private WriteResult FailDueToNoConnection(Message message)
{
message.Cancel();
Multiplexer?.OnMessageFaulted(message, null);
message.Complete();
return(WriteResult.NoConnectionAvailable);
}
private WriteResult TimedOutBeforeWrite(Message message)
{
message.Cancel();
Multiplexer?.OnMessageFaulted(message, null);
message.Complete();
return(WriteResult.TimeoutBeforeWrite);
}
internal WriteResult WriteMessageTakingWriteLockSync(PhysicalConnection physical, Message message)
{
Trace("Writing: " + message);
message.SetEnqueued(physical); // this also records the read/write stats at this point
LockToken token = default;
try
{
token = _singleWriterMutex.TryWait(WaitOptions.NoDelay);
if (!token.Success)
{
// we can't get it *instantaneously*; is there
// perhaps a backlog and active backlog processor?
bool haveBacklog;
lock (_backlog)
{
haveBacklog = _backlog.Count != 0;
}
if (haveBacklog)
{
PushToBacklog(message);
return(WriteResult.Success); // queued counts as success
}
// no backlog... try to wait with the timeout;
// if we *still* can't get it: that counts as
// an actual timeout
token = _singleWriterMutex.TryWait();
if (!token.Success)
{
message.Cancel();
Multiplexer?.OnMessageFaulted(message, null);
message.Complete();
return(WriteResult.TimeoutBeforeWrite);
}
}
var result = WriteMessageInsideLock(physical, message);
if (result == WriteResult.Success)
{
#pragma warning disable CS0618
result = physical.FlushSync(false, TimeoutMilliseconds);
#pragma warning restore CS0618
}
UnmarkActiveMessage(message);
physical.SetIdle();
return(result);
}
catch (Exception ex) { return(HandleWriteException(message, ex)); }
finally { token.Dispose(); }
}
private WriteResult WriteMessageInsideLock(PhysicalConnection physical, Message message)
{
WriteResult result;
var existingMessage = Interlocked.CompareExchange(ref _activeMesssage, message, null);
if (existingMessage != null)
{
Multiplexer?.OnInfoMessage($"reentrant call to WriteMessageTakingWriteLock for {message.CommandAndKey}, {existingMessage.CommandAndKey} is still active");
return(WriteResult.NoConnectionAvailable);
}
physical.SetWriting();
var messageIsSent = false;
if (message is IMultiMessage)
{
SelectDatabaseInsideWriteLock(physical, message); // need to switch database *before* the transaction
foreach (var subCommand in ((IMultiMessage)message).GetMessages(physical))
{
result = WriteMessageToServerInsideWriteLock(physical, subCommand);
if (result != WriteResult.Success)
{
// we screwed up; abort; note that WriteMessageToServer already
// killed the underlying connection
Trace("Unable to write to server");
message.Fail(ConnectionFailureType.ProtocolFailure, null, "failure before write: " + result.ToString());
message.Complete();
return(result);
}
//The parent message (next) may be returned from GetMessages
//and should not be marked as sent again below
messageIsSent = messageIsSent || subCommand == message;
}
if (!messageIsSent)
{
message.SetRequestSent(); // well, it was attempted, at least...
}
return(WriteResult.Success);
}
else
{
return(WriteMessageToServerInsideWriteLock(physical, message));
}
}
private WriteResult QueueOrFailMessage(Message message)
{
if (message.IsInternalCall && message.Command != RedisCommand.QUIT)
{
// you can go in the queue, but we won't be starting
// a worker, because the handshake has not completed
lock (_backlog)
{
_backlog.Enqueue(message);
}
message.SetEnqueued(null);
return(WriteResult.Success); // we'll take it...
}
else
{
// sorry, we're just not ready for you yet;
message.Cancel();
Multiplexer?.OnMessageFaulted(message, null);
message.Complete();
return(WriteResult.NoConnectionAvailable);
}
}
private WriteResult WriteMessageToServerInsideWriteLock(PhysicalConnection connection, Message message)
{
if (message == null)
{
return(WriteResult.Success); // for some definition of success
}
bool isQueued = false;
try
{
var cmd = message.Command;
LastCommand = cmd;
bool isMasterOnly = message.IsMasterOnly();
if (isMasterOnly && ServerEndPoint.IsSlave && (ServerEndPoint.SlaveReadOnly || !ServerEndPoint.AllowSlaveWrites))
{
throw ExceptionFactory.MasterOnly(Multiplexer.IncludeDetailInExceptions, message.Command, message, ServerEndPoint);
}
switch (cmd)
{
case RedisCommand.QUIT:
connection.RecordQuit();
break;
case RedisCommand.EXEC:
Multiplexer.OnPreTransactionExec(message); // testing purposes, to force certain errors
break;
}
SelectDatabaseInsideWriteLock(connection, message);
if (!connection.TransactionActive)
{
var readmode = connection.GetReadModeCommand(isMasterOnly);
if (readmode != null)
{
connection.EnqueueInsideWriteLock(readmode);
readmode.WriteTo(connection);
readmode.SetRequestSent();
IncrementOpCount();
}
if (message.IsAsking)
{
var asking = ReusableAskingCommand;
connection.EnqueueInsideWriteLock(asking);
asking.WriteTo(connection);
asking.SetRequestSent();
IncrementOpCount();
}
}
switch (cmd)
{
case RedisCommand.WATCH:
case RedisCommand.MULTI:
connection.TransactionActive = true;
break;
case RedisCommand.UNWATCH:
case RedisCommand.EXEC:
case RedisCommand.DISCARD:
connection.TransactionActive = false;
break;
}
connection.EnqueueInsideWriteLock(message);
isQueued = true;
message.WriteTo(connection);
message.SetRequestSent();
IncrementOpCount();
// some commands smash our ability to trust the database; some commands
// demand an immediate flush
switch (cmd)
{
case RedisCommand.EVAL:
case RedisCommand.EVALSHA:
if (!ServerEndPoint.GetFeatures().ScriptingDatabaseSafe)
{
connection.SetUnknownDatabase();
}
break;
case RedisCommand.UNKNOWN:
case RedisCommand.DISCARD:
case RedisCommand.EXEC:
connection.SetUnknownDatabase();
break;
}
return(WriteResult.Success);
}
catch (RedisCommandException ex) when(!isQueued)
{
Trace("Write failed: " + ex.Message);
message.Fail(ConnectionFailureType.InternalFailure, ex, null);
message.Complete();
// this failed without actually writing; we're OK with that... unless there's a transaction
if (connection?.TransactionActive == true)
{
// we left it in a broken state; need to kill the connection
connection.RecordConnectionFailed(ConnectionFailureType.ProtocolFailure, ex);
return(WriteResult.WriteFailure);
}
return(WriteResult.Success);
}
catch (Exception ex)
{
Trace("Write failed: " + ex.Message);
message.Fail(ConnectionFailureType.InternalFailure, ex, null);
message.Complete();
// we're not sure *what* happened here; probably an IOException; kill the connection
connection?.RecordConnectionFailed(ConnectionFailureType.InternalFailure, ex);
return(WriteResult.WriteFailure);
}
}
