SDL_timer.c
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/*
Simple DirectMedia Layer
Copyright (C) 1997-2018 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_TimerThread
static int SDL_TimerThread(void *_data)
Definition: SDL_timer.c:101
SDL_LockMutex
#define SDL_LockMutex
Definition: SDL_dynapi_overrides.h:260
SDL_TimerQuit
void SDL_TimerQuit(void)
Definition: SDL_timer.c:239
SDL_TimerMap::timer
SDL_Timer * timer
Definition: SDL_timer.c:45
SDL_TRUE
Definition: SDL_stdinc.h:142
SDL_TimerData::timermap
SDL_TimerMap * timermap
Definition: SDL_timer.c:54
SDL_AtomicLock
#define SDL_AtomicLock
Definition: SDL_dynapi_overrides.h:64
SDL_TimerCallback
Uint32(* SDL_TimerCallback)(Uint32 interval, void *param)
Definition: SDL_timer.h:81
SDL_atomic_t
A type representing an atomic integer value. It is a struct so people don&#39;t accidentally use numeric ...
Definition: SDL_atomic.h:198
SDL_AtomicCAS
#define SDL_AtomicCAS
Definition: SDL_dynapi_overrides.h:66
SDL_Timer::interval
Uint32 interval
Definition: SDL_timer.c:36
SDL_CreateSemaphore
#define SDL_CreateSemaphore
Definition: SDL_dynapi_overrides.h:264
SDL_FALSE
Definition: SDL_stdinc.h:141
SDL_CreateMutex
#define SDL_CreateMutex
Definition: SDL_dynapi_overrides.h:259
SDL_TimerInit
int SDL_TimerInit(void)
Definition: SDL_timer.c:207
SDL_TimerData::thread
SDL_Thread * thread
Definition: SDL_timer.c:52
data
GLint GLenum GLsizei GLsizei GLsizei GLint GLsizei const GLvoid * data
Definition: SDL_opengl.h:1974
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
Uint32
uint32_t Uint32
Definition: SDL_stdinc.h:181
SDL_TimerData::nextID
SDL_atomic_t nextID
Definition: SDL_timer.c:53
name
GLuint const GLchar * name
Definition: SDL_opengl_glext.h:660
SDL_SemPost
#define SDL_SemPost
Definition: SDL_dynapi_overrides.h:269
SDL_mutex
Definition: SDL_sysmutex.c:29
SDL_cpuinfo.h
SDL_AtomicUnlock
#define SDL_AtomicUnlock
Definition: SDL_dynapi_overrides.h:65
SDL_RemoveTimer
SDL_bool SDL_RemoveTimer(SDL_TimerID id)
Remove a timer knowing its ID.
Definition: SDL_timer.c:342
SDL_TimerMap
Definition: SDL_timer.c:42
SDL_atomic.h
SDL_CreateThreadInternal
SDL_Thread * SDL_CreateThreadInternal(int(*fn)(void *), const char *name, const size_t stacksize, void *data)
Definition: SDL_thread.c:427
SDL_SemWaitTimeout
#define SDL_SemWaitTimeout
Definition: SDL_dynapi_overrides.h:268
SDL_Timer::next
struct _SDL_Timer * next
Definition: SDL_timer.c:39
SDL_MUTEX_MAXWAIT
#define SDL_MUTEX_MAXWAIT
Definition: SDL_mutex.h:49
SDL_TimerData::active
SDL_atomic_t active
Definition: SDL_timer.c:65
SDL_GetTicks
Uint32 SDL_GetTicks(void)
Get the number of milliseconds since the SDL library initialization.
SDL_free
#define SDL_free
Definition: SDL_dynapi_overrides.h:377
SDL_Timer::scheduled
Uint32 scheduled
Definition: SDL_timer.c:37
SDL_Timer::callback
SDL_TimerCallback callback
Definition: SDL_timer.c:34
SDL_Timer::timerID
int timerID
Definition: SDL_timer.c:33
SDL_CACHELINE_SIZE
#define SDL_CACHELINE_SIZE
Definition: SDL_cpuinfo.h:92
callback
static Uint32 callback(Uint32 interval, void *param)
Definition: testtimer.c:34
Sint32
int32_t Sint32
Definition: SDL_stdinc.h:175
SDL_TimerData::sem
SDL_sem * sem
Definition: SDL_timer.c:62
SDL_AtomicIncRef
#define SDL_AtomicIncRef(a)
Increment an atomic variable used as a reference count.
Definition: SDL_atomic.h:234
SDL_TimerMap::next
struct _SDL_TimerMap * next
Definition: SDL_timer.c:46
NULL
#define NULL
Definition: begin_code.h:164
SDL_Timer::param
void * param
Definition: SDL_timer.c:35
SDL_OutOfMemory
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
SDL_bool
SDL_bool
Definition: SDL_stdinc.h:139
SDL_timer_c.h
SDL_AddTimerInternal
static void SDL_AddTimerInternal(SDL_TimerData *data, SDL_Timer *timer)
Definition: SDL_timer.c:80
SDL_TimerData::freelist
SDL_Timer * freelist
Definition: SDL_timer.c:64
SDL_TimerData::timermap_lock
SDL_mutex * timermap_lock
Definition: SDL_timer.c:55
SDL_TimerData::pending
SDL_Timer * pending
Definition: SDL_timer.c:63
SDL_DestroyMutex
#define SDL_DestroyMutex
Definition: SDL_dynapi_overrides.h:263
SDL_Timer
Definition: SDL_timer.c:31
SDL_DestroySemaphore
#define SDL_DestroySemaphore
Definition: SDL_dynapi_overrides.h:265
SDL_timer_data
static SDL_TimerData SDL_timer_data
Definition: SDL_timer.c:71
SDL_AtomicSet
#define SDL_AtomicSet
Definition: SDL_dynapi_overrides.h:67
SDL_Timer::canceled
SDL_atomic_t canceled
Definition: SDL_timer.c:38
SDL_AtomicGet
#define SDL_AtomicGet
Definition: SDL_dynapi_overrides.h:68
SDL_Thread
Definition: SDL_thread_c.h:54
SDL_UnlockMutex
#define SDL_UnlockMutex
Definition: SDL_dynapi_overrides.h:262
SDL_malloc
#define SDL_malloc
Definition: SDL_dynapi_overrides.h:374
SDL_TimerData::lock
SDL_SpinLock lock
Definition: SDL_timer.c:61
SDL_SpinLock
int SDL_SpinLock
Definition: SDL_atomic.h:89
SDL_timer.h
param
GLfloat param
Definition: SDL_opengl_glext.h:370
SDL_TimerData::timers
SDL_Timer * timers
Definition: SDL_timer.c:68
SDLCALL
#define SDLCALL
Definition: SDL_internal.h:45
SDL_TimerData
Definition: SDL_timer.c:50
SDL_TimerID
int SDL_TimerID
Definition: SDL_timer.h:86
SDL_WaitThread
#define SDL_WaitThread
Definition: SDL_dynapi_overrides.h:478
SDL_TimerMap::timerID
int timerID
Definition: SDL_timer.c:44