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// RUN: %clangxx_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <time.h>
#include <errno.h>
#include <vector>
#include <algorithm>
#include <sys/time.h>
const int kThreads = 4;
const int kMutexes = 16 << 10;
const int kIters = 400 << 10;
const int kMaxPerThread = 10;
const int kStateInited = 0;
const int kStateNotInited = -1;
const int kStateLocked = -2;
struct Mutex {
int state;
pthread_rwlock_t m;
};
Mutex mtx[kMutexes];
void check(int res) {
if (res != 0) {
printf("SOMETHING HAS FAILED\n");
exit(1);
}
}
bool cas(int *a, int oldval, int newval) {
return __atomic_compare_exchange_n(a, &oldval, newval, false,
__ATOMIC_ACQ_REL, __ATOMIC_RELAXED);
}
void *Thread(void *seed) {
unsigned rnd = (unsigned)(unsigned long)seed;
int err;
std::vector<int> locked;
for (int i = 0; i < kIters; i++) {
int what = rand_r(&rnd) % 10;
if (what < 4 && locked.size() < kMaxPerThread) {
// lock
int max_locked = -1;
if (!locked.empty()) {
max_locked = *std::max_element(locked.begin(), locked.end());
if (max_locked == kMutexes - 1) {
i--;
continue;
}
}
int id = (rand_r(&rnd) % (kMutexes - max_locked - 1)) + max_locked + 1;
Mutex *m = &mtx[id];
// init the mutex if necessary or acquire a reference
for (;;) {
int old = __atomic_load_n(&m->state, __ATOMIC_RELAXED);
if (old == kStateLocked) {
sched_yield();
continue;
}
int newv = old + 1;
if (old == kStateNotInited)
newv = kStateLocked;
if (cas(&m->state, old, newv)) {
if (old == kStateNotInited) {
if ((err = pthread_rwlock_init(&m->m, 0))) {
fprintf(stderr, "pthread_rwlock_init failed with %d\n", err);
exit(1);
}
if (!cas(&m->state, kStateLocked, 1)) {
fprintf(stderr, "init commit failed\n");
exit(1);
}
}
break;
}
}
// now we have an inited and referenced mutex, choose what to do
bool failed = false;
switch (rand_r(&rnd) % 4) {
case 0:
if ((err = pthread_rwlock_wrlock(&m->m))) {
fprintf(stderr, "pthread_rwlock_wrlock failed with %d\n", err);
exit(1);
}
break;
case 1:
if ((err = pthread_rwlock_rdlock(&m->m))) {
fprintf(stderr, "pthread_rwlock_rdlock failed with %d\n", err);
exit(1);
}
break;
case 2:
err = pthread_rwlock_trywrlock(&m->m);
if (err != 0 && err != EBUSY) {
fprintf(stderr, "pthread_rwlock_trywrlock failed with %d\n", err);
exit(1);
}
failed = err == EBUSY;
break;
case 3:
err = pthread_rwlock_tryrdlock(&m->m);
if (err != 0 && err != EBUSY) {
fprintf(stderr, "pthread_rwlock_tryrdlock failed with %d\n", err);
exit(1);
}
failed = err == EBUSY;
break;
}
if (failed) {
if (__atomic_fetch_sub(&m->state, 1, __ATOMIC_ACQ_REL) <= 0) {
fprintf(stderr, "failed to unref after failed trylock\n");
exit(1);
}
continue;
}
locked.push_back(id);
} else if (what < 9 && !locked.empty()) {
// unlock
int pos = rand_r(&rnd) % locked.size();
int id = locked[pos];
locked[pos] = locked[locked.size() - 1];
locked.pop_back();
Mutex *m = &mtx[id];
if ((err = pthread_rwlock_unlock(&m->m))) {
fprintf(stderr, "pthread_rwlock_unlock failed with %d\n", err);
exit(1);
}
if (__atomic_fetch_sub(&m->state, 1, __ATOMIC_ACQ_REL) <= 0) {
fprintf(stderr, "failed to unref after unlock\n");
exit(1);
}
} else {
// Destroy a random mutex.
int id = rand_r(&rnd) % kMutexes;
Mutex *m = &mtx[id];
if (!cas(&m->state, kStateInited, kStateLocked)) {
i--;
continue;
}
if ((err = pthread_rwlock_destroy(&m->m))) {
fprintf(stderr, "pthread_rwlock_destroy failed with %d\n", err);
exit(1);
}
if (!cas(&m->state, kStateLocked, kStateNotInited)) {
fprintf(stderr, "destroy commit failed\n");
exit(1);
}
}
}
// Unlock all previously locked mutexes, otherwise other threads can deadlock.
for (int i = 0; i < locked.size(); i++) {
int id = locked[i];
Mutex *m = &mtx[id];
if ((err = pthread_rwlock_unlock(&m->m))) {
fprintf(stderr, "pthread_rwlock_unlock failed with %d\n", err);
exit(1);
}
}
return 0;
}
int main() {
struct timeval tv;
gettimeofday(&tv, NULL);
unsigned s = tv.tv_sec + tv.tv_usec;
fprintf(stderr, "seed %d\n", s);
srand(s);
for (int i = 0; i < kMutexes; i++)
mtx[i].state = kStateNotInited;
pthread_t t[kThreads];
for (int i = 0; i < kThreads; i++)
pthread_create(&t[i], 0, Thread, (void*)(unsigned long)rand());
for (int i = 0; i < kThreads; i++)
pthread_join(t[i], 0);
fprintf(stderr, "DONE\n");
return 0;
}
// CHECK-NOT: WARNING: ThreadSanitizer
// CHECK: DONE
|
