1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/os/windows/vm/threadCritical_windows.cpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,106 @@
1.4 +/*
1.5 + * Copyright 2001-2003 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +# include "incls/_precompiled.incl"
1.29 +# include "incls/_threadCritical_windows.cpp.incl"
1.30 +
1.31 +// OS-includes here
1.32 +# include <windows.h>
1.33 +# include <winbase.h>
1.34 +
1.35 +//
1.36 +// See threadCritical.hpp for details of this class.
1.37 +//
1.38 +
1.39 +static bool initialized = false;
1.40 +static volatile jint lock_count = -1;
1.41 +static HANDLE lock_event;
1.42 +static DWORD lock_owner = -1;
1.43 +
1.44 +//
1.45 +// Note that Microsoft's critical region code contains a race
1.46 +// condition, and is not suitable for use. A thread holding the
1.47 +// critical section cannot safely suspend a thread attempting
1.48 +// to enter the critical region. The failure mode is that both
1.49 +// threads are permanently suspended.
1.50 +//
1.51 +// I experiemented with the use of ordinary windows mutex objects
1.52 +// and found them ~30 times slower than the critical region code.
1.53 +//
1.54 +
1.55 +void ThreadCritical::initialize() {
1.56 +}
1.57 +
1.58 +void ThreadCritical::release() {
1.59 + assert(lock_owner == -1, "Mutex being deleted while owned.");
1.60 + assert(lock_count == -1, "Mutex being deleted while recursively locked");
1.61 + assert(lock_event != NULL, "Sanity check");
1.62 + CloseHandle(lock_event);
1.63 +}
1.64 +
1.65 +ThreadCritical::ThreadCritical() {
1.66 + DWORD current_thread = GetCurrentThreadId();
1.67 +
1.68 + if (lock_owner != current_thread) {
1.69 + // Grab the lock before doing anything.
1.70 + while (Atomic::cmpxchg(0, &lock_count, -1) != -1) {
1.71 + if (initialized) {
1.72 + DWORD ret = WaitForSingleObject(lock_event, INFINITE);
1.73 + assert(ret == WAIT_OBJECT_0, "unexpected return value from WaitForSingleObject");
1.74 + }
1.75 + }
1.76 +
1.77 + // Make sure the event object is allocated.
1.78 + if (!initialized) {
1.79 + // Locking will not work correctly unless this is autoreset.
1.80 + lock_event = CreateEvent(NULL, false, false, NULL);
1.81 + initialized = true;
1.82 + }
1.83 +
1.84 + assert(lock_owner == -1, "Lock acquired illegally.");
1.85 + lock_owner = current_thread;
1.86 + } else {
1.87 + // Atomicity isn't required. Bump the recursion count.
1.88 + lock_count++;
1.89 + }
1.90 +
1.91 + assert(lock_owner == GetCurrentThreadId(), "Lock acquired illegally.");
1.92 +}
1.93 +
1.94 +ThreadCritical::~ThreadCritical() {
1.95 + assert(lock_owner == GetCurrentThreadId(), "unlock attempt by wrong thread");
1.96 + assert(lock_count >= 0, "Attempt to unlock when already unlocked");
1.97 +
1.98 + if (lock_count == 0) {
1.99 + // We're going to unlock
1.100 + lock_owner = -1;
1.101 + lock_count = -1;
1.102 + // No lost wakeups, lock_event stays signaled until reset.
1.103 + DWORD ret = SetEvent(lock_event);
1.104 + assert(ret != 0, "unexpected return value from SetEvent");
1.105 + } else {
1.106 + // Just unwinding a recursive lock;
1.107 + lock_count--;
1.108 + }
1.109 +}
