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