array_allocator.h (array::allocate): Check for valid array object, use its size member function directly.

2004-10-26  Benjamin Kosnik  <bkoz@redhat.com>

	* include/ext/array_allocator.h (array::allocate): Check for valid
	array object, use its size member function directly.
	* testsuite/ext/array_allocator/3.cc: New.
	* docs/html/20_util/allocator.html: Add docs.

From-SVN: r89573

libstdc++-v3/ChangeLog

@@ -1,3 +1,10 @@
+2004-10-26  Benjamin Kosnik  <bkoz@redhat.com>
+
+	* include/ext/array_allocator.h (array::allocate): Check for valid
+	array object, use its size member function directly.
+	* testsuite/ext/array_allocator/3.cc: New.
+	* docs/html/20_util/allocator.html: Add docs.
+	
 2004-10-25  Geoffrey Keating  <geoffk@apple.com>
 
 	* libsupc++/new_op.cc (new): Make weak.

libstdc++-v3/docs/html/20_util/allocator.html

@@ -297,7 +297,7 @@
     <td>&lt;memory&gt;</td>
   </tr>
   <tr>
-    <td>__gnu_cxx::__pool_alloc&lt;bool, int&gt;</td>
+    <td>__gnu_cxx::__pool_alloc&lt;T&gt;</td>
     <td>&lt;ext/pool_allocator.h&gt;</td>
     <td>std::__default_alloc_template&lt;bool,int&gt;</td>
     <td>&lt;memory&gt;</td>
@@ -316,7 +316,26 @@
   </tr>
 </table>
 
-   <p>More details on each of these allocators follows. </p>
+   <p> Releases after gcc-3.4 have continued to add to the collection
+   of available allocators. All of these new allocators are
+   standard-style. The following table includes details, along with
+   the first released version of GCC that included the extension allocator.
+   </p>
+
+<table title="more extension allocators" border="1">
+  <tr>
+    <th>Allocator</th>
+    <th>Include</th>
+    <th>Version</th>
+  </tr>
+  <tr>
+    <td>__gnu_cxx::array_allocator&lt;T&gt;</td>
+    <td>&lt;ext/array_allocator.h&gt;</td>
+    <td>4.0.0</td>
+  </tr>
+</table>
+
+   <p>More details on each of these extension allocators follows. </p>
    <ul>
      <li><code>new_allocator</code> 
      <p>Simply wraps <code>::operator new</code>
@@ -330,6 +349,18 @@
          elsewhere).  
      </p>
      </li>
+     <li><code>array_allocator</code> 
+     <p>Allows allocations of known and fixed sizes using existing
+         global or external storage allocated via construction of
+         std::tr1::array objects. By using this allocator, fixed size
+         containers (including std::string) can be used without
+         instances calling <code>::operator new</code> and
+         <code>::operator delete</code>. This capability allows the
+         use of STL abstractions without runtime complications or
+         overhead, even in situations such as program startup. For
+         usage examples, please consult the libstdc++ testsuite.
+     </p>
+     </li>
      <li><code>debug_allocator</code> 
      <p> A wrapper around an
          arbitrary allocator A.  It passes on slightly increased size
@@ -347,10 +378,15 @@
       and the allocate/deallocate request is passed to
       <code>::operator new</code> directly.  </p>
 
-   <p> This class take a boolean template parameter, called
+   <p> For versions of <code>__pool_alloc</code> after 3.4.0, there is
-      <code>thr</code>, and an integer template parameter, called
+   only one template parameter, as per the standard.
-      <code>inst</code>.
    </p>
+
+   <p> Older versions of this class take a boolean template parameter,
+      called <code>thr</code>, and an integer template parameter,
+      called <code>inst</code>.
+   </p>
+
    <p>The <code>inst</code> number is used to track additional memory
       pools.  The point of the number is to allow multiple
       instantiations of the classes without changing the semantics at
@@ -374,6 +410,12 @@
       is is threadsafe, while thr=false, and is slightly faster but
       unsafe for multiple threads.
    </p>
+
+   <p>For thread-enabled configurations, the pool is locked with a
+   single big lock. In some situations, this implementation detail may
+   result in severe performance degredation.
+   </p>
+
    <p>(Note that the GCC thread abstraction layer allows us to provide safe
       zero-overhead stubs for the threading routines, if threads were
       disabled at configuration time.)

libstdc++-v3/include/ext/array_allocator.h

@@ -118,7 +118,7 @@ namespace __gnu_cxx
       allocate(size_type __n, const void* = 0)
       {
 	static size_type __used;
-	if (__builtin_expect(__used + __n > array_type::_S_index, false))
+	if (_M_array == 0 || __used + __n > _M_array->size())
 	  std::__throw_bad_alloc();
 	pointer __ret = _M_array->begin() + __used;
 	__used += __n;

libstdc++-v3/testsuite/ext/array_allocator/3.cc

@@ -0,0 +1,66 @@
+// 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 <cassert>
+#include <string>
+#include <ext/array_allocator.h>
+
+typedef char char_type;
+typedef std::char_traits<char_type> traits_type;
+typedef std::tr1::array<char_type, 4> array_type;
+
+array_type extern_array;
+
+void test01() 
+{
+  using std::basic_string;
+  typedef __gnu_cxx::array_allocator<char_type, array_type> allocator_type;
+  typedef basic_string<char_type, traits_type, allocator_type> string_type;
+
+  // Construct array_allocator without underlying array.
+  allocator_type a;
+  string_type s(a);
+    
+  try
+    {
+      s.reserve(4); // Actually need 4 + 1 + sizeof(std::string::_Rep).
+    }
+  catch(std::bad_alloc& obj)
+    {
+      assert(true);
+    }
+  catch(...)
+    {
+      assert(false);
+    }
+}
+
+int main()
+{
+  test01();
+  return 0;
+}