| /* |
| * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "runtime/atomic.hpp" |
| #include "runtime/thread.inline.hpp" |
| #include "runtime/threadCritical.hpp" |
| |
| // OS-includes here |
| # include <windows.h> |
| # include <winbase.h> |
| |
| // |
| // See threadCritical.hpp for details of this class. |
| // |
| |
| static bool initialized = false; |
| static volatile jint lock_count = -1; |
| static HANDLE lock_event; |
| static DWORD lock_owner = -1; |
| |
| // |
| // Note that Microsoft's critical region code contains a race |
| // condition, and is not suitable for use. A thread holding the |
| // critical section cannot safely suspend a thread attempting |
| // to enter the critical region. The failure mode is that both |
| // threads are permanently suspended. |
| // |
| // I experiemented with the use of ordinary windows mutex objects |
| // and found them ~30 times slower than the critical region code. |
| // |
| |
| void ThreadCritical::initialize() { |
| } |
| |
| void ThreadCritical::release() { |
| assert(lock_owner == -1, "Mutex being deleted while owned."); |
| assert(lock_count == -1, "Mutex being deleted while recursively locked"); |
| assert(lock_event != NULL, "Sanity check"); |
| CloseHandle(lock_event); |
| } |
| |
| ThreadCritical::ThreadCritical() { |
| DWORD current_thread = GetCurrentThreadId(); |
| |
| if (lock_owner != current_thread) { |
| // Grab the lock before doing anything. |
| while (Atomic::cmpxchg(0, &lock_count, -1) != -1) { |
| if (initialized) { |
| DWORD ret = WaitForSingleObject(lock_event, INFINITE); |
| assert(ret == WAIT_OBJECT_0, "unexpected return value from WaitForSingleObject"); |
| } |
| } |
| |
| // Make sure the event object is allocated. |
| if (!initialized) { |
| // Locking will not work correctly unless this is autoreset. |
| lock_event = CreateEvent(NULL, false, false, NULL); |
| initialized = true; |
| } |
| |
| assert(lock_owner == -1, "Lock acquired illegally."); |
| lock_owner = current_thread; |
| } else { |
| // Atomicity isn't required. Bump the recursion count. |
| lock_count++; |
| } |
| |
| assert(lock_owner == GetCurrentThreadId(), "Lock acquired illegally."); |
| } |
| |
| ThreadCritical::~ThreadCritical() { |
| assert(lock_owner == GetCurrentThreadId(), "unlock attempt by wrong thread"); |
| assert(lock_count >= 0, "Attempt to unlock when already unlocked"); |
| |
| if (lock_count == 0) { |
| // We're going to unlock |
| lock_owner = -1; |
| lock_count = -1; |
| // No lost wakeups, lock_event stays signaled until reset. |
| DWORD ret = SetEvent(lock_event); |
| assert(ret != 0, "unexpected return value from SetEvent"); |
| } else { |
| // Just unwinding a recursive lock; |
| lock_count--; |
| } |
| } |