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comparison src/fschmidt/util/locks/TimedReadWriteLocker.java @ 68:00520880ad02

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add fschmidt source
author Franklin Schmidt <fschmidt@gmail.com>
date Sun, 05 Oct 2025 17:24:15 -0600
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67:9d0fefce6985 68:00520880ad02
1 /*
2 Copyright (c) 2008 Franklin Schmidt <fschmidt@gmail.com>
3
4 Permission is hereby granted, free of charge, to any person obtaining a copy
5 of this software and associated documentation files (the "Software"), to deal
6 in the Software without restriction, including without limitation the rights
7 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8 copies of the Software, and to permit persons to whom the Software is
9 furnished to do so, subject to the following conditions:
10
11 The above copyright notice and this permission notice shall be included in
12 all copies or substantial portions of the Software.
13
14 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
17 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
20 THE SOFTWARE.
21 */
22
23 package fschmidt.util.locks;
24
25 import java.util.Map;
26 import java.util.HashMap;
27 import java.util.concurrent.TimeUnit;
28 import java.util.concurrent.locks.Lock;
29 import java.util.concurrent.locks.ReadWriteLock;
30 import java.util.concurrent.locks.ReentrantReadWriteLock;
31
32
33 public final class TimedReadWriteLocker<T> implements ReadWriteLocker<T> {
34
35 private static class Tracker {
36 final ReentrantReadWriteLock lock0 = new ReentrantReadWriteLock();
37 final ReadWriteLock lock = new TimedReadWriteLock(lock0);
38 int waiters = 0;
39 }
40
41 private final Map<T,Tracker> map = new HashMap<T,Tracker>();
42
43 private Tracker getTracker(T obj) {
44 Tracker t = map.get(obj);
45 if( t==null ) {
46 t = new Tracker();
47 map.put(obj,t);
48 }
49 return t;
50 }
51
52 private Tracker getTrackerForWait(T obj) {
53 synchronized(map) {
54 Tracker t = getTracker(obj);
55 t.waiters++;
56 return t;
57 }
58 }
59
60 private void afterWait(Tracker t) {
61 synchronized(map) {
62 t.waiters--;
63 }
64 }
65
66 private void maybeRemove(T obj,Tracker t) {
67 if( t.waiters==0 && !t.lock0.isWriteLocked() && t.lock0.getReadLockCount()==0 ) {
68 map.remove(obj);
69 }
70 }
71
72 private final Locker<T> writeLocker = new Locker<T>() {
73
74 public void lock(T obj) {
75 Tracker t = getTrackerForWait(obj);
76 try {
77 t.lock.writeLock().lock();
78 } finally {
79 afterWait(t);
80 }
81 }
82
83 public boolean tryLock(T obj) {
84 synchronized(map) {
85 return getTracker(obj).lock.writeLock().tryLock();
86 }
87 }
88
89 public boolean tryLock(T obj,long time,TimeUnit unit)
90 throws InterruptedException
91 {
92 Tracker t = getTrackerForWait(obj);
93 try {
94 return t.lock.writeLock().tryLock(time,unit);
95 } finally {
96 afterWait(t);
97 }
98 }
99
100 public void unlock(T obj) {
101 synchronized(map) {
102 Tracker t = map.get(obj);
103 t.lock.writeLock().unlock();
104 maybeRemove(obj,t);
105 }
106 }
107 };
108
109 private final Locker<T> readLocker = new Locker<T>() {
110
111 public void lock(T obj) {
112 Tracker t = getTrackerForWait(obj);
113 try {
114 t.lock.readLock().lock();
115 } finally {
116 afterWait(t);
117 }
118 }
119
120 public boolean tryLock(T obj) {
121 synchronized(map) {
122 return getTracker(obj).lock.readLock().tryLock();
123 }
124 }
125
126 public boolean tryLock(T obj,long time,TimeUnit unit)
127 throws InterruptedException
128 {
129 Tracker t = getTrackerForWait(obj);
130 try {
131 return t.lock.readLock().tryLock(time,unit);
132 } finally {
133 afterWait(t);
134 }
135 }
136
137 public void unlock(T obj) {
138 synchronized(map) {
139 Tracker t = map.get(obj);
140 t.lock.readLock().unlock();
141 maybeRemove(obj,t);
142 }
143 }
144 };
145
146 public Locker<T> readLocker() {
147 return readLocker;
148 }
149
150 public Locker<T> writeLocker() {
151 return writeLocker;
152 }
153
154 }