com.cinchapi.concourse.util.ByteBuffers Maven / Gradle / Ivy
/*
* Copyright (c) 2013-2017 Cinchapi Inc.
*
* 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.cinchapi.concourse.util;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CodingErrorAction;
import java.nio.charset.StandardCharsets;
import java.util.concurrent.ConcurrentLinkedQueue;
import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import com.google.common.io.BaseEncoding;
/**
* Additional utility methods for ByteBuffers that are not found in the
* {@link ByteBuffer} class.
*
* @author Jeff Nelson
*/
public abstract class ByteBuffers {
/**
* Return a ByteBuffer that is a new read-only buffer that shares the
* content of {@code source} and has the same byte order, but maintains a
* distinct position, mark and limit.
*
* @param source
* @return the new, read-only byte buffer
*/
public static ByteBuffer asReadOnlyBuffer(ByteBuffer source) {
int position = source.position();
source.rewind();
ByteBuffer duplicate = source.asReadOnlyBuffer();
duplicate.order(source.order()); // byte order is not natively preserved
// when making duplicates:
// http://blog.mustardgrain.com/2008/04/04/bytebufferduplicate-does-not-preserve-byte-order/
source.position(position);
duplicate.rewind();
return duplicate;
}
/**
* Return a clone of {@code buffer} that has a copy of all its
* content and the same position and limit. Unlike the
* {@link ByteBuffer#slice()} method, the returned clone
* does not share its content with {@code buffer}, so
* subsequent operations to {@code buffer} or its clone will be
* completely independent and won't affect the other.
*
* @param buffer
* @return a clone of {@code buffer}
*/
public static ByteBuffer clone(ByteBuffer buffer) {
ByteBuffer clone = ByteBuffer.allocate(buffer.capacity());
int position = buffer.position();
int limit = buffer.limit();
buffer.rewind();
clone.put(buffer);
buffer.position(position);
clone.position(position);
buffer.limit(limit);
clone.limit(limit);
return clone;
}
/**
* Transfer the bytes from {@code source} to {@code destination} and resets
* {@code source} so that its position remains unchanged. The position of
* the {@code destination} is incremented by the number of bytes that are
* transferred.
*
* @param source
* @param destination
*/
public static void copyAndRewindSource(ByteBuffer source,
ByteBuffer destination) {
int position = source.position();
destination.put(source);
source.position(position);
}
/**
* Decode the {@code hex}adeciaml string and return the resulting binary
* data.
*
* @param hex
* @return the binary data
*/
public static ByteBuffer decodeFromHex(String hex) {
return ByteBuffer.wrap(BaseEncoding.base16().decode(hex));
}
/**
* Encode the {@code bytes} as a hexadecimal string.
*
* @param bytes
* @return the hex string
*/
public static String encodeAsHex(ByteBuffer bytes) {
bytes.rewind();
return BaseEncoding.base16().encode(ByteBuffers.toByteArray(bytes));
}
/**
* Encode the remaining bytes in as {@link ByteBuffer} as a hex string and
* maintain the current position.
*
* @param buffer
* @return the hex string
*/
public static String encodeAsHexString(ByteBuffer buffer) {
StringBuilder sb = new StringBuilder();
buffer.mark();
while (buffer.hasRemaining()) {
sb.append(String.format("%02x", buffer.get()));
}
buffer.reset();
return sb.toString();
}
/**
* Copy the remaining bytes in the {@code source} buffer to the
* {@code destination}, expanding if necessary in
* order to accommodate the bytes from {@code source}.
*
*
* NOTE: This method may modify the {@code limit} for the
* destination buffer.
*
*
* @param destination the buffer into which the {@code source} is copied
* @param source the buffer that is copied into the {@code destination}
* @return a possibly expanded copy of {@code destination} with the
* {@code source} bytes copied
*/
public static ByteBuffer expand(ByteBuffer destination, ByteBuffer source) {
destination = ensureRemainingCapacity(destination, source.remaining());
int newLimit = destination.position() + source.remaining();
if(destination.limit() < newLimit) {
destination.limit(newLimit);
}
destination.put(source);
return destination;
}
/**
* Put the {@code value} into {@code destination}, expanding if necessary in
* order to accommodate the new bytes.
*
*
* NOTE: This method may modify the {@code limit} for the
* destination buffer.
