|
0
|
1 /*
|
|
|
2 * Copyright 2001 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
|
|
|
20 * CA 95054 USA or visit www.sun.com if you need additional information or
|
|
|
21 * have any questions.
|
|
|
22 *
|
|
|
23 */
|
|
|
24
|
|
|
25 #include <stdio.h>
|
|
|
26 #include <assert.h>
|
|
|
27 #include "Monitor.hpp"
|
|
|
28
|
|
|
29 Monitor::Monitor() {
|
|
|
30 _lock_count = -1; // No threads have entered the critical section
|
|
|
31 _owner = NULL;
|
|
|
32 _lock_event = CreateEvent(NULL, false, false, NULL);
|
|
|
33 _wait_event = CreateEvent(NULL, true, false, NULL);
|
|
|
34 _counter = 0;
|
|
|
35 _tickets = 0;
|
|
|
36 _waiters = 0;
|
|
|
37 }
|
|
|
38
|
|
|
39 Monitor::~Monitor() {
|
|
|
40 assert(_owner == NULL); // Otherwise, owned monitor being deleted
|
|
|
41 assert(_lock_count == -1); // Otherwise, monitor being deleted with non -1 lock count
|
|
|
42 CloseHandle(_lock_event);
|
|
|
43 CloseHandle(_wait_event);
|
|
|
44 }
|
|
|
45
|
|
|
46 void
|
|
|
47 Monitor::lock() {
|
|
|
48 if (InterlockedIncrement(&_lock_count) == 0) {
|
|
|
49 // Success, we now own the lock
|
|
|
50 } else {
|
|
|
51 DWORD dwRet = WaitForSingleObject((HANDLE)_lock_event, INFINITE);
|
|
|
52 assert(dwRet == WAIT_OBJECT_0); // Unexpected return value from WaitForSingleObject
|
|
|
53 }
|
|
|
54 assert(owner() == NULL); // Otherwise, lock count and owner are inconsistent
|
|
|
55 setOwner(GetCurrentThread());
|
|
|
56 }
|
|
|
57
|
|
|
58 void
|
|
|
59 Monitor::unlock() {
|
|
|
60 setOwner(NULL);
|
|
|
61 if (InterlockedDecrement(&_lock_count) >= 0) {
|
|
|
62 // Wake a waiting thread up
|
|
|
63 DWORD dwRet = SetEvent(_lock_event);
|
|
|
64 assert(dwRet != 0); // Unexpected return value from SetEvent
|
|
|
65 }
|
|
|
66 }
|
|
|
67
|
|
|
68 bool
|
|
|
69 Monitor::wait(long timeout) {
|
|
|
70 assert(owner() != NULL);
|
|
|
71 assert(owner() == GetCurrentThread());
|
|
|
72
|
|
|
73 // 0 means forever. Convert to Windows specific code.
|
|
|
74 DWORD timeout_value = (timeout == 0) ? INFINITE : timeout;
|
|
|
75 DWORD which;
|
|
|
76
|
|
|
77 long c = _counter;
|
|
|
78 bool retry = false;
|
|
|
79
|
|
|
80 _waiters++;
|
|
|
81 // Loop until condition variable is signaled. The event object is
|
|
|
82 // set whenever the condition variable is signaled, and tickets will
|
|
|
83 // reflect the number of threads which have been notified. The counter
|
|
|
84 // field is used to make sure we don't respond to notifications that
|
|
|
85 // have occurred *before* we started waiting, and is incremented each
|
|
|
86 // time the condition variable is signaled.
|
|
|
87
|
|
|
88 while (true) {
|
|
|
89
|
|
|
90 // Leave critical region
|
|
|
91 unlock();
|
|
|
92
|
|
|
93 // If this is a retry, let other low-priority threads have a chance
|
|
|
94 // to run. Make sure that we sleep outside of the critical section.
|
|
|
95 if (retry) {
|
|
|
96 Sleep(1);
|
|
|
97 } else {
|
|
|
98 retry = true;
|
|
|
99 }
|
|
|
100
|
|
|
101 which = WaitForSingleObject(_wait_event, timeout_value);
|
|
|
102 // Enter critical section
|
|
|
103 lock();
|
|
|
104
|
|
|
105 if (_tickets != 0 && _counter != c) break;
|
|
|
106
|
|
|
107 if (which == WAIT_TIMEOUT) {
|
|
|
108 --_waiters;
|
|
|
109 return true;
|
|
|
110 }
|
|
|
111 }
|
|
|
112 _waiters--;
|
|
|
113
|
|
|
114 // If this was the last thread to be notified, then we need to reset
|
|
|
115 // the event object.
|
|
|
116 if (--_tickets == 0) {
|
|
|
117 ResetEvent(_wait_event);
|
|
|
118 }
|
|
|
119
|
|
|
120 return false;
|
|
|
121 }
|
|
|
122
|
|
|
123 // Notify a single thread waiting on this monitor
|
|
|
124 bool
|
|
|
125 Monitor::notify() {
|
|
|
126 assert(ownedBySelf()); // Otherwise, notify on unknown thread
|
|
|
127
|
|
|
128 if (_waiters > _tickets) {
|
|
|
129 if (!SetEvent(_wait_event)) {
|
|
|
130 return false;
|
|
|
131 }
|
|
|
132 _tickets++;
|
|
|
133 _counter++;
|
|
|
134 }
|
|
|
135
|
|
|
136 return true;
|
|
|
137 }
|
|
|
138
|
|
|
139 // Notify all threads waiting on this monitor
|
|
|
140 bool
|
|
|
141 Monitor::notifyAll() {
|
|
|
142 assert(ownedBySelf()); // Otherwise, notifyAll on unknown thread
|
|
|
143
|
|
|
144 if (_waiters > 0) {
|
|
|
145 if (!SetEvent(_wait_event)) {
|
|
|
146 return false;
|
|
|
147 }
|
|
|
148 _tickets = _waiters;
|
|
|
149 _counter++;
|
|
|
150 }
|
|
|
151
|
|
|
152 return true;
|
|
|
153 }
|
|
|
154
|
|
|
155 HANDLE
|
|
|
156 Monitor::owner() {
|
|
|
157 return _owner;
|
|
|
158 }
|
|
|
159
|
|
|
160 void
|
|
|
161 Monitor::setOwner(HANDLE owner) {
|
|
|
162 if (owner != NULL) {
|
|
|
163 assert(_owner == NULL); // Setting owner thread of already owned monitor
|
|
|
164 assert(owner == GetCurrentThread()); // Else should not be doing this
|
|
|
165 } else {
|
|
|
166 HANDLE oldOwner = _owner;
|
|
|
167 assert(oldOwner != NULL); // Removing the owner thread of an unowned mutex
|
|
|
168 assert(oldOwner == GetCurrentThread());
|
|
|
169 }
|
|
|
170 _owner = owner;
|
|
|
171 }
|
|
|
172
|
|
|
173 bool
|
|
|
174 Monitor::ownedBySelf() {
|
|
|
175 return (_owner == GetCurrentThread());
|
|
|
176 }
|
