SDL_timer.c
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/*
Simple DirectMedia Layer
Copyright (C) 1997-2019 Sam Lantinga <slouken@libsdl.org>
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/
#include "../SDL_internal.h"
#include "SDL_timer.h"
#include "SDL_timer_c.h"
#include "SDL_atomic.h"
#include "SDL_cpuinfo.h"
#include "../thread/SDL_systhread.h"
/* #define DEBUG_TIMERS */
typedef struct _SDL_Timer
{
int timerID;
SDL_TimerCallback callback;
void *param;
Uint32 interval;
Uint32 scheduled;
SDL_atomic_t canceled;
struct _SDL_Timer *next;
} SDL_Timer;
typedef struct _SDL_TimerMap
{
int timerID;
SDL_Timer *timer;
struct _SDL_TimerMap *next;
} SDL_TimerMap;
/* The timers are kept in a sorted list */
typedef struct {
/* Data used by the main thread */
SDL_Thread *thread;
SDL_atomic_t nextID;
SDL_TimerMap *timermap;
SDL_mutex *timermap_lock;
/* Padding to separate cache lines between threads */
char cache_pad[SDL_CACHELINE_SIZE];
/* Data used to communicate with the timer thread */
SDL_SpinLock lock;
SDL_sem *sem;
SDL_Timer *pending;
SDL_Timer *freelist;
SDL_atomic_t active;
/* List of timers - this is only touched by the timer thread */
SDL_Timer *timers;
} SDL_TimerData;
static SDL_TimerData SDL_timer_data;
/* The idea here is that any thread might add a timer, but a single
* thread manages the active timer queue, sorted by scheduling time.
*
* Timers are removed by simply setting a canceled flag
*/
static void
SDL_AddTimerInternal(SDL_TimerData *data, SDL_Timer *timer)
{
SDL_Timer *prev, *curr;
prev = NULL;
for (curr = data->timers; curr; prev = curr, curr = curr->next) {
if ((Sint32)(timer->scheduled-curr->scheduled) < 0) {
break;
}
}
/* Insert the timer here! */
if (prev) {
prev->next = timer;
} else {
data->timers = timer;
}
timer->next = curr;
}
static int SDLCALL
SDL_TimerThread(void *_data)
{
SDL_TimerData *data = (SDL_TimerData *)_data;
SDL_Timer *pending;
SDL_Timer *current;
SDL_Timer *freelist_head = NULL;
SDL_Timer *freelist_tail = NULL;
Uint32 tick, now, interval, delay;
/* Threaded timer loop:
* 1. Queue timers added by other threads
* 2. Handle any timers that should dispatch this cycle
* 3. Wait until next dispatch time or new timer arrives
*/
for ( ; ; ) {
/* Pending and freelist maintenance */
SDL_AtomicLock(&data->lock);
{
/* Get any timers ready to be queued */
pending = data->pending;
data->pending = NULL;
/* Make any unused timer structures available */
if (freelist_head) {
freelist_tail->next = data->freelist;
data->freelist = freelist_head;
}
}
SDL_AtomicUnlock(&data->lock);
/* Sort the pending timers into our list */
while (pending) {
current = pending;
pending = pending->next;
SDL_AddTimerInternal(data, current);
}
freelist_head = NULL;
freelist_tail = NULL;
/* Check to see if we're still running, after maintenance */
if (!SDL_AtomicGet(&data->active)) {
break;
}
/* Initial delay if there are no timers */
delay = SDL_MUTEX_MAXWAIT;
tick = SDL_GetTicks();
/* Process all the pending timers for this tick */
while (data->timers) {
current = data->timers;
if ((Sint32)(tick-current->scheduled) < 0) {
/* Scheduled for the future, wait a bit */
delay = (current->scheduled - tick);
break;
}
/* We're going to do something with this timer */
data->timers = current->next;
if (SDL_AtomicGet(&current->canceled)) {
interval = 0;
} else {
interval = current->callback(current->interval, current->param);
}
if (interval > 0) {
/* Reschedule this timer */
current->interval = interval;
current->scheduled = tick + interval;
SDL_AddTimerInternal(data, current);
} else {
if (!freelist_head) {
freelist_head = current;
}
if (freelist_tail) {
freelist_tail->next = current;
}
freelist_tail = current;
SDL_AtomicSet(&current->canceled, 1);
}
}
/* Adjust the delay based on processing time */
now = SDL_GetTicks();
interval = (now - tick);
if (interval > delay) {
delay = 0;
} else {
delay -= interval;
}
/* Note that each time a timer is added, this will return
immediately, but we process the timers added all at once.
