private async ValueTask <WriteResult> WriteMessageTakingWriteLockAsync_Awaited(ValueTask <LockToken> pending, PhysicalConnection physical, Message message)
{
try
{
using (var token = await pending)
{
if (!token.Success)
{
return(TimedOutBeforeWrite(message));
}
var result = WriteMessageInsideLock(physical, message);
if (result == WriteResult.Success)
{
result = await physical.FlushAsync(false);
}
UnmarkActiveMessage(message);
physical.SetIdle();
return(result);
}
}
catch (Exception ex)
{
return(HandleWriteException(message, ex));
}
}
private async ValueTask <WriteResult> WriteMessageTakingDelayedWriteLockAsync(ValueTask <LockToken> pendingLock, PhysicalConnection physical, Message message)
{
try
{
// WriteMessageTakingWriteLockAsync will have checked for immediate availability,
// so this is the fallback case - fine to go straight to "await"
// note: timeout is specified in mutex-constructor
using (var token = await pendingLock)
{
if (!token.Success)
{
message.Cancel();
Multiplexer?.OnMessageFaulted(message, null);
this.CompleteSyncOrAsync(message);
return(WriteResult.TimeoutBeforeWrite);
}
var result = WriteMessageInsideLock(physical, message);
if (result == WriteResult.Success)
{
result = await physical.FlushAsync(false).ForAwait();
}
physical.SetIdle();
UnmarkActiveMessage(message);
return(result);
}
}
catch (Exception ex) { return(HandleWriteException(message, ex)); }
}
private async Task <WriteResult> WriteMessageTakingDelayedWriteLockAsync(PhysicalConnection physical, Message message)
{
bool haveLock = false;
try
{
// WriteMessageTakingWriteLockAsync will have checked for immediate availability,
// so this is the fallback case - fine to go straight to "await"
haveLock = await _SingleWriterLock.WaitAsync(TimeoutMilliseconds).ForAwait();
if (!haveLock)
{
message.Cancel();
Multiplexer?.OnMessageFaulted(message, null);
this.CompleteSyncOrAsync(message);
return(WriteResult.TimeoutBeforeWrite);
}
var result = WriteMessageInsideLock(physical, message);
if (result == WriteResult.Success)
{
result = await physical.FlushAsync(false).ForAwait();
}
physical.SetIdle();
return(result);
}
catch (Exception ex) { return(HandleWriteException(message, ex)); }
finally { if (haveLock)
{
ReleaseSingleWriterLock(message);
}
}
}
/// <summary>
/// This writes a message to the output stream
/// </summary>
/// <param name="physical">The phsyical connection to write to.</param>
/// <param name="message">The message to be written.</param>
internal ValueTask <WriteResult> WriteMessageTakingWriteLockAsync(PhysicalConnection physical, Message message)
{
Trace("Writing: " + message);
message.SetEnqueued(physical); // this also records the read/write stats at this point
bool releaseLock = false;
LockToken token = default;
try
{
// try to acquire it synchronously
// note: timeout is specified in mutex-constructor
var pending = _singleWriterMutex.TryWaitAsync(options: MutexSlim.WaitOptions.DisableAsyncContext);
if (!pending.IsCompletedSuccessfully)
{
return(WriteMessageTakingDelayedWriteLockAsync(pending, physical, message));
}
releaseLock = true;
token = pending.Result; // we can't use "using" for this, because we might not want to kill it yet
if (!token.Success) // (in particular, me might hand the lifetime to CompleteWriteAndReleaseLockAsync)
{
message.Cancel();
Multiplexer?.OnMessageFaulted(message, null);
this.CompleteSyncOrAsync(message);
return(new ValueTask <WriteResult>(WriteResult.TimeoutBeforeWrite));
}
var result = WriteMessageInsideLock(physical, message);
if (result == WriteResult.Success)
{
var flush = physical.FlushAsync(false);
if (!flush.IsCompletedSuccessfully)
{
releaseLock = false; // so we don't release prematurely
return(CompleteWriteAndReleaseLockAsync(token, flush, message));
}
result = flush.Result; // we know it was completed, this is fine
}
UnmarkActiveMessage(message);
