benchmarks/nidhugg/linuxrwlock/linuxrwlocks.c.in

   1 #include <stdio.h>
   2 #include <pthread.h>
   3 #include <atomic>
   4
   5
   6 #define RW_LOCK_BIAS            0x00100000
   7 #define WRITE_LOCK_CMP          RW_LOCK_BIAS
   8
   9 /** Example implementation of linux rw lock along with 2 thread test
  10  *  driver... */
  11
  12 typedef union {
  13         std::atomic<int> lock;
  14 } rwlock_t;
  15
  16 static inline int write_trylock(rwlock_t *rw)
  17 {
  18         int priorvalue = atomic_fetch_sub(&rw->lock, RW_LOCK_BIAS);
  19         if (priorvalue == RW_LOCK_BIAS)
  20                 return 1;
  21
  22         atomic_fetch_add(&rw->lock, RW_LOCK_BIAS);
  23         return 0;
  24 }
  25
  26 static inline void write_unlock(rwlock_t *rw)
  27 {
  28         atomic_fetch_add(&rw->lock, RW_LOCK_BIAS);
  29 }
  30
  31 rwlock_t mylock;
  32 int shareddata;
  33
  34 void * a(void *obj) {
  35 problemsize if (write_trylock(&mylock)) {write_unlock(&mylock);}
  36  return NULL;
  37 }
  38
  39 int main(int argc, char **argv)
  40 {
  41         pthread_t t1, t2;
  42         mylock.lock = RW_LOCK_BIAS;
  43
  44         pthread_create(&t1, 0, &a, NULL);
  45         pthread_create(&t2, 0, &a, NULL);
  46
  47         pthread_join(t1, 0);
  48         pthread_join(t2, 0);
  49
  50         return 0;
  51 }