ActiveMQ example source code file (BTreeIndexTest.java)

This example ActiveMQ source code file (BTreeIndexTest.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 - ActiveMQ tags/keywords

btreeindex, btreeindex, depth, exception, exception, index, indextestsupport, io, long, long, override, override, random, string, text, tree, util

The ActiveMQ BTreeIndexTest.java source code

/**
 * 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.
 */
package org.apache.kahadb.index;

import java.io.PrintWriter;
import java.text.NumberFormat;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Random;

import org.apache.kahadb.index.BTreeIndex;
import org.apache.kahadb.index.Index;
import org.apache.kahadb.util.LongMarshaller;
import org.apache.kahadb.util.StringMarshaller;

public class BTreeIndexTest extends IndexTestSupport {

    private NumberFormat nf;

    @Override
    protected void setUp() throws Exception {
        super.setUp();
        nf = NumberFormat.getIntegerInstance();
        nf.setMinimumIntegerDigits(6);
        nf.setGroupingUsed(false);
    }
    
    @Override
    protected Index<String, Long> createIndex() throws Exception {
        
        long id = tx.allocate().getPageId();
        tx.commit();

        BTreeIndex<String, Long> index = new BTreeIndex(pf, id);
        index.setKeyMarshaller(StringMarshaller.INSTANCE);
        index.setValueMarshaller(LongMarshaller.INSTANCE);
        
        return index;
    }

    /**
     * Yeah, the current implementation does NOT try to balance the tree.  Here is 
     * a test case showing that it gets out of balance.  
     * 
     * @throws Exception
     */
    public void disabled_testTreeBalancing() throws Exception {
        createPageFileAndIndex(100);

        BTreeIndex index = ((BTreeIndex)this.index);
        this.index.load(tx);
        tx.commit();
        
        doInsert(50);
        
        int minLeafDepth = index.getMinLeafDepth(tx);
        int maxLeafDepth = index.getMaxLeafDepth(tx);
        assertTrue("Tree is balanced", maxLeafDepth-minLeafDepth <= 1);

        // Remove some of the data
        doRemove(16);
        minLeafDepth = index.getMinLeafDepth(tx);
        maxLeafDepth = index.getMaxLeafDepth(tx);

        System.out.println( "min:"+minLeafDepth );
        System.out.println( "max:"+maxLeafDepth );
        index.printStructure(tx, new PrintWriter(System.out));

        assertTrue("Tree is balanced", maxLeafDepth-minLeafDepth <= 1);

        this.index.unload(tx);
    }
    
    public void testPruning() throws Exception {
        createPageFileAndIndex(100);

        BTreeIndex<String,Long> index = ((BTreeIndex)this.index);

        this.index.load(tx);
        tx.commit();
     
        int minLeafDepth = index.getMinLeafDepth(tx);
        int maxLeafDepth = index.getMaxLeafDepth(tx);
        assertEquals(1, minLeafDepth);
        assertEquals(1, maxLeafDepth);
        
        doInsert(1000);
        
        minLeafDepth = index.getMinLeafDepth(tx);
        maxLeafDepth = index.getMaxLeafDepth(tx);
        assertTrue("Depth of tree grew", minLeafDepth > 1);
        assertTrue("Depth of tree grew", maxLeafDepth > 1);

        // Remove the data.
        doRemove(1000);
        minLeafDepth = index.getMinLeafDepth(tx);
        maxLeafDepth = index.getMaxLeafDepth(tx);

        assertEquals(1, minLeafDepth);
        assertEquals(1, maxLeafDepth);

        this.index.unload(tx);
        tx.commit();
    }

    public void testIteration() throws Exception {
        createPageFileAndIndex(100);
        BTreeIndex<String,Long> index = ((BTreeIndex)this.index);
        this.index.load(tx);
        tx.commit();
          
        // Insert in reverse order..
        doInsertReverse(1000);
        
        this.index.unload(tx);
        tx.commit();
        this.index.load(tx);
        tx.commit();

        // BTree should iterate it in sorted order.
        int counter=0;
        for (Iterator<Map.Entry i = index.iterator(tx); i.hasNext();) {
            Map.Entry<String,Long> entry = (Map.Entry)i.next();
            assertEquals(key(counter),entry.getKey());
            assertEquals(counter,(long)entry.getValue());
            counter++;
        }

        this.index.unload(tx);
        tx.commit();
    }
    
    
    public void testVisitor() throws Exception {
        createPageFileAndIndex(100);
        BTreeIndex<String,Long> index = ((BTreeIndex)this.index);
        this.index.load(tx);
        tx.commit();
          
        // Insert in reverse order..
        doInsert(1000);
        
        this.index.unload(tx);
        tx.commit();
        this.index.load(tx);
        tx.commit();

        // BTree should iterate it in sorted order.
        
        index.visit(tx, new BTreeVisitor<String, Long>(){
            public boolean isInterestedInKeysBetween(String first, String second) {
                return true;
            }
            public void visit(List<String> keys, List values) {
            }
        });
        

        this.index.unload(tx);
        tx.commit();
    }


    public void testRandomRemove() throws Exception {

        createPageFileAndIndex(100);
        BTreeIndex<String,Long> index = ((BTreeIndex)this.index);
        this.index.load(tx);
        tx.commit();

        final int count = 4000;
        doInsert(count);

        Random rand = new Random(System.currentTimeMillis());
        int i = 0, prev = 0;
        while (!index.isEmpty(tx)) {
            prev = i;
            i = rand.nextInt(count);
            try {
                index.remove(tx, key(i));
            } catch (Exception e) {
                e.printStackTrace();
                fail("unexpected exception on " + i + ", prev: " + prev + ", ex: " + e);
            }
        }
    }

    public void testRemovePattern() throws Exception {
        createPageFileAndIndex(100);
        BTreeIndex<String,Long> index = ((BTreeIndex)this.index);
        this.index.load(tx);
        tx.commit();

        final int count = 4000;
        doInsert(count);

        index.remove(tx, key(3697));
        index.remove(tx, key(1566));
    }
    
    void doInsertReverse(int count) throws Exception {
        for (int i = count-1; i >= 0; i--) {
            index.put(tx, key(i), (long)i);
            tx.commit();
        }
    }
    /**
     * Overriding so that this generates keys that are the worst case for the BTree. Keys that
     * always insert to the end of the BTree.  
     */
    @Override
    protected String key(int i) {
        return "key:"+nf.format(i);
    }
}