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Lucene example source code file (TestDoubleBarrelLRUCache.java)

This example Lucene source code file (TestDoubleBarrelLRUCache.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

cache_size, cachethread, cloneableinteger, cloneableinteger, cloneableobject, cloneableobject, doublebarrellrucache, exception, num_threads, object, object, override, override, testdoublebarrellrucache

The Lucene TestDoubleBarrelLRUCache.java source code

package org.apache.lucene.util;

/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements.  See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License.  You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

import org.apache.lucene.util.LuceneTestCase;

public class TestDoubleBarrelLRUCache extends LuceneTestCase {

  private void testCache(DoubleBarrelLRUCache<CloneableInteger,Object> cache, int n) throws Exception {
    Object dummy = new Object();
    
    for (int i = 0; i < n; i++) {
      cache.put(new CloneableInteger(i), dummy);
    }
    
    // access every 2nd item in cache
    for (int i = 0; i < n; i+=2) {
      assertNotNull(cache.get(new CloneableInteger(i)));
    }
    
    // add n/2 elements to cache, the ones that weren't
    // touched in the previous loop should now be thrown away
    for (int i = n; i < n + (n / 2); i++) {
      cache.put(new CloneableInteger(i), dummy);
    }
    
    // access every 4th item in cache
    for (int i = 0; i < n; i+=4) {
      assertNotNull(cache.get(new CloneableInteger(i)));
    }

    // add 3/4n elements to cache, the ones that weren't
    // touched in the previous loops should now be thrown away
    for (int i = n; i < n + (n * 3 / 4); i++) {
      cache.put(new CloneableInteger(i), dummy);
    }
    
    // access every 4th item in cache
    for (int i = 0; i < n; i+=4) {
      assertNotNull(cache.get(new CloneableInteger(i)));
    }
  }
    
  public void testLRUCache() throws Exception {
    final int n = 100;
    testCache(new DoubleBarrelLRUCache<CloneableInteger,Object>(n), n);
  }

  private class CacheThread extends Thread {
    private final CloneableObject[] objs;
    private final DoubleBarrelLRUCache<CloneableObject,Object> c;
    private final long endTime;
    volatile boolean failed;

    public CacheThread(DoubleBarrelLRUCache<CloneableObject,Object> c,
                       CloneableObject[] objs, long endTime) {
      this.c = c;
      this.objs = objs;
      this.endTime = endTime;
    }

    @Override
    public void run() {
      try {
        long count = 0;
        long miss = 0;
        long hit = 0;
        final int limit = objs.length;

        while(true) {
          final CloneableObject obj = objs[(int) ((count/2) % limit)];
          Object v = c.get(obj);
          if (v == null) {
            c.put(new CloneableObject(obj), obj);
            miss++;
          } else {
            assert obj == v;
            hit++;
          }
          if ((++count % 10000) == 0) {
            if (System.currentTimeMillis() >= endTime)  {
              break;
            }
          }
        }

        addResults(miss, hit);
      } catch (Throwable t) {
        failed = true;
        throw new RuntimeException(t);
      }
    }
  }

  long totMiss, totHit;
  void addResults(long miss, long hit) {
    totMiss += miss;
    totHit += hit;
  }

  public void testThreadCorrectness() throws Exception {
    final int NUM_THREADS = 4;
    final int CACHE_SIZE = 512;
    final int OBJ_COUNT = 3*CACHE_SIZE;

    DoubleBarrelLRUCache<CloneableObject,Object> c = new DoubleBarrelLRUCache(1024);

    CloneableObject[] objs = new CloneableObject[OBJ_COUNT];
    for(int i=0;i<OBJ_COUNT;i++) {
      objs[i] = new CloneableObject(new Object());
    }
    
    final CacheThread[] threads = new CacheThread[NUM_THREADS];
    final long endTime = System.currentTimeMillis()+1000L;
    for(int i=0;i<NUM_THREADS;i++) {
      threads[i] = new CacheThread(c, objs, endTime);
      threads[i].start();
    }
    for(int i=0;i<NUM_THREADS;i++) {
      threads[i].join();
      assert !threads[i].failed;
    }
    //System.out.println("hits=" + totHit + " misses=" + totMiss);
  }
  
  private static class CloneableObject extends DoubleBarrelLRUCache.CloneableKey {
    private Object value;

    public CloneableObject(Object value) {
      this.value = value;
    }

    @Override
    public boolean equals(Object other) {
      return this.value.equals(((CloneableObject) other).value);
    }

    @Override
    public int hashCode() {
      return value.hashCode();
    }

    @Override
    public Object clone() {
      return new CloneableObject(value);
    }
  }

  protected static class CloneableInteger extends DoubleBarrelLRUCache.CloneableKey {
    private Integer value;

    public CloneableInteger(Integer value) {
      this.value = value;
    }

    @Override
    public boolean equals(Object other) {
      return this.value.equals(((CloneableInteger) other).value);
    }

    @Override
    public int hashCode() {
      return value.hashCode();
    }

    @Override
    public Object clone() {
      return new CloneableInteger(value);
    }
  }


}

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