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1 package org.shiftone.cache.util;
2
3
4
5
9 public class RingFifo
10 {
11
12 private Object  [] array;
13 private int maxSize;
14 private int head;
15 private int size;
16
17 public RingFifo(int maxSize)
18 {
19
20 this.maxSize = maxSize;
21
22 clear();
23 }
24
25
26 public void clear()
27 {
28
29 array = new Object [maxSize];
30 head = 0;
31 size = 0;
32 }
33
34
35 public void enqueue(Object obj)
36 {
37
38 array[head] = obj;
39 head = (head + 1) % maxSize;
40
41 if (size < maxSize)
42 {
43 size++;
44 }
45 }
46
47
48 private final int peekIndex()
49 {
50 return (head + maxSize - size) % maxSize;
51 }
52
53
54 public Object peek()
55 {
56 return array[peekIndex()];
57 }
58
59
60 public Object dequeue()
61 {
62
63 Object obj = null;
64
65 if (size > 0)
66 {
67 int index = peekIndex();
68
69 obj = array[index];
70 array[index] = null;
71
72 size--;
73 }
74
75 return obj;
76 }
77
78
79 public int getMaxSize()
80 {
81 return maxSize;
82 }
83
84
85 public int size()
86 {
87 return size;
88 }
89
90
91 public String dump()
92 {
93
94 StringBuffer sb = new StringBuffer ();
95
96 for (int i = 0; i < maxSize; i++)
97 {
98 if (i != 0)
99 {
100 sb.append(",");
101 }
102
103 if (array[i] != null)
104 {
105 sb.append(array[i]);
106 }
107 }
108
109 System.out.println(sb);
110
111 return sb.toString();
112 }
113 }
114 |
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