netsurf/riscos/schedule.c
Richard Wilson 9702484306 [project @ 2005-05-17 23:25:32 by rjw]
Don't allow things to be scheduled twice.

svn path=/import/netsurf/; revision=1725
2005-05-17 23:25:32 +00:00

146 lines
3.2 KiB
C

/*
* This file is part of NetSurf, http://netsurf.sourceforge.net/
* Licensed under the GNU General Public License,
* http://www.opensource.org/licenses/gpl-license
* Copyright 2004 James Bursa <bursa@users.sourceforge.net>
*/
/** \file
* Scheduled callback queue (implementation).
*
* The queue is simply implemented as a linked list.
*/
#include <stdbool.h>
#include <stdlib.h>
#include "oslib/os.h"
#include "netsurf/riscos/gui.h"
#include "netsurf/utils/log.h"
/** Entry in the queue of scheduled callbacks. */
struct sched_entry {
/** Preferred time for callback. */
os_t time;
/** Function to call at the specified time. */
void (*callback)(void *p);
/** User parameter for callback. */
void *p;
/** Next (later) entry in queue. */
struct sched_entry *next;
};
/** Queue of scheduled callbacks (sentinel at head). */
static struct sched_entry sched_queue = { 0, 0, 0, 0 };
/** Items have been scheduled. */
bool sched_active = false;
/** Time of soonest scheduled event (valid only if sched_active is true). */
os_t sched_time;
/**
* Schedule a callback.
*
* \param t interval before the callback should be made / cs
* \param callback callback function
* \param p user parameter, passed to callback function
*
* The callback function will be called as soon as possible after t cs have
* passed.
*/
void schedule(int t, void (*callback)(void *p), void *p)
{
struct sched_entry *entry;
struct sched_entry *queue;
os_t time;
schedule_remove(callback, p);
time = os_read_monotonic_time() + t;
entry = malloc(sizeof *entry);
if (!entry) {
LOG(("malloc failed"));
return;
}
entry->time = time;
entry->callback = callback;
entry->p = p;
for (queue = &sched_queue;
queue->next && queue->next->time <= time;
queue = queue->next)
;
entry->next = queue->next;
queue->next = entry;
sched_active = true;
sched_time = sched_queue.next->time;
}
/**
* Unschedule a callback.
*
* \param callback callback function
* \param p user parameter, passed to callback function
*
* All scheduled callbacks matching both callback and p are removed.
*/
void schedule_remove(void (*callback)(void *p), void *p)
{
struct sched_entry *entry, *next;
for (entry = &sched_queue; entry->next; entry = entry->next) {
if (entry->next->callback != callback || entry->next->p != p)
continue;
next = entry->next;
entry->next = entry->next->next;
free(next);
if (!entry->next)
break;
}
if (sched_queue.next) {
sched_active = true;
sched_time = sched_queue.next->time;
} else
sched_active = false;
}
/**
* Process events up to current time.
*/
void schedule_run(void)
{
struct sched_entry *entry;
void (*callback)(void *p);
void *p;
os_t now;
now = os_read_monotonic_time();
while (sched_queue.next && sched_queue.next->time <= now) {
entry = sched_queue.next;
callback = entry->callback;
p = entry->p;
sched_queue.next = entry->next;
free(entry);
/* The callback may call schedule() or schedule_remove(), so
* leave the queue in a safe state. */
callback(p);
}
if (sched_queue.next) {
sched_active = true;
sched_time = sched_queue.next->time;
} else
sched_active = false;
}