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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.tv.tuner.exoplayer.buffer;
     18 
     19 import com.google.android.exoplayer.SampleHolder;
     20 
     21 import java.util.LinkedList;
     22 
     23 /**
     24  * Pool of samples to recycle ByteBuffers as much as possible.
     25  */
     26 public class SamplePool {
     27     private final LinkedList<SampleHolder> mSamplePool = new LinkedList<>();
     28 
     29     /**
     30      * Acquires a sample with a buffer larger than size from the pool. Allocate new one or resize
     31      * an existing buffer if necessary.
     32      */
     33     public synchronized SampleHolder acquireSample(int size) {
     34         if (mSamplePool.isEmpty()) {
     35             SampleHolder sample = new SampleHolder(SampleHolder.BUFFER_REPLACEMENT_MODE_NORMAL);
     36             sample.ensureSpaceForWrite(size);
     37             return sample;
     38         }
     39         SampleHolder smallestSufficientSample = null;
     40         SampleHolder maxSample = mSamplePool.getFirst();
     41         for (SampleHolder sample : mSamplePool) {
     42             // Grab the smallest sufficient sample.
     43             if (sample.data.capacity() >= size && (smallestSufficientSample == null
     44                     || smallestSufficientSample.data.capacity() > sample.data.capacity())) {
     45                 smallestSufficientSample = sample;
     46             }
     47 
     48             // Grab the max size sample.
     49             if (maxSample.data.capacity() < sample.data.capacity()) {
     50                 maxSample = sample;
     51             }
     52         }
     53         SampleHolder sampleFromPool = smallestSufficientSample;
     54 
     55         // If there's no sufficient sample, grab the maximum sample and resize it to size.
     56         if (sampleFromPool == null) {
     57             sampleFromPool = maxSample;
     58             sampleFromPool.ensureSpaceForWrite(size);
     59         }
     60         mSamplePool.remove(sampleFromPool);
     61         return sampleFromPool;
     62     }
     63 
     64     /**
     65      * Releases the sample back to the pool.
     66      */
     67     public synchronized void releaseSample(SampleHolder sample) {
     68         sample.clearData();
     69         mSamplePool.offerLast(sample);
     70     }
     71 }
     72