CachedStreamInput.java

/*
 * Licensed to ElasticSearch and Shay Banon under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. ElasticSearch 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.elasticsearch.common.io.stream;

import org.elasticsearch.common.compress.Compressor;

import java.io.IOException;
import java.lang.ref.SoftReference;

/**
 *
 */
public class CachedStreamInput {

    static class Entry {
        char[] chars = new char[80];
        final HandlesStreamInput handles;

        Entry(HandlesStreamInput handles) {
            this.handles = handles;
        }
    }

    private static final ThreadLocal<SoftReference<Entry>> cache = new ThreadLocal<SoftReference<Entry>>();

    static Entry instance() {
        SoftReference<Entry> ref = cache.get();
        Entry entry = ref == null ? null : ref.get();
        if (entry == null) {
            HandlesStreamInput handles = new HandlesStreamInput();
            entry = new Entry(handles);
            cache.set(new SoftReference<Entry>(entry));
        }
        return entry;
    }

    public static void clear() {
        cache.remove();
    }

    public static StreamInput compressed(Compressor compressor, StreamInput in) throws IOException {
        return compressor.streamInput(in);
    }

    public static HandlesStreamInput cachedHandles(StreamInput in) {
        HandlesStreamInput handles = instance().handles;
        handles.reset(in);
        return handles;
    }

    public static HandlesStreamInput cachedHandlesCompressed(Compressor compressor, StreamInput in) throws IOException {
        Entry entry = instance();
        entry.handles.reset(compressor.streamInput(in));
        return entry.handles;
    }

    public static char[] getCharArray(int size) {
        Entry entry = instance();
        if (entry.chars.length < size) {
            entry.chars = new char[size];
        }
        return entry.chars;
    }
}