1 /* 2 * Copyright (C) 2012 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.gallery3d.data; 18 19 import com.android.gallery3d.util.ThreadPool.JobContext; 20 21 import java.io.FileDescriptor; 22 import java.io.FileInputStream; 23 import java.io.IOException; 24 import java.util.ArrayList; 25 26 public class BytesBufferPool { 27 28 private static final int READ_STEP = 4096; 29 30 public static class BytesBuffer { 31 public byte[] data; 32 public int offset; 33 public int length; 34 BytesBuffer(int capacity)35 private BytesBuffer(int capacity) { 36 this.data = new byte[capacity]; 37 } 38 39 // an helper function to read content from FileDescriptor readFrom(JobContext jc, FileDescriptor fd)40 public void readFrom(JobContext jc, FileDescriptor fd) throws IOException { 41 FileInputStream fis = new FileInputStream(fd); 42 length = 0; 43 try { 44 int capacity = data.length; 45 while (true) { 46 int step = Math.min(READ_STEP, capacity - length); 47 int rc = fis.read(data, length, step); 48 if (rc < 0 || jc.isCancelled()) return; 49 length += rc; 50 51 if (length == capacity) { 52 byte[] newData = new byte[data.length * 2]; 53 System.arraycopy(data, 0, newData, 0, data.length); 54 data = newData; 55 capacity = data.length; 56 } 57 } 58 } finally { 59 fis.close(); 60 } 61 } 62 } 63 64 private final int mPoolSize; 65 private final int mBufferSize; 66 private final ArrayList<BytesBuffer> mList; 67 BytesBufferPool(int poolSize, int bufferSize)68 public BytesBufferPool(int poolSize, int bufferSize) { 69 mList = new ArrayList<BytesBuffer>(poolSize); 70 mPoolSize = poolSize; 71 mBufferSize = bufferSize; 72 } 73 get()74 public synchronized BytesBuffer get() { 75 int n = mList.size(); 76 return n > 0 ? mList.remove(n - 1) : new BytesBuffer(mBufferSize); 77 } 78 recycle(BytesBuffer buffer)79 public synchronized void recycle(BytesBuffer buffer) { 80 if (buffer.data.length != mBufferSize) return; 81 if (mList.size() < mPoolSize) { 82 buffer.offset = 0; 83 buffer.length = 0; 84 mList.add(buffer); 85 } 86 } 87 clear()88 public synchronized void clear() { 89 mList.clear(); 90 } 91 } 92