From patchwork Sat Dec  4 02:40:08 2010
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Subject: std::try_lock problems
Date: Fri, 03 Dec 2010 16:40:08 -0000
From: Jonathan Wakely <jwakely.gcc@gmail.com>
X-Patchwork-Id: 74234
Message-Id: <AANLkTi=_th+Ga0_WorcF9fAuHMctKQsxNEkML00HiN_t@mail.gmail.com>
To: "libstdc++" <libstdc++@gcc.gnu.org>
Cc: gcc-patches <gcc-patches@gcc.gnu.org>

This fixes the problems described on the libstdc++ list, tested
x86_64-linux and committed to trunk

2010-12-04  Jonathan Wakely  <jwakely.gcc@gmail.com>

	* include/std/mutex (try_lock, __try_lock_impl): Fix.
	(lock): Implement using __try_lock_impl.
	* testsuite/30_threads/try_lock/2.cc: Fix logic.
	* testsuite/30_threads/try_lock/4.cc: New.
	* testsuite/30_threads/lock/1.cc: New.
	* testsuite/30_threads/lock/2.cc: New.
	* testsuite/30_threads/lock/3.cc: New.
	* testsuite/30_threads/lock/4.cc: New.


Index: include/std/mutex
===================================================================
--- include/std/mutex	(revision 167396)
+++ include/std/mutex	(working copy)
@@ -663,16 +663,19 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
 	static int
 	__do_try_lock(tuple<_Lock&...>& __locks)
 	{
-	  if(std::get<_Idx>(__locks).try_lock())
-	    {
-	      return __try_lock_impl<_Idx + 1,
-		_Idx + 2 < sizeof...(_Lock)>::__do_try_lock(__locks);
-	    }
-	  else
-	    {
-	      __unlock_impl<_Idx>::__do_unlock(__locks);
-	      return _Idx;
-	    }
+          __try
+            {
+              if(std::get<_Idx>(__locks).try_lock())
+                {
+                  return __try_lock_impl<_Idx + 1,
+                    _Idx + 2 < sizeof...(_Lock)>::__do_try_lock(__locks);
+                }
+            }
+          __catch(...)
+            {
+            }
+          __unlock_impl<_Idx - 1>::__do_unlock(__locks);
+          return _Idx;
 	}
     };
 
@@ -683,13 +686,16 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
 	static int
 	__do_try_lock(tuple<_Lock&...>& __locks)
 	{
-	  if(std::get<_Idx>(__locks).try_lock())
-	    return -1;
-	  else
+          __try
+            {
+	      if(std::get<_Idx>(__locks).try_lock())
+	        return -1;
+	    }
+          __catch(...)
 	    {
-	      __unlock_impl<_Idx>::__do_unlock(__locks);
-	      return _Idx;
 	    }
+	  __unlock_impl<_Idx - 1>::__do_unlock(__locks);
+	  return _Idx;
 	}
     };