Class Writer

3rdparty/libprocess/include/process/http.hpp:354–394

  };

  class Writer
  {
  public:
    // Returns false if the data could not be written because
    // either end of the pipe was already closed. Note that an
    // empty write has no effect.
    bool write(std::string s);

    // Closing the write-end of the pipe will send end-of-file
    // to the reader. Returns false if the write-end of the pipe
    // was already closed or failed.
    bool close();

    // Closes the write-end of the pipe but sends a failure
    // to the reader rather than end-of-file. Returns false
    // if the write-end of the pipe was already closed or failed.
    bool fail(const std::string& message);

    // Returns Nothing when the read-end of the pipe is closed
    // before the write-end is closed, which means the reader
    // was unable to continue reading!
    Future<Nothing> readerClosed() const;

    // Comparison operators useful for checking connection equality.
    bool operator==(const Writer& other) const { return data == other.data; }
    bool operator!=(const Writer& other) const { return !(*this == other); }
  private:
    friend class Pipe;

    enum State
    {
      OPEN,
      CLOSED,
      FAILED,
    };

    explicit Writer(const std::shared_ptr<Data>& _data)
      : data(_data) {}

    std::shared_ptr<Data> data;
  };

  Pipe()
    : data(new Data()) {}