[PROTON-1171] [proton-j] transport SSL wrapper does not flush all decoded bytes to the underlying input

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: proton-0.12.0, proton-0.12.1
• Fix Version/s: proton-0.12.2, proton-0.13.0
• Component/s: proton-j
• Environment: Any
• Assignee: Robbie Gemmell
• Reporter: Sreeram Garlapati
• Created: 06/Apr/16 16:21
• Updated: 28/Apr/16 17:23
• Resolved: 18/Apr/16 11:29

Description

Actual Issue/scenario hit by Microsoft Azure EventHubs:
We have a pattern where customers sends messages in a burst to our Queue and stop sending and then wait for all of them to be received.
Because of this issue in Proton-j Amqp implementation - we can see many bytes were stuck in the SSL Decode Buffer and were only picked up when new transport frames arrive.
Given that this is a 1 line fix - it would be great if you folks can publish an incremental minor update to 0.12.X.

Here are my findings after debugging through this issue:

• When incoming bytes arrive on the SocketChannel – proton-j client gets signaled by nio & as a result it unwinds the transport stack – as a result all the TransportInput implementations performs its task on the Read Bytes and hands off to the Next Layer in the stack (transport to ssl, ssl to frameparser etc).

• While unwinding that stack, SimpleSSLTransportWrapper.unwrapInput reads(16k bytes) from _inputBuffer and the result - decoded bytes are written to _decodedInputBuffer – as an intermediate buffer.

• It then flushes bytes from intermediate buffer to the next layer & invokes an _underlyingInput.Process() – to signal it that it has bytes in its input buffer.

• If the underlyingInput (lets say FrameParser) buffer size is small – lets say 4k – then decodedInputBuffer will be left with 12k bytes & Over time this accrues.

The fix here is to flush decodedInputBuffer to the Next transport in the Network Stack & call _underlyingInput.Process() - until decodedInputBuffer is empty. Here’s the pull request:
https://github.com/apache/qpid-proton/pull/73

Issue Links

• relates to: PROTON-1185 [proton-j] Send operations like SendLink.send() & RecvLink.flow() (aka writing to the transport stack) doesn't flush all bytes to the Network