Mercurial > jdk8-mips64-public > hotspot / annotate
src/os/windows/vm/threadCritical_windows.cpp@f90c822e73f8 (annotated)
src/os/windows/vm/threadCritical_windows.cpp
Wed, 27 Apr 2016 01:25:04 +0800
- author
- aoqi
- date
- Wed, 27 Apr 2016 01:25:04 +0800
- changeset 0
- f90c822e73f8
- child 6876
- 710a3c8b516e
- permissions
- -rw-r--r--
Initial load
http://hg.openjdk.java.net/jdk8u/jdk8u/hotspot/
changeset: 6782:28b50d07f6f8
tag: jdk8u25-b17
| aoqi@0 | 1 | /* |
| aoqi@0 | 2 | * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved. |
| aoqi@0 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| aoqi@0 | 4 | * |
| aoqi@0 | 5 | * This code is free software; you can redistribute it and/or modify it |
| aoqi@0 | 6 | * under the terms of the GNU General Public License version 2 only, as |
| aoqi@0 | 7 | * published by the Free Software Foundation. |
| aoqi@0 | 8 | * |
| aoqi@0 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| aoqi@0 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| aoqi@0 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| aoqi@0 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
| aoqi@0 | 13 | * accompanied this code). |
| aoqi@0 | 14 | * |
| aoqi@0 | 15 | * You should have received a copy of the GNU General Public License version |
| aoqi@0 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
| aoqi@0 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| aoqi@0 | 18 | * |
| aoqi@0 | 19 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| aoqi@0 | 20 | * or visit www.oracle.com if you need additional information or have any |
| aoqi@0 | 21 | * questions. |
| aoqi@0 | 22 | * |
| aoqi@0 | 23 | */ |
| aoqi@0 | 24 | |
| aoqi@0 | 25 | #include "precompiled.hpp" |
| aoqi@0 | 26 | #include "runtime/thread.inline.hpp" |
| aoqi@0 | 27 | #include "runtime/threadCritical.hpp" |
| aoqi@0 | 28 | |
| aoqi@0 | 29 | // OS-includes here |
| aoqi@0 | 30 | # include <windows.h> |
| aoqi@0 | 31 | # include <winbase.h> |
| aoqi@0 | 32 | |
| aoqi@0 | 33 | // |
| aoqi@0 | 34 | // See threadCritical.hpp for details of this class. |
| aoqi@0 | 35 | // |
| aoqi@0 | 36 | |
| aoqi@0 | 37 | static bool initialized = false; |
| aoqi@0 | 38 | static volatile jint lock_count = -1; |
| aoqi@0 | 39 | static HANDLE lock_event; |
| aoqi@0 | 40 | static DWORD lock_owner = -1; |
| aoqi@0 | 41 | |
| aoqi@0 | 42 | // |
| aoqi@0 | 43 | // Note that Microsoft's critical region code contains a race |
| aoqi@0 | 44 | // condition, and is not suitable for use. A thread holding the |
| aoqi@0 | 45 | // critical section cannot safely suspend a thread attempting |
| aoqi@0 | 46 | // to enter the critical region. The failure mode is that both |
| aoqi@0 | 47 | // threads are permanently suspended. |
| aoqi@0 | 48 | // |
| aoqi@0 | 49 | // I experiemented with the use of ordinary windows mutex objects |
| aoqi@0 | 50 | // and found them ~30 times slower than the critical region code. |
| aoqi@0 | 51 | // |
| aoqi@0 | 52 | |
| aoqi@0 | 53 | void ThreadCritical::initialize() { |
| aoqi@0 | 54 | } |
| aoqi@0 | 55 | |
| aoqi@0 | 56 | void ThreadCritical::release() { |
| aoqi@0 | 57 | assert(lock_owner == -1, "Mutex being deleted while owned."); |
| aoqi@0 | 58 | assert(lock_count == -1, "Mutex being deleted while recursively locked"); |
| aoqi@0 | 59 | assert(lock_event != NULL, "Sanity check"); |
| aoqi@0 | 60 | CloseHandle(lock_event); |
| aoqi@0 | 61 | } |
| aoqi@0 | 62 | |
| aoqi@0 | 63 | ThreadCritical::ThreadCritical() { |
| aoqi@0 | 64 | DWORD current_thread = GetCurrentThreadId(); |
| aoqi@0 | 65 | |
| aoqi@0 | 66 | if (lock_owner != current_thread) { |
| aoqi@0 | 67 | // Grab the lock before doing anything. |
| aoqi@0 | 68 | while (Atomic::cmpxchg(0, &lock_count, -1) != -1) { |
| aoqi@0 | 69 | if (initialized) { |
| aoqi@0 | 70 | DWORD ret = WaitForSingleObject(lock_event, INFINITE); |
| aoqi@0 | 71 | assert(ret == WAIT_OBJECT_0, "unexpected return value from WaitForSingleObject"); |
| aoqi@0 | 72 | } |
| aoqi@0 | 73 | } |
| aoqi@0 | 74 | |
| aoqi@0 | 75 | // Make sure the event object is allocated. |
| aoqi@0 | 76 | if (!initialized) { |
| aoqi@0 | 77 | // Locking will not work correctly unless this is autoreset. |
| aoqi@0 | 78 | lock_event = CreateEvent(NULL, false, false, NULL); |
| aoqi@0 | 79 | initialized = true; |
| aoqi@0 | 80 | } |
| aoqi@0 | 81 | |
| aoqi@0 | 82 | assert(lock_owner == -1, "Lock acquired illegally."); |
| aoqi@0 | 83 | lock_owner = current_thread; |
| aoqi@0 | 84 | } else { |
| aoqi@0 | 85 | // Atomicity isn't required. Bump the recursion count. |
| aoqi@0 | 86 | lock_count++; |
| aoqi@0 | 87 | } |
| aoqi@0 | 88 | |
| aoqi@0 | 89 | assert(lock_owner == GetCurrentThreadId(), "Lock acquired illegally."); |
| aoqi@0 | 90 | } |
| aoqi@0 | 91 | |
| aoqi@0 | 92 | ThreadCritical::~ThreadCritical() { |
| aoqi@0 | 93 | assert(lock_owner == GetCurrentThreadId(), "unlock attempt by wrong thread"); |
| aoqi@0 | 94 | assert(lock_count >= 0, "Attempt to unlock when already unlocked"); |
| aoqi@0 | 95 | |
| aoqi@0 | 96 | if (lock_count == 0) { |
| aoqi@0 | 97 | // We're going to unlock |
| aoqi@0 | 98 | lock_owner = -1; |
| aoqi@0 | 99 | lock_count = -1; |
| aoqi@0 | 100 | // No lost wakeups, lock_event stays signaled until reset. |
| aoqi@0 | 101 | DWORD ret = SetEvent(lock_event); |
| aoqi@0 | 102 | assert(ret != 0, "unexpected return value from SetEvent"); |
| aoqi@0 | 103 | } else { |
| aoqi@0 | 104 | // Just unwinding a recursive lock; |
| aoqi@0 | 105 | lock_count--; |
| aoqi@0 | 106 | } |
| aoqi@0 | 107 | } |
