filebuf_sgetn_unbuf.cc

Mac OS X 10.4.9 for x86 Source Code gcc 实现源代码

// Copyright (C) 2004 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

#include <cstdio>
#include <fstream>
#include <testsuite_performance.h>

// libstdc++/11722
int main()
{
  using namespace std;
  using namespace __gnu_test;

  time_counter time;
  resource_counter resource;

  const int iterations = 500000;
  const int chunksize = 100;

  char* chunk = new char[chunksize];
  const char* name1 = "/usr/share/dict/words";
  const char* name2 = "/usr/share/dict/linux.words";
  const char* name = name1;

  // C
  FILE* file;
  if (!(file = fopen(name, "r")))
    {
      name = name2;
      if (!(file = fopen(name, "r")))
	exit(1);
    }
  setvbuf(file, 0, _IONBF, 0);
  start_counters(time, resource);
  for (int i = 0; i < iterations; ++i)
    if (fread(chunk, 1, chunksize, file) < chunksize)
      fseek(file, 0, SEEK_SET);
  stop_counters(time, resource);
  fclose(file);
  report_performance(__FILE__, "C", time, resource);
  clear_counters(time, resource);

  // C unlocked
  file = fopen(name, "r");
  setvbuf(file, 0, _IONBF, 0);
  start_counters(time, resource);
  for (int i = 0; i < iterations; ++i)
    if (fread_unlocked(chunk, 1, chunksize, file) < chunksize)
      fseek(file, 0, SEEK_SET);
  stop_counters(time, resource);
  fclose(file);
  report_performance(__FILE__, "C unlocked", time, resource);
  clear_counters(time, resource);
  
  // C++
  filebuf buf;
  buf.pubsetbuf(0, 0);
  buf.open(name, ios_base::in);
  start_counters(time, resource);
  for (int i = 0; i < iterations; ++i)
    if (buf.sgetn(chunk, chunksize) < chunksize)
      buf.pubseekoff(0, ios::beg);
  stop_counters(time, resource);
  report_performance(__FILE__, "C++", time, resource);

  delete [] chunk;

  return 0;
}