i++)
            {
                m_connections[i] = new TrackedConnection(this);
            }

            m_isActiveCompletionSource = TaskSourceSlim.Create <bool>();
        }
        /// <summary>
        /// Creates a task for a bond proxy method call
        /// </summary>
        /// <typeparam name="TInput">the input type</typeparam>
        /// <typeparam name="T">the return type</typeparam>
        /// <param name="connection">the connection containing the active bond proxy</param>
        /// <param name="input">the input value</param>
        /// <param name="callTracker">the call tracker containing data about the call state</param>
        /// <param name="cancellationToken">cancellation token used to cancel the call</param>
        /// <returns>a task representing the result of the call</returns>
        private async Task <T> CreateTaskForProxyCall <TInput, T>(
            TrackedConnection connection,
            TInput input,
            BondCallTracker callTracker,
            CancellationToken cancellationToken = default(CancellationToken))
            where TInput : RpcMessageBase, IBondSerializable, new()
            where T : IBondSerializable, new()
        {
            using (var bufferProvider = m_bufferManager.GetBufferProvider())
            {
                IBondAdaptable adaptable = input as IBondAdaptable;
                if (adaptable != null)
                {
                    callTracker.OnStateChanged(BondCallState.Converting);
                    adaptable.Adapt(bufferProvider);
                    callTracker.OnStateChanged(BondCallState.Converted);
                }

                // Create a cancellation token source which can be disposed after call completes.
                // Need to unregister cancellation when call completes but this is difficult to do with
                // the CancellationTokenRegistration returned by CancellationToken.Register since it
                // is created inside the begin method delegate
                using (var cancellationTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken))
                {
                    input.SenderName = m_thisMachineName;
                    input.SenderId   = m_thisMachineId;
                    input.BuildId    = m_services.BuildId;

                    var message = new Message <TInput>(input);

                    // Assign checksum so messages can be verified on receipt
                    m_services.AssignChecksum(message);
                    message.Context.PacketHeaders.m_nettrace.m_callID.SetFromSystemGuid(callTracker.CallId);
                    Func <AsyncCallback, object, IAsyncResult> beginMethod = (callback, state) =>
                    {
                        var asyncResult = connection.Proxy.BeginRequest(callTracker.FunctionName, message, callback, bufferProvider.Allocator);
                        callTracker.OnStateChanged(BondCallState.InitiatedRequest);
                        cancellationTokenSource.Token.Register(() => connection.Proxy.CancelRequest(callTracker.FunctionName, asyncResult), useSynchronizationContext: false);
                        return(asyncResult);
                    };

                    // Use the overload which takes an async callback to circumvent need to wait on wait handle in thread pool
                    var resultMessage = await Task.Factory.FromAsync(beginMethod, asyncResult => connection.Proxy.EndRequest <T>(callTracker.FunctionName, asyncResult), state : null);

                    return(resultMessage.Payload.Value);
                }
            }
        }
        protected void AddWatchedConnection(IPEndPoint endPoint, string reason)
        {
            if (ignoredConnections.ContainsKey(endPoint))
            {
                return;
            }

            TrackedConnection tracked;

            if (trackedConnections.TryGetValue(endPoint, out tracked))
            {
                tracked.PacketsFrom++;
                tracked.Accumulator++;
            }
            else
            {
                tracked = new TrackedConnection(endPoint);
                if (trackedConnections.TryAdd(endPoint, tracked))
                {
                    NetLogger.LogWarning("[WATCH:{0}] {1}", endPoint, reason);
                }
            }
        }
 public TrackedConnectionScope(TrackedConnection connection)
 {
     m_succeeded = false;
     Connection  = connection;
 }
        private async Task <RpcCallResult <T> > CallCore <T>(
            Func <TrackedConnection, BondCallTracker, Task <T> > callAsync,
            CancellationToken cancellationToken,
            string functionName,
            BondCallTracker callTracker,
            bool allowInactive         = false,
            Func <T, bool> shouldRetry = null,
            uint maxTryCount           = 0)
        {
            Contract.Requires(functionName != null);
            callTracker = callTracker ?? CreateLoggingCallTracker(functionName);

            TimeSpan waitForConnectionDuration = default(TimeSpan);
            Failure  lastFailure = null;

            m_outstandingCalls.AddOrUpdate(functionName, 1, (k, i) => i + 1);

            // For heartbeat only try once
            if (maxTryCount == 0)
            {
                maxTryCount = DefaultMaxRetryCount;
            }

            for (uint retryCount = 0; retryCount < maxTryCount; retryCount++)
            {
                callTracker.TryCount = retryCount;

                if (retryCount != 0)
                {
                    // For retries, log a call start with the call tracker's updated retry count
                    callTracker.OnStateChanged(BondCallState.Started);
                    // Yield after first iteration to ensure
                    // we don't overflow the stack with async continuations
                    await Task.Yield();
                }

                TrackedConnection connection = null;
                try
                {
                    var startWaitForConnection = m_stopwatch.Elapsed;
                    callTracker.OnStateChanged(BondCallState.WaitingForConnection);