*
*
* @param destination the buffer into which the {@code source} is copied
* @param value the value to add to the {@code destination}
* @return a possibly expanded copy of {@code destination} with the
* {@code value} bytes copied
*/
public static ByteBuffer expandInt(ByteBuffer destination, int value) {
destination = ensureRemainingCapacity(destination, 4);
int newLimit = destination.position() + 4;
if(destination.limit() < newLimit) {
destination.limit(newLimit);
}
destination.putInt(value);
return destination;
}
/**
* Return a byte buffer that has the UTF-8 encoding for {@code string}. This
* method uses some optimization techniques and is the preferable way to
* convert strings to byte buffers than doing so manually.
*
* @param string
* @return the byte buffer with the {@code string} data.
*/
public static ByteBuffer fromString(String string) {
try {
return ByteBuffer.wrap(string.getBytes(CHARSET));
}
catch (Exception e) {
throw Throwables.propagate(e);
}
}
/**
* Return a ByteBuffer that has a copy of {@code length} bytes from
* {@code buffer} starting from the current position. This method will
* advance the position of the source buffer.
*
* @param buffer
* @param length
* @return a ByteBuffer that has {@code length} bytes from {@code buffer}
*/
public static ByteBuffer get(ByteBuffer buffer, int length) {
Preconditions.checkArgument(buffer.remaining() >= length,
"The number of bytes remaining in the buffer cannot be less than length");
byte[] backingArray = new byte[length];
buffer.get(backingArray);
return ByteBuffer.wrap(backingArray);
}
/**
* Relative get method. Reads the byte at the current position in
* {@code buffer} as a boolean, and then increments the position.
*
* @param buffer
* @return the boolean value at the current position
*/
public static boolean getBoolean(ByteBuffer buffer) {
return buffer.get() > 0 ? true : false;
}
/**
* Relative get method. Reads the enum at the current position in
* {@code buffer} and then increments the position by four.
*
* @param buffer
* @param clazz
* @return the enum value at the current position
*/
public static > T getEnum(ByteBuffer buffer,
Class clazz) {
return clazz.getEnumConstants()[buffer.getInt()];
}
/**
* Return a ByteBuffer that has a copy of all the remaining bytes from
* {@code buffer} starting from the current position. This method will
* advance the position of the source buffer.
*
* @param buffer the source buffer
* @return a ByteBuffer that has the remaining bytes from {@code buffer}
*/
public static ByteBuffer getRemaining(ByteBuffer buffer) {
return get(buffer, buffer.remaining());
}
/**
* Relative get method. Reads the UTF-8 encoded string at
* the current position in {@code buffer}.
*
* @param buffer
* @return the string value at the current position
*/
public static String getString(ByteBuffer buffer) {
return getString(buffer, StandardCharsets.UTF_8);
}
/**
* Relative get method. Reads the {@code charset} encoded string at
* the current position in {@code buffer}.
*
* @param buffer
* @param charset
* @return the string value at the current position
*/
public static String getString(ByteBuffer buffer, Charset charset) {
CharsetDecoder decoder = null;
try {
if(charset == StandardCharsets.UTF_8) {
while (decoder == null) {
decoder = DECODERS.poll();
}
}
else {
decoder = charset.newDecoder();
}
decoder.onMalformedInput(CodingErrorAction.IGNORE);
return decoder.decode(buffer).toString();
}
catch (CharacterCodingException e) {
throw Throwables.propagate(e);
}
finally {
if(decoder != null && charset == StandardCharsets.UTF_8) {
DECODERS.offer(decoder);
}
}
}
/**
* Return a ByteBuffer that contains a single null byte.
*
* @return a null byte buffer
*/
public static ByteBuffer nullByteBuffer() {
ByteBuffer nullByte = ByteBuffer.allocate(1);
nullByte.put((byte) 0);
nullByte.rewind();
return nullByte;
}
/**
* Put the UTF-8 encoding for the {@code source} string into the
* {@code destination} byte buffer and increment the position by the length
* of the strings byte sequence. This method uses some optimization
* techniques and is the preferable way to add strings to byte buffers than
* doing so manually.
*
* @param source
* @param destination
*/
public static void putString(String source, ByteBuffer destination) {
try {
byte[] bytes = source.getBytes(CHARSET);
destination.put(bytes);
}
catch (Exception e) {
throw Throwables.propagate(e);
}
}
/**
* The exact same as {@link ByteBuffer#rewind()} except it returns a typed
* {@link ByteBuffer} instead of a generic {@link Buffer}.
