duke@435: /*
duke@435:  * Copyright 2001-2002 Sun Microsystems, Inc.  All Rights Reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
duke@435:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435:  * CA 95054 USA or visit www.sun.com if you need additional information or
duke@435:  * have any questions.
duke@435:  *
duke@435:  */
duke@435: 
duke@435: // ThreadCritical is used to protect short non-blocking critical sections.
duke@435: // This class must use no vm facilities that require initialization.
duke@435: // It is used very early in the vm's initialization, in allocation
duke@435: // code and other areas. ThreadCritical regions are reentrant.
duke@435: //
duke@435: // Due to race conditions during vm exit, some of the os level
duke@435: // synchronization primitives may not be deallocated at exit. It
twisti@1040: // is a good plan to implement the platform dependent sections of
duke@435: // code with resources that are recoverable during process
duke@435: // cleanup by the os. Calling the initialize method before use
duke@435: // is also problematic, it is best to use preinitialized primitives
duke@435: // if possible. As an example:
duke@435: //
duke@435: // mutex_t  mp  =  DEFAULTMUTEX;
duke@435: //
duke@435: // Also note that this class is declared as a StackObj to enforce
duke@435: // block structured short locks. It cannot be declared a ResourceObj
duke@435: // or CHeapObj, due to initialization issues.
duke@435: 
duke@435: class ThreadCritical : public StackObj {
duke@435:  friend class os;
duke@435:  private:
duke@435:   static void initialize();
duke@435:   static void release();
duke@435: 
duke@435:  public:
duke@435:   ThreadCritical();
duke@435:   ~ThreadCritical();
duke@435: };