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/*
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* Copyright 2001-2003 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*
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*/
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# include "incls/_precompiled.incl"
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# include "incls/_threadCritical_windows.cpp.incl"
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// OS-includes here
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# include <windows.h>
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# include <winbase.h>
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//
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// See threadCritical.hpp for details of this class.
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//
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static bool initialized = false;
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static volatile jint lock_count = -1;
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static HANDLE lock_event;
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static DWORD lock_owner = -1;
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//
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// Note that Microsoft's critical region code contains a race
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// condition, and is not suitable for use. A thread holding the
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// critical section cannot safely suspend a thread attempting
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// to enter the critical region. The failure mode is that both
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// threads are permanently suspended.
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//
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// I experiemented with the use of ordinary windows mutex objects
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// and found them ~30 times slower than the critical region code.
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//
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void ThreadCritical::initialize() {
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}
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void ThreadCritical::release() {
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assert(lock_owner == -1, "Mutex being deleted while owned.");
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assert(lock_count == -1, "Mutex being deleted while recursively locked");
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assert(lock_event != NULL, "Sanity check");
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CloseHandle(lock_event);
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}
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ThreadCritical::ThreadCritical() {
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DWORD current_thread = GetCurrentThreadId();
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if (lock_owner != current_thread) {
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// Grab the lock before doing anything.
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while (Atomic::cmpxchg(0, &lock_count, -1) != -1) {
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if (initialized) {
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DWORD ret = WaitForSingleObject(lock_event, INFINITE);
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assert(ret == WAIT_OBJECT_0, "unexpected return value from WaitForSingleObject");
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}
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}
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// Make sure the event object is allocated.
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if (!initialized) {
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// Locking will not work correctly unless this is autoreset.
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lock_event = CreateEvent(NULL, false, false, NULL);
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initialized = true;
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}
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assert(lock_owner == -1, "Lock acquired illegally.");
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lock_owner = current_thread;
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} else {
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// Atomicity isn't required. Bump the recursion count.
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lock_count++;
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}
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assert(lock_owner == GetCurrentThreadId(), "Lock acquired illegally.");
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}
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ThreadCritical::~ThreadCritical() {
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assert(lock_owner == GetCurrentThreadId(), "unlock attempt by wrong thread");
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assert(lock_count >= 0, "Attempt to unlock when already unlocked");
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if (lock_count == 0) {
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// We're going to unlock
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lock_owner = -1;
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lock_count = -1;
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// No lost wakeups, lock_event stays signaled until reset.
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DWORD ret = SetEvent(lock_event);
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assert(ret != 0, "unexpected return value from SetEvent");
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} else {
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// Just unwinding a recursive lock;
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lock_count--;
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}
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}
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