1 /**
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18 package org.apache.hadoop.hbase.metrics;
19
20 import org.apache.hadoop.hbase.HBaseInterfaceAudience;
21 import org.apache.hadoop.hbase.classification.InterfaceAudience;
22 import org.apache.hadoop.hbase.classification.InterfaceStability;
23
24 /**
25 * A metric which measure the rate at which some operation is invoked.
26 */
27 @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
28 @InterfaceStability.Evolving
29 public interface Meter extends Metric {
30
31 /**
32 * Records one occurrence.
33 */
34 void mark();
35
36 /**
37 * Records {@code events} occurrences.
38 *
39 * @param events Number of occurrences to record.
40 */
41 void mark(long events);
42
43 /**
44 * Returns the number of events.
45 * @return the number of events.
46 */
47 long getCount();
48
49 /**
50 * Returns the mean rate at which events have occurred since the meter was created.
51 * @return the mean rate at which events have occurred since the meter was created
52 */
53 double getMeanRate();
54
55 /**
56 * Returns the one-minute exponentially-weighted moving average rate at which events have
57 * occurred since the meter was created.
58 * <p/>
59 * This rate has the same exponential decay factor as the one-minute load average in the {@code
60 * top} Unix command.
61 *
62 * @return the one-minute exponentially-weighted moving average rate at which events have
63 * occurred since the meter was created
64 */
65 double getOneMinuteRate();
66
67 /**
68 * Returns the five-minute exponentially-weighted moving average rate at which events have
69 * occurred since the meter was created.
70 * <p/>
71 * This rate has the same exponential decay factor as the five-minute load average in the {@code
72 * top} Unix command.
73 *
74 * @return the five-minute exponentially-weighted moving average rate at which events have
75 * occurred since the meter was created
76 */
77 double getFiveMinuteRate();
78
79 /**
80 * Returns the fifteen-minute exponentially-weighted moving average rate at which events have
81 * occurred since the meter was created.
82 * <p/>
83 * This rate has the same exponential decay factor as the fifteen-minute load average in the
84 * {@code top} Unix command.
85 *
86 * @return the fifteen-minute exponentially-weighted moving average rate at which events have
87 * occurred since the meter was created
88 */
89 double getFifteenMinuteRate();
90 }