drd/tests/swapcontext.c

   1 /* See also https://bugs.kde.org/show_bug.cgi?id=432381. */
   2
   3 #define _GNU_SOURCE
   4
   5 #include "../../config.h"
   6 #if defined(VGO_darwin)
   7 #define _XOPEN_SOURCE
   8 #endif
   9
  10 #include <assert.h>
  11 #include <limits.h>
  12 #include <pthread.h>
  13 #include <signal.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <sys/time.h>
  17 #include <ucontext.h>
  18 #include <unistd.h>
  19 #include "valgrind.h"
  20
  21 #define STACKSIZE (PTHREAD_STACK_MIN + 4096)
  22
  23 typedef struct threadlocal {
  24   ucontext_t uc[3];
  25   size_t nrsw;
  26 } thread_local_t;
  27
  28 static void sig_alrm_handler(int signo) {
  29     _exit(1);
  30 }
  31
  32 static void f(void *data, int n)
  33 {
  34   enum { NR_SWITCHES = 200000 };
  35   thread_local_t *tlocal = data;
  36
  37   while (1) {
  38     struct timespec delay = { .tv_nsec = 1000 };
  39     nanosleep(&delay, NULL);
  40     if (++tlocal->nrsw == NR_SWITCHES)
  41       return;
  42     swapcontext(&tlocal->uc[n], &tlocal->uc[3 - n]);
  43   }
  44 }
  45
  46 void *worker(void *data)
  47 {
  48   thread_local_t *tlocal = data;
  49
  50   if (getcontext(&(tlocal->uc[1])) < 0)
  51     abort();
  52   if (getcontext(&(tlocal->uc[2])) < 0)
  53     abort();
  54
  55   tlocal->uc[1].uc_link = &tlocal->uc[0];
  56   tlocal->uc[1].uc_stack.ss_sp = malloc(STACKSIZE);
  57   tlocal->uc[1].uc_stack.ss_size = STACKSIZE;
  58   makecontext(&tlocal->uc[1], (void (*)(void))f, 2, tlocal, 1);
  59   (void)VALGRIND_STACK_REGISTER(tlocal->uc[1].uc_stack.ss_sp,
  60                                 tlocal->uc[1].uc_stack.ss_sp +
  61                                 tlocal->uc[1].uc_stack.ss_size);
  62
  63   tlocal->uc[2].uc_link = &tlocal->uc[0];
  64   tlocal->uc[2].uc_stack.ss_sp = malloc(STACKSIZE);
  65   tlocal->uc[2].uc_stack.ss_size = STACKSIZE;
  66   makecontext(&tlocal->uc[2], (void (*)(void))f, 2, tlocal, 2);
  67   (void)VALGRIND_STACK_REGISTER(tlocal->uc[2].uc_stack.ss_sp,
  68                                 tlocal->uc[2].uc_stack.ss_sp +
  69                                 tlocal->uc[2].uc_stack.ss_size);
  70
  71   swapcontext(&tlocal->uc[0], &tlocal->uc[1]);
  72   return NULL;
  73 }
  74
  75 int main(int argc, char *argv[])
  76 {
  77   enum { NR = 32 };
  78   thread_local_t tlocal[NR];
  79   pthread_t thread[NR];
  80   pthread_attr_t attr;
  81   int i, res;
  82
  83   signal(SIGALRM, sig_alrm_handler);
  84   memset(tlocal, 0, sizeof(tlocal));
  85
  86   pthread_attr_init(&attr);
  87   res = pthread_attr_setstacksize(&attr, STACKSIZE);
  88   assert(res == 0);
  89
  90   for (i = 0; i < NR; i++)
  91     pthread_create(&thread[i], &attr, worker, &tlocal[i]);
  92
  93   pthread_attr_destroy(&attr);
  94
  95   // Wait until the threads have been created.
  96   sleep(1);
  97   for (i = 0; i < NR; i++)
  98     pthread_kill(thread[i], SIGALRM);
  99
 100   for (i = 0; i < NR; i++)
 101     pthread_join(thread[i], NULL);
 102
 103   return 0;
 104 }