1/*
2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25#ifndef SHARE_RUNTIME_THREADCRITICAL_HPP
26#define SHARE_RUNTIME_THREADCRITICAL_HPP
27
28#include "memory/allocation.hpp"
29
30// ThreadCritical is used to protect short non-blocking critical sections.
31// This class must use no vm facilities that require initialization.
32// It is used very early in the vm's initialization, in allocation
33// code and other areas. ThreadCritical regions are reentrant.
34//
35// Due to race conditions during vm exit, some of the os level
36// synchronization primitives may not be deallocated at exit. It
37// is a good plan to implement the platform dependent sections of
38// code with resources that are recoverable during process
39// cleanup by the os. Calling the initialize method before use
40// is also problematic, it is best to use preinitialized primitives
41// if possible. As an example:
42//
43// mutex_t mp = DEFAULTMUTEX;
44//
45// Also note that this class is declared as a StackObj to enforce
46// block structured short locks. It cannot be declared a ResourceObj
47// or CHeapObj, due to initialization issues.
48
49class ThreadCritical : public StackObj {
50 public:
51 ThreadCritical();
52 ~ThreadCritical();
53};
54
55#endif // SHARE_RUNTIME_THREADCRITICAL_HPP
56