1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000 1.2 +++ b/src/os/windows/vm/threadCritical_windows.cpp Wed Apr 27 01:25:04 2016 +0800 1.3 @@ -0,0 +1,107 @@ 1.4 +/* 1.5 + * Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 1.23 + * or visit www.oracle.com if you need additional information or have any 1.24 + * questions. 1.25 + * 1.26 + */ 1.27 + 1.28 +#include "precompiled.hpp" 1.29 +#include "runtime/thread.inline.hpp" 1.30 +#include "runtime/threadCritical.hpp" 1.31 + 1.32 +// OS-includes here 1.33 +# include <windows.h> 1.34 +# include <winbase.h> 1.35 + 1.36 +// 1.37 +// See threadCritical.hpp for details of this class. 1.38 +// 1.39 + 1.40 +static bool initialized = false; 1.41 +static volatile jint lock_count = -1; 1.42 +static HANDLE lock_event; 1.43 +static DWORD lock_owner = -1; 1.44 + 1.45 +// 1.46 +// Note that Microsoft's critical region code contains a race 1.47 +// condition, and is not suitable for use. A thread holding the 1.48 +// critical section cannot safely suspend a thread attempting 1.49 +// to enter the critical region. The failure mode is that both 1.50 +// threads are permanently suspended. 1.51 +// 1.52 +// I experiemented with the use of ordinary windows mutex objects 1.53 +// and found them ~30 times slower than the critical region code. 1.54 +// 1.55 + 1.56 +void ThreadCritical::initialize() { 1.57 +} 1.58 + 1.59 +void ThreadCritical::release() { 1.60 + assert(lock_owner == -1, "Mutex being deleted while owned."); 1.61 + assert(lock_count == -1, "Mutex being deleted while recursively locked"); 1.62 + assert(lock_event != NULL, "Sanity check"); 1.63 + CloseHandle(lock_event); 1.64 +} 1.65 + 1.66 +ThreadCritical::ThreadCritical() { 1.67 + DWORD current_thread = GetCurrentThreadId(); 1.68 + 1.69 + if (lock_owner != current_thread) { 1.70 + // Grab the lock before doing anything. 1.71 + while (Atomic::cmpxchg(0, &lock_count, -1) != -1) { 1.72 + if (initialized) { 1.73 + DWORD ret = WaitForSingleObject(lock_event, INFINITE); 1.74 + assert(ret == WAIT_OBJECT_0, "unexpected return value from WaitForSingleObject"); 1.75 + } 1.76 + } 1.77 + 1.78 + // Make sure the event object is allocated. 1.79 + if (!initialized) { 1.80 + // Locking will not work correctly unless this is autoreset. 1.81 + lock_event = CreateEvent(NULL, false, false, NULL); 1.82 + initialized = true; 1.83 + } 1.84 + 1.85 + assert(lock_owner == -1, "Lock acquired illegally."); 1.86 + lock_owner = current_thread; 1.87 + } else { 1.88 + // Atomicity isn't required. Bump the recursion count. 1.89 + lock_count++; 1.90 + } 1.91 + 1.92 + assert(lock_owner == GetCurrentThreadId(), "Lock acquired illegally."); 1.93 +} 1.94 + 1.95 +ThreadCritical::~ThreadCritical() { 1.96 + assert(lock_owner == GetCurrentThreadId(), "unlock attempt by wrong thread"); 1.97 + assert(lock_count >= 0, "Attempt to unlock when already unlocked"); 1.98 + 1.99 + if (lock_count == 0) { 1.100 + // We're going to unlock 1.101 + lock_owner = -1; 1.102 + lock_count = -1; 1.103 + // No lost wakeups, lock_event stays signaled until reset. 1.104 + DWORD ret = SetEvent(lock_event); 1.105 + assert(ret != 0, "unexpected return value from SetEvent"); 1.106 + } else { 1.107 + // Just unwinding a recursive lock; 1.108 + lock_count--; 1.109 + } 1.110 +}