ACE_Notification_Queue Class Reference

Implements a user-space queue to send Reactor notifications. More...

#include <Notification_Queue.h>

Inheritance diagram for ACE_Notification_Queue:

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Collaboration diagram for ACE_Notification_Queue:

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List of all members.

Public Member Functions
	ACE_Notification_Queue ()
	~ACE_Notification_Queue ()
int	open ()
	Pre-allocate resources in the queue.
void	reset ()
	Release all resources in the queue.
int	purge_pending_notifications (ACE_Event_Handler *eh, ACE_Reactor_Mask mask)
	Remove all elements in the queue matching eh and mask.
int	push_new_notification (ACE_Notification_Buffer const &buffer)
	Add a new notification to the queue.
int	pop_next_notification (ACE_Notification_Buffer &current, bool &more_messages_queued, ACE_Notification_Buffer &next)
	Extract the next notification from the queue.
Private Types
typedef ACE_Intrusive_List < ACE_Notification_Queue_Node >	Buffer_List
Private Member Functions
int	allocate_more_buffers ()
	Allocate more memory for the queue.
Private Attributes
ACE_Unbounded_Queue < ACE_Notification_Queue_Node * >	alloc_queue_
Buffer_List	notify_queue_
	Keeps track of all pending notifications.
Buffer_List	free_queue_
	Keeps track of all free buffers.
ACE_SYNCH_MUTEX	notify_queue_lock_
	Synchronization for handling of queues.

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Detailed Description

Implements a user-space queue to send Reactor notifications.

The ACE_Reactor uses a pipe to send wake up the thread running the event loop from other threads. This pipe can be limited in size under some operating systems. For some applications, this limit presents a problem. A user-space notification queue is used to overcome those limitations. The queue tries to use as few resources on the pipe as possible, while keeping all the data in user space.

This code was refactored from Select_Reactor_Base.

Definition at line 80 of file Notification_Queue.h.

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Member Typedef Documentation

typedef ACE_Intrusive_List<ACE_Notification_Queue_Node> ACE_Notification_Queue::Buffer_List [private]

Definition at line 136 of file Notification_Queue.h.

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Constructor & Destructor Documentation

ACE_Notification_Queue::ACE_Notification_Queue

(

)

Definition at line 14 of file Notification_Queue.cpp.

  : ACE_Copy_Disabled()
  , alloc_queue_()
  , notify_queue_()
  , free_queue_()
{
}

ACE_Notification_Queue::~ACE_Notification_Queue

(

)

Definition at line 23 of file Notification_Queue.cpp.

{
  reset();
}

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Member Function Documentation

int ACE_Notification_Queue::allocate_more_buffers

(

)

[private]

Allocate more memory for the queue.

Definition at line 77 of file Notification_Queue.cpp.

{
  ACE_TRACE ("ACE_Notification_Queue::allocate_more_buffers");

  ACE_Notification_Queue_Node *temp = 0;

  ACE_NEW_RETURN (temp,
                  ACE_Notification_Queue_Node[ACE_REACTOR_NOTIFICATION_ARRAY_SIZE],
                  -1);

  if (this->alloc_queue_.enqueue_head (temp) == -1)
    {
      delete [] temp;
      return -1;
    }

  for (size_t i = 0; i < ACE_REACTOR_NOTIFICATION_ARRAY_SIZE; ++i)
    {
      free_queue_.push_front(temp + i);
    }

  return 0;
}

int ACE_Notification_Queue::open

(

void

)

Pre-allocate resources in the queue.

Definition at line 29 of file Notification_Queue.cpp.

{
  ACE_TRACE ("ACE_Notification_Queue::open");

  ACE_GUARD_RETURN (ACE_SYNCH_MUTEX, mon, this->notify_queue_lock_, -1);

  if (!this->free_queue_.is_empty ())
    return 0;

  return allocate_more_buffers();
}

int ACE_Notification_Queue::pop_next_notification	(	ACE_Notification_Buffer &	current,
		bool &	more_messages_queued,
		ACE_Notification_Buffer &	next
	)

Extract the next notification from the queue.

Returns:

-1 on failure, 1 if a message was popped, 0 otherwise

Definition at line 195 of file Notification_Queue.cpp.

{
  ACE_TRACE ("ACE_Notification_Queue::pop_next_notification");

  more_messages_queued = false;

  ACE_GUARD_RETURN (ACE_SYNCH_MUTEX, mon, this->notify_queue_lock_, -1);

  if (notify_queue_.is_empty ())
    {
      return 0;
    }

  ACE_Notification_Queue_Node * node = notify_queue_.pop_front();

  current = node->get();
  free_queue_.push_front(node);

  if(!this->notify_queue_.is_empty())
    {
      more_messages_queued = true;
      next = notify_queue_.head()->get();
    }

  return 1;
}

int ACE_Notification_Queue::purge_pending_notifications	(	ACE_Event_Handler *	eh,
		ACE_Reactor_Mask	mask
	)

Remove all elements in the queue matching eh and mask.

