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Add semaphore for accessing send stream

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This commit is contained in:
Christian Kratky
2017-09-28 09:29:47 +02:00
parent e947881aca
commit d09455f78e
2 changed files with 32 additions and 30 deletions
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MQTTnet.Core/Adapter/MqttChannelCommunicationAdapter.cs
+22 -20
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@@ -16,8 +16,7 @@ namespace MQTTnet.Core.Adapter
public class MqttChannelCommunicationAdapter : IMqttCommunicationAdapter
{
private readonly IMqttCommunicationChannel _channel;
private readonly Task _waitTask = Task.FromResult(0); // this task is used to prevent overlapping write
private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(1, 1);
public MqttChannelCommunicationAdapter(IMqttCommunicationChannel channel, IMqttPacketSerializer serializer)
{
@@ -77,32 +76,31 @@ namespace MQTTnet.Core.Adapter
public async Task SendPacketsAsync(TimeSpan timeout, CancellationToken cancellationToken, IEnumerable<MqttBasePacket> packets)
{
await _semaphore.WaitAsync(cancellationToken);
try
{
var waitTask = _waitTask;
foreach (var packet in packets)
{
if (packet == null) { continue; }
MqttTrace.Information(nameof(MqttChannelCommunicationAdapter), $"TX >>> {packet} [Timeout={timeout}]");
var writeBuffer = PacketSerializer.Serialize(packet);
waitTask = waitTask.ContinueWith(t => _channel.SendStream.WriteAsync(writeBuffer, 0, writeBuffer.Length, cancellationToken).ConfigureAwait(false), cancellationToken);
}
waitTask = waitTask.ContinueWith(t =>
{
if (timeout > TimeSpan.Zero)
if (packet == null)
{
return _channel.SendStream.FlushAsync(cancellationToken).TimeoutAfter(timeout).ConfigureAwait(false);
continue;
}
return _channel.SendStream.FlushAsync(cancellationToken).ConfigureAwait(false);
}, cancellationToken);
MqttTrace.Information(nameof(MqttChannelCommunicationAdapter), $"TX >>> {0} [Timeout={1}]", packet, timeout);
await waitTask; // configure await false generates stackoverflow
var writeBuffer = PacketSerializer.Serialize(packet);
await _channel.SendStream.WriteAsync(writeBuffer, 0, writeBuffer.Length, cancellationToken).ConfigureAwait(false);
}
if (timeout > TimeSpan.Zero)
{
await _channel.SendStream.FlushAsync(cancellationToken).TimeoutAfter(timeout).ConfigureAwait(false);
}
else
{
await _channel.SendStream.FlushAsync(cancellationToken).ConfigureAwait(false);
}
}
catch (TaskCanceledException)
{
@@ -120,6 +118,10 @@ namespace MQTTnet.Core.Adapter
{
throw new MqttCommunicationException(exception);
}
finally
{
_semaphore.Release();
}
}
public async Task<MqttBasePacket> ReceivePacketAsync(TimeSpan timeout, CancellationToken cancellationToken)