physical.SetIdle();
return(new ValueTask <WriteResult>(result));
}
catch (Exception ex) { return(new ValueTask <WriteResult>(HandleWriteException(message, ex))); }
finally
{
if (releaseLock)
{
token.Dispose();
}
}
}
/// <summary>
/// This writes a message to the output stream
/// </summary>
/// <param name="physical">The phsyical connection to write to.</param>
/// <param name="message">The message to be written.</param>
internal ValueTask <WriteResult> WriteMessageTakingWriteLockAsync(PhysicalConnection physical, Message message)
{
Trace("Writing: " + message);
message.SetEnqueued(physical); // this also records the read/write stats at this point
bool releaseLock = true;
LockToken token = default;
try
{
// try to acquire it synchronously
// note: timeout is specified in mutex-constructor
token = _singleWriterMutex.TryWait(options: WaitOptions.NoDelay);
if (!token.Success) // (in particular, me might hand the lifetime to CompleteWriteAndReleaseLockAsync)
{
PushToBacklog(message);
return(new ValueTask <WriteResult>(WriteResult.Success)); // queued counts as success
}
var result = WriteMessageInsideLock(physical, message);
if (result == WriteResult.Success)
{
var flush = physical.FlushAsync(false);
if (!flush.IsCompletedSuccessfully)
{
releaseLock = false; // so we don't release prematurely
return(CompleteWriteAndReleaseLockAsync(token, flush, message));
}
result = flush.Result; // we know it was completed, this is fine
}
UnmarkActiveMessage(message);
physical.SetIdle();
return(new ValueTask <WriteResult>(result));
}
catch (Exception ex) { return(new ValueTask <WriteResult>(HandleWriteException(message, ex))); }
finally
{
if (releaseLock)
{
token.Dispose();
}
}
}
/// <summary>
/// This writes a message to the output stream
/// </summary>
/// <param name="physical">The phsyical connection to write to.</param>
/// <param name="message">The message to be written.</param>
internal ValueTask <WriteResult> WriteMessageTakingWriteLockAsync(PhysicalConnection physical, Message message)
{
Trace("Writing: " + message);
message.SetEnqueued(physical); // this also records the read/write stats at this point
bool haveLock = false;
try
{
// try to acquire it synchronously
haveLock = _SingleWriterLock.Wait(0);
if (!haveLock)
{
return(new ValueTask <WriteResult>(WriteMessageTakingDelayedWriteLockAsync(physical, message)));
}
var result = WriteMessageInsideLock(physical, message);
if (result == WriteResult.Success)
{
var flush = physical.FlushAsync(false);
if (!flush.IsCompletedSuccessfully)
{
haveLock = false; // so we don't release prematurely
return(new ValueTask <WriteResult>(CompleteWriteAndReleaseLockAsync(flush, message)));
}
result = flush.Result; // we know it was completed, this is fine
}
physical.SetIdle();
return(new ValueTask <WriteResult>(result));
}
catch (Exception ex) { return(new ValueTask <WriteResult>(HandleWriteException(message, ex))); }
finally { if (haveLock)
{
ReleaseSingleWriterLock(message);
}
}
}
private Task HandshakeAsync(PhysicalConnection connection, TextWriter log)
{
Multiplexer.LogLocked(log, "Server handshake");
if (connection == null)
{
Multiplexer.Trace("No connection!?");
return(Task.CompletedTask);
}
Message msg;
string password = Multiplexer.RawConfig.Password;
if (!string.IsNullOrWhiteSpace(password))
{
Multiplexer.LogLocked(log, "Authenticating (password)");
msg = Message.Create(-1, CommandFlags.FireAndForget, RedisCommand.AUTH, (RedisValue)password);
msg.SetInternalCall();
WriteDirectOrQueueFireAndForget(connection, msg, ResultProcessor.DemandOK);
}
if (Multiplexer.CommandMap.IsAvailable(RedisCommand.CLIENT))
{
string name = Multiplexer.ClientName;
if (!string.IsNullOrWhiteSpace(name))
{
name = nameSanitizer.Replace(name, "");
if (!string.IsNullOrWhiteSpace(name))
{
Multiplexer.LogLocked(log, "Setting client name: {0}", name);
msg = Message.Create(-1, CommandFlags.FireAndForget, RedisCommand.CLIENT, RedisLiterals.SETNAME, (RedisValue)name);
msg.SetInternalCall();
WriteDirectOrQueueFireAndForget(connection, msg, ResultProcessor.DemandOK);
}
}
}
var bridge = connection.BridgeCouldBeNull;
if (bridge == null)
{
return(Task.CompletedTask);
}
var connType = bridge.ConnectionType;
if (connType == ConnectionType.Interactive)
{
Multiplexer.LogLocked(log, "Auto-configure...");
AutoConfigure(connection);
}
Multiplexer.LogLocked(log, "Sending critical tracer: {0}", bridge);
var tracer = GetTracerMessage(true);
tracer = LoggingMessage.Create(log, tracer);
WriteDirectOrQueueFireAndForget(connection, tracer, ResultProcessor.EstablishConnection);
// note: this **must** be the last thing on the subscription handshake, because after this
// we will be in subscriber mode: regular commands cannot be sent
if (connType == ConnectionType.Subscription)
{
var configChannel = Multiplexer.ConfigurationChangedChannel;
if (configChannel != null)
{
msg = Message.Create(-1, CommandFlags.FireAndForget, RedisCommand.SUBSCRIBE, (RedisChannel)configChannel);
WriteDirectOrQueueFireAndForget(connection, msg, ResultProcessor.TrackSubscriptions);
}
}
Multiplexer.LogLocked(log, "Flushing outbound buffer");
return(connection.FlushAsync());
}
/// <summary>
/// This writes a message to the output stream
/// </summary>
/// <param name="physical">The phsyical connection to write to.</param>
/// <param name="message">The message to be written.</param>
internal ValueTask <WriteResult> WriteMessageTakingWriteLockAsync(PhysicalConnection physical, Message message)
{
/* design decision/choice; the code works fine either way, but if this is
* set to *true*, then when we can't take the writer-lock *right away*,
* we push the message to the backlog (starting a worker if needed)
*
* otherwise, we go for a TryWaitAsync and rely on the await machinery
*
* "true" seems to give faster times *when under heavy contention*, based on profiling
* but it involves the backlog concept; "false" works well under low contention, and
* makes more use of async
*/
const bool ALWAYS_USE_BACKLOG_IF_CANNOT_GET_SYNC_LOCK = true;
Trace("Writing: " + message);
message.SetEnqueued(physical); // this also records the read/write stats at this point
bool releaseLock = true; // fine to default to true, as it doesn't matter until token is a "success"
LockToken token = default;
try
{
// try to acquire it synchronously
// note: timeout is specified in mutex-constructor
token = _singleWriterMutex.TryWait(options: WaitOptions.NoDelay);
if (!token.Success)
{
// we can't get it *instantaneously*; is there
// perhaps a backlog and active backlog processor?
if (PushToBacklog(message, onlyIfExists: !ALWAYS_USE_BACKLOG_IF_CANNOT_GET_SYNC_LOCK))
{
return(new ValueTask <WriteResult>(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
var pending = _singleWriterMutex.TryWaitAsync(options: WaitOptions.DisableAsyncContext);
if (!pending.IsCompletedSuccessfully)
{
return(WriteMessageTakingWriteLockAsync_Awaited(pending, physical, message));
}
token = pending.Result; // fine since we know we got a result
if (!token.Success)
{
return(new ValueTask <WriteResult>(TimedOutBeforeWrite(message)));
}
}
var result = WriteMessageInsideLock(physical, message);
if (result == WriteResult.Success)
{
var flush = physical.FlushAsync(false);
if (!flush.IsCompletedSuccessfully)
{
releaseLock = false; // so we don't release prematurely
return(CompleteWriteAndReleaseLockAsync(token, flush, message));
}
result = flush.Result; // we know it was completed, this is fine
}
UnmarkActiveMessage(message);
physical.SetIdle();
return(new ValueTask <WriteResult>(result));
}
catch (Exception ex) { return(new ValueTask <WriteResult>(HandleWriteException(message, ex))); }
finally
{
if (releaseLock)
{
token.Dispose();
}
}
}