Make bthread_id_join destroy race test deterministic

Author: songgaoye

src/bthread/id.cpp

@@ -30,6 +30,11 @@
 
 namespace bthread {
 
+#if defined(UNIT_TEST)
+void (*g_bthread_id_join_before_wait_for_test)(void*) = nullptr;
+void* g_bthread_id_join_before_wait_arg_for_test = nullptr;
+#endif
+
 // This queue reduces the chance to allocate memory for deque
 template <typename T, int N>
 class SmallQueue {
@@ -549,6 +554,12 @@ int bthread_id_join(bthread_id_t id) {
         if (!has_ver) {
             break;
         }
+#if defined(UNIT_TEST)
+        if (bthread::g_bthread_id_join_before_wait_for_test != nullptr) {
+            bthread::g_bthread_id_join_before_wait_for_test(
+                bthread::g_bthread_id_join_before_wait_arg_for_test);
+        }
+#endif
         if (bthread::butex_wait(join_butex, expected_ver, nullptr) < 0 &&
             errno != EWOULDBLOCK && errno != EINTR) {
             return errno;

test/bthread_id_unittest.cpp

@@ -28,6 +28,8 @@
 namespace bthread {
 void id_status(bthread_id_t, std::ostream &);
 uint32_t id_value(bthread_id_t id);
+extern void (*g_bthread_id_join_before_wait_for_test)(void*);
+extern void* g_bthread_id_join_before_wait_arg_for_test;
 }
 
 namespace {
@@ -116,33 +118,47 @@ TEST(BthreadIdTest, join_before_destroy) {
 
 struct JoinRaceArgs {
     bthread_id_t id;
-    std::atomic<bool> entered;
+    std::atomic<bool> join_butex_read;
+    std::atomic<bool> allow_wait;
 };
 
+void pause_join_before_wait(void* arg) {
+    JoinRaceArgs* args = static_cast<JoinRaceArgs*>(arg);
+    args->join_butex_read.store(true, std::memory_order_release);
+    while (!args->allow_wait.load(std::memory_order_acquire)) {
+        std::this_thread::yield();
+    }
+}
+
 void* join_race_waiter(void* arg) {
     JoinRaceArgs* args = static_cast<JoinRaceArgs*>(arg);
-    args->entered.store(true, std::memory_order_release);
     EXPECT_EQ(0, bthread_id_join(args->id));
     return nullptr;
 }
 
 TEST(BthreadIdTest, join_races_with_destroy) {
-    for (int i = 0; i < 100; ++i) {
-        bthread_id_t id;
-        ASSERT_EQ(0, bthread_id_create(&id, nullptr, nullptr));
-        JoinRaceArgs args;
-        args.id = id;
-        args.entered.store(false, std::memory_order_relaxed);
-        pthread_t waiter;
-        ASSERT_EQ(0, pthread_create(&waiter, nullptr, join_race_waiter, &args));
-        while (!args.entered.load(std::memory_order_acquire)) {
-            std::this_thread::yield();
-        }
-        void* data = nullptr;
-        ASSERT_EQ(0, bthread_id_trylock(id, &data));
-        ASSERT_EQ(0, bthread_id_unlock_and_destroy(id));
-        ASSERT_EQ(0, pthread_join(waiter, nullptr));
+    bthread_id_t id;
+    ASSERT_EQ(0, bthread_id_create(&id, nullptr, nullptr));
+    JoinRaceArgs args;
+    args.id = id;
+    args.join_butex_read.store(false, std::memory_order_relaxed);
+    args.allow_wait.store(false, std::memory_order_relaxed);
+    bthread::g_bthread_id_join_before_wait_for_test = pause_join_before_wait;
+    bthread::g_bthread_id_join_before_wait_arg_for_test = &args;
+
+    pthread_t waiter;
+    ASSERT_EQ(0, pthread_create(&waiter, nullptr, join_race_waiter, &args));
+    while (!args.join_butex_read.load(std::memory_order_acquire)) {
+        std::this_thread::yield();
     }
+    void* data = nullptr;
+    ASSERT_EQ(0, bthread_id_trylock(id, &data));
+    ASSERT_EQ(0, bthread_id_unlock_and_destroy(id));
+    args.allow_wait.store(true, std::memory_order_release);
+    ASSERT_EQ(0, pthread_join(waiter, nullptr));
+
+    bthread::g_bthread_id_join_before_wait_for_test = nullptr;
+    bthread::g_bthread_id_join_before_wait_arg_for_test = nullptr;
 }
 
 struct OnResetArg {