Mercurial > hg > truffle
annotate src/os/windows/vm/threadCritical_windows.cpp @ 18131:85cec9cab17b
Truffle: format fix.
author | Christian Humer <christian.humer@gmail.com> |
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date | Tue, 21 Oct 2014 00:30:06 +0200 |
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0 | 1 /* |
1972 | 2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
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26 #include "runtime/thread.inline.hpp" |
1972 | 27 #include "runtime/threadCritical.hpp" |
0 | 28 |
29 // OS-includes here | |
30 # include <windows.h> | |
31 # include <winbase.h> | |
32 | |
33 // | |
34 // See threadCritical.hpp for details of this class. | |
35 // | |
36 | |
37 static bool initialized = false; | |
38 static volatile jint lock_count = -1; | |
39 static HANDLE lock_event; | |
40 static DWORD lock_owner = -1; | |
41 | |
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 // | |
52 | |
53 void ThreadCritical::initialize() { | |
54 } | |
55 | |
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 } | |
62 | |
63 ThreadCritical::ThreadCritical() { | |
64 DWORD current_thread = GetCurrentThreadId(); | |
65 | |
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 } | |
74 | |
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 } | |
81 | |
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 } | |
88 | |
89 assert(lock_owner == GetCurrentThreadId(), "Lock acquired illegally."); | |
90 } | |
91 | |
92 ThreadCritical::~ThreadCritical() { | |
93 assert(lock_owner == GetCurrentThreadId(), "unlock attempt by wrong thread"); | |
94 assert(lock_count >= 0, "Attempt to unlock when already unlocked"); | |
95 | |
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 } |