re PR libstdc++/11378 (Unbuffered sputn is slow)

2003-07-04  Paolo Carlini  <pcarlini@unitus.it>

	PR libstdc++/11378
	* include/std/std_fstream.h (xsputn): In the unbuffered case,
	provided always_noconv(), issue directly _M_file.xsputn.
	* testsuite/performance/filebuf_unbuf_sputn.cc: New.

From-SVN: r68921

libstdc++-v3/ChangeLog

@@ -1,3 +1,10 @@
+2003-07-04  Paolo Carlini  <pcarlini@unitus.it>
+
+	PR libstdc++/11378
+	* include/std/std_fstream.h (xsputn): In the unbuffered case,
+	provided always_noconv(), issue directly _M_file.xsputn.
+	* testsuite/performance/filebuf_unbuf_sputn.cc: New.
+
 2003-07-04  Paolo Carlini  <pcarlini@unitus.it>
 
 	* include/bits/stl_list.h: Fully qualify standard

libstdc++-v3/include/std/std_fstream.h

@@ -397,8 +397,20 @@ namespace std
       virtual streamsize
       xsputn(const char_type* __s, streamsize __n)
       {
-	_M_destroy_pback();
+	streamsize __ret = 0;
-	return __streambuf_type::xsputn(__s, __n);
+ 
+	const bool __testout = this->_M_mode & ios_base::out;
+	if (__testout && !_M_reading && this->_M_buf_size == 1
+	    && __check_facet(_M_codecvt).always_noconv())
+	  {
+	    __ret = _M_file.xsputn(reinterpret_cast<const char*>(__s), __n);
+	    if (__ret == __n)
+	      _M_writing = true;
+	  }
+	else
+	  __ret = __streambuf_type::xsputn(__s, __n);
+      
+	return __ret;
       }          
 
       /**

libstdc++-v3/testsuite/performance/filebuf_unbuf_sputn.cc

@@ -0,0 +1,130 @@
+// 2003-07-04  Petur Runolfsson <peturr02@ru.is>
+//
+// Copyright (C) 2003 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 <cstring>
+#include <fstream>
+#include <iostream>
+
+// Contributed as part of libstdc++/11378.
+int main(int argc, char** argv)
+{
+  using namespace std;
+  
+  if (argc < 3)
+    {
+      cerr << "Usage: " << argv[0] << " type iters [chunksize]\n";
+      return -1;
+    }
+
+  enum { type_stdio, type_iostream } type;
+  
+  if (!strcmp(argv[1], "stdio"))
+    type = type_stdio;
+  else if (!strcmp(argv[1], "iostream"))
+    type = type_iostream;
+  else
+    {
+      cerr << "Type must be one of {stdio, iostream}\n";
+      return -1;
+    }
+
+  int iters = atoi(argv[2]);
+  if (iters < 1)
+    {
+      cerr << "Iters must be an positive integer\n";
+      return -1;
+    }
+  
+  int chunksize = 1;
+  if (argc > 3)
+    chunksize = atoi(argv[3]);
+  
+  if (iters < 1)
+    {
+      cerr << "Chunksize must be an positive integer\n";
+      return -1;
+    }
+  
+  char* chunk = 0;
+  if (chunksize > 1)
+    {
+      chunk = new char[chunksize];
+      memset(chunk, 'a', chunksize);
+    }
+
+  switch (type)
+    {
+    case type_stdio:
+      {
+	FILE* f = fopen("tmp", "w");
+	setvbuf(f, 0, _IONBF, 0);
+	
+	if (chunksize > 1)
+	  {
+	    for (int i = 0; i < iters; ++i)
+	      fwrite_unlocked(chunk, 1, chunksize, f);
+	  }
+	else
+	  {
+	    for (int i = 0; i < iters; ++i)
+	      putc_unlocked('a', f);
+	  }
+	
+	fclose(f);
+	break;
+      }
+
+    case type_iostream:
+      {
+	filebuf f;
+	f.pubsetbuf(0, 0);
+	
+	f.open("tmp", ios_base::out);
+
+	if (chunksize > 1)
+	  {
+	    for (int i = 0; i < iters; ++i)
+	      f.sputn(chunk, chunksize);
+	  }
+	else
+	  {
+	    for (int i = 0; i < iters; ++i)
+	      f.sputc('a');
+	  }
+	
+	f.close();
+	
+	break;
+      }
+    }
+
+  delete[] chunk;
+  return 0;
+}