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https://issues.apache.org/jira/browse/QPID-2451?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12847066#action_12847066
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Alan Conway commented on QPID-2451:
-----------------------------------
An alternative API proposal. This is slightly more low level but still should
be easy to use, and it provides greater flexibility. This doesn't directly
support MessageListeners, but does support a thread pool polling a set of
sessions and dispatching messages. A MessageListener solution like the one
above can be implemented in terms of a SessionPoller.
Currently there is only one event type to poll for - session has messages. The
interface reserves a set of flags to allow us to add support for multiple event
types in a binary compatible way.
namespace qpid {
namespace messaging {
class Session;
struct PollerStopped : public Exception {
QPID_CLIENT_EXTERN PollerStopped(const std::string&);
};
/**
* Poll a group of sessions waiting for messages.
*
* Thread safe: can be used to implement a thread group dispatching a
* set of sessions by starting multiple threads each calling wait() in
* a loop.
*/
class SessionPoller {
public:
/**
* Add a session for polling. A session may only be in one poller
* at a time.
*
*...@param session Session to be added.
*...@param flags Ignored, reserved for future use.
*...@exception PollerStopped The poller is stopped.
*/
QPID_CLIENT_EXTERN void add(const Session& session, int flags=0);
/** Remove a session from the poller. */
QPID_CLIENT_EXTERN void remove(const Session&);
/**
* Wait up to timeout for a session with messages. The returned
* session is automatically removed from the poller, call add() to
* put it back.
*
*...@param session Out paramemter, set to the session.
*...@param timeout Maximum time to wait for a session before returning.
*...@return True if session has been set, false if the call timed out.
*...@exception PollerStopped The poller was stopped.
*/
QPID_CLIENT_EXTERN bool wait(Session& session, Duration
timeout=INFINITE_DURATION);
/**
* Stop the poller. Threads blocked in wait() will be thrown PollerStopped.
* Once stopped a poller cannot be re-started.
*/
QPID_CLIENT_EXTERN void stop();
};
}} // qpid::messaging
#endif /*!QPID_MESSAGING_SESSIONPOLLER_H*/
> Add support for MessageListener callback objects in new messaging API
> ---------------------------------------------------------------------
>
> Key: QPID-2451
> URL: https://issues.apache.org/jira/browse/QPID-2451
> Project: Qpid
> Issue Type: New Feature
> Components: C++ Client
> Reporter: Alan Conway
> Assignee: Alan Conway
>
> The old C++ client API allows the use to register an object derived from
> MessageListener as a callback to receive messages from the subscriptions
> associated with a session. The user can start a thread for each session to
> dispatch callbacks.
> We need a callback API for the new messaging API. The new API should allow
> the user to create a thread pool to dispatch to any number of sessions rather
> than requiring a thread per session. Note the pool model does also support
> thread-per-session by creating a pool of size 1 for each session.
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