1 //
2 // ========================================================================
3 // Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
4 // ------------------------------------------------------------------------
5 // All rights reserved. This program and the accompanying materials
6 // are made available under the terms of the Eclipse Public License v1.0
7 // and Apache License v2.0 which accompanies this distribution.
8 //
9 // The Eclipse Public License is available at
10 // http://www.eclipse.org/legal/epl-v10.html
11 //
12 // The Apache License v2.0 is available at
13 // http://www.opensource.org/licenses/apache2.0.php
14 //
15 // You may elect to redistribute this code under either of these licenses.
16 // ========================================================================
17 //
18
19 package org.eclipse.jetty.util.statistic;
20
21 import java.util.concurrent.atomic.AtomicLong;
22
23 import org.eclipse.jetty.util.Atomics;
24
25
26 /* ------------------------------------------------------------ */
27 /** Statistics on a counter value.
28 * <p>
29 * Keep total, current and maximum values of a counter that
30 * can be incremented and decremented. The total refers only
31 * to increments.
32 *
33 */
34 public class CounterStatistic
35 {
36 protected final AtomicLong _max = new AtomicLong();
37 protected final AtomicLong _curr = new AtomicLong();
38 protected final AtomicLong _total = new AtomicLong();
39
40 /* ------------------------------------------------------------ */
41 public void reset()
42 {
43 reset(0);
44 }
45
46 /* ------------------------------------------------------------ */
47 public void reset(final long value)
48 {
49 _max.set(value);
50 _curr.set(value);
51 _total.set(0); // total always set to 0 to properly calculate cumulative total
52 }
53
54 /* ------------------------------------------------------------ */
55 /**
56 * @param delta the amount to add to the count
57 */
58 public void add(final long delta)
59 {
60 long value=_curr.addAndGet(delta);
61 if (delta > 0)
62 _total.addAndGet(delta);
63 Atomics.updateMax(_max,value);
64 }
65
66 /* ------------------------------------------------------------ */
67 /**
68 * @param delta the amount to subtract the count by.
69 */
70 public void subtract(final long delta)
71 {
72 add(-delta);
73 }
74
75 /* ------------------------------------------------------------ */
76 /**
77 */
78 public void increment()
79 {
80 add(1);
81 }
82
83 /* ------------------------------------------------------------ */
84 /**
85 */
86 public void decrement()
87 {
88 add(-1);
89 }
90
91 /* ------------------------------------------------------------ */
92 /**
93 * @return max value
94 */
95 public long getMax()
96 {
97 return _max.get();
98 }
99
100 /* ------------------------------------------------------------ */
101 /**
102 * @return current value
103 */
104 public long getCurrent()
105 {
106 return _curr.get();
107 }
108
109 /* ------------------------------------------------------------ */
110 /**
111 * @return total value
112 */
113 public long getTotal()
114 {
115 return _total.get();
116 }
117 }