logfile.hpp

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/***
 *** See the file "L2_RTI_EO1/disclaimers-and-notices-L2.txt" for 
 *** information on usage and redistribution of this file, 
 *** and for a DISCLAIMER OF ALL WARRANTIES.
 ***/
#ifndef LOGFILE_H
#define LOGFILE_H

#include <stdio.h>           // for FILE

class LOG_MSG;

/**
 * Encapsulates information about a log stream, allowing files to be of
 * bounded size, with round-robin alternation among versions.
 * \ingroup RTI
 */
class LogFile {

public:

  /**
   * The only constructor.
   * \param pathname the pathname of the log file
   * \param linesPerVersion the number of lines to be written to a log file
   * before it is closed and a different version is opened; must be positive
   * \param numberOfVersions the number of different versions of a log file to
   * be created; must be positive.
   */
  LogFile(const char* pathname,
	  unsigned bytesPerVersion,
	  unsigned numberOfVersions);

  /** Non-default destructor. */
  ~LogFile();

  /** Return the pathname of the log file. */
  const char* getPathname() const { return d_pathname; }

  /**
   * Open the file if needed. Write the message to the log file. If the log
   * file is full, switch to a different file version.
   * \param logMsg a LOG_MSG object
   */
  void writeToDisk(const LOG_MSG& logMsg);

  /** Is the log file stream open? */
  bool isOpen() const { return (d_file != 0); }

  /**
   * Close the log file stream and set it to 0. The log files must be closed
   * explicitly, taking care of order. This can not be left to the destructor.
   */
  void closeFile();

private:

  /** Insert the version number before the final period. */
  void makeVersionPathname(char versionPathname[]);

  /** If d_file is not open, try to open it. */
  void assureOpen();

private:

  /** The pathname of the log file. */
  const char* const d_pathname;

  /**
   * The number of lines to be written to a log file before it is closed and a
   * different version is opened. Must be positive.
   */
  const unsigned d_bytesPerVersion;

  /**
   * The number of different versions of a log file to be created. Must be
   * positive.
   */
  const unsigned d_numberOfVersions;

  /** The current version that is being written (if any).*/
  unsigned d_currentVersion;

  /** The number of bytes that have been written to the current file version.*/
  unsigned d_byteCount;

  /** The log file descriptor. */
  int d_file;
};

#endif // LOGFILE_H