1 /*
2  * Copyright 2017, OpenCensus Authors
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 io.opencensus.stats;
18 
19 import com.google.auto.value.AutoValue;
20 import io.opencensus.internal.Utils;
21 import java.util.ArrayList;
22 import java.util.Collections;
23 import java.util.List;
24 import javax.annotation.concurrent.Immutable;
25 
26 /**
27  * The bucket boundaries for a histogram.
28  *
29  * @since 0.8
30  */
31 @Immutable
32 @AutoValue
33 public abstract class BucketBoundaries {
34 
35   /**
36    * Returns a {@code BucketBoundaries} with the given buckets.
37    *
38    * @param bucketBoundaries the boundaries for the buckets in the underlying histogram.
39    * @return a new {@code BucketBoundaries} with the specified boundaries.
40    * @throws NullPointerException if {@code bucketBoundaries} is null.
41    * @throws IllegalArgumentException if {@code bucketBoundaries} is not sorted.
42    * @since 0.8
43    */
create(List<Double> bucketBoundaries)44   public static final BucketBoundaries create(List<Double> bucketBoundaries) {
45     Utils.checkNotNull(bucketBoundaries, "bucketBoundaries");
46     List<Double> bucketBoundariesCopy = new ArrayList<Double>(bucketBoundaries); // Deep copy.
47     // Check if sorted.
48     if (bucketBoundariesCopy.size() > 1) {
49       double lower = bucketBoundariesCopy.get(0);
50       for (int i = 1; i < bucketBoundariesCopy.size(); i++) {
51         double next = bucketBoundariesCopy.get(i);
52         Utils.checkArgument(lower < next, "Bucket boundaries not sorted.");
53         lower = next;
54       }
55     }
56     return new AutoValue_BucketBoundaries(Collections.unmodifiableList(bucketBoundariesCopy));
57   }
58 
59   /**
60    * Returns a list of histogram bucket boundaries.
61    *
62    * @return a list of histogram bucket boundaries.
63    * @since 0.8
64    */
65   public abstract List<Double> getBoundaries();
66 }
67