【Linux C 几种锁的性能对比】 1.读写锁 2.互斥锁 3.自旋锁 4.信号量 5.rcu

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <limits.h>
#include <semaphore.h>
#include <urcu.h>
/* 1.读写锁
   2.互斥锁
   3.自旋锁
   4.信号量
   5.rcu
*/
#define RW_LOCK  0
#define MUTEX_LOCK  0
#define SPIN_LOCK 0
#define _SEM  0
#define URCU  1 
struct point{
  int x;
  int y;
};
struct point *gp;
int done = 0;
long reads = 0;
pthread_rwlock_t rwlock;
pthread_mutex_t mutex_t;
pthread_spinlock_t spinlock;
sem_t sem;
void *timer(void *arg){
  struct timespec ts, ts2;
  timespec_get(&ts, TIME_UTC);
  while(!done){
    sleep(1);
    timespec_get(&ts2, TIME_UTC);
    time_t sec = ts2.tv_sec - ts.tv_sec;
    printf("reads: %ld, %ld K reads/sec\n", reads, (reads/sec)/1000);
  }
}
void *updater(void *arg){
  struct point *p;
  struct point *old;
  int i = 0;
  for(i = 0; i< INT_MAX; i ++){
    p = malloc(sizeof(struct point));
    p->x = i;
    p->y = i+1;
    old = gp;
#if 0
    gp = p;
#elif RW_LOCK
    pthread_rwlock_wrlock(&rwlock);
    gp = p;
    pthread_rwlock_unlock(&rwlock);
#elif MUTEX_LOCK
    pthread_mutex_lock(&mutex_t);
    gp = p;
    pthread_mutex_unlock(&mutex_t);
#elif SPIN_LOCK 
    pthread_spin_lock(&spinlock);
    gp = p;
    pthread_spin_unlock(&spinlock);
#elif URCU
    rcu_assign_pointer(gp, p);
    synchronize_rcu();
#else 
    sem_wait(&sem);
    gp = p;
    sem_post(&sem);
#endif
    free(old);
  }
}
void *reader(void *arg){
  rcu_register_thread();//urcu
  while(!done){
    int x, y;
#if 0
    x = gp->x;
    y = gp->y;
#elif RW_LOCK 
    pthread_rwlock_rdlock(&rwlock);
    x = gp->x;
    y = gp->y;
    pthread_rwlock_unlock(&rwlock);
#elif MUTEX_LOCK   
    pthread_mutex_lock(&mutex_t);
    x = gp->x;
    y = gp->y;
    pthread_mutex_unlock(&mutex_t);
#elif SPIN_LOCK 
    pthread_spin_lock(&spinlock);
    x = gp->x;
    y = gp->y;
    pthread_spin_unlock(&spinlock);
#elif URCU
    rcu_read_lock();
    struct point *p = rcu_dereference(gp);
    x = p->x;
    y = p->y;
    rcu_read_unlock();
#else
    sem_wait(&sem);
    x = gp->x;
    y = gp->y;
    sem_post(&sem);
#endif
    reads ++;
    if(y != x+1){
      printf("Error: x:%d, y:%d\n", x, y);
      done = 1;
      break;
    }
  }
  rcu_unregister_thread();
  exit(1);
}
// gcc -o rcu rcu.c -lpthread -lurcu
int main(){
  pthread_t tid[3];
  pthread_rwlock_init(&rwlock, NULL);
  pthread_mutex_init(&mutex_t, NULL);
  pthread_spin_init(&spinlock, PTHREAD_PROCESS_SHARED);
  sem_init(&sem, 0, 1);
  rcu_init();//rcu
  gp = malloc(sizeof(struct point));
  gp->x = 1;
  gp->y = 2;
  pthread_create(&tid[0], NULL, updater, NULL);
  pthread_create(&tid[1], NULL, reader, NULL);
  pthread_create(&tid[2], NULL, timer, NULL);
  int i = 0;
  for(i = 0; i < 3; i ++){
    pthread_join(tid[i], NULL); 
  }
  free(gp);
  pthread_rwlock_destroy(&rwlock);
  pthread_mutex_destroy(&mutex_t);
  pthread_spin_destroy(&spinlock);
  return 0;
}