1 /***
2 * Copyright 2003-2010 Terracotta, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package net.sf.ehcache.util.counter.sampled;
18
19 import java.util.TimerTask;
20
21 import net.sf.ehcache.util.CircularLossyQueue;
22 import net.sf.ehcache.util.counter.CounterImpl;
23
24 /***
25 * An implementation of {@link SampledCounter}
26 *
27 * @author <a href="mailto:asanoujam@terracottatech.com">Abhishek Sanoujam</a>
28 * @since 1.7
29 *
30 */
31 public class SampledCounterImpl extends CounterImpl implements SampledCounter {
32 private static final int MILLIS_PER_SEC = 1000;
33
34 /***
35 * The history of this counter
36 */
37 protected final CircularLossyQueue<TimeStampedCounterValue> history;
38
39 /***
40 * Should the counter reset on each sample?
41 */
42 protected final boolean resetOnSample;
43 private final TimerTask samplerTask;
44 private final long intervalMillis;
45
46 /***
47 * todo GL how many threads is this creating?
48 * Constructor accepting a {@link SampledCounterConfig}
49 *
50 * @param config
51 */
52 public SampledCounterImpl(SampledCounterConfig config) {
53 super(config.getInitialValue());
54
55 this.intervalMillis = config.getIntervalSecs() * MILLIS_PER_SEC;
56 this.history = new CircularLossyQueue<TimeStampedCounterValue>(config.getHistorySize());
57 this.resetOnSample = config.isResetOnSample();
58
59 this.samplerTask = new TimerTask() {
60 @Override
61 public void run() {
62 recordSample();
63 }
64 };
65
66 recordSample();
67 }
68
69 /***
70 * {@inheritDoc}
71 */
72 public TimeStampedCounterValue getMostRecentSample() {
73 return this.history.peek();
74 }
75
76 /***
77 * {@inheritDoc}
78 */
79 public TimeStampedCounterValue[] getAllSampleValues() {
80 return this.history.toArray(new TimeStampedCounterValue[this.history.depth()]);
81 }
82
83 /***
84 * {@inheritDoc}
85 */
86 public void shutdown() {
87 if (samplerTask != null) {
88 samplerTask.cancel();
89 }
90 }
91
92 /***
93 * Returns the timer task for this sampled counter
94 *
95 * @return the timer task for this sampled counter
96 */
97 public TimerTask getTimerTask() {
98 return this.samplerTask;
99 }
100
101 /***
102 * Returns the sampling thread interval in millis
103 *
104 * @return the sampling thread interval in millis
105 */
106 public long getIntervalMillis() {
107 return intervalMillis;
108 }
109
110 /***
111 * {@inheritDoc}
112 */
113 void recordSample() {
114 final long sample;
115 if (resetOnSample) {
116 sample = getAndReset();
117 } else {
118 sample = getValue();
119 }
120
121 final long now = System.currentTimeMillis();
122 TimeStampedCounterValue timedSample = new TimeStampedCounterValue(now, sample);
123
124 history.push(timedSample);
125 }
126
127 /***
128 * {@inheritDoc}
129 */
130 public long getAndReset() {
131 return getAndSet(0L);
132 }
133 }