KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > EDU > oswego > cs > dl > util > concurrent > SynchronizedInt


1 /*
2   File: SynchronizedInt.java
3
4   Originally written by Doug Lea and released into the public domain.
5   This may be used for any purposes whatsoever without acknowledgment.
6   Thanks for the assistance and support of Sun Microsystems Labs,
7   and everyone contributing, testing, and using this code.
8
9   History:
10   Date Who What
11   19Jun1998 dl Create public version
12 */
13
14 package EDU.oswego.cs.dl.util.concurrent;
15
16 /**
17  * A class useful for offloading synch for int instance variables.
18  *
19  * <p>[<a HREF="http://gee.cs.oswego.edu/dl/classes/EDU/oswego/cs/dl/util/concurrent/intro.html"> Introduction to this package. </a>]
20  **/
21
22 public class SynchronizedInt extends SynchronizedVariable implements Comparable JavaDoc, Cloneable JavaDoc {
23
24   protected int value_;
25
26   /**
27    * Make a new SynchronizedInt with the given initial value,
28    * and using its own internal lock.
29    **/
30   public SynchronizedInt(int initialValue) {
31     super();
32     value_ = initialValue;
33   }
34
35   /**
36    * Make a new SynchronizedInt with the given initial value,
37    * and using the supplied lock.
38    **/
39   public SynchronizedInt(int initialValue, Object JavaDoc lock) {
40     super(lock);
41     value_ = initialValue;
42   }
43
44   /**
45    * Return the current value
46    **/
47   public final int get() { synchronized(lock_) { return value_; } }
48
49   /**
50    * Set to newValue.
51    * @return the old value
52    **/
53
54   public int set(int newValue) {
55     synchronized (lock_) {
56       int old = value_;
57       value_ = newValue;
58       return old;
59     }
60   }
61
62   /**
63    * Set value to newValue only if it is currently assumedValue.
64    * @return true if successful
65    **/
66   public boolean commit(int assumedValue, int newValue) {
67     synchronized(lock_) {
68       boolean success = (assumedValue == value_);
69       if (success) value_ = newValue;
70       return success;
71     }
72   }
73
74   /**
75    * Atomically swap values with another SynchronizedInt.
76    * Uses identityHashCode to avoid deadlock when
77    * two SynchronizedInts attempt to simultaneously swap with each other.
78    * (Note: Ordering via identyHashCode is not strictly guaranteed
79    * by the language specification to return unique, orderable
80    * values, but in practice JVMs rely on them being unique.)
81    * @return the new value
82    **/
83
84   public int swap(SynchronizedInt other) {
85     if (other == this) return get();
86     SynchronizedInt fst = this;
87     SynchronizedInt snd = other;
88     if (System.identityHashCode(fst) > System.identityHashCode(snd)) {
89       fst = other;
90       snd = this;
91     }
92     synchronized(fst.lock_) {
93       synchronized(snd.lock_) {
94         fst.set(snd.set(fst.get()));
95         return get();
96       }
97     }
98   }
99
100   /**
101    * Increment the value.
102    * @return the new value
103    **/
104   public int increment() {
105     synchronized (lock_) {
106       return ++value_;
107     }
108   }
109
110   /**
111    * Decrement the value.
112    * @return the new value
113    **/
114   public int decrement() {
115     synchronized (lock_) {
116       return --value_;
117     }
118   }
119
120   /**
121    * Add amount to value (i.e., set value += amount)
122    * @return the new value
123    **/
124   public int add(int amount) {
125     synchronized (lock_) {
126       return value_ += amount;
127     }
128   }
129
130   /**
131    * Subtract amount from value (i.e., set value -= amount)
132    * @return the new value
133    **/
134   public int subtract(int amount) {
135     synchronized (lock_) {
136       return value_ -= amount;
137     }
138   }
139
140   /**
141    * Multiply value by factor (i.e., set value *= factor)
142    * @return the new value
143    **/
144   public synchronized int multiply(int factor) {
145     synchronized (lock_) {
146       return value_ *= factor;
147     }
148   }
149
150   /**
151    * Divide value by factor (i.e., set value /= factor)
152    * @return the new value
153    **/
154   public int divide(int factor) {
155     synchronized (lock_) {
156       return value_ /= factor;
157     }
158   }
159
160   /**
161    * Set the value to the negative of its old value
162    * @return the new value
163    **/
164   public int negate() {
165     synchronized (lock_) {
166       value_ = -value_;
167       return value_;
168     }
169   }
170
171   /**
172    * Set the value to its complement
173    * @return the new value
174    **/
175   public int complement() {
176     synchronized (lock_) {
177       value_ = ~value_;
178       return value_;
179     }
180   }
181
182   /**
183    * Set value to value &amp; b.
184    * @return the new value
185    **/
186   public int and(int b) {
187     synchronized (lock_) {
188       value_ = value_ & b;
189       return value_;
190     }
191   }
192
193   /**
194    * Set value to value | b.
195    * @return the new value
196    **/
197   public int or(int b) {
198     synchronized (lock_) {
199       value_ = value_ | b;
200       return value_;
201     }
202   }
203
204
205   /**
206    * Set value to value ^ b.
207    * @return the new value
208    **/
209   public int xor(int b) {
210     synchronized (lock_) {
211       value_ = value_ ^ b;
212       return value_;
213     }
214   }
215
216   public int compareTo(int other) {
217     int val = get();
218     return (val < other)? -1 : (val == other)? 0 : 1;
219   }
220
221   public int compareTo(SynchronizedInt other) {
222     return compareTo(other.get());
223   }
224
225   public int compareTo(Object JavaDoc other) {
226     return compareTo((SynchronizedInt)other);
227   }
228
229   public boolean equals(Object JavaDoc other) {
230     if (other != null &&
231         other instanceof SynchronizedInt)
232       return get() == ((SynchronizedInt)other).get();
233     else
234       return false;
235   }
236
237   public int hashCode() { return get(); }
238
239   public String JavaDoc toString() { return String.valueOf(get()); }
240
241 }
242
243
Popular Tags