Client can fail to notify all framelisteners
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Key: QPID-1431
URL: https://issues.apache.org/jira/browse/QPID-1431
Project: Qpid
Issue Type: Bug
Components: Java Client
Affects Versions: M3, M2.1
Reporter: Martin Ritchie
Assignee: Martin Ritchie
Priority: Critical
Fix For: M4
Summary:
Due to our desire to reduce synchronization on the client it is possible to
fail to notify a client of an exception state.
As highlighted by the two thread processes below, the _frameListeners can be
updated such that the notification fails to take place.
Thread 1. Thread 2.
Synchronous Op.(Commit, Create...) Error Occurs
AMQProtocolHandler AMQProtocolHandler
syncWrite(frame)
propagateExceptionToFrameListeners(error)
writeCommandAndWait(frame,listener)
synchronize(_frameListeners) if
(_frameListeners.isEmpty())
frameListener.add(listener) _frameListeners.iterator();
This is due to our use of CopyOnWrite lists. As the Exception handler is
propagating the exception a new syncWait can occur, which will fail as the
connection is closed. There is a question of why the socket write does not fail
but that may be because the close has not yet occurred.
Suggested change:
All uses of the _frameListeners should be synchronized and the syncWrite should
check to see if the connection is closed before allowing the adding the
listener. Throwing any exception that has already been set.
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