1/*
2 * Copyright (C) 2010 Google 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
17package benchmarks.regression;
18
19import com.google.caliper.BeforeExperiment;
20import com.google.caliper.Param;
21import java.util.ArrayList;
22import java.util.Collections;
23import java.util.List;
24import java.util.PriorityQueue;
25import java.util.Random;
26
27public class PriorityQueueBenchmark {
28    @Param({"100", "1000", "10000"}) private int queueSize;
29    @Param({"0", "25", "50", "75", "100"}) private int hitRate;
30
31    private PriorityQueue<Integer> pq;
32    private PriorityQueue<Integer> usepq;
33    private List<Integer> seekElements;
34    private Random random = new Random(189279387L);
35
36    @BeforeExperiment
37    protected void setUp() throws Exception {
38        pq = new PriorityQueue<Integer>();
39        usepq = new PriorityQueue<Integer>();
40        seekElements = new ArrayList<Integer>();
41        List<Integer> allElements = new ArrayList<Integer>();
42        int numShared = (int)(queueSize * ((double)hitRate / 100));
43        // the total number of elements we require to engineer a hit rate of hitRate%
44        int totalElements = 2 * queueSize - numShared;
45        for (int i = 0; i < totalElements; i++) {
46            allElements.add(i);
47        }
48        // shuffle these elements so that we get a reasonable distribution of missed elements
49        Collections.shuffle(allElements, random);
50        // add shared elements
51        for (int i = 0; i < numShared; i++) {
52            pq.add(allElements.get(i));
53            seekElements.add(allElements.get(i));
54        }
55        // add priority queue only elements (these won't be touched)
56        for (int i = numShared; i < queueSize; i++) {
57            pq.add(allElements.get(i));
58        }
59        // add non-priority queue elements (these will be misses)
60        for (int i = queueSize; i < totalElements; i++) {
61            seekElements.add(allElements.get(i));
62        }
63        usepq = new PriorityQueue<Integer>(pq);
64        // shuffle again so that elements are accessed in a different pattern than they were
65        // inserted
66        Collections.shuffle(seekElements, random);
67    }
68
69    public boolean timeRemove(int reps) {
70        boolean dummy = false;
71        int elementsSize = seekElements.size();
72        // At most allow the queue to empty 10%.
73        int resizingThreshold = queueSize / 10;
74        for (int i = 0; i < reps; i++) {
75            // Reset queue every so often. This will be called more often for smaller
76            // queueSizes, but since a copy is linear, it will also cost proportionally
77            // less, and hopefully it will approximately balance out.
78            if (i % resizingThreshold == 0) {
79                usepq = new PriorityQueue<Integer>(pq);
80            }
81            dummy = usepq.remove(seekElements.get(i % elementsSize));
82        }
83        return dummy;
84    }
85}
86