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/*
* 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;
import java.util.ListIterator;
/** 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();
}
public int size() {
return mChunks.size();
}
public int getByteSize() {
int total = 0;
ListIterator<Chunk> it = mChunks.listIterator(0);
while (it.hasNext()) {
Chunk c = it.next();
total += c.mLength;
}
return total;
}
public synchronized void clear() {
Chunk c = getFirstChunk();
while (c != null) {
releaseChunk(c);
c = getFirstChunk();
}
}
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;
}
}
}
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