                    // Wait for a connection to become active via the a successful heartbeat
                    using (var connectionScope = await WaitForConnectionAsync(callTracker, allowInactive, cancellationToken))
                    {
                        // Log wait for connection success
                        var iterationWaitForConnectionDuration = GetElapsed(startWaitForConnection);
                        waitForConnectionDuration += iterationWaitForConnectionDuration;
                        callTracker.OnStateChanged(BondCallState.CompletedWaitForConnection);

                        // connection is not returned in the case that the proxy is shutting down or timed out
                        // other case is that this is a failed heartbeat call. In which case, just continue.
                        if (connectionScope.Connection == null)
                        {
                            if (m_isShuttingDown || m_exceededInactivityTimeout)
                            {
                                // Log the failure
                                lastFailure = new RecoverableExceptionFailure(new BuildXLException(m_isShuttingDown ?
                                                                                                   "Bond RPC Call failure: Proxy is shutting down" :
                                                                                                   "Bond RPC Call failure: Proxy timed out"));

                                callTracker.LogMessage("Could not retrieve connection. Failure={0}", lastFailure.DescribeIncludingInnerFailures());
                                callTracker.OnStateChanged(BondCallState.Failed);
                                return(new RpcCallResult <T>(RpcCallResultState.Failed, retryCount + 1, callTracker.TotalDuration, waitForConnectionDuration, lastFailure));
                            }

                            continue;
                        }

                        connection = connectionScope.Connection;

                        // Make the actual call
                        var result = await callAsync(connection, callTracker);

                        // Check if call should be retried
                        if (shouldRetry != null && shouldRetry(result))
                        {
                            continue;
                        }

                        // Log the call completion
                        callTracker.OnStateChanged(BondCallState.Succeeded);
                        m_proxyLogger.LogSuccessfulCall(m_loggingContext, functionName, retryCount);
                        connectionScope.MarkSucceeded();
                        m_services.Counters.AddToCounter(DistributionCounter.SendPipBuildRequestCallDurationMs, (long)callTracker.TotalDuration.TotalMilliseconds);
                        return(new RpcCallResult <T>(result, retryCount + 1, callTracker.TotalDuration, waitForConnectionDuration));
                    }
                }
                catch (OperationCanceledException)
                {
                    callTracker.OnStateChanged(BondCallState.Canceled);
                    return(new RpcCallResult <T>(RpcCallResultState.Cancelled, retryCount + 1, callTracker.TotalDuration, waitForConnectionDuration));
                }
                catch (Exception ex)
                {
                    // If shutting down just return the failed result
                    if (ex is ObjectDisposedException && m_isShuttingDown)
                    {
                        lastFailure = new RecoverableExceptionFailure(new BuildXLException("Bond RPC Call failure: Proxy is shutting down", ex));
                        callTracker.LogMessage("{0}", lastFailure.DescribeIncludingInnerFailures());
                        callTracker.OnStateChanged(BondCallState.Failed);
                        return(new RpcCallResult <T>(RpcCallResultState.Failed, retryCount + 1, callTracker.TotalDuration, waitForConnectionDuration));
                    }

                    if (DistributionServices.IsBuildIdMismatchException(ex))
                    {
                        m_proxyLogger.LogCallException(m_loggingContext, functionName, retryCount, ex);

                        // If a message with different build is received, it means that the sender has participated in a different distributed build.
                        // Then, we need to lose the connection with the sender.
                        OnConnectionTimeOut?.Invoke(this, EventArgs.Empty);
                        return(new RpcCallResult <T>(RpcCallResultState.Failed, retryCount + 1, callTracker.TotalDuration, waitForConnectionDuration));
                    }

                    // If not a transient exception, log and throw
                    if (!DistributionHelpers.IsTransientBondException(ex, m_services.Counters) && !m_services.IsChecksumMismatchException(ex))
                    {
                        m_proxyLogger.LogCallException(m_loggingContext, functionName, retryCount, ex);
                        throw;
                    }

                    // Otherwise, the exception is transient, so log exception and try again
                    lastFailure = new RecoverableExceptionFailure(new BuildXLException("Failed Bond RPC call", ex));
                    callTracker.LogMessage("{0}", lastFailure.DescribeIncludingInnerFailures());

                    // Deactivate connection so subsequent calls on the proxy will wait for heartbeat before trying to make call.
                    DeactivateConnection(connection);

                    m_services.Counters.AddToCounter(DistributionCounter.FailedSendPipBuildRequestCallDurationMs, (long)callTracker.TotalDuration.TotalMilliseconds);
                    m_services.Counters.IncrementCounter(DistributionCounter.FailedSendPipBuildRequestCount);
                    m_proxyLogger.LogFailedCall(m_loggingContext, functionName, retryCount, lastFailure);
                }
                finally
                {
                    m_outstandingCalls.AddOrUpdate(functionName, 0, (k, i) => i - 1);
                }
            }

            // Exceeded retry count.
            callTracker.LogMessage("Call failed and exhausted allowed retries. LastFailure={0}", lastFailure?.DescribeIncludingInnerFailures() ?? string.Empty);
            callTracker.OnStateChanged(BondCallState.Failed);
            return(new RpcCallResult <T>(RpcCallResultState.Failed, DefaultMaxRetryCount, callTracker.TotalDuration, waitForConnectionDuration, lastFailure));
        }