| /* |
| * Copyright (C) 2006 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 android.webkit; |
| |
| import java.util.LinkedList; |
| |
| /** Utility class optimized for accumulating bytes, and then spitting |
| them back out. It does not optimize for returning the result in a |
| single array, though this is supported in the API. It is fastest |
| if the retrieval can be done via iterating through chunks. |
| |
| Things to add: |
| - consider dynamically increasing our min_capacity, |
| as we see mTotalSize increase |
| */ |
| class ByteArrayBuilder { |
| |
| private static final int DEFAULT_CAPACITY = 8192; |
| |
| private LinkedList<Chunk> mChunks; |
| |
| /** free pool */ |
| private LinkedList<Chunk> mPool; |
| |
| private int mMinCapacity; |
| |
| public ByteArrayBuilder() { |
| init(0); |
| } |
| |
| public ByteArrayBuilder(int minCapacity) { |
| init(minCapacity); |
| } |
| |
| private void init(int minCapacity) { |
| mChunks = new LinkedList<Chunk>(); |
| mPool = new LinkedList<Chunk>(); |
| |
| if (minCapacity <= 0) { |
| minCapacity = DEFAULT_CAPACITY; |
| } |
| mMinCapacity = minCapacity; |
| } |
| |
| public void append(byte[] array) { |
| append(array, 0, array.length); |
| } |
| |
| public synchronized void append(byte[] array, int offset, int length) { |
| while (length > 0) { |
| Chunk c = appendChunk(length); |
| int amount = Math.min(length, c.mArray.length - c.mLength); |
| System.arraycopy(array, offset, c.mArray, c.mLength, amount); |
| c.mLength += amount; |
| length -= amount; |
| offset += amount; |
| } |
| } |
| |
| /** |
| * The fastest way to retrieve the data is to iterate through the |
| * chunks. This returns the first chunk. Note: this pulls the |
| * chunk out of the queue. The caller must call releaseChunk() to |
| * dispose of it. |
| */ |
| public synchronized Chunk getFirstChunk() { |
| if (mChunks.isEmpty()) return null; |
| return mChunks.removeFirst(); |
| } |
| |
| /** |
| * recycles chunk |
| */ |
| public synchronized void releaseChunk(Chunk c) { |
| c.mLength = 0; |
| mPool.addLast(c); |
| } |
| |
| public boolean isEmpty() { |
| return mChunks.isEmpty(); |
| } |
| |
| private Chunk appendChunk(int length) { |
| if (length < mMinCapacity) { |
| length = mMinCapacity; |
| } |
| |
| Chunk c; |
| if (mChunks.isEmpty()) { |
| c = obtainChunk(length); |
| } else { |
| c = mChunks.getLast(); |
| if (c.mLength == c.mArray.length) { |
| c = obtainChunk(length); |
| } |
| } |
| return c; |
| } |
| |
| private Chunk obtainChunk(int length) { |
| Chunk c; |
| if (mPool.isEmpty()) { |
| c = new Chunk(length); |
| } else { |
| c = mPool.removeFirst(); |
| } |
| mChunks.addLast(c); |
| return c; |
| } |
| |
| public static class Chunk { |
| public byte[] mArray; |
| public int mLength; |
| |
| public Chunk(int length) { |
| mArray = new byte[length]; |
| mLength = 0; |
| } |
| } |
| } |