[reSIProcate] dum shutdown issues (IMPORTANT)

[Jason Fischl]

An additional change to the DialogUsageManager interface:

If you are not running a separate StackThread inside of  dum the 
interface is unchanged. If you want a separate StackThread, call 
DialogUsageManager::run() to start the thread and then periodically call 
DialogUsageManager::process() from your application's thread to handle 
dum events. If process() returns true, an event was handled.

      // Runs the SipStack in its own StackThread. call process() from 
the application
      void run();

      // Call this version of process if you are running the sipstack in 
its own
      // thread. you must call run() before calling process()
      bool process();

      // Call this version of process if you want to run the stack in the
      // application's thread
      void process(FdSet& fdset);


Jason Fischl wrote:

> Someof the changes I've made to dum as part of my shutdown-related 
> changes:
>
> added a pure virtual BaseUsage::end() so the HandleManager can end any 
> usages that are still kicking around. Note that end() is now void and 
> does not return the SipMessage&. This necessitated a number of changes 
> to the derived Usage code. It will also require some minor changes to 
> application code.
>
> Jason
>
>
>
> Jason Fischl wrote:
>
>> Hi all,
>>
>> After fighting with shutdown for an entire day, I'd like to propose 
>> some changes. Here are the current issues:
>>
>> Shutting down a useragent requires us to:
>> - async end all active usages
>> - async shutdown call to DialogUsageManager
>> - async shutdown call to SipStack
>> - async end the StackThread (if we are using one)
>>
>> The application is required to somehow coordinate all of these 
>> requests to shutdown and wait for appropriate callbacks before moving 
>> on to the next one.
>>
>> There is no way to request dum to shutdown all usages. The order of 
>> usage termination may be important for some applications. For 
>> instance, some applications may require the registrations to be ended 
>> last since they may have GRUUs bound to them. In other cases, the 
>> order of unPUBLISH vs unSUBSCRIBE may also be important.
>>
>> In the current implementation, if the application calls shutdown and 
>> there are active usages, dum will wait for those usages to all end 
>> and will then call the handler onDumCanBeDeleted. However, if there 
>> are active ClientSubscriptions and dum never receives  NOTIFY 
>> messages with SubscriptionState == Terminated, dum will never exit. 
>> This can happen if the presence server crashes.
>>
>> Proposed changes:
>> - SipStack should be owned by DialogUsageManager. Is there really any 
>> case where the application would want to reuse a SipStack object 
>> after shutting down the dum?
>> - Application should be able to shutdown without having to explicitly 
>> end all active Usages. Either dum should end the usages or it should 
>> be able to shutdown without ending them. Either way, it should not 
>> leak memory.
>>
>> Current Interface:
>>
>> void
>> DialogUsageManager::shutdown(DumShutdownHandler* handler);
>>
>> virtual void
>> DumShutdownHandler::onDumCanBeDeleted()=0;
>>
>>
>> Proposed Interface:
>>
>> // In all cases, no leaks (obviously :)
>>
>> // End usages in the following order:  ServerInviteSession, 
>> ServerSubscription,  ClientInviteSession, ClientSubscription,
>> // ClientPagerMessage, ClientPublication, ClientRegistration
>> // call DumShutdownHandler::onDumCanBeDeleted when all usages are 
>> ended, SipStack is ended and StackThread is shutdown
>> // After giveUpSeconds, exit regardless. If giveUpSeconds == 0,  wait 
>> indefinitely
>> void DialogUsageManager::shutdown(DumShutdownHandler* handler, 
>> unsigned long giveUpSeconds=0);
>>
>> // call DumShutdownHandler::onDumCanBeDeleted when all usages are 
>> ended, SipStack is ended and StackThread is shutdown
>> // After giveUpSeconds, exit regardless. If giveUpSeconds == 0,  wait 
>> indefinitely
>> void DialogUsageManager::shutdownIfNoUsages(DumShutdownHandler* 
>> handler, unsigned long giveUpSeconds=0);
>>
>> // Shutdown immediately - ignore existing usages.
>> // call DumShutdownHandler::onDumCanBeDeleted when all usages are 
>> ended, SipStack is ended and StackThread is shutdown
>> void DialogUsageManager::forceShutdown(DumShutdownHandler* handler);
>
>
>
>
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