/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed 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.android.tv.tuner.exoplayer.buffer;

import com.google.android.exoplayer.SampleHolder;

import java.util.LinkedList;

/**
 * Pool of samples to recycle ByteBuffers as much as possible.
 */
public class SamplePool {
    private final LinkedList<SampleHolder> mSamplePool = new LinkedList<>();

    /**
     * Acquires a sample with a buffer larger than size from the pool. Allocate new one or resize
     * an existing buffer if necessary.
     */
    public synchronized SampleHolder acquireSample(int size) {
        if (mSamplePool.isEmpty()) {
            SampleHolder sample = new SampleHolder(SampleHolder.BUFFER_REPLACEMENT_MODE_NORMAL);
            sample.ensureSpaceForWrite(size);
            return sample;
        }
        SampleHolder smallestSufficientSample = null;
        SampleHolder maxSample = mSamplePool.getFirst();
        for (SampleHolder sample : mSamplePool) {
            // Grab the smallest sufficient sample.
            if (sample.data.capacity() >= size && (smallestSufficientSample == null
                    || smallestSufficientSample.data.capacity() > sample.data.capacity())) {
                smallestSufficientSample = sample;
            }

            // Grab the max size sample.
            if (maxSample.data.capacity() < sample.data.capacity()) {
                maxSample = sample;
            }
        }
        SampleHolder sampleFromPool = smallestSufficientSample;

        // If there's no sufficient sample, grab the maximum sample and resize it to size.
        if (sampleFromPool == null) {
            sampleFromPool = maxSample;
            sampleFromPool.ensureSpaceForWrite(size);
        }
        mSamplePool.remove(sampleFromPool);
        return sampleFromPool;
    }

    /**
     * Releases the sample back to the pool.
     */
    public synchronized void releaseSample(SampleHolder sample) {
        sample.clearData();
        mSamplePool.offerLast(sample);
    }
}