lib/cpp/transport/TTransport.h

#ifndef T_TRANSPORT_H
#define T_TRANSPORT_H

#include <string>
#include "transport/TTransportException.h"

/**
 * Generic interface for a method of transporting data. A TTransport may be
 * capable of either reading or writing, but not necessarily both.
 *
 * @author Mark Slee <mcslee@facebook.com>
 */
class TTransport {
 public:
  /**
   * Virtual deconstructor.
   */
  virtual ~TTransport() {}

  /**
   * Whether this transport is open.
   */
  virtual bool isOpen() { return false; }

  /**
   * Opens the transport for communications.
   *
   * @return bool Whether the transport was successfully opened
   * @throws TTransportException if opening failed
   */
  virtual void open() {
    throw TTransportException(TTX_NOT_OPEN, "Cannot open base TTransport.");
  }

  /**
   * Closes the transport.
   */
  virtual void close() {
    throw TTransportException(TTX_NOT_OPEN, "Cannot close base TTransport.");
  }

  /**
   * Attempt to read up to the specified number of bytes into the string.
   *
   * @param s     Reference to the location to append the read data
   * @param len  How many bytes to read
   * @return How many bytes were actually read
   * @throws TTransportException If an error occurs
   */
  virtual uint32_t read(uint8_t* buf, uint32_t len) {
    throw TTransportException(TTX_NOT_OPEN, "Base TTransport cannot read.");
  }

  /**
   * Reads the given amount of data in its entirety no matter what.
   *
   * @param s     Reference to location for read data
   * @param len   How many bytes to read
   * @return How many bytes read, which must be equal to size
   * @throws TTransportException If insufficient data was read
   */
  virtual uint32_t readAll(uint8_t* buf, uint32_t len) {
    uint32_t have = 0;
    
    while (have < len) {
      have += read(buf+have, len-have);
    }

    return have;
  }

  /**
   * Writes the string in its entirety to the buffer.
   *
   * @param s The string to write out
   * @throws TTransportException if an error occurs
   */
  virtual void write(const uint8_t* buf, uint32_t len) {
    throw TTransportException(TTX_NOT_OPEN, "Base TTransport cannot write.");
  }

  /**
   * Flushes any pending data to be written. Typically used with buffered
   * transport mechanisms.
   *
   * @throws TTransportException if an error occurs
   */
  virtual void flush() {}

 protected:
  /**
   * Simple constructor.
   */
  TTransport() {}
};

#endif