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comparison src/timer/unix/SDL_systimer.c @ 5113:481dabb098ef

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Improved timer implementation The new timer model is formalized as using a separate thread to handle timer callbacks. This was the case on almost every platform before, but it's now a requirement, and simplifies the implementation and makes it perform consistently across platforms. Goals: * Minimize timer thread blocking * Dispatch timers as accurately as possible * SDL_AddTimer() and SDL_RemoveTimer() are completely threadsafe * SDL_RemoveTimer() doesn't crash with a timer that's expired or removed
author Sam Lantinga <slouken@libsdl.org>
date Thu, 27 Jan 2011 14:45:06 -0800
parents 54cbc34229f4
children b530ef003506
comparison
equal deleted inserted replaced
5112:0846f18eb625 5113:481dabb098ef
23 23
24 #ifdef SDL_TIMER_UNIX 24 #ifdef SDL_TIMER_UNIX
25 25
26 #include <stdio.h> 26 #include <stdio.h>
27 #include <sys/time.h> 27 #include <sys/time.h>
28 #include <signal.h>
29 #include <unistd.h> 28 #include <unistd.h>
30 #include <string.h>
31 #include <errno.h> 29 #include <errno.h>
32 30
33 #include "SDL_timer.h" 31 #include "SDL_timer.h"
34 #include "../SDL_systimer.h"
35 #include "../SDL_timer_c.h"
36 32
37 /* The clock_gettime provides monotonous time, so we should use it if 33 /* The clock_gettime provides monotonous time, so we should use it if
38 it's available. The clock_gettime function is behind ifdef 34 it's available. The clock_gettime function is behind ifdef
39 for __USE_POSIX199309 35 for __USE_POSIX199309
40 Tommi Kyntola (tommi.kyntola@ray.fi) 27/09/2005 36 Tommi Kyntola (tommi.kyntola@ray.fi) 27/09/2005
41 */ 37 */
42 #if HAVE_NANOSLEEP || HAVE_CLOCK_GETTIME 38 #if HAVE_NANOSLEEP || HAVE_CLOCK_GETTIME
43 #include <time.h> 39 #include <time.h>
44 #endif
45
46 #if SDL_THREADS_DISABLED
47 #define USE_ITIMER
48 #endif 40 #endif
49 41
50 /* The first ticks value of the application */ 42 /* The first ticks value of the application */
51 #ifdef HAVE_CLOCK_GETTIME 43 #ifdef HAVE_CLOCK_GETTIME
52 static struct timespec start; 44 static struct timespec start;
129 was_error = select(0, NULL, NULL, NULL, &tv); 121 was_error = select(0, NULL, NULL, NULL, &tv);
130 #endif /* HAVE_NANOSLEEP */ 122 #endif /* HAVE_NANOSLEEP */
131 } while (was_error && (errno == EINTR)); 123 } while (was_error && (errno == EINTR));
132 } 124 }
133 125
134 #ifdef USE_ITIMER 126 #endif /* SDL_TIMER_UNIX */
135 127
136 static void
137 HandleAlarm(int sig)
138 {
139 Uint32 ms;
140
141 if (SDL_alarm_callback) {
142 ms = (*SDL_alarm_callback) (SDL_alarm_interval);
143 if (ms != SDL_alarm_interval) {
144 SDL_SetTimer(ms, SDL_alarm_callback);
145 }
146 }
147 }
148
149 int
150 SDL_SYS_TimerInit(void)
151 {
152 struct sigaction action;
153
154 /* Set the alarm handler (Linux specific) */
155 SDL_memset(&action, 0, sizeof(action));
156 action.sa_handler = HandleAlarm;
157 action.sa_flags = SA_RESTART;
158 sigemptyset(&action.sa_mask);
159 sigaction(SIGALRM, &action, NULL);
160 return (0);
161 }
162
163 void
164 SDL_SYS_TimerQuit(void)
165 {
166 SDL_SetTimer(0, NULL);
167 }
168
169 int
170 SDL_SYS_StartTimer(void)
171 {
172 struct itimerval timer;
173
174 timer.it_value.tv_sec = (SDL_alarm_interval / 1000);
175 timer.it_value.tv_usec = (SDL_alarm_interval % 1000) * 1000;
176 timer.it_interval.tv_sec = (SDL_alarm_interval / 1000);
177 timer.it_interval.tv_usec = (SDL_alarm_interval % 1000) * 1000;
178 setitimer(ITIMER_REAL, &timer, NULL);
179 return (0);
180 }
181
182 void
183 SDL_SYS_StopTimer(void)
184 {
185 struct itimerval timer;
186
187 SDL_memset(&timer, 0, (sizeof timer));
188 setitimer(ITIMER_REAL, &timer, NULL);
189 }
190
191 #else /* USE_ITIMER */
192
193 #include "SDL_thread.h"
194
195 /* Data to handle a single periodic alarm */
196 static int timer_alive = 0;
197 static SDL_Thread *timer = NULL;
198
199 static int
200 RunTimer(void *unused)
201 {
202 while (timer_alive) {
203 if (SDL_timer_running) {
204 SDL_ThreadedTimerCheck();
205 }
206 SDL_Delay(1);
207 }
208 return (0);
209 }
210
211 /* This is only called if the event thread is not running */
212 int
213 SDL_SYS_TimerInit(void)
214 {
215 timer_alive = 1;
216 timer = SDL_CreateThread(RunTimer, NULL);
217 if (timer == NULL)
218 return (-1);
219 return (SDL_SetTimerThreaded(1));
220 }
221
222 void
223 SDL_SYS_TimerQuit(void)
224 {
225 timer_alive = 0;
226 if (timer) {
227 SDL_WaitThread(timer, NULL);
228 timer = NULL;
229 }
230 }
231
232 int
233 SDL_SYS_StartTimer(void)
234 {
235 SDL_SetError("Internal logic error: Linux uses threaded timer");
236 return (-1);
237 }
238
239 void
240 SDL_SYS_StopTimer(void)
241 {
242 return;
243 }
244
245 #endif /* USE_ITIMER */
246
247 #endif /* SDL_TIMER_UNIX */
248 /* vi: set ts=4 sw=4 expandtab: */ 128 /* vi: set ts=4 sw=4 expandtab: */