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/**
* 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.hadoop.hbase.nio;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.ReadableByteChannel;
import java.util.List;
import org.apache.hadoop.hbase.io.ByteBuffAllocator.Recycler;
import org.apache.hadoop.hbase.util.ByteBufferUtils;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.ObjectIntPair;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.hbase.thirdparty.io.netty.util.internal.ObjectUtil;
/**
* An abstract class that abstracts out as to how the byte buffers are used, either single or
* multiple. We have this interface because the java's ByteBuffers cannot be sub-classed. This class
* provides APIs similar to the ones provided in java's nio ByteBuffers and allows you to do
* positional reads/writes and relative reads and writes on the underlying BB. In addition to it, we
* have some additional APIs which helps us in the read path.
* The ByteBuff implement {@link HBaseReferenceCounted} interface which mean need to maintains a
* {@link RefCnt} inside, if ensure that the ByteBuff won't be used any more, we must do a
* {@link ByteBuff#release()} to recycle its NIO ByteBuffers. when considering the
* {@link ByteBuff#duplicate()} or {@link ByteBuff#slice()}, releasing either the duplicated one or
* the original one will free its memory, because they share the same NIO ByteBuffers. when you want
* to retain the NIO ByteBuffers even if the origin one called {@link ByteBuff#release()}, you can
* do like this:
*
*
* ByteBuff original = ...;
* ByteBuff dup = original.duplicate();
* dup.retain();
* original.release();
* // The NIO buffers can still be accessed unless you release the duplicated one
* dup.get(...);
* dup.release();
* // Both the original and dup can not access the NIO buffers any more.
*
*/
@InterfaceAudience.Private
public abstract class ByteBuff implements HBaseReferenceCounted {
private static final String REFERENCE_COUNT_NAME = "ReferenceCount";
private static final int NIO_BUFFER_LIMIT = 64 * 1024; // should not be more than 64KB.
protected RefCnt refCnt;
/*************************** Methods for reference count **********************************/
protected void checkRefCount() {
ObjectUtil.checkPositive(refCnt(), REFERENCE_COUNT_NAME);
}
public int refCnt() {
return refCnt.refCnt();
}
@Override
public boolean release() {
return refCnt.release();
}
/******************************* Methods for ByteBuff **************************************/
/**
* @return this ByteBuff's current position
*/
public abstract int position();
/**
* Sets this ByteBuff's position to the given value.
* @param position
* @return this object
*/
public abstract ByteBuff position(int position);
/**
* Jumps the current position of this ByteBuff by specified length.
* @param len the length to be skipped
*/
public abstract ByteBuff skip(int len);
/**
* Jumps back the current position of this ByteBuff by specified length.
* @param len the length to move back
*/
public abstract ByteBuff moveBack(int len);
/**
* @return the total capacity of this ByteBuff.
*/
public abstract int capacity();
/**
* Returns the limit of this ByteBuff
* @return limit of the ByteBuff
*/
public abstract int limit();
/**
* Marks the limit of this ByteBuff.
* @param limit
* @return This ByteBuff
*/
public abstract ByteBuff limit(int limit);
/**
* Rewinds this ByteBuff and the position is set to 0
* @return this object
*/
public abstract ByteBuff rewind();
/**
* Marks the current position of the ByteBuff
* @return this object
*/
public abstract ByteBuff mark();
/**
* Returns bytes from current position till length specified, as a single ByteBuffer. When all
* these bytes happen to be in a single ByteBuffer, which this object wraps, that ByteBuffer item
* as such will be returned. So users are warned not to change the position or limit of this
* returned ByteBuffer. The position of the returned byte buffer is at the begin of the required
* bytes. When the required bytes happen to span across multiple ByteBuffers, this API will copy
* the bytes to a newly created ByteBuffer of required size and return that.
*
* @param length number of bytes required.
* @return bytes from current position till length specified, as a single ByteButter.
*/
public abstract ByteBuffer asSubByteBuffer(int length);
/**
* Returns bytes from given offset till length specified, as a single ByteBuffer. When all these
* bytes happen to be in a single ByteBuffer, which this object wraps, that ByteBuffer item as
* such will be returned (with offset in this ByteBuffer where the bytes starts). So users are
* warned not to change the position or limit of this returned ByteBuffer. When the required bytes
* happen to span across multiple ByteBuffers, this API will copy the bytes to a newly created
* ByteBuffer of required size and return that.
*
* @param offset the offset in this ByteBuff from where the subBuffer should be created
* @param length the length of the subBuffer
* @param pair a pair that will have the bytes from the current position till length specified,
* as a single ByteBuffer and offset in that Buffer where the bytes starts.
* Since this API gets called in a loop we are passing a pair to it which could be created
* outside the loop and the method would set the values on the pair that is passed in by
* the caller. Thus it avoids more object creations that would happen if the pair that is
* returned is created by this method every time.
*/
public abstract void asSubByteBuffer(int offset, int length, ObjectIntPair pair);
/**
* Returns the number of elements between the current position and the
* limit.
* @return the remaining elements in this ByteBuff
*/
public abstract int remaining();
/**
* Returns true if there are elements between the current position and the limt
* @return true if there are elements, false otherwise
*/
public abstract boolean hasRemaining();
/**
* Similar to {@link ByteBuffer}.reset(), ensures that this ByteBuff
* is reset back to last marked position.
* @return This ByteBuff
*/
public abstract ByteBuff reset();
/**
* Returns an ByteBuff which is a sliced version of this ByteBuff. The position, limit and mark
* of the new ByteBuff will be independent than that of the original ByteBuff.
* The content of the new ByteBuff will start at this ByteBuff's current position
* @return a sliced ByteBuff
*/
public abstract ByteBuff slice();
/**
* Returns an ByteBuff which is a duplicate version of this ByteBuff. The
* position, limit and mark of the new ByteBuff will be independent than that
* of the original ByteBuff. The content of the new ByteBuff will start at
* this ByteBuff's current position The position, limit and mark of the new
* ByteBuff would be identical to this ByteBuff in terms of values.
*
* @return a sliced ByteBuff
*/
public abstract ByteBuff duplicate();
/**
* A relative method that returns byte at the current position. Increments the
* current position by the size of a byte.
* @return the byte at the current position
*/
public abstract byte get();
/**
* Fetches the byte at the given index. Does not change position of the underlying ByteBuffers
* @param index
* @return the byte at the given index
*/
public abstract byte get(int index);
/**
* Fetches the byte at the given offset from current position. Does not change position
* of the underlying ByteBuffers.