That's okay, it just means we run through the loop a few
extra times.
*/
SDL_SemWaitTimeout(data->sem, delay);
}
return 0;
}
int
SDL_TimerInit(void)
{
SDL_TimerData *data = &SDL_timer_data;
if (!SDL_AtomicGet(&data->active)) {
const char *name = "SDLTimer";
data->timermap_lock = SDL_CreateMutex();
if (!data->timermap_lock) {
return -1;
}
data->sem = SDL_CreateSemaphore(0);
if (!data->sem) {
SDL_DestroyMutex(data->timermap_lock);
return -1;
}
SDL_AtomicSet(&data->active, 1);
/* Timer threads use a callback into the app, so we can't set a limited stack size here. */
data->thread = SDL_CreateThreadInternal(SDL_TimerThread, name, 0, data);
if (!data->thread) {
SDL_TimerQuit();
return -1;
}
SDL_AtomicSet(&data->nextID, 1);
}
return 0;
}
void
SDL_TimerQuit(void)
{
SDL_TimerData *data = &SDL_timer_data;
SDL_Timer *timer;
SDL_TimerMap *entry;
if (SDL_AtomicCAS(&data->active, 1, 0)) { /* active? Move to inactive. */
/* Shutdown the timer thread */
if (data->thread) {
SDL_SemPost(data->sem);
SDL_WaitThread(data->thread, NULL);
data->thread = NULL;
}
SDL_DestroySemaphore(data->sem);
data->sem = NULL;
/* Clean up the timer entries */
while (data->timers) {
timer = data->timers;
data->timers = timer->next;
SDL_free(timer);
}
while (data->freelist) {
timer = data->freelist;
data->freelist = timer->next;
SDL_free(timer);
}
while (data->timermap) {
entry = data->timermap;
data->timermap = entry->next;
SDL_free(entry);
}
SDL_DestroyMutex(data->timermap_lock);
data->timermap_lock = NULL;
}
}
SDL_TimerID
SDL_AddTimer(Uint32 interval, SDL_TimerCallback callback, void *param)
{
SDL_TimerData *data = &SDL_timer_data;
SDL_Timer *timer;
SDL_TimerMap *entry;
SDL_AtomicLock(&data->lock);
if (!SDL_AtomicGet(&data->active)) {
if (SDL_TimerInit() < 0) {
SDL_AtomicUnlock(&data->lock);
return 0;
}
}
timer = data->freelist;
if (timer) {
data->freelist = timer->next;
}
SDL_AtomicUnlock(&data->lock);
if (timer) {
SDL_RemoveTimer(timer->timerID);
} else {
timer = (SDL_Timer *)SDL_malloc(sizeof(*timer));
if (!timer) {
SDL_OutOfMemory();
return 0;
}
}
timer->timerID = SDL_AtomicIncRef(&data->nextID);
timer->callback = callback;
timer->param = param;
timer->interval = interval;
timer->scheduled = SDL_GetTicks() + interval;
SDL_AtomicSet(&timer->canceled, 0);
entry = (SDL_TimerMap *)SDL_malloc(sizeof(*entry));
if (!entry) {
SDL_free(timer);
SDL_OutOfMemory();
return 0;
}
entry->timer = timer;
entry->timerID = timer->timerID;
SDL_LockMutex(data->timermap_lock);
entry->next = data->timermap;
data->timermap = entry;
SDL_UnlockMutex(data->timermap_lock);
/* Add the timer to the pending list for the timer thread */
SDL_AtomicLock(&data->lock);
timer->next = data->pending;
data->pending = timer;
SDL_AtomicUnlock(&data->lock);
/* Wake up the timer thread if necessary */
SDL_SemPost(data->sem);
return entry->timerID;
}
SDL_bool
SDL_RemoveTimer(SDL_TimerID id)
{
SDL_TimerData *data = &SDL_timer_data;
SDL_TimerMap *prev, *entry;
SDL_bool canceled = SDL_FALSE;
/* Find the timer */
SDL_LockMutex(data->timermap_lock);
prev = NULL;
for (entry = data->timermap; entry; prev = entry, entry = entry->next) {
