SDL_timer.c
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/*
Simple DirectMedia Layer
Copyright (C) 1997-2016 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 "SDL_thread.h"
/* #define DEBUG_TIMERS */
typedef struct _SDL_Timer
{
int timerID;
SDL_TimerCallback callback;
void *param;
Uint32 interval;
Uint32 scheduled;
volatile SDL_bool 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 * volatile pending;
SDL_Timer * volatile freelist;
volatile SDL_bool 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
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 (!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 (current->canceled) {
interval = 0;
} else {
interval = current->callback(current->interval, current->param);
}
if (interval > 0) {
/* Reschedule this timer */
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;
current->canceled = SDL_TRUE;
}
}
/* 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 (!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;
}
data->active = SDL_TRUE;
/* !!! FIXME: this is nasty. */
#if defined(__WIN32__) && !defined(HAVE_LIBC)
#undef SDL_CreateThread
#if SDL_DYNAMIC_API
data->thread = SDL_CreateThread_REAL(SDL_TimerThread, name, data, NULL, NULL);
#else
data->thread = SDL_CreateThread(SDL_TimerThread, name, data, NULL, NULL);
#endif
#else
data->thread = SDL_CreateThread(SDL_TimerThread, name, data);
#endif
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 (data->active) {
data->active = SDL_FALSE;
/* 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;
if (!data->active) {
int status = 0;
SDL_AtomicLock(&data->lock);
if (!data->active) {
status = SDL_TimerInit();
}
SDL_AtomicUnlock(&data->lock);
if (status < 0) {
return 0;
}
}
SDL_AtomicLock(&data->lock);
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;
timer->canceled = SDL_FALSE;
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 (!entry->timer->canceled) {
entry->timer->canceled = SDL_TRUE;
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:266
SDL_TimerQuit
void SDL_TimerQuit(void)
Definition: SDL_timer.c:246
SDL_TimerMap::timer
SDL_Timer * timer
Definition: SDL_timer.c:45
SDL_Timer::canceled
volatile SDL_bool canceled
Definition: SDL_timer.c:38
Uint32
uint32_t Uint32
An unsigned 32-bit integer type.
Definition: SDL_stdinc.h:157
SDL_TimerData::timermap
SDL_TimerMap * timermap
Definition: SDL_timer.c:54
SDL_AtomicLock
#define SDL_AtomicLock
Definition: SDL_dynapi_overrides.h:70
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:189
SDL_Timer::interval
Uint32 interval
Definition: SDL_timer.c:36
SDL_CreateSemaphore
#define SDL_CreateSemaphore
Definition: SDL_dynapi_overrides.h:270
SDL_CreateMutex
#define SDL_CreateMutex
Definition: SDL_dynapi_overrides.h:265
data
GLint GLenum GLsizei GLsizei GLsizei GLint GLsizei const GLvoid * data
Definition: SDL_opengl.h:1967
SDL_TimerInit
int SDL_TimerInit(void)
Definition: SDL_timer.c:206
SDL_TimerData::thread
SDL_Thread * thread
Definition: SDL_timer.c:52
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:288
name
GLuint const GLchar * name
Definition: SDL_opengl_glext.h:660
SDL_TimerData::nextID
SDL_atomic_t nextID
Definition: SDL_timer.c:53
SDL_TimerData::active
volatile SDL_bool active
Definition: SDL_timer.c:65
param
GLfloat param
Definition: SDL_opengl_glext.h:370
SDL_thread.h
SDL_SemPost
#define SDL_SemPost
Definition: SDL_dynapi_overrides.h:275
SDL_mutex
Definition: SDL_sysmutex.c:29
SDL_cpuinfo.h
SDL_AtomicUnlock
#define SDL_AtomicUnlock
Definition: SDL_dynapi_overrides.h:71
SDL_bool
SDL_bool
Definition: SDL_stdinc.h:126
SDL_RemoveTimer
SDL_bool SDL_RemoveTimer(SDL_TimerID id)
Remove a timer knowing its ID.
Definition: SDL_timer.c:358
SDL_TimerMap
Definition: SDL_timer.c:42
SDL_TimerData::freelist
SDL_Timer *volatile freelist
Definition: SDL_timer.c:64
SDL_atomic.h
SDL_SemWaitTimeout
#define SDL_SemWaitTimeout
Definition: SDL_dynapi_overrides.h:274
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_GetTicks
Uint32 SDL_GetTicks(void)
Get the number of milliseconds since the SDL library initialization.
SDL_Timer::scheduled
Uint32 scheduled
Definition: SDL_timer.c:37
SDL_free
void SDL_free(void *mem)
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:77
callback
static Uint32 callback(Uint32 interval, void *param)
Definition: testtimer.c:34
SDL_TRUE
Definition: SDL_stdinc.h:129
Sint32
int32_t Sint32
Definition: SDL_stdinc.h:153
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:225
SDL_CreateThread
#define SDL_CreateThread
Definition: SDL_dynapi_overrides.h:47
SDL_TimerMap::next
struct _SDL_TimerMap * next
Definition: SDL_timer.c:46
NULL
#define NULL
Definition: begin_code.h:143
SDL_Timer::param
void * param
Definition: SDL_timer.c:35
SDL_OutOfMemory
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
SDL_timer_c.h
SDL_AddTimerInternal
static void SDL_AddTimerInternal(SDL_TimerData *data, SDL_Timer *timer)
Definition: SDL_timer.c:80
SDL_TimerData::timermap_lock
SDL_mutex * timermap_lock
Definition: SDL_timer.c:55
SDL_DestroyMutex
#define SDL_DestroyMutex
Definition: SDL_dynapi_overrides.h:269
SDL_TimerData::pending
SDL_Timer *volatile pending
Definition: SDL_timer.c:63
SDL_Timer
Definition: SDL_timer.c:31
SDL_DestroySemaphore
#define SDL_DestroySemaphore
Definition: SDL_dynapi_overrides.h:271
SDL_timer_data
static SDL_TimerData SDL_timer_data
Definition: SDL_timer.c:71
SDL_FALSE
Definition: SDL_stdinc.h:128
SDL_AtomicSet
#define SDL_AtomicSet
Definition: SDL_dynapi_overrides.h:73
SDL_Thread
Definition: SDL_thread_c.h:54
SDL_UnlockMutex
#define SDL_UnlockMutex
Definition: SDL_dynapi_overrides.h:268
SDL_malloc
#define SDL_malloc
Definition: SDL_dynapi_overrides.h:380
SDL_TimerData::lock
SDL_SpinLock lock
Definition: SDL_timer.c:61
SDL_SpinLock
int SDL_SpinLock
Definition: SDL_atomic.h:89
SDL_timer.h
SDL_TimerData::timers
SDL_Timer * timers
Definition: SDL_timer.c:68
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:482
SDL_TimerMap::timerID
int timerID
Definition: SDL_timer.c:44