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Subject: svn commit: r563682 - in /incubator/stdcxx/trunk/src: once.cpp once.h
Date: Tue, 07 Aug 2007 22:24:11 -0000
To: stdcxx-commits@incubator.apache.org
From: sebor@apache.org
Message-Id: <20070807222411.3E1C81A981A@eris.apache.org>

Author: sebor
Date: Tue Aug  7 15:24:10 2007
New Revision: 563682

URL: http://svn.apache.org/viewvc?view=rev&rev=563682
Log:
2007-08-07  Martin Sebor  <sebor@roguewave.com>

	* once.h: New implementation-private header. Declares __rw_once_t
	and __rw_once() for portable, thread-safe one-time initialization.
	* once.cpp: New. Defines the above.

Added:
    incubator/stdcxx/trunk/src/once.cpp   (with props)
    incubator/stdcxx/trunk/src/once.h   (with props)

Added: incubator/stdcxx/trunk/src/once.cpp
URL: http://svn.apache.org/viewvc/incubator/stdcxx/trunk/src/once.cpp?view=auto&rev=563682
==============================================================================
--- incubator/stdcxx/trunk/src/once.cpp (added)
+++ incubator/stdcxx/trunk/src/once.cpp Tue Aug  7 15:24:10 2007
@@ -0,0 +1,130 @@
+/***************************************************************************
+ *
+ * once.cpp - one time initialization
+ *
+ * $Id$
+ *
+ ***************************************************************************
+ *
+ * Licensed to the Apache Software  Foundation (ASF) under one or more
+ * contributor  license agreements.  See  the NOTICE  file distributed
+ * with  this  work  for  additional information  regarding  copyright
+ * ownership.   The ASF  licenses this  file to  you under  the Apache
+ * License, Version  2.0 (the  License); you may  not use  this file
+ * except in  compliance with the License.   You may obtain  a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the  License is distributed on an  "AS IS" BASIS,
+ * WITHOUT  WARRANTIES OR CONDITIONS  OF ANY  KIND, either  express or
+ * implied.   See  the License  for  the  specific language  governing
+ * permissions and limitations under the License.
+ *
+ * Copyright 2007 Rogue Wave Software.
+ * 
+ **************************************************************************/
+
+#define _RWSTD_LIB_SRC
+#include <rw/_defs.h>
+#include <rw/_mutex.h>
+
+#include "once.h"
+
+
+_RWSTD_NAMESPACE (__rw) {
+
+
+extern "C" {
+
+
+#ifdef _RWSTD_THREAD_ONCE
+
+
+_RWSTD_EXPORT int
+__rw_once (__rw_once_t *once, void (*func)())
+{
+    return _RWSTD_THREAD_ONCE (once, func);
+}
+
+
+#elif defined (_RWSTD_REENTRANT)
+
+
+_RWSTD_EXPORT int
+__rw_once (__rw_once_t *once, void (*func)())
+{
+    _RWSTD_ASSERT (0 != once);
+
+    volatile int &init = once->_C_init;
+
+restart:
+
+    if (init == 0 && 1 == _RWSTD_ATOMIC_PREINCREMENT (init, false)) {
+
+        // entered by the first thread and only the first time around,
+        // unless the initialization function throws
+
+        _TRY {
+            func ();
+        }
+        _CATCH (...) {
+            _RWSTD_ATOMIC_PREDECREMENT (init, false);
+            _RETHROW;
+        }
+
+        init = 1000;
+    }
+    else {
+        // entered by the second and subsequent threads or on the second
+        // and subsequent calls by the first thread after (or duing)
+        // a successful initialization 
+
+        for (int loop = 0; init < 1000; ++loop) {
+            if (0 == init) {
+                // first time initialization failed via an exception,
+                // try again
+                goto restart;
+            }
+
+            if (32 < loop) {
+                // avoid wasting too many CPU cycles
+                _RWSTD_THREAD_YIELD ();
+            }
+        }
+    }
+
+    return 0;
+}
+
+
+#else   // if !defined (_RWSTD_THREAD_ONCE)
+
+
+_RWSTD_EXPORT int
+__rw_once (__rw_once_t *once, void (*func)())
+{
+    _RWSTD_ASSERT (0 != once);
+
+    // detect uninitialized __rw_once_t objects to help reveal problems
+    // in reentrant code on platforms such as HP-UX that require
+    // pthread_once_t objects to be explicitly initialized (i.e., not
+    // all bits tobe zeroed out) in order for pthread_once() to succeed
+    _RWSTD_ASSERT (-1 == once->_C_init || 1 == once->_C_init);
+
+    if (once->_C_init == -1) {
+
+        func ();
+
+        once->_C_init = 1;
+    }
+
+    return 0;
+}
+
+#endif   // _RWSTD_THREAD_ONCE
+
+}   // extern "C"
+
+}   // namespace __rw

