Method FlashRandomAccessFile

src/leveldb/util/env_flash.cc:186–228

 public:
  FlashRandomAccessFile(FlashEnv* flash_env, const std::string& fname, uint64_t fsize,
                        const EnvOptions& options)
      : flash_env_(flash_env),
        dfs_file_(NULL),
        flash_file_(NULL),
        fname_(fname),
        local_fname_(flash_env->FlashPath(fname) + fname),
        fsize_(fsize),
        flash_file_is_checking_(false),
        flash_file_last_check_micros_(0),
        flash_file_check_interval_micros_(kFlashFileCheckIntervalMicros),
        read_dfs_count_(0),
        env_opt_(options),
        logical_sector_size_(kDefaultPageSize) {
    // copy file to cache if force read from cache
    if (flash_env_->ForceReadFromCache()) {
      Status copy_status = CopyToLocal(local_fname_, flash_env_->BaseEnv(), fname, fsize,
                                       flash_env_->VanishAllowed());
      if (!copy_status.ok()) {
        LOG(WARNING) << "[env_flash] copy to local fail [" << copy_status.ToString().c_str()
                     << "]: " << local_fname_.c_str();
      }
    }

    // if cache file is identical with dfs file, use cache file
    if (flash_env_->FlashFileIdentical(fname, fsize)) {
      Status s = flash_env_->CacheEnv()->NewRandomAccessFile(local_fname_, &flash_file_, env_opt_);
      if (s.ok()) {
        logical_sector_size_ = flash_file_->GetRequiredBufferAlignment();
        return;
      }
      LOG(WARNING) << "[env_flash] local file check pass, but open for "
                      "RandomAccess fail [" << s.ToString().c_str()
                   << "]: " << local_fname_.c_str();
    } else {
      LOG(WARNING) << "[env_flash] local file check fail: " << local_fname_.c_str();
    }

    // else, use dfs file
    flash_env_->ScheduleUpdateFlash(fname, fsize, 1);
    flash_env_->BaseEnv()->NewRandomAccessFile(fname, &dfs_file_, env_opt_);
    flash_file_last_check_micros_ = Env::Default()->NowMicros();
  }
  ~FlashRandomAccessFile() {
    delete dfs_file_;
    delete flash_file_;