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 long add(final long delta)
59 {
60 long value=_curr.addAndGet(delta);
61 if (delta > 0)
62 {
63 _total.addAndGet(delta);
64 Atomics.updateMax(_max,value);
65 }
66 return value;
67 }
68
69 /* ------------------------------------------------------------ */
70 /**
71 */
72 public long increment()
73 {
74 return add(1);
75 }
76
77 /* ------------------------------------------------------------ */
78 /**
79 */
80 public long decrement()
81 {
82 return add(-1);
83 }
84
85 /* ------------------------------------------------------------ */
86 /**
87 * @return max value
88 */
89 public long getMax()
90 {
91 return _max.get();
92 }
93
94 /* ------------------------------------------------------------ */
95 /**
96 * @return current value
97 */
98 public long getCurrent()
99 {
100 return _curr.get();
101 }
102
103 /* ------------------------------------------------------------ */
104 /**
105 * @return total value
106 */
107 public long getTotal()
108 {
109 return _total.get();
110 }
111
112 /* ------------------------------------------------------------ */
113 @Override
114 public String toString()
115 {
116 return String.format("%s@%x{c=%d,m=%d,t=%d}",this.getClass().getSimpleName(),hashCode(),_curr.get(),_max.get(),_total.get());
117 }
118 }