threadCritical.hpp revision 1472:c18cbe5936b8
1/* 2 * Copyright (c) 2001, 2002, 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// 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