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1
18 package freecs.util;
19
20 import freecs.Server;
21
22
27 public class ObjectBuffer {
28 private Object  elements[];
29 private volatile int nextAdd;
30 private volatile int nextRemove;
31 private volatile int capacity;
32 private volatile int counter=0;
33
34 public ObjectBuffer (int cap) throws IllegalArgumentException {
35 if (cap < 2)
36 throw new IllegalArgumentException ("Capacity must be higher than 1 to make sense");
37 this.capacity = cap;
38 this.nextAdd=0;
39 this.nextRemove=0;
40 elements = new Object [capacity];
41 if (Server.TRACE_CREATE_AND_FINALIZE)
42 Server.log (this, "++++++++++++++++++++++++++++++++++++++++CREATE", Server.MSG_STATE, Server.LVL_VERY_VERBOSE);
43 }
44
45 public int size () {
46 return counter;
47 }
48
49 public int capacity () {
50 return capacity;
51 }
52
53 public boolean isEmpty () {
54 return counter==0;
55 }
56
57 public boolean isFull () {
58 return counter==capacity;
59 }
60
61 public boolean put (Object o) {
62 if (o==null)
63 throw new NullPointerException ("ObjectBuffer unable to store null");
64 if (this.isFull ())
65 return false;
66 elements[nextAdd] = o;
67 nextAdd++;
68 if (nextAdd >= capacity)
69 nextAdd = 0;
70 counter++;
71 return true;
72 }
73
74 public boolean contains (Object o) {
75 for (int i = 0, j=nextRemove; i < counter; i++, j++) {
76 if (j >= capacity) j = 0;
77 if (elements[j].equals (o)) return true;
78 }
79 return false;
80 }
81
82 public Object get () {
83 if (this.isEmpty ()) return null;
84 return elements[nextRemove];
85 }
86
87 public Object pop () {
88 if (this.isEmpty ()) return null;
89 Object retObj = elements[nextRemove];
90 elements[nextRemove]=null;
91 nextRemove++;
92 if (nextRemove >= capacity)
93 nextRemove = 0;
94 counter--;
95 return (retObj);
96 }
97
98 public void inhale (ObjectBuffer ob) {
99 elements = new Object [ob.capacity()];
100 while (!ob.isEmpty())
101 this.put(ob.pop());
102 }
103
104 public void resizeTo (int size) throws IllegalArgumentException {
105 if (size < this.size())
106 throw new IllegalArgumentException ("new capacity may not be lower than current size");
107 if (size == elements.length)
108 return;
109 Object newelements[] = new Object [size];
110 synchronized (this) {
111 int csize = this.size();
112 if (isEmpty()) {
113 elements = newelements;
114 return;
115 }
116 if (nextAdd <= nextRemove) {
117 System.arraycopy(elements,nextRemove,newelements,0,this.capacity()-nextRemove);
118 System.arraycopy(elements, 0, newelements, this.capacity()-nextRemove, nextAdd);
119 } else {
120 System.arraycopy(elements,nextRemove,newelements,0,nextAdd+1);
121 }
122 nextAdd = this.size();
123 nextRemove=0;
124 elements = newelements;
125 }
126 }
127
128 public void finalize() {
129 if (Server.TRACE_CREATE_AND_FINALIZE)
130 Server.log(this, "----------------------------------------FINALIZED", Server.MSG_STATE, Server.LVL_VERY_VERBOSE);
131 }
132 } |
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