johnzon-core/src/main/java/org/apache/johnzon/core/ThreadLocalBufferCache.java

/*
 * 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.johnzon.core;

import java.io.Serializable;

public abstract class ThreadLocalBufferCache<T> implements Serializable {
    // alloc are expensive so using a very trivial buffer, we remove from TL to say we use it and reset it when we are done (close)
    private final ThreadLocal<T> buffers;
    private final int defaultSize;

    public ThreadLocalBufferCache(final int defaultSize) {
        this.buffers = new ThreadLocal<T>() {
            @Override
            protected T initialValue() {
                return ThreadLocalBufferCache.this.newValue(defaultSize);
            }
        };
        this.defaultSize = defaultSize;
    }

    protected abstract T newValue(final int defaultSize);

    public T getCache() {
        final T cachedLoadedChars = buffers.get();
        if (cachedLoadedChars == null) {
            return newValue(defaultSize);
        }
        buffers.set(null); // remove just kills the buffers
        return cachedLoadedChars;
    }


    public void release(final T buffer) {
        buffers.set(buffer);
    }
}