Method seekToChunk

lib/cpp/src/thrift/transport/TFileTransport.cpp:793–850

}

void TFileTransport::seekToChunk(int32_t chunk) {
  if (fd_ <= 0) {
    throw TTransportException("File not open");
  }

  int32_t numChunks = getNumChunks();

  // file is empty, seeking to chunk is pointless
  if (numChunks == 0) {
    return;
  }

  // negative indicates reverse seek (from the end)
  if (chunk < 0) {
    chunk += numChunks;
  }

  // too large a value for reverse seek, just seek to beginning
  if (chunk < 0) {
    T_DEBUG("%s", "Incorrect value for reverse seek. Seeking to beginning...");
    chunk = 0;
  }

  // cannot seek past EOF
  bool seekToEnd = false;
  off_t minEndOffset = 0;
  if (chunk >= numChunks) {
    T_DEBUG("%s", "Trying to seek past EOF. Seeking to EOF instead...");
    seekToEnd = true;
    chunk = numChunks - 1;
    // this is the min offset to process events till
    minEndOffset = ::THRIFT_LSEEK(fd_, 0, SEEK_END);
  }

  off_t newOffset = off_t(chunk) * chunkSize_;
  offset_ = ::THRIFT_LSEEK(fd_, newOffset, SEEK_SET);
  readState_.resetAllValues();
  currentEvent_ = nullptr;
  if (offset_ == -1) {
    TOutput::instance()("TFileTransport: lseek error in seekToChunk");
    throw TTransportException("TFileTransport: lseek error in seekToChunk");
  }

  // seek to EOF if user wanted to go to last chunk
  if (seekToEnd) {
    uint32_t oldReadTimeout = getReadTimeout();
    setReadTimeout(NO_TAIL_READ_TIMEOUT);
    // keep on reading unti the last event at point of seekChunk call
    shared_ptr<eventInfo> event;
    while ((offset_ + readState_.bufferPtr_) < minEndOffset) {
      event.reset(readEvent());
      if (event.get() == nullptr) {
        break;
      }
    }
    setReadTimeout(oldReadTimeout);
  }
}