238 lines
7.4 KiB
C
238 lines
7.4 KiB
C
/* $Header: /pjproject-0.3/pjlib/include/pj/timer.h 7 10/14/05 12:26a Bennylp $ */
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/* (C)1993-2003 Douglas C. Schmidt
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*
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* This file is originaly from ACE library by Doug Schmidt
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* ACE(TM), TAO(TM) and CIAO(TM) are copyrighted by Douglas C. Schmidt and his research
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* group at Washington University, University of California, Irvine, and Vanderbilt
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* University Copyright (c) 1993-2003, all rights reserved.
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*
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*/
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#ifndef __PJ_TIMER_H__
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#define __PJ_TIMER_H__
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/**
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* @file timer.h
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* @brief Timer Heap
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*/
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#include <pj/types.h>
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PJ_BEGIN_DECL
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/**
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* @defgroup PJ_TIMER Timer Heap Management.
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* @ingroup PJ_MISC
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* @brief
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* The timer scheduling implementation here is based on ACE library's
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* ACE_Timer_Heap, with only little modification to suit our library's style
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* (I even left most of the comments in the original source).
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*
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* To quote the original quote in ACE_Timer_Heap_T class:
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*
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* This implementation uses a heap-based callout queue of
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* absolute times. Therefore, in the average and worst case,
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* scheduling, canceling, and expiring timers is O(log N) (where
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* N is the total number of timers). In addition, we can also
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* preallocate as many \a ACE_Timer_Nodes as there are slots in
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* the heap. This allows us to completely remove the need for
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* dynamic memory allocation, which is important for real-time
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* systems.
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* @{
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*
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* \section pj_timer_examples_sec Examples
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*
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* For some examples on how to use the timer heap, please see the link below.
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*
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* - \ref page_pjlib_timer_test
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*/
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/**
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* The type for internal timer ID.
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*/
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typedef int pj_timer_id_t;
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/**
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* Forward declaration for pj_timer_entry.
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*/
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struct pj_timer_entry;
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/**
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* The type of callback function to be called by timer scheduler when a timer
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* has expired.
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*
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* @param timer_heap The timer heap.
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* @param entry Timer entry which timer's has expired.
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*/
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typedef void pj_timer_heap_callback(pj_timer_heap_t *timer_heap,
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struct pj_timer_entry *entry);
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/**
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* This structure represents an entry to the timer.
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*/
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struct pj_timer_entry
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{
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/**
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* User data to be associated with this entry.
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* Applications normally will put the instance of object that
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* owns the timer entry in this field.
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*/
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void *user_data;
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/**
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* Arbitrary ID assigned by the user/owner of this entry.
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* Applications can use this ID to distinguish multiple
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* timer entries that share the same callback and user_data.
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*/
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int id;
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/**
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* Callback to be called when the timer expires.
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*/
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pj_timer_heap_callback *cb;
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/**
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* Internal unique timer ID, which is assigned by the timer heap.
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* Application should not touch this ID.
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*/
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pj_timer_id_t _timer_id;
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/**
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* The future time when the timer expires, which the value is updated
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* by timer heap when the timer is scheduled.
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*/
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pj_time_val _timer_value;
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};
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/**
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* Default flag for timer heap, indicates that synchronization will be
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* used.
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*/
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#define PJ_TIMER_HEAP_SYNCHRONIZE (0)
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/**
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* Flag to indicate that thread synchronization is NOT needed for the
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* timer heap.
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*/
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#define PJ_TIMER_HEAP_NO_SYNCHRONIZE (1)
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/**
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* Calculate memory size required to create a timer heap.
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*
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* @param count Number of timer entries to be supported.
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* @return Memory size requirement in bytes.
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*/
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PJ_DECL(pj_size_t) pj_timer_heap_mem_size(pj_size_t count);
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/**
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* Create a timer heap.
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*
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* @param pool The pool where allocations in the timer heap will be
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* allocated. The timer heap will dynamicly allocate
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* more storate from the pool if the number of timer
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* entries registered is more than the size originally
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* requested when calling this function.
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* @param count The maximum number of timer entries to be supported
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* initially. If the application registers more entries
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* during runtime, then the timer heap will resize.
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* @param flag Creation flag, currently only PJ_TIMER_HEAP_NO_SYNCHRONIZE
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* is recognized..
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* @param ht Pointer to receive the created timer heap.
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*
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* @return PJ_SUCCESS, or the appropriate error code.
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*/
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PJ_DECL(pj_status_t) pj_timer_heap_create( pj_pool_t *pool,
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pj_size_t count,
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unsigned flag,
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pj_timer_heap_t **ht);
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/**
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* Initialize a timer entry. Application should call this function at least
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* once before scheduling the entry to the timer heap, to properly initialize
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* the timer entry.
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*
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* @param entry The timer entry to be initialized.
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* @param id Arbitrary ID assigned by the user/owner of this entry.
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* Applications can use this ID to distinguish multiple
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* timer entries that share the same callback and user_data.
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* @param user_data User data to be associated with this entry.
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* Applications normally will put the instance of object that
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* owns the timer entry in this field.
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* @param cb Callback function to be called when the timer elapses.
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*
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* @return The timer entry itself.
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*/
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PJ_DECL(pj_timer_entry*) pj_timer_entry_init( pj_timer_entry *entry,
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int id,
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void *user_data,
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pj_timer_heap_callback *cb );
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/**
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* Schedule a timer entry which will expire AFTER the specified delay.
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*
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* @param ht The timer heap.
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* @param entry The entry to be registered.
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* @param delay The interval to expire.
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* @return PJ_SUCCESS, or the appropriate error code.
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*/
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PJ_DECL(pj_status_t) pj_timer_heap_schedule( pj_timer_heap_t *ht,
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pj_timer_entry *entry,
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const pj_time_val *delay);
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/**
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* Cancel a previously registered timer.
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*
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* @param ht The timer heap.
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* @param entry The entry to be cancelled.
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* @return The number of timer cancelled, which should be one if the
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* entry has really been registered, or zero if no timer was
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* cancelled.
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*/
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PJ_DECL(int) pj_timer_heap_cancel( pj_timer_heap_t *ht,
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pj_timer_entry *entry);
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/**
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* Get the number of timer entries.
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*
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* @param ht The timer heap.
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* @return The number of timer entries.
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*/
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PJ_DECL(pj_size_t) pj_timer_heap_count( pj_timer_heap_t *ht );
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/**
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* Get the earliest time registered in the timer heap. The timer heap
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* MUST have at least one timer being scheduled (application should use
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* #pj_timer_heap_count() before calling this function).
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*
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* @param ht The timer heap.
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* @param timeval The time deadline of the earliest timer entry.
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*
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* @return PJ_SUCCESS, or PJ_ENOTFOUND if no entry is scheduled.
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*/
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PJ_DECL(pj_status_t) pj_timer_heap_earliest_time( pj_timer_heap_t *ht,
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pj_time_val *timeval);
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/**
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* Poll the timer heap, check for expired timers and call the callback for
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* each of the expired timers.
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*
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* @param ht The timer heap.
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* @param next_delay If this parameter is not NULL, it will be filled up with
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* the time delay until the next timer elapsed, or -1 in
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* the sec part if no entry exist.
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* @return The number of timers expired.
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*/
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PJ_DECL(int) pj_timer_heap_poll( pj_timer_heap_t *ht, pj_time_val *next_delay);
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/**
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* @}
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*/
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PJ_END_DECL
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#endif /* __PJ_TIMER_H__ */
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