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#ifndef ACE_NOTIFICATION_QUEUE_H
#define ACE_NOTIFICATION_QUEUE_H
#include /**/ "ace/pre.h"
#include "ace/Event_Handler.h"
/**
* @file Notification_Queue.h
*
* $Id$
*
* @author Carlos O'Ryan <coryan@atdesk.com>
*/
#include "ace/Copy_Disabled.h"
#include "ace/Unbounded_Queue.h"
/**
* @class ACE_Notification_Queue
*
* @brief 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.
*/
class ACE_Notification_Queue : private ACE_Copy_Disabled
{
public:
ACE_Notification_Queue();
~ACE_Notification_Queue();
/**
* @brief Pre-allocate resources in the queue
*/
int open();
/**
* @brief Release all resources in the queue
*/
void reset();
/**
* @brief Remove all elements in the queue matching @c eh and @c mask
*
* I suggest reading the documentation in ACE_Reactor to find a more
* detailed description. This is just a helper function.
*/
int purge_pending_notifications(ACE_Event_Handler * eh,
ACE_Reactor_Mask mask);
/**
* @brief Add a new notification to the queue
*
* @return -1 on failure, 1 if a new message should be sent through
* the pipe and 0 otherwise.
*/
int push_new_notification(ACE_Notification_Buffer const & buffer);
/**
* @brief Extract the next notification from the queue
*
* @return -1 on failure, 1 if a message was popped, 0 otherwise
*/
int pop_next_notification(
ACE_Notification_Buffer & current,
bool & more_messages_queued,
ACE_Notification_Buffer & next);
private:
/**
* @brief Allocate more memory for the queue
*/
int allocate_more_buffers();
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.
ACE_Unbounded_Queue <ACE_Notification_Buffer *> alloc_queue_;
/// Keeps track of all pending notifications.
ACE_Unbounded_Queue <ACE_Notification_Buffer *> notify_queue_;
/// Keeps track of all free buffers.
ACE_Unbounded_Queue <ACE_Notification_Buffer *> free_queue_;
/// Synchronization for handling of queues.
ACE_SYNCH_MUTEX notify_queue_lock_;
};
#include /**/ "ace/post.h"
#endif /* ACE_NOTIFICATION_QUEUE_H */
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