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Use atomic variables for thread communication

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Fixes https://github.com/libsdl-org/SDL/issues/10711

(cherry picked from commit a0f36fb85b)
This commit is contained in:
Sam Lantinga 2024-09-05 05:35:03 -07:00
parent 37d3eea939
commit a75227aaeb
2 changed files with 12 additions and 11 deletions
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12
test/testthread.c
View file

@ -20,7 +20,7 @@
#include "SDL_test.h" #include "SDL_test.h"
static SDL_TLSID tls; static SDL_TLSID tls;
static int alive = 0; static SDL_atomic_t alive;
static int testprio = 0; static int testprio = 0;
static SDLTest_CommonState *state; static SDLTest_CommonState *state;
@ -58,7 +58,7 @@ ThreadFunc(void *data)
SDL_TLSSet(tls, "baby thread", NULL); SDL_TLSSet(tls, "baby thread", NULL);
SDL_Log("Started thread %s: My thread id is %lu, thread data = %s\n", SDL_Log("Started thread %s: My thread id is %lu, thread data = %s\n",
(char *)data, SDL_ThreadID(), (const char *)SDL_TLSGet(tls)); (char *)data, SDL_ThreadID(), (const char *)SDL_TLSGet(tls));
while (alive) { while (SDL_AtomicGet(&alive)) {
SDL_Log("Thread '%s' is alive!\n", (char *)data); SDL_Log("Thread '%s' is alive!\n", (char *)data);
if (testprio) { if (testprio) {
@ -79,7 +79,7 @@ killed(int sig)
{ {
SDL_Log("Killed with SIGTERM, waiting 5 seconds to exit\n"); SDL_Log("Killed with SIGTERM, waiting 5 seconds to exit\n");
SDL_Delay(5 * 1000); SDL_Delay(5 * 1000);
alive = 0; SDL_AtomicSet(&alive, 0);
quit(0); quit(0);
} }
@ -133,7 +133,7 @@ int main(int argc, char *argv[])
SDL_TLSSet(tls, "main thread", NULL); SDL_TLSSet(tls, "main thread", NULL);
SDL_Log("Main thread data initially: %s\n", (const char *)SDL_TLSGet(tls)); SDL_Log("Main thread data initially: %s\n", (const char *)SDL_TLSGet(tls));
alive = 1; SDL_AtomicSet(&alive, 1);
thread = SDL_CreateThread(ThreadFunc, "One", "#1"); thread = SDL_CreateThread(ThreadFunc, "One", "#1");
if (!thread) { if (!thread) {
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't create thread: %s\n", SDL_GetError()); SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't create thread: %s\n", SDL_GetError());
@ -141,12 +141,12 @@ int main(int argc, char *argv[])
} }
SDL_Delay(5 * 1000); SDL_Delay(5 * 1000);
SDL_Log("Waiting for thread #1\n"); SDL_Log("Waiting for thread #1\n");
alive = 0; SDL_AtomicSet(&alive, 0);
SDL_WaitThread(thread, NULL); SDL_WaitThread(thread, NULL);
SDL_Log("Main thread data finally: %s\n", (const char *)SDL_TLSGet(tls)); SDL_Log("Main thread data finally: %s\n", (const char *)SDL_TLSGet(tls));
alive = 1; SDL_AtomicSet(&alive, 1);
(void)signal(SIGTERM, killed); (void)signal(SIGTERM, killed);
thread = SDL_CreateThread(ThreadFunc, "Two", "#2"); thread = SDL_CreateThread(ThreadFunc, "Two", "#2");
if (!thread) { if (!thread) {

11
test/torturethread.c
View file

@ -34,8 +34,9 @@ quit(int rc)
int SDLCALL int SDLCALL
SubThreadFunc(void *data) SubThreadFunc(void *data)
{ {
while (!*(int volatile *)data) { SDL_atomic_t *flag = (SDL_atomic_t *)data;
; /* SDL_Delay(10); */ /* do nothing */ while (!SDL_AtomicGet(flag)) {
SDL_Delay(10);
} }
return 0; return 0;
} }
@ -44,7 +45,7 @@ int SDLCALL
ThreadFunc(void *data) ThreadFunc(void *data)
{ {
SDL_Thread *sub_threads[NUMTHREADS]; SDL_Thread *sub_threads[NUMTHREADS];
int flags[NUMTHREADS]; SDL_atomic_t flags[NUMTHREADS];
int i; int i;
int tid = (int)(uintptr_t)data; int tid = (int)(uintptr_t)data;
@ -53,7 +54,7 @@ ThreadFunc(void *data)
for (i = 0; i < NUMTHREADS; i++) { for (i = 0; i < NUMTHREADS; i++) {
char name[64]; char name[64];
(void)SDL_snprintf(name, sizeof(name), "Child%d_%d", tid, i); (void)SDL_snprintf(name, sizeof(name), "Child%d_%d", tid, i);
flags[i] = 0; SDL_AtomicSet(&flags[i], 0);
sub_threads[i] = SDL_CreateThread(SubThreadFunc, name, &flags[i]); sub_threads[i] = SDL_CreateThread(SubThreadFunc, name, &flags[i]);
} }
@ -64,7 +65,7 @@ ThreadFunc(void *data)
SDL_Log("Thread '%d' sending signals to subthreads\n", tid); SDL_Log("Thread '%d' sending signals to subthreads\n", tid);
for (i = 0; i < NUMTHREADS; i++) { for (i = 0; i < NUMTHREADS; i++) {
flags[i] = 1; SDL_AtomicSet(&flags[i], 1);
SDL_WaitThread(sub_threads[i], NULL); SDL_WaitThread(sub_threads[i], NULL);
} }