Method BGThread

src/leveldb/util/thread_pool.cc:159–195

}

void ThreadPool::BGThread() {
  while (true) {
    MutexLock lock(&mutex_);
    while (pri_queue_.empty() && !exit_all_threads_) {
      work_cv_.Wait();
    }
    if (exit_all_threads_) {
      break;
    }
    ++active_number_;
    BGItem bg_item = pri_queue_.top();
    pri_queue_.pop();
    BGMap::iterator it = latest_.find(bg_item.id);
    // only execute the function if the task is the latest one
    if (IsLatest(it->second, bg_item.priority, bg_item.exe_time)) {
      --pending_task_num_;
      void (*function)(void*) = bg_item.function;
      void* arg = bg_item.arg;
      latest_.erase(it);
      mutex_.Unlock();
      LOG(INFO) << "[ThreadPool(" << active_number_ << "/" << total_threads_limit_
                << ")] Do thread id = " << bg_item.id << " score = " << bg_item.priority;
      (*function)(arg);
      mutex_.Lock();
    }
    --active_number_;
    if (static_cast<int>(bg_threads_.size()) > total_threads_limit_) {
      pthread_t current = pthread_self();
      ThreadVector::iterator it = bg_threads_.begin();
      while (*it != current) {
        ++it;
      }
      bg_threads_.erase(it);
      break;
    }
  }
}

void ThreadPool::PutInQueue(BGItem& bg_item, int64_t wait_time_millisec) {
  if (wait_time_millisec == 0) {