if (entry->timerID == id) {
if (prev) {
prev->next = entry->next;
} else {
data->timermap = entry->next;
}
break;
}
}
SDL_UnlockMutex(data->timermap_lock);
if (entry) {
if (!SDL_AtomicGet(&entry->timer->canceled)) {
SDL_AtomicSet(&entry->timer->canceled, 1);
canceled = SDL_TRUE;
}
SDL_free(entry);
}
return canceled;
}
/* vi: set ts=4 sw=4 expandtab: */
_SDL_TimerMap::timer
SDL_Timer * timer
Definition: SDL_timer.c:45
SDL_CACHELINE_SIZE
#define SDL_CACHELINE_SIZE
Definition: SDL_cpuinfo.h:114
Uint32
uint32_t Uint32
Definition: SDL_stdinc.h:203
Sint32
int32_t Sint32
Definition: SDL_stdinc.h:197
SDL_TimerQuit
void SDL_TimerQuit(void)
Definition: SDL_timer.c:239
_SDL_TimerMap
Definition: SDL_timer.c:42
SDL_CreateSemaphore
#define SDL_CreateSemaphore
Definition: SDL_dynapi_overrides.h:264
SDL_AtomicCAS
#define SDL_AtomicCAS
Definition: SDL_dynapi_overrides.h:66
SDL_LockMutex
#define SDL_LockMutex
Definition: SDL_dynapi_overrides.h:260
SDL_atomic.h
NULL
#define NULL
Definition: begin_code.h:167
SDL_timer.h
SDL_TimerData::thread
SDL_Thread * thread
Definition: SDL_timer.c:52
SDL_AtomicLock
#define SDL_AtomicLock
Definition: SDL_dynapi_overrides.h:64
SDL_mutex
Definition: SDL_sysmutex.c:29
SDL_TimerInit
int SDL_TimerInit(void)
Definition: SDL_timer.c:207
SDL_TimerData::nextID
SDL_atomic_t nextID
Definition: SDL_timer.c:53
SDLCALL
#define SDLCALL
Definition: SDL_internal.h:49
SDL_TimerID
int SDL_TimerID
Definition: SDL_timer.h:86
SDL_AtomicIncRef
#define SDL_AtomicIncRef(a)
Increment an atomic variable used as a reference count.
Definition: SDL_atomic.h:252
SDL_AddTimer
SDL_TimerID SDL_AddTimer(Uint32 interval, SDL_TimerCallback callback, void *param)
Add a new timer to the pool of timers already running.
Definition: SDL_timer.c:279
SDL_CreateMutex
#define SDL_CreateMutex
Definition: SDL_dynapi_overrides.h:259
_SDL_Timer::callback
SDL_TimerCallback callback
Definition: SDL_timer.c:34
callback
static Uint32 callback(Uint32 interval, void *param)
Definition: testtimer.c:34
SDL_Thread
Definition: SDL_thread_c.h:54
SDL_SemPost
#define SDL_SemPost
Definition: SDL_dynapi_overrides.h:269
SDL_TimerData::sem
SDL_sem * sem
Definition: SDL_timer.c:62
data
GLint GLenum GLsizei GLsizei GLsizei GLint GLsizei const GLvoid * data
Definition: SDL_opengl.h:1974
_SDL_Timer::timerID
int timerID
Definition: SDL_timer.c:33
SDL_TimerData::timers
SDL_Timer * timers
Definition: SDL_timer.c:68
_SDL_Timer::scheduled
Uint32 scheduled
Definition: SDL_timer.c:37
SDL_SemWaitTimeout
#define SDL_SemWaitTimeout
Definition: SDL_dynapi_overrides.h:268
SDL_TimerData::freelist
SDL_Timer * freelist
Definition: SDL_timer.c:64
SDL_FALSE
@ SDL_FALSE
Definition: SDL_stdinc.h:163
SDL_TimerData::pending
SDL_Timer * pending
Definition: SDL_timer.c:63
SDL_AtomicUnlock
#define SDL_AtomicUnlock
Definition: SDL_dynapi_overrides.h:65
SDL_CreateThreadInternal
SDL_Thread * SDL_CreateThreadInternal(int(*fn)(void *), const char *name, const size_t stacksize, void *data)
Definition: SDL_thread.c:429
SDL_RemoveTimer
SDL_bool SDL_RemoveTimer(SDL_TimerID id)
Remove a timer knowing its ID.
