fault_injection_test: add a test case to cover log syncing after a log roll

Summary:
Add a test case:
Write some keys without sync, flush, write other keys and do sync. Before flush finishes, host crashes and unsync data is dropped.
Tag the new test as disabled since it is not passing.

Test Plan: Run the test

Reviewers: MarkCallaghan, rven, anthony, igor, kradhakrishnan

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D36741

db/fault_injection_test.cc

@@ -726,6 +726,76 @@ TEST_F(FaultInjectionTest, FaultTest) {
   } while (ChangeOptions());
 }
 
+class SleepingBackgroundTask {
+ public:
+  SleepingBackgroundTask()
+      : bg_cv_(&mutex_), should_sleep_(true), done_with_sleep_(false) {}
+  void DoSleep() {
+    MutexLock l(&mutex_);
+    while (should_sleep_) {
+      bg_cv_.Wait();
+    }
+    done_with_sleep_ = true;
+    bg_cv_.SignalAll();
+  }
+  void WakeUp() {
+    MutexLock l(&mutex_);
+    should_sleep_ = false;
+    bg_cv_.SignalAll();
+    while (!done_with_sleep_) {
+      bg_cv_.Wait();
+    }
+  }
+
+  static void DoSleepTask(void* arg) {
+    reinterpret_cast<SleepingBackgroundTask*>(arg)->DoSleep();
+  }
+
+ private:
+  port::Mutex mutex_;
+  port::CondVar bg_cv_;  // Signalled when background work finishes
+  bool should_sleep_;
+  bool done_with_sleep_;
+};
+
+// Disable the test because it is not passing.
+// Previous log file is not fsynced if sync is forced after log rolling.
+// TODO(FB internal task#6730880) Fix the bug
+TEST_F(FaultInjectionTest, DISABLED_WriteOptionSyncTest) {
+  SleepingBackgroundTask sleeping_task_low;
+  env_->SetBackgroundThreads(1, Env::HIGH);
+  // Block the job queue to prevent flush job from running.
+  env_->Schedule(&SleepingBackgroundTask::DoSleepTask, &sleeping_task_low,
+                 Env::Priority::HIGH);
+
+  WriteOptions write_options;
+  write_options.sync = false;
+
+  std::string key_space, value_space;
+  ASSERT_OK(
+      db_->Put(write_options, Key(1, &key_space), Value(1, &value_space)));
+  FlushOptions flush_options;
+  flush_options.wait = false;
+  ASSERT_OK(db_->Flush(flush_options));
+  write_options.sync = true;
+  ASSERT_OK(
+      db_->Put(write_options, Key(2, &key_space), Value(2, &value_space)));
+
+  env_->SetFilesystemActive(false);
+  NoWriteTestReopenWithFault(kResetDropAndDeleteUnsynced);
+  sleeping_task_low.WakeUp();
+
+  ASSERT_OK(OpenDB());
+  std::string val;
+  Value(2, &value_space);
+  ASSERT_OK(ReadValue(2, &val));
+  ASSERT_EQ(value_space, val);
+
+  Value(1, &value_space);
+  ASSERT_OK(ReadValue(1, &val));
+  ASSERT_EQ(value_space, val);
+}
+
 }  // namespace rocksdb
 
 int main(int argc, char** argv) {