public void Send(MemcachedCommand command)
{
Thread.MemoryBarrier();
InitiateCommand(command);
_writeAsync.BeginAsync(_stream);
}
private MemcachedCommand GetNextCommandAfterPreviousSendCompleted(MemcachedCommand command)
{
lock (_gate)
{
_pendingSends.Dequeue();
if (_isWriterConnectionOpen && _isReaderConnectionOpen && !_hasBeenDisposed && _pendingSends.Count > 0)
{
var commandBeingSent = _pendingSends.Peek();
_pendingReceives[commandBeingSent.Id] = commandBeingSent;
return commandBeingSent;
}
return null;
}
}
private void WriteCommandHeader(MemcachedCommand command)
{
command.BeginWriting();
WriteRequestHeader(_sendBuffer, command.Opcode, command.RequestHeader);
const int requestHeaderSize = 24;
_currentByteInSendBuffer += requestHeaderSize;
command.WriteExtras(new ArraySegment<byte>(_sendBuffer, _currentByteInSendBuffer, command.RequestHeader.ExtrasLength));
_currentByteInSendBuffer += command.RequestHeader.ExtrasLength;
command.WriteKey(new ArraySegment<byte>(_sendBuffer, _currentByteInSendBuffer, command.RequestHeader.KeyLength));
_currentByteInSendBuffer += command.RequestHeader.KeyLength;
}
public WriteState(MemcachedCommand command)
{
Command = command;
TotalBytesInValue = command.RequestHeader.TotalBodyLength - command.RequestHeader.KeyLength - command.RequestHeader.ExtrasLength;
CurrentByteInValue = 0;
}
public bool TrySend(MemcachedCommand command)
{
bool isWriterIdle = false;
lock (_gate)
{
if (_hasBeenDisposed)
return false;
var areEitherReaderOrWriterClosed = !_isReaderConnectionOpen || !_isWriterConnectionOpen;
if (areEitherReaderOrWriterClosed || _hasBeenDisposed)
{
return false;
}
_pendingSends.Enqueue(command);
isWriterIdle = _pendingSends.Count == 1;
if (isWriterIdle)
{
_pendingReceives[command.Id] = command;
}
}
if (isWriterIdle)
{
_requestWriter.Send(command);
}
return true;
}
private void RemoveFromPendingReceives(MemcachedCommand command)
{
lock (_gate)
{
_pendingReceives.Remove(command.Id);
}
}
private void OnErrorReceived(MemcachedCommand command)
{
RemoveFromPendingReceives(command);
switch (command.ResponseStatus)
{
case ResponseStatus.VbucketBelongsToAnotherServer:
case ResponseStatus.Busy:
case ResponseStatus.TemporaryFailure:
{
var ev = OnRecoverableError;
if (ev != null)
{
ev(this.ServerId, command);
}
}
break;
case ResponseStatus.NoError:
throw new Exception("Should be impossible to get here...");
default:
//The error is not something we can deal with inside the library itself, either the caller screwed up, or there was a catastrophic failure.
command.NotifyComplete();
break;
}
}
private void SendCommandWithVBucketId(MemcachedCommand command)
{
Cluster cluster = _cluster;
command.SetVBucketId(cluster.GetVBucket(command.Key));
SendCommand(cluster, command);
}
private static void SendByLinearlyPollingServers(Cluster cluster, string lastServerTriedToSendToId, MemcachedCommand command)
{
int indexOfServerToTry = GetIndexOfNextServerInCluster(cluster, lastServerTriedToSendToId);
for (int i = 0; i < cluster.Servers.Count; i++)
{
if (cluster.Servers[indexOfServerToTry].TrySend(command))
{
return;
}
indexOfServerToTry = MathUtils.CircularIncrement(indexOfServerToTry, cluster.Servers.Count);
}
command.NotifyComplete(ResponseStatus.DisconnectionOccuredWhileOperationWaitingToBeSent);
}
private void OnWrongVBucketForServer(string lastServerTriedToSendToId, MemcachedCommand command)
{
Cluster cluster = _cluster;
var fastForwardedServers = cluster.GetFastForwardedServersForVBucket(command.VBucketId);
if (fastForwardedServers == null ||
!TrySendCommand(fastForwardedServers, command))
{
SendByLinearlyPollingServers(cluster, lastServerTriedToSendToId, command);
return;
}
}
private void OnPossiblyRecoverableMemcachedError(string serverid, MemcachedCommand command)
{
var cluster = _cluster;
switch (command.ResponseStatus)
{
case ResponseStatus.VbucketBelongsToAnotherServer:
OnWrongVBucketForServer(serverid, command);
break;
case ResponseStatus.Busy:
case ResponseStatus.TemporaryFailure:
SendCommand(cluster, command); //Retry
break;
default:
throw new Exception("Should be impossible to get here...");
}
}
private static bool TrySendCommand(List<Server> serversForVbucket, MemcachedCommand command)
{
for (int iServer = 0; iServer < serversForVbucket.Count; iServer++)
{
if (serversForVbucket[iServer].TrySend(command))
{
return true;
}
}
return false;
}
private static bool TrySendCommand(Cluster cluster, MemcachedCommand command)
{
var serversForVbucket = cluster.GetServersForVBucket(command.VBucketId);
return TrySendCommand(serversForVbucket, command);
}
private static void SendCommand(Cluster cluster, MemcachedCommand command)
{
if (!TrySendCommand(cluster, command))
{
command.NotifyComplete(ResponseStatus.DisconnectionOccuredWhileOperationWaitingToBeSent);
}
}
private void InitiateCommand(MemcachedCommand command)
{
WriteCommandHeader(command);
_writeState = new WriteState(command);
}
private void OnCommandResponseReceived(MemcachedCommand command)
{
RemoveFromPendingReceives(command);
command.NotifyComplete();
}
public bool TrySend(MemcachedCommand command)
{
return this.MemcachedClient.TrySend(command);
}