DispatchHandler class used to synchronize with response messages. More...

#include <DispatchHandlerSynchronizer.h>

Inheritance diagram for Hypertable::DispatchHandlerSynchronizer:

Collaboration diagram for Hypertable::DispatchHandlerSynchronizer:

Public Member Functions
	DispatchHandlerSynchronizer ()
	Constructor. More...

virtual	~DispatchHandlerSynchronizer ()

virtual void	handle (EventPtr &event)
	Event Dispatch method. More...

bool	wait_for_reply (EventPtr &event)
	This method is used by a client to synchronize. More...

bool	wait_for_connection ()
	Waits for CONNECTION_ESTABLISHED event. More...

Public Member Functions inherited from Hypertable::DispatchHandler
virtual	~DispatchHandler ()
	Destructor. More...

Private Attributes
std::mutex	m_mutex
	Mutex for serializing concurrent access. More...

std::condition_variable	m_cond
	Condition variable for signalling change in queue state. More...

std::queue< EventPtr >	m_receive_queue
	Event queue. More...

Detailed Description

DispatchHandler class used to synchronize with response messages.

This class is a specialization of DispatchHandler that is used to synchronize with responses resulting from previously sent request messages. It contains a queue of events (response events) and a condition variable that gets signalled when an event gets put on the queue.

Example usage:

{
  DispatchHandlerSynchronizer sync_handler;
  EventPtr event;
  CommBufPtr cbp(... create protocol message here ...);
  if ((error = m_comm->send_request(m_addr, cbp, &sync_handler))
      != Error::OK) {
     // log error message here ...
     return error;
  }
  if (!sync_handler.wait_for_reply(event))
      // log error message here ...
  error = (int)Protocol::response_code(event);
  return error;
}

Definition at line 70 of file DispatchHandlerSynchronizer.h.

Constructor & Destructor Documentation

DispatchHandlerSynchronizer::DispatchHandlerSynchronizer ( )

Constructor.

Initializes state.

Definition at line 39 of file DispatchHandlerSynchronizer.cc.

virtual Hypertable::DispatchHandlerSynchronizer::~DispatchHandlerSynchronizer ( )

inlinevirtual

Definition at line 77 of file DispatchHandlerSynchronizer.h.

Member Function Documentation

void DispatchHandlerSynchronizer::handle ( EventPtr & event )

virtual

Event Dispatch method.

This gets called by the AsyncComm layer when an event occurs in response to a previously sent request that was supplied with this dispatch handler. It pushes the event onto the event queue and signals (notify_one) the condition variable.

Parameters

event Smart pointer to event object

Implements Hypertable::DispatchHandler.

Definition at line 43 of file DispatchHandlerSynchronizer.cc.

bool DispatchHandlerSynchronizer::wait_for_connection ( )

Waits for CONNECTION_ESTABLISHED event.

This function waits for an event to arrive on m_receive_queue and if it is an ERROR event, it throws an exception, if it is a DISCONNECT event it returns false, and if it is a CONNECTION_ESTABLISHED event, it returns true.

Returns: true if CONNECTION_ESTABLISHED event received, false if DISCONNECT event received.

Exceptions

Exception with code set to ERROR event error code.

Definition at line 66 of file DispatchHandlerSynchronizer.cc.

bool DispatchHandlerSynchronizer::wait_for_reply ( EventPtr & event )

This method is used by a client to synchronize.

The client sends a request via the AsyncComm layer with this object as the dispatch handler. It then calls this method to wait for the response (or timeout event). This method just blocks on the condition variable until the event queue is non-empty and then removes and returns the head of the queue.

Parameters

event Smart pointer to event object