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//------------------------------------------------------------
// Copyright (c) Microsoft Corporation. All rights reserved.
//------------------------------------------------------------
namespace System.ServiceModel.Channels
{
using System.Diagnostics;
using System.Runtime;
using System.ServiceModel;
using System.ServiceModel.Diagnostics;
using System.ServiceModel.Dispatcher;
using System.Threading;
using System.Runtime.Diagnostics;
using System.ServiceModel.Diagnostics.Application;
delegate void ConnectionAvailableCallback(IConnection connection, Action connectionDequeuedCallback);
delegate void ErrorCallback(Exception exception);
class ConnectionAcceptor : IDisposable
{
int maxAccepts;
int maxPendingConnections;
int connections;
int pendingAccepts;
IConnectionListener listener;
AsyncCallback acceptCompletedCallback;
Action<object> scheduleAcceptCallback;
Action onConnectionDequeued;
bool isDisposed;
ConnectionAvailableCallback callback;
ErrorCallback errorCallback;
public ConnectionAcceptor(IConnectionListener listener, int maxAccepts, int maxPendingConnections,
ConnectionAvailableCallback callback)
: this(listener, maxAccepts, maxPendingConnections, callback, null)
{
// empty
}
public ConnectionAcceptor(IConnectionListener listener, int maxAccepts, int maxPendingConnections,
ConnectionAvailableCallback callback, ErrorCallback errorCallback)
{
if (maxAccepts <= 0)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("maxAccepts", maxAccepts,
SR.GetString(SR.ValueMustBePositive)));
}
Fx.Assert(maxPendingConnections > 0, "maxPendingConnections must be positive");
this.listener = listener;
this.maxAccepts = maxAccepts;
this.maxPendingConnections = maxPendingConnections;
this.callback = callback;
this.errorCallback = errorCallback;
this.onConnectionDequeued = new Action(OnConnectionDequeued);
this.acceptCompletedCallback = Fx.ThunkCallback(new AsyncCallback(AcceptCompletedCallback));
this.scheduleAcceptCallback = new Action<object>(ScheduleAcceptCallback);
}
bool IsAcceptNecessary
{
get
{
return (pendingAccepts < maxAccepts)
&& ((connections + pendingAccepts) < maxPendingConnections)
&& !isDisposed;
}
}
public int ConnectionCount
{
get { return connections; }
}
object ThisLock
{
get { return this; }
}
void AcceptIfNecessary(bool startAccepting)
{
if (IsAcceptNecessary)
{
lock (ThisLock)
{
while (IsAcceptNecessary)
{
IAsyncResult result = null;
Exception unexpectedException = null;
try
{
result = listener.BeginAccept(acceptCompletedCallback, null);
}
catch (CommunicationException exception)
{
DiagnosticUtility.TraceHandledException(exception, TraceEventType.Information);
}
catch (Exception exception)
{
if (Fx.IsFatal(exception))
{
throw;
}
if (startAccepting)
{
// Since we're under a call to StartAccepting(), just throw the exception up the stack.
throw;
}
if ((errorCallback == null) && !ExceptionHandler.HandleTransportExceptionHelper(exception))
{
throw;
}
unexpectedException = exception;
}
if ((unexpectedException != null) && (errorCallback != null))
{
errorCallback(unexpectedException);
}
if (result != null)
{
// don't block our accept processing loop
if (result.CompletedSynchronously)
{
ActionItem.Schedule(scheduleAcceptCallback, result);
}
pendingAccepts++;
}
}
}
}
}
void AcceptCompletedCallback(IAsyncResult result)
{
if (result.CompletedSynchronously)
{
return;
}
HandleCompletedAccept(result);
}
public void Dispose()
{
lock (ThisLock)
{
if (!isDisposed)
{
isDisposed = true;
listener.Dispose();
}
}
}
void HandleCompletedAccept(IAsyncResult result)
{
IConnection connection = null;
lock (ThisLock)
{
bool success = false;
Exception unexpectedException = null;
try
{
if (!isDisposed)
{
connection = listener.EndAccept(result);
if (connection != null)
{
if (connections + 1 >= maxPendingConnections)
{
if (TD.MaxPendingConnectionsExceededIsEnabled())
{
TD.MaxPendingConnectionsExceeded(SR.GetString(SR.TraceCodeMaxPendingConnectionsReached));
}
if (DiagnosticUtility.ShouldTraceWarning)
{
TraceUtility.TraceEvent(TraceEventType.Warning,
TraceCode.MaxPendingConnectionsReached, SR.GetString(SR.TraceCodeMaxPendingConnectionsReached),
new StringTraceRecord("MaxPendingConnections", maxPendingConnections.ToString(System.Globalization.CultureInfo.InvariantCulture)),
this,
null);
}
}
else if (TD.PendingConnectionsRatioIsEnabled())
{
TD.PendingConnectionsRatio(connections + 1, maxPendingConnections);
}
// This is incremented after the Trace just in case the Trace throws.
connections++;
}
}
success = true;
}
catch (CommunicationException exception)
{
DiagnosticUtility.TraceHandledException(exception, TraceEventType.Information);
}
catch (Exception exception)
{
if (Fx.IsFatal(exception))
{
throw;
}
if ((errorCallback == null) && !ExceptionHandler.HandleTransportExceptionHelper(exception))
{
throw;
}
unexpectedException = exception;
}
finally
{
if (!success)
{
connection = null;
}
pendingAccepts--;
if (pendingAccepts == 0 && TD.PendingAcceptsAtZeroIsEnabled())
{
TD.PendingAcceptsAtZero();
}
}
if ((unexpectedException != null) && (errorCallback != null))
{
errorCallback(unexpectedException);
}
}
AcceptIfNecessary(false);
if (connection != null)
{
callback(connection, onConnectionDequeued);
}
}
void OnConnectionDequeued()
{
lock (ThisLock)
{
connections--;
if (TD.PendingConnectionsRatioIsEnabled())
{
TD.PendingConnectionsRatio(connections, maxPendingConnections);
}
}
AcceptIfNecessary(false);
}
void ScheduleAcceptCallback(object state)
{
HandleCompletedAccept((IAsyncResult)state);
}
public void StartAccepting()
{
listener.Listen();
AcceptIfNecessary(true);
}
}
}
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