| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 org.apache.cassandra.io.util; |
| |
| import java.io.IOException; |
| import java.nio.ByteBuffer; |
| import java.nio.channels.WritableByteChannel; |
| |
| import org.apache.cassandra.config.Config; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| import com.google.common.base.Preconditions; |
| |
| /** |
| * An implementation of the DataOutputStream interface using a FastByteArrayOutputStream and exposing |
| * its buffer so copies can be avoided. |
| * |
| * This class is completely thread unsafe. |
| */ |
| public class DataOutputBuffer extends BufferedDataOutputStreamPlus |
| { |
| /* |
| * Threshold at which resizing transitions from doubling to increasing by 50% |
| */ |
| static final long DOUBLING_THRESHOLD = Long.getLong(Config.PROPERTY_PREFIX + "DOB_DOUBLING_THRESHOLD_MB", 64); |
| |
| public DataOutputBuffer() |
| { |
| this(128); |
| } |
| |
| public DataOutputBuffer(int size) |
| { |
| super(ByteBuffer.allocate(size)); |
| } |
| |
| protected DataOutputBuffer(ByteBuffer buffer) |
| { |
| super(buffer); |
| } |
| |
| @Override |
| public void flush() throws IOException |
| { |
| throw new UnsupportedOperationException(); |
| } |
| |
| //The actual value observed in Hotspot is only -2 |
| //ByteArrayOutputStream uses -8 |
| @VisibleForTesting |
| static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; |
| |
| @VisibleForTesting |
| static int saturatedArraySizeCast(long size) |
| { |
| Preconditions.checkArgument(size >= 0); |
| return (int)Math.min(MAX_ARRAY_SIZE, size); |
| } |
| |
| @VisibleForTesting |
| static int checkedArraySizeCast(long size) |
| { |
| Preconditions.checkArgument(size >= 0); |
| Preconditions.checkArgument(size <= MAX_ARRAY_SIZE); |
| return (int)size; |
| } |
| |
| @Override |
| protected void doFlush(int count) throws IOException |
| { |
| expandToFit(count); |
| } |
| |
| //Hack for test, make it possible to override checking the buffer capacity |
| @VisibleForTesting |
| long capacity() |
| { |
| return buffer.capacity(); |
| } |
| |
| @VisibleForTesting |
| long validateReallocation(long newSize) |
| { |
| int saturatedSize = saturatedArraySizeCast(newSize); |
| if (saturatedSize <= capacity()) |
| throw new RuntimeException(); |
| return saturatedSize; |
| } |
| |
| @VisibleForTesting |
| long calculateNewSize(long count) |
| { |
| long capacity = capacity(); |
| //Both sides of this max expression need to use long arithmetic to avoid integer overflow |
| //count and capacity are longs so that ensures it right now. |
| long newSize = capacity + count; |
| |
| //For large buffers don't double, increase by 50% |
| if (capacity > 1024L * 1024L * DOUBLING_THRESHOLD) |
| newSize = Math.max((capacity * 3L) / 2L, newSize); |
| else |
| newSize = Math.max(capacity * 2L, newSize); |
| |
| return validateReallocation(newSize); |
| } |
| |
| protected void expandToFit(long count) |
| { |
| if (count <= 0) |
| return; |
| ByteBuffer newBuffer = ByteBuffer.allocate(checkedArraySizeCast(calculateNewSize(count))); |
| buffer.flip(); |
| newBuffer.put(buffer); |
| buffer = newBuffer; |
| } |
| |
| @Override |
| protected WritableByteChannel newDefaultChannel() |
| { |
| return new GrowingChannel(); |
| } |
| |
| @VisibleForTesting |
| final class GrowingChannel implements WritableByteChannel |
| { |
| public int write(ByteBuffer src) throws IOException |
| { |
| int count = src.remaining(); |
| expandToFit(count); |
| buffer.put(src); |
| return count; |
| } |
| |
| public boolean isOpen() |
| { |
| return true; |
| } |
| |
| public void close() |
| { |
| } |
| } |
| |
| @Override |
| public void close() |
| { |
| } |
| |
| public ByteBuffer buffer() |
| { |
| return buffer(true); |
| } |
| |
| public ByteBuffer buffer(boolean duplicate) |
| { |
| if (!duplicate) |
| { |
| ByteBuffer buf = buffer; |
| buf.flip(); |
| buffer = null; |
| return buf; |
| } |
| |
| ByteBuffer result = buffer.duplicate(); |
| result.flip(); |
| return result; |
| } |
| |
| public byte[] getData() |
| { |
| return buffer.array(); |
| } |
| |
| public int getLength() |
| { |
| return buffer.position(); |
| } |
| |
| public boolean hasPosition() |
| { |
| return true; |
| } |
| |
| public long position() |
| { |
| return getLength(); |
| } |
| |
| public byte[] toByteArray() |
| { |
| ByteBuffer buffer = buffer(); |
| byte[] result = new byte[buffer.remaining()]; |
| buffer.get(result); |
| return result; |
| } |
| } |