Fix race in unit test.

Summary: Avoid falling victim to race condition.

Test Plan: Run the unit test

Reviewers: sdong igor

CC: leveldb@

Task ID: #7312624

Blame Rev:

db/db_test.cc

@@ -72,21 +72,39 @@ static std::string RandomString(Random* rnd, int len) {
 namespace anon {
 class AtomicCounter {
  private:
+  Env* env_;
   port::Mutex mu_;
+  port::CondVar cond_count_;
   int count_;
  public:
-  AtomicCounter() : count_(0) { }
+  AtomicCounter(Env* env = NULL) : env_(env), cond_count_(&mu_), count_(0) {}
   void Increment() {
     MutexLock l(&mu_);
     count_++;
+    cond_count_.SignalAll();
   }
   int Read() {
     MutexLock l(&mu_);
     return count_;
   }
+  bool WaitFor(int count) {
+    MutexLock l(&mu_);
+
+    uint64_t start = env_->NowMicros();
+    while (count_ < count) {
+      uint64_t now = env_->NowMicros();
+      cond_count_.TimedWait(now + /*1s*/ 1 * 000 * 000);
+      if (env_->NowMicros() - start > /*1s*/ 1 * 000 * 000) {
+        return false;
+      }
+    }
+
+    return true;
+  }
   void Reset() {
     MutexLock l(&mu_);
     count_ = 0;
+    cond_count_.SignalAll();
   }
 };
 
@@ -159,7 +177,11 @@ class SpecialEnv : public EnvWrapper {
   bool no_sleep_;
 
   explicit SpecialEnv(Env* base)
-      : EnvWrapper(base), rnd_(301), addon_time_(0), no_sleep_(false) {
+      : EnvWrapper(base),
+        rnd_(301),
+        sleep_counter_(this),
+        addon_time_(0),
+        no_sleep_(false) {
     delay_sstable_sync_.store(false, std::memory_order_release);
     drop_writes_.store(false, std::memory_order_release);
     no_space_.store(false, std::memory_order_release);
@@ -7553,7 +7575,7 @@ TEST_F(DBTest, DropWrites) {
     ASSERT_LT(CountFiles(), num_files + 3);
 
     // Check that compaction attempts slept after errors
-    ASSERT_GE(env_->sleep_counter_.Read(), 5);
+    ASSERT_TRUE(env_->sleep_counter_.WaitFor(5));
   } while (ChangeCompactOptions());
 }