Definition: SDL_timer.c:342
_SDL_TimerMap::timerID
int timerID
Definition: SDL_timer.c:44
SDL_free
#define SDL_free
Definition: SDL_dynapi_overrides.h:377
SDL_cpuinfo.h
name
GLuint const GLchar * name
Definition: SDL_opengl_glext.h:660
SDL_TimerCallback
Uint32(* SDL_TimerCallback)(Uint32 interval, void *param)
Definition: SDL_timer.h:81
SDL_MUTEX_MAXWAIT
#define SDL_MUTEX_MAXWAIT
Definition: SDL_mutex.h:49
SDL_GetTicks
Uint32 SDL_GetTicks(void)
Get the number of milliseconds since the SDL library initialization.
SDL_TimerData::lock
SDL_SpinLock lock
Definition: SDL_timer.c:61
param
GLfloat param
Definition: SDL_opengl_glext.h:370
SDL_TimerData::timermap
SDL_TimerMap * timermap
Definition: SDL_timer.c:54
SDL_AddTimerInternal
static void SDL_AddTimerInternal(SDL_TimerData *data, SDL_Timer *timer)
Definition: SDL_timer.c:80
SDL_SpinLock
int SDL_SpinLock
Definition: SDL_atomic.h:89
SDL_TimerData
Definition: SDL_timer.c:50
SDL_OutOfMemory
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
SDL_TimerData::timermap_lock
SDL_mutex * timermap_lock
Definition: SDL_timer.c:55
SDL_TRUE
@ SDL_TRUE
Definition: SDL_stdinc.h:164
_SDL_Timer
Definition: SDL_timer.c:31
SDL_atomic_t
A type representing an atomic integer value. It is a struct so people don't accidentally use numeric ...
Definition: SDL_atomic.h:216
SDL_DestroyMutex
#define SDL_DestroyMutex
Definition: SDL_dynapi_overrides.h:263
SDL_TimerData::active
SDL_atomic_t active
Definition: SDL_timer.c:65
SDL_timer_data
static SDL_TimerData SDL_timer_data
Definition: SDL_timer.c:71
SDL_DestroySemaphore
#define SDL_DestroySemaphore
Definition: SDL_dynapi_overrides.h:265
_SDL_Timer::interval
Uint32 interval
Definition: SDL_timer.c:36
_SDL_Timer::canceled
SDL_atomic_t canceled
Definition: SDL_timer.c:38
SDL_AtomicSet
#define SDL_AtomicSet
Definition: SDL_dynapi_overrides.h:67
SDL_malloc
#define SDL_malloc
Definition: SDL_dynapi_overrides.h:374
SDL_AtomicGet
#define SDL_AtomicGet
Definition: SDL_dynapi_overrides.h:68
_SDL_Timer::param
void * param
Definition: SDL_timer.c:35
SDL_UnlockMutex
#define SDL_UnlockMutex
Definition: SDL_dynapi_overrides.h:262
SDL_WaitThread
#define SDL_WaitThread
Definition: SDL_dynapi_overrides.h:478
SDL_timer_c.h
SDL_TimerThread
static int SDL_TimerThread(void *_data)
Definition: SDL_timer.c:101
SDL_bool
SDL_bool
Definition: SDL_stdinc.h:161
_SDL_TimerMap::next
struct _SDL_TimerMap * next
Definition: SDL_timer.c:46
_SDL_Timer::next
struct _SDL_Timer * next
Definition: SDL_timer.c:39