Propchange: incubator/stdcxx/trunk/src/once.cpp
------------------------------------------------------------------------------
    svn:eol-style = native

Propchange: incubator/stdcxx/trunk/src/once.cpp
------------------------------------------------------------------------------
    svn:keywords = Id

Added: incubator/stdcxx/trunk/src/once.h
URL: http://svn.apache.org/viewvc/incubator/stdcxx/trunk/src/once.h?view=auto&rev=563682
==============================================================================
--- incubator/stdcxx/trunk/src/once.h (added)
+++ incubator/stdcxx/trunk/src/once.h Tue Aug  7 15:24:10 2007
@@ -0,0 +1,109 @@
+/***************************************************************************
+ *
+ * once.h - one time initialization helpers
+ *
+ * $Id$
+ *
+ ***************************************************************************
+ *
+ * Licensed to the Apache Software  Foundation (ASF) under one or more
+ * contributor  license agreements.  See  the NOTICE  file distributed
+ * with  this  work  for  additional information  regarding  copyright
+ * ownership.   The ASF  licenses this  file to  you under  the Apache
+ * License, Version  2.0 (the  License); you may  not use  this file
+ * except in  compliance with the License.   You may obtain  a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the  License is distributed on an  "AS IS" BASIS,
+ * WITHOUT  WARRANTIES OR CONDITIONS  OF ANY  KIND, either  express or
+ * implied.   See  the License  for  the  specific language  governing
+ * permissions and limitations under the License.
+ *
+ * Copyright 2007 Rogue Wave Software, Inc.
+ * 
+ **************************************************************************/
+
+#include <rw/_defs.h>
+
+
+#ifdef _RWSTD_REENTRANT
+#  ifdef _RWSTD_OS_SUNOS
+
+#    include <pthread.h>
+#    include <thread.h>
+
+#    define _RWSTD_THREAD_ONCE(once, func)   pthread_once (once, func)
+#    define _RWSTD_THREAD_YIELD()            thr_yield ()
+
+typedef pthread_once_t __rw_once_t;
+
+#  elif defined (_RWSTD_POSIX_THREADS)
+
+#    include <pthread.h>
+
+typedef pthread_once_t __rw_once_t;
+
+#    define _RWSTD_THREAD_ONCE(once, func)   pthread_once (once, func)
+
+#    ifndef _RWSTD_NO_SCHED_YIELD
+#      define _RWSTD_THREAD_YIELD()   sched_yield ()
+#    endif   // _RWSTD_NO_SCHED_YIELD
+#  elif defined (_RWSTD_DCE_THREADS)
+
+#    if defined (_RWSTD_NO_DCE_PTHREAD_H)
+#      include <pthread.h>
+#    else
+#      include <dce/pthread.h>
+#    endif
+
+typedef pthread_once_t __rw_once_t;
+
+#    define _RWSTD_THREAD_ONCE(once, func)   pthread_once (once, func)
+#    define _RWSTD_THREAD_YIELD()            pthread_yield ()
+
+#  elif defined (_WIN32)
+
+#    include <windows.h>
+
+struct __rw_once_t { int _C_init; };
+
+#    define _RWSTD_THREAD_YIELD()   Sleep (0)
+#  endif   // _RWSTD_*_THREADS
+
+
+#  ifdef PTHREAD_ONCE_INIT
+#    define _RWSTD_ONCE_INIT   PTHREAD_ONCE_INIT
+#  endif   // PTHREAD_ONCE_INIT
+
+#else   // if !defined (_RWSTD_REENTRANT)
+
+struct __rw_once_t { int _C_init; };
+
+   // defined to a non-zero value to help detect uninitialized
+   // __rw_once_t objects
+#  define _RWSTD_ONCE_INIT   { -1 }
+
+   // not defined
+#  undef  _RWSTD_THREAD_ONCE
+#endif   // _RWSTD_REENTRANT
+
+
+#ifndef _RWSTD_THREAD_YIELD
+#  define _RWSTD_THREAD_YIELD()   (void)0
+#endif   // _RWSTD_THREAD_YIELD
+
+
+_RWSTD_NAMESPACE (__rw) {
+
+extern "C" {
+
+_RWSTD_EXPORT int
+__rw_once (__rw_once_t*, void (*)());
+
+}   // extern "C"
+
+
+}   // namespace __rw

Propchange: incubator/stdcxx/trunk/src/once.h
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    svn:eol-style = native

Propchange: incubator/stdcxx/trunk/src/once.h
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    svn:keywords = Id