381 lines
8.7 KiB
C
381 lines
8.7 KiB
C
/**
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* @file event_queue.c
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*
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* @brief Event-Queue based on class linked_list_t
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*
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*/
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/*
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* Copyright (C) 2005 Jan Hutter, Martin Willi
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* Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#include <pthread.h>
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#include <stdlib.h>
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#include "event_queue.h"
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#include <types.h>
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#include <utils/allocator.h>
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#include <utils/linked_list.h>
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typedef struct event_t event_t;
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/**
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* @brief Represents an event as it is stored in the event queue.
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*
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* A event consists of a event time and an assigned job object.
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*
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*/
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struct event_t{
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/**
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* Time to fire the event.
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*/
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timeval_t time;
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/**
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* Every event has its assigned job.
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*/
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job_t * job;
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/**
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* @brief Destroys a event_t object.
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*
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* @param event_t calling object
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* @returns always SUCCESS
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*/
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status_t (*destroy) (event_t *event);
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};
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/**
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* @brief implements function destroy of event_t
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*/
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static status_t event_destroy(event_t *event)
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{
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allocator_free(event);
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return SUCCESS;
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}
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/**
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* @brief Creates a event for a specific time
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*
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* @param time absolute time to fire the event
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* @param job job to add to job-queue at specific time
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*
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* @returns
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* - created event_t object
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* - NULL if memory allocation failed
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*/
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static event_t *event_create(timeval_t time, job_t *job)
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{
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event_t *this = allocator_alloc_thing(event_t);
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if (this == NULL)
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{
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return this;
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}
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this->destroy = event_destroy;
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this->time = time;
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this->job = job;
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return this;
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}
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typedef struct private_event_queue_t private_event_queue_t;
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/**
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* @brief Private Variables and Functions of event_queue_t class.
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*
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*/
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struct private_event_queue_t {
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/**
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* Public part.
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*/
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event_queue_t public;
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/**
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* The events are stored in a linked list of type linked_list_t.
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*/
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linked_list_t *list;
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/**
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* Access to linked_list is locked through this mutex.
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*/
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pthread_mutex_t mutex;
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/**
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* If the queue is empty or an event has not to be fired
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* a thread has to wait.
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*
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* This condvar is used to wake up such a thread.
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*/
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pthread_cond_t condvar;
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};
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/**
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* Returns the difference of to timeval structs in microseconds
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*
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* @param end_time end time
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* @param start_time start time
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*
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* @warning this function is also defined in the tester class
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* In later improvements, this function can be added to a general
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* class type!
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*
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* @return difference in microseconds (end time - start time)
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*/
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static long time_difference(struct timeval *end_time, struct timeval *start_time)
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{
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long seconds, microseconds;
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seconds = (end_time->tv_sec - start_time->tv_sec);
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microseconds = (end_time->tv_usec - start_time->tv_usec);
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return ((seconds * 1000000) + microseconds);
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}
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/**
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* Implements function get_count of event_queue_t.
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* See #event_queue_s.get_count for description.
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*/
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static int get_count (private_event_queue_t *this)
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{
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int count;
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pthread_mutex_lock(&(this->mutex));
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count = this->list->get_count(this->list);
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pthread_mutex_unlock(&(this->mutex));
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return count;
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}
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/**
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* Implements function get of event_queue_t.
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* See #event_queue_s.get for description.
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*/
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static status_t get(private_event_queue_t *this, job_t **job)
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{
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timespec_t timeout;
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timeval_t current_time;
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event_t * next_event;
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int oldstate;
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pthread_mutex_lock(&(this->mutex));
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while (1)
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{
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while(this->list->get_count(this->list) == 0)
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{
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/* add mutex unlock handler for cancellation, enable cancellation */
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pthread_cleanup_push((void(*)(void*))pthread_mutex_unlock, (void*)&(this->mutex));
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pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &oldstate);
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pthread_cond_wait( &(this->condvar), &(this->mutex));
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/* reset cancellation, remove mutex-unlock handler (without executing) */
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pthread_setcancelstate(oldstate, NULL);
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pthread_cleanup_pop(0);
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}
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this->list->get_first(this->list,(void **) &next_event);
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gettimeofday(¤t_time,NULL);
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long difference = time_difference(¤t_time,&(next_event->time));
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if (difference <= 0)
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{
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timeout.tv_sec = next_event->time.tv_sec;
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timeout.tv_nsec = next_event->time.tv_usec * 1000;
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pthread_cond_timedwait( &(this->condvar), &(this->mutex),&timeout);
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}
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else
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{
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/* event available */
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this->list->remove_first(this->list,(void **) &next_event);
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*job = next_event->job;
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next_event->destroy(next_event);
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break;
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}
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}
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pthread_cond_signal( &(this->condvar));
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pthread_mutex_unlock(&(this->mutex));
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return SUCCESS;
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}
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/**
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* Implements function add_absolute of event_queue_t.
