com.esri.gpt.catalog.lucene.ReferencedSearcher.java Source code

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Here is the source code for com.esri.gpt.catalog.lucene.ReferencedSearcher.java

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/* See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * Esri Inc. 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 com.esri.gpt.catalog.lucene;

import java.io.IOException;
import java.util.logging.Level;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.store.Directory;

import com.esri.gpt.framework.util.LogUtil;

/**
 * This is an experimental class to attempt to deal with the 
 * issues of opening many IndexReader(s) against the same 
 * Lucene index (issues; performance, memory, file handles).
 *
 */
class ReferencedSearcher {

    /** instance variables ====================================================== */
    private IndexSearcher currentSearcher;
    private boolean reopening;

    /** constructors ============================================================ */

    /**
     * Constructs with a supplied directory.
     * @param dir the directory
     */
    public ReferencedSearcher(Directory dir) throws IOException {
        this.currentSearcher = new IndexSearcher(IndexReader.open(dir, true));
        this.warm(this.currentSearcher);
    }

    /** methods ================================================================= */

    protected void close() throws IOException {
        this.swap(null);
    }

    protected synchronized IndexSearcher get() {
        this.currentSearcher.getIndexReader().incRef();
        return this.currentSearcher;
    }

    private synchronized void onReopenBegin() throws InterruptedException {
        while (this.reopening) {
            wait();
        }
        this.reopening = true;
    }

    private synchronized void onReopenEnd() {
        this.reopening = false;
        notifyAll();
    }

    protected synchronized void release(IndexSearcher searcher) throws IOException {
        searcher.getIndexReader().decRef();
    }

    protected void checkForReopen() throws InterruptedException, IOException {
        this.onReopenBegin();
        try {
            final IndexSearcher searcher = get();
            try {
                IndexReader newReader = this.currentSearcher.getIndexReader().reopen();
                if (newReader != this.currentSearcher.getIndexReader()) {
                    IndexSearcher newSearcher = new IndexSearcher(newReader);
                    this.warm(newSearcher);
                    this.swap(newSearcher);
                }
            } catch (IOException e) {
                LogUtil.getLogger().log(Level.SEVERE, "Error during index re-open.", e);
            } finally {
                this.release(searcher);
            }
        } finally {
            onReopenEnd();
        }
    }

    private synchronized void swap(IndexSearcher newSearcher) throws IOException {
        this.release(this.currentSearcher);
        this.currentSearcher = newSearcher;
    }

    private void warm(IndexSearcher searcher) throws IOException {
    }

}