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Diffstat (limited to 'core/src/main/java/com/android/volley/toolbox/PoolingByteArrayOutputStream.java')
-rw-r--r-- | core/src/main/java/com/android/volley/toolbox/PoolingByteArrayOutputStream.java | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/core/src/main/java/com/android/volley/toolbox/PoolingByteArrayOutputStream.java b/core/src/main/java/com/android/volley/toolbox/PoolingByteArrayOutputStream.java new file mode 100644 index 0000000..bdcc45e --- /dev/null +++ b/core/src/main/java/com/android/volley/toolbox/PoolingByteArrayOutputStream.java @@ -0,0 +1,92 @@ +/* + * Copyright (C) 2012 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.volley.toolbox; + +import java.io.ByteArrayOutputStream; +import java.io.IOException; + +/** + * A variation of {@link java.io.ByteArrayOutputStream} that uses a pool of byte[] buffers instead + * of always allocating them fresh, saving on heap churn. + */ +public class PoolingByteArrayOutputStream extends ByteArrayOutputStream { + /** + * If the {@link #PoolingByteArrayOutputStream(ByteArrayPool)} constructor is called, this is + * the default size to which the underlying byte array is initialized. + */ + private static final int DEFAULT_SIZE = 256; + + private final ByteArrayPool mPool; + + /** + * Constructs a new PoolingByteArrayOutputStream with a default size. If more bytes are written + * to this instance, the underlying byte array will expand. + */ + public PoolingByteArrayOutputStream(ByteArrayPool pool) { + this(pool, DEFAULT_SIZE); + } + + /** + * Constructs a new {@code ByteArrayOutputStream} with a default size of {@code size} bytes. If + * more than {@code size} bytes are written to this instance, the underlying byte array will + * expand. + * + * @param size initial size for the underlying byte array. The value will be pinned to a default + * minimum size. + */ + public PoolingByteArrayOutputStream(ByteArrayPool pool, int size) { + mPool = pool; + buf = mPool.getBuf(Math.max(size, DEFAULT_SIZE)); + } + + @Override + public void close() throws IOException { + mPool.returnBuf(buf); + buf = null; + super.close(); + } + + @Override + public void finalize() { + mPool.returnBuf(buf); + } + + /** Ensures there is enough space in the buffer for the given number of additional bytes. */ + @SuppressWarnings("UnsafeFinalization") + private void expand(int i) { + /* Can the buffer handle @i more bytes, if not expand it */ + if (count + i <= buf.length) { + return; + } + byte[] newbuf = mPool.getBuf((count + i) * 2); + System.arraycopy(buf, 0, newbuf, 0, count); + mPool.returnBuf(buf); + buf = newbuf; + } + + @Override + public synchronized void write(byte[] buffer, int offset, int len) { + expand(len); + super.write(buffer, offset, len); + } + + @Override + public synchronized void write(int oneByte) { + expand(1); + super.write(oneByte); + } +} |