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* See #event_queue_s.add_absolute for description.
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*/
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static status_t add_absolute(private_event_queue_t *this, job_t *job, timeval_t time)
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{
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event_t *event = event_create(time,job);
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event_t *current_event;
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status_t status;
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if (event == NULL)
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{
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return FAILED;
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}
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pthread_mutex_lock(&(this->mutex));
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/* while just used to break out */
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while(1)
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{
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if (this->list->get_count(this->list) == 0)
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{
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status = this->list->insert_first(this->list,event);
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break;
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}
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/* check last entry */
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this->list->get_last(this->list,(void **) ¤t_event);
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if (time_difference(&(event->time), &(current_event->time)) >= 0)
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{
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/* my event has to be fired after the last event in list */
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status = this->list->insert_last(this->list,event);
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break;
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}
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/* check first entry */
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this->list->get_first(this->list,(void **) ¤t_event);
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if (time_difference(&(event->time), &(current_event->time)) < 0)
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{
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/* my event has to be fired before the first event in list */
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status = this->list->insert_first(this->list,event);
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break;
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}
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linked_list_iterator_t * iterator;
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status = this->list->create_iterator(this->list,&iterator,TRUE);
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if (status != SUCCESS)
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{
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break;
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}
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iterator->has_next(iterator);
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/* first element has not to be checked (already done) */
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while(iterator->has_next(iterator))
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{
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status = iterator->current(iterator,(void **) ¤t_event);
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if (time_difference(&(event->time), &(current_event->time)) <= 0)
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{
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/* my event has to be fired before the current event in list */
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status = iterator->insert_before(iterator,event);
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break;
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}
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}
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iterator->destroy(iterator);
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break;
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}
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pthread_cond_signal( &(this->condvar));
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pthread_mutex_unlock(&(this->mutex));
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if (status != SUCCESS)
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{
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event->destroy(event);
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}
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return status;
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}
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/**
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* Implements function add_relative of event_queue_t.
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* See #event_queue_s.add_relative for description.
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*/
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static status_t add_relative(event_queue_t *this, job_t *job, u_int32_t ms)
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{
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timeval_t current_time;
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timeval_t time;
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int micros = ms * 1000;
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gettimeofday(¤t_time, NULL);
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time.tv_usec = ((current_time.tv_usec + micros) % 1000000);
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time.tv_sec = current_time.tv_sec + ((current_time.tv_usec + micros)/ 1000000);
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return this->add_absolute(this, job, time);
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}
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/**
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* Implements function destroy of event_queue_t.
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* See #event_queue_s.destroy for description.
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*/
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static status_t event_queue_destroy(private_event_queue_t *this)
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{
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while (this->list->get_count(this->list) > 0)
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{
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event_t *event;
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if (this->list->remove_first(this->list,(void *) &event) != SUCCESS)
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{
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this->list->destroy(this->list);
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break;
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}
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event->job->destroy_all(event->job);
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event->destroy(event);
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}
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this->list->destroy(this->list);
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pthread_mutex_destroy(&(this->mutex));
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pthread_cond_destroy(&(this->condvar));
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allocator_free(this);
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return SUCCESS;
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}
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/*
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* Documented in header
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*/
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event_queue_t *event_queue_create()
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{
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linked_list_t *linked_list = linked_list_create();
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if (linked_list == NULL)
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{
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return NULL;
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}
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private_event_queue_t *this = allocator_alloc_thing(private_event_queue_t);
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if (this == NULL)
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{
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linked_list->destroy(linked_list);
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return NULL;
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}
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this->public.get_count = (int (*) (event_queue_t *event_queue)) get_count;
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this->public.get = (status_t (*) (event_queue_t *event_queue, job_t **job)) get;
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this->public.add_absolute = (status_t (*) (event_queue_t *event_queue, job_t *job, timeval_t time)) add_absolute;
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this->public.add_relative = (status_t (*) (event_queue_t *event_queue, job_t *job, u_int32_t ms)) add_relative;
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this->public.destroy = (status_t (*) (event_queue_t *event_queue)) event_queue_destroy;
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this->list = linked_list;
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pthread_mutex_init(&(this->mutex), NULL);
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pthread_cond_init(&(this->condvar), NULL);
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return (&this->public);
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}
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