Re: [PATCH][libstdc++-v3 parallel mode]

[Johannes Singler <singler at ira dot uka dot de>]

Benjamin Kosnik wrote:
> > 2008-07-08  Johannes Singler  <singler@ira.uka.de>
> >
> >           * include/parallel/random_shuffle.h:
> >           (sequential_random_shuffle) Copy data back.
>
> OK, but this seems like the kind of thing you should really add a
> testcase for so that it doesn't regress.

Okay, so here is the first functionality test case for random_shuffle 
(That's why I called it 1.cc, not after the PR). However, to trigger the 
bug, a quite long sequence must be permuted, which costs time and space.
Okay?

-- Johannes
Index: include/parallel/random_shuffle.h
===================================================================
--- include/parallel/random_shuffle.h	(revision 137616)
+++ include/parallel/random_shuffle.h	(working copy)
@@ -491,6 +491,9 @@
                                       rng);
           }
 
+        // Copy elements back.
+        std::copy(target, target + n, begin);
+
         delete[] dist0;
         delete[] dist1;
         delete[] oracles;
Index: testsuite/25_algorithms/random_shuffle/1.cc
===================================================================
--- testsuite/25_algorithms/random_shuffle/1.cc	(revision 0)
+++ testsuite/25_algorithms/random_shuffle/1.cc	(revision 0)
@@ -0,0 +1,75 @@
+// Copyright (C) 2001 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+// USA.
+
+// 25.2.11 random_shuffle()
+
+#include <algorithm>
+#include <testsuite_hooks.h>
+
+bool test __attribute__((unused)) = true;
+
+const int N = 200000;
+int A[N], s1[N];
+
+#if _GLIBCXX_PARALLEL
+#define TAG , __gnu_parallel::sequential_tag()
+#else
+#define TAG
+#endif
+
+void fill_ascending()
+{
+  for (int i = 0; i < N; ++i)
+    A[i] = i;
+}
+
+void
+test01()
+{
+  fill_ascending();
+#if _GLIBCXX_PARALLEL
+  for (int num_threads = 1; num_threads <= 2; ++num_threads)
+  {
+    omp_set_num_threads(num_threads);
+#endif
+    std::copy(A, A + N, s1);
+    VERIFY(std::equal(s1, s1 + N, A TAG));
+
+    std::random_shuffle(s1, s1 + N);
+    // the chance that random_shuffle leaves the order as is by coincidence
+    // is negligible, so we expect it to be permuted
+    VERIFY(!std::equal(s1, s1 + N, A TAG));
+
+    std::sort(s1, s1 + N TAG);
+    VERIFY(std::equal(s1, s1 + N, A TAG));
+#if _GLIBCXX_PARALLEL
+  }
+#endif
+}
+
+int
+main()
+{
+#if _GLIBCXX_PARALLEL
+  __gnu_parallel::_Settings gpms = __gnu_parallel::_Settings::get();
+  gpms.algorithm_strategy = __gnu_parallel::force_parallel;
+  __gnu_parallel::_Settings::set(gpms);
+#endif
+  test01();
+  return 0;
+}