I suggest reading the documentation in ACE_Reactor to find a more detailed description. This is just a helper function.

Definition at line 102 of file Notification_Queue.cpp.

{
  ACE_TRACE ("ACE_Notification_Queue::purge_pending_notifications");

  ACE_GUARD_RETURN (ACE_SYNCH_MUTEX, mon, this->notify_queue_lock_, -1);

  if (this->notify_queue_.is_empty ())
    return 0;

  int number_purged = 0;
  ACE_Notification_Queue_Node * node = notify_queue_.head();
  while(node != 0)
    {
      if (!node->matches_for_purging(eh))
        {
          // Easy case, skip to the next node
          node = node->next();
          continue;
        }

      if (!node->mask_disables_all_notifications(mask))
        {
          // ... another easy case, skip this node too, but clear the
          // mask first ...
          node->clear_mask(mask);
          node = node->next();
          continue;
        }

      // ... this is the more complicated case, we want to remove the
      // node from the notify_queue_ list.  First save the next node
      // on the list:
      ACE_Notification_Queue_Node * next = node->next();

      // ... then remove it ...
      notify_queue_.unsafe_remove(node);
      ++number_purged;

      // ... release resources ...
      ACE_Event_Handler *event_handler = node->get().eh_;
      event_handler->remove_reference ();

      // ... now this is a free node ...
      free_queue_.push_front(node);

      // ... go to the next node, if there is one ...
      node = next;
    }

  return number_purged;
}

int ACE_Notification_Queue::push_new_notification

(

ACE_Notification_Buffer const &

buffer

)

Add a new notification to the queue.

Returns:

-1 on failure, 1 if a new message should be sent through the pipe and 0 otherwise.

Definition at line 157 of file Notification_Queue.cpp.

{
  ACE_TRACE ("ACE_Notification_Queue::push_new_notification");

  bool notification_required = false;

  ACE_GUARD_RETURN (ACE_SYNCH_MUTEX, mon, this->notify_queue_lock_, -1);

  // No pending notifications.
  if (this->notify_queue_.is_empty ())
    notification_required = true;

  if (free_queue_.is_empty())
    {
      if (allocate_more_buffers() == -1)
        {
          return -1;
        }
    }

  ACE_Notification_Queue_Node * node =
    free_queue_.pop_front();

  ACE_ASSERT (node != 0);
  node->set(buffer);

  notify_queue_.push_back(node);

  if (!notification_required)
    {
      return 0;
    }

  return 1;
}

void ACE_Notification_Queue::reset

(

void

)

Release all resources in the queue.

Definition at line 42 of file Notification_Queue.cpp.

{
  ACE_TRACE ("ACE_Notification_Queue::reset");

  // Release all the event handlers still in the queue ...
  for (ACE_Notification_Queue_Node * node = notify_queue_.head();
       node != 0;
       node = node->next())
    {
      if (node->get().eh_ == 0)
        {
          continue;
        }
      (void) node->get().eh_->remove_reference();
    }

  // ... free up the dynamically allocated resources ...
  ACE_Notification_Queue_Node **b = 0;
  for (ACE_Unbounded_Queue_Iterator<ACE_Notification_Queue_Node *> alloc_iter (this->alloc_queue_);
       alloc_iter.next (b) != 0;
       alloc_iter.advance ())
    {
      delete [] *b;
      *b = 0;
    }

  // ... cleanup the list of allocated blocks ...
  this->alloc_queue_.reset ();

  // ... swap with empty lists to reset the contents ...
  Buffer_List().swap(notify_queue_);
  Buffer_List().swap(free_queue_);
}

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Member Data Documentation

ACE_Unbounded_Queue<ACE_Notification_Queue_Node*> ACE_Notification_Queue::alloc_queue_ [private]

Keeps track of allocated arrays of type ACE_Notification_Buffer. The idea is to amortize allocation costs by allocating multiple ACE_Notification_Buffer objects at a time.

Definition at line 134 of file Notification_Queue.h.

Buffer_List ACE_Notification_Queue::free_queue_ [private]

Keeps track of all free buffers.

Definition at line 142 of file Notification_Queue.h.

Buffer_List ACE_Notification_Queue::notify_queue_ [private]

Keeps track of all pending notifications.

Definition at line 139 of file Notification_Queue.h.

ACE_SYNCH_MUTEX ACE_Notification_Queue::notify_queue_lock_ [private]

Synchronization for handling of queues.

Definition at line 145 of file Notification_Queue.h.

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The documentation for this class was generated from the following files:

• Notification_Queue.h
• Notification_Queue.cpp