*
* @param buffer
* @return {@code buffer}
*/
public static ByteBuffer rewind(ByteBuffer buffer) {
buffer.rewind();
return buffer;
}
/**
* Return a new ByteBuffer whose content is a shared subsequence of the
* content in {@code buffer} starting at the current position to
* current position + {@code length} (non-inclusive). Invoking this method
* has the same affect as doing the following:
*
*
* buffer.mark();
* int oldLimit = buffer.limit();
* buffer.limit(buffer.position() + length);
*
* ByteBuffer slice = buffer.slice();
*
* buffer.reset();
* buffer.limit(oldLimit);
*
*
* @param buffer
* @param length
* @return the new ByteBuffer slice
* @see ByteBuffer#slice()
*/
public static ByteBuffer slice(ByteBuffer buffer, int length) {
return slice(buffer, buffer.position(), length);
}
/**
* Return a new ByteBuffer whose content is a shared subsequence of the
* content in {@code buffer} starting at {@code position} to
* {@code position} + {@code length} (non-inclusive). Invoking this method
* has the same affect as doing the following:
*
*
* buffer.mark();
* int oldLimit = buffer.limit();
* buffer.position(position);
* buffer.limit(position + length);
*
* ByteBuffer slice = buffer.slice();
*
* buffer.reset();
* buffer.limit(oldLimit);
*
*
* @param buffer
* @param position
* @param length
* @return the new ByteBuffer slice
* @see ByteBuffer#slice()
*/
public static ByteBuffer slice(ByteBuffer buffer, int position,
int length) {
int oldPosition = buffer.position();
int oldLimit = buffer.limit();
buffer.position(position);
buffer.limit(position + length);
ByteBuffer slice = buffer.slice();
buffer.limit(oldLimit);
buffer.position(oldPosition);
return slice;
}
/**
* Return a byte array with the content of {@code buffer}. This method
* returns the byte array that backs {@code buffer} if one exists, otherwise
* it creates a new byte array with the content between the current position
* of {@code buffer} and its limit.
*
* @param buffer
* @return the byte array with the content of {@code buffer}
*/
public static byte[] toByteArray(ByteBuffer buffer) {
if(buffer.hasArray()) {
return buffer.array();
}
else {
buffer.mark();
byte[] array = new byte[buffer.remaining()];
buffer.get(array);
buffer.reset();
return array;
}
}
/**
* Return a UTF-8 {@link CharBuffer} representation of the bytes in the
* {@code buffer}.
*
* @param buffer
* @return the char buffer
*/
public static CharBuffer toCharBuffer(ByteBuffer buffer) {
return toCharBuffer(buffer, StandardCharsets.UTF_8);
}
/**
* Return a {@link CharBuffer} representation of the bytes in the
* {@code buffer} encoded with the {@code charset}.
*
* @param buffer
* @param charset
* @return the char buffer
*/
public static CharBuffer toCharBuffer(ByteBuffer buffer, Charset charset) {
buffer.mark();
CharBuffer chars = charset.decode(buffer);
buffer.reset();
return chars;
}
/**
* Ensure that {@code buffer} has {@code capacity} bytes
* {@link ByteBuffer#remaining() remaining} and return either {@code buffer}
* or a copy that has enough capacity.
*
* @param buffer the buffer to check for remaining capacity
* @param capacity the number of bytes required
* @return a {@link ByteBuffer} with all the contents of {@code buffer} and
* enough remaining room for {@code capacity} bytes
*/
private static ByteBuffer ensureRemainingCapacity(ByteBuffer buffer,
int capacity) {
if((buffer.capacity() - buffer.position()) < capacity) {
ByteBuffer copy = ByteBuffer
.allocate(((buffer.capacity() + capacity) * 3) / 2 + 1);
buffer.limit(buffer.position());
buffer.rewind();
copy.put(buffer);
buffer = copy;
}
return buffer;
}
/**
* The name of the Charset to use for encoding/decoding. We use the name
* instead of the charset object because Java caches encoders when
* referencing them by name, but creates a new encorder object when
* referencing them by Charset object.
*/
private static final String CHARSET = StandardCharsets.UTF_8.name();
/**
* A collection of UTF-8 decoders that can be concurrently used. We use this
* to avoid creating a new decoder every time we need to decode a string
* while still allowing multi-threaded access.
*/
private static final ConcurrentLinkedQueue DECODERS = new ConcurrentLinkedQueue();
/**
* The number of UTF-8 decoders to create for concurrent access.
*/
private static final int NUM_DECODERS = 10;
static {
try {
for (int i = 0; i < NUM_DECODERS; ++i) {
DECODERS.add(StandardCharsets.UTF_8.newDecoder());
}
}
catch (Exception e) {
throw Throwables.propagate(e);
}
}
}
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