aoqi@0: /*
aoqi@0:  * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #ifndef SHARE_VM_RUNTIME_THREADCRITICAL_HPP
aoqi@0: #define SHARE_VM_RUNTIME_THREADCRITICAL_HPP
aoqi@0: 
aoqi@0: #include "memory/allocation.hpp"
aoqi@0: 
aoqi@0: // ThreadCritical is used to protect short non-blocking critical sections.
aoqi@0: // This class must use no vm facilities that require initialization.
aoqi@0: // It is used very early in the vm's initialization, in allocation
aoqi@0: // code and other areas. ThreadCritical regions are reentrant.
aoqi@0: //
aoqi@0: // Due to race conditions during vm exit, some of the os level
aoqi@0: // synchronization primitives may not be deallocated at exit. It
aoqi@0: // is a good plan to implement the platform dependent sections of
aoqi@0: // code with resources that are recoverable during process
aoqi@0: // cleanup by the os. Calling the initialize method before use
aoqi@0: // is also problematic, it is best to use preinitialized primitives
aoqi@0: // if possible. As an example:
aoqi@0: //
aoqi@0: // mutex_t  mp  =  DEFAULTMUTEX;
aoqi@0: //
aoqi@0: // Also note that this class is declared as a StackObj to enforce
aoqi@0: // block structured short locks. It cannot be declared a ResourceObj
aoqi@0: // or CHeapObj, due to initialization issues.
aoqi@0: 
aoqi@0: class ThreadCritical : public StackObj {
aoqi@0:  friend class os;
aoqi@0:  private:
aoqi@0:   static void initialize();
aoqi@0:   static void release();
aoqi@0: 
aoqi@0:  public:
aoqi@0:   ThreadCritical();
aoqi@0:   ~ThreadCritical();
aoqi@0: };
aoqi@0: 
aoqi@0: #endif // SHARE_VM_RUNTIME_THREADCRITICAL_HPP