Fri, 30 Nov 2012 15:23:16 -0800
8003240: x86: move MacroAssembler into separate file
Reviewed-by: kvn
1 /*
2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #include "precompiled.hpp"
26 #include "runtime/threadCritical.hpp"
27 #include "thread_windows.inline.hpp"
29 // OS-includes here
30 # include <windows.h>
31 # include <winbase.h>
33 //
34 // See threadCritical.hpp for details of this class.
35 //
37 static bool initialized = false;
38 static volatile jint lock_count = -1;
39 static HANDLE lock_event;
40 static DWORD lock_owner = -1;
42 //
43 // Note that Microsoft's critical region code contains a race
44 // condition, and is not suitable for use. A thread holding the
45 // critical section cannot safely suspend a thread attempting
46 // to enter the critical region. The failure mode is that both
47 // threads are permanently suspended.
48 //
49 // I experiemented with the use of ordinary windows mutex objects
50 // and found them ~30 times slower than the critical region code.
51 //
53 void ThreadCritical::initialize() {
54 }
56 void ThreadCritical::release() {
57 assert(lock_owner == -1, "Mutex being deleted while owned.");
58 assert(lock_count == -1, "Mutex being deleted while recursively locked");
59 assert(lock_event != NULL, "Sanity check");
60 CloseHandle(lock_event);
61 }
63 ThreadCritical::ThreadCritical() {
64 DWORD current_thread = GetCurrentThreadId();
66 if (lock_owner != current_thread) {
67 // Grab the lock before doing anything.
68 while (Atomic::cmpxchg(0, &lock_count, -1) != -1) {
69 if (initialized) {
70 DWORD ret = WaitForSingleObject(lock_event, INFINITE);
71 assert(ret == WAIT_OBJECT_0, "unexpected return value from WaitForSingleObject");
72 }
73 }
75 // Make sure the event object is allocated.
76 if (!initialized) {
77 // Locking will not work correctly unless this is autoreset.
78 lock_event = CreateEvent(NULL, false, false, NULL);
79 initialized = true;
80 }
82 assert(lock_owner == -1, "Lock acquired illegally.");
83 lock_owner = current_thread;
84 } else {
85 // Atomicity isn't required. Bump the recursion count.
86 lock_count++;
87 }
89 assert(lock_owner == GetCurrentThreadId(), "Lock acquired illegally.");
90 }
92 ThreadCritical::~ThreadCritical() {
93 assert(lock_owner == GetCurrentThreadId(), "unlock attempt by wrong thread");
94 assert(lock_count >= 0, "Attempt to unlock when already unlocked");
96 if (lock_count == 0) {
97 // We're going to unlock
98 lock_owner = -1;
99 lock_count = -1;
100 // No lost wakeups, lock_event stays signaled until reset.
101 DWORD ret = SetEvent(lock_event);
102 assert(ret != 0, "unexpected return value from SetEvent");
103 } else {
104 // Just unwinding a recursive lock;
105 lock_count--;
106 }
107 }