libresiprocate-1.9-dev 1.9.6-1 / usr / include / repro / AsyncProcessor.hxx

#if !defined(RESIP_ASYNC_PROCESSOR_HXX)
#define RESIP_ASYNC_PROCESSOR_HXX 

#include <iosfwd>
#include <vector>
#include "repro/Processor.hxx"
#include "repro/ProcessorMessage.hxx"
#include "repro/Dispatcher.hxx"

namespace repro
{
class AsyncProcessorMessage;

// This class is used to create Processors that need to accomplish blocking
// tasks, such as database access.  The request/event is delivered to this 
// Processor, like any other via the virtual method:
// virtual processor_action_t process(RequestContext &)
//
// When a blocking task is required, it can be queued up for the thread pool 
// of workers, that are implemented in the constructor provided asyncDispatcher, by
// constructing a new AsyncProcessorMessage and calling mAsyncDispatcher->post
// AsyncProcessorMessage implementations should contain any data needed by the 
// threads and contain any members required to hold the blocking functions
// return data or results.
//
// When a worker thread picks up the message it will call the virtual method:
// virtual void asyncProcess(AsyncProcessorMessage* msg)
// The implementation of this method should perform the actual blocking function
// calls - ie. database access call.  If there is any data to return it should be
// set in the provided AsyncProcessorMessage before returning from asyncProcess.
//
// The dispatcher will then queue this message up to be sent back to the 
// AsyncProcessor, via the virtual method:
// virtual processor_action_t process(RequestContext &)
// This virtual method will need to examine the event type to see if the event is
// a new request or an asynchronous result message (AsyncProcessorMessage).
// 

/* Example:
class MyAsyncProcessorAsyncMessage : public AsyncProcessorMessage 
{
public:
   MyAsyncProcessorAsyncMessage(AsyncProcessor& proc,
                         const resip::Data& tid,
                         resip::TransactionUser* passedtu):
      AsyncProcessorMessage(proc,tid,passedtu)  { }

   virtual EncodeStream& encode(EncodeStream& strm) const 
   { 
      strm << "MyAsyncProcessorAsyncMessage(tid="<<mTid<<")"; return strm; 
   }

   Data mDataRequiredToCallBlockingFunction;
   Data mDataReturnedFromBlockingFunction;
};

class MyAsyncProcessor : public AsyncProcessor
{
   public:
      MyAsyncProcessor(ProxyConfig& config, Dispatcher* asyncDispatcher) :
         AsyncProcessor("MyAsyncProcessor", asyncDispatcher) {}
      ~MyAsyncProcessor() {}

      // Processor virtual method
      virtual processor_action_t process(RequestContext &rc)
      {
         Message *message = rc.getCurrentEvent();

         MyAsyncProcessorAsyncMessage *async = dynamic_cast<MyAsyncProcessorAsyncMessage*>(message);
         if (async)
         {
            // Async Function is complete - do something with results and continue
            InfoLog(<< "Async function is complete, results are: " << async->mDataReturnedFromBlockingFunction);
            return Continue;
         }
         else
         {
            // Control enters here when request arrives and is passed through process chain
            // Dispatch async request to worker thread pool
            MyAsyncProcessorAsyncMessage* async = new MyAsyncProcessorAsyncMessage(*this, rc.getTransactionId(), &rc.getProxy());
            async->mDataRequiredToCallBlockingFunction = "foo";
            mAsyncDispatcher->post(std::auto_ptr<ApplicationMessage>(async));
            return WaitingForEvent;
         }
      }

      // Virtual method called from WorkerThreads - return true to queue to stack when complete,
      // false when no response is required
      virtual bool asyncProcess(AsyncProcessorMessage* msg)
      {
         MyAsyncProcessorAsyncMessage* async = dynamic_cast<MyAsyncProcessorAsyncMessage*>(msg);
         if(async)
         {
            // Running inside a worker thread here, do blocking work here
            // set any results in MyAsyncProcessorAsyncMessage and return control to Dispatcher
            // that will queue this message back to this processor.
            async->mDataReturnedFromBlockingFunction = "bar";
         }
      }

   private:
};
*/


class AsyncProcessor : public Processor
{
   public:
      AsyncProcessor(const resip::Data& name, Dispatcher* asyncDispatcher, ChainType type=NO_TYPE) :
         Processor(name, type),
         mAsyncDispatcher(asyncDispatcher) {}
      virtual ~AsyncProcessor() {}

      // Processor virtual method
      virtual processor_action_t process(RequestContext &)=0;

      // Virtual method called from WorkerThreads
      // return true to queue to stack when complete, false when no response is required
      virtual bool asyncProcess(AsyncProcessorMessage* msg)=0;

   protected:
      Dispatcher* mAsyncDispatcher;
};

}


#endif

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