threadCritical.hpp revision 605:98cb887364d3 
1/*
2 * Copyright 2001-2002 Sun Microsystems, Inc.  All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
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23 */
24
25// ThreadCritical is used to protect short non-blocking critical sections.
26// This class must use no vm facilities that require initialization.
27// It is used very early in the vm's initialization, in allocation
28// code and other areas. ThreadCritical regions are reentrant.
29//
30// Due to race conditions during vm exit, some of the os level
31// synchronization primitives may not be deallocated at exit. It
32// is a good plan to implement the platform dependent sections of
33// code with resources that are recoverable during process
34// cleanup by the os. Calling the initialize method before use
35// is also problematic, it is best to use preinitialized primitives
36// if possible. As an example:
37//
38// mutex_t  mp  =  DEFAULTMUTEX;
39//
40// Also note that this class is declared as a StackObj to enforce
41// block structured short locks. It cannot be declared a ResourceObj
42// or CHeapObj, due to initialization issues.
43
44class ThreadCritical : public StackObj {
45 friend class os;
46 private:
47  static void initialize();
48  static void release();
49
50 public:
51  ThreadCritical();
52  ~ThreadCritical();
53};
54