clebert suconic created PROTON-645:
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Summary: Implement session flow control independently of
transport.capacity
Key: PROTON-645
URL: https://issues.apache.org/jira/browse/PROTON-645
Project: Qpid Proton
Issue Type: Improvement
Components: proton-j
Reporter: clebert suconic
When integrating with any asynchronous IO we are obligated to implement flow
control based on the capacity of the Transport.
Things get especially harder because when you pop bytes in a asynchronous
method for after completion:
e.g. on Netty:
channel.writeAndFlush(bytes).addListener(new ChannelFutureListener()
{
@Override
public void operationComplete(ChannelFuture future) throws Exception
{
transport.pop(bufferSize);
/// perform process, and dispatch!
performDispatchEtc();
if (transport.capacity() > 0)
{
channel.read();
}
}
});
this makes things specially harder as we are eventually losing events or bytes.
We could make things work with some hacks (like having recursive loops on the
methods for writing and reading)...
Making Proton-J to work with asynchronous pop is definitely a black art.
Instead of working around with recursive workarounds we should provide an
easier path. such as plugging SessionFlowController where we could activate /
deactivate producers on a server, or use Semaphores on a client where a client
could block until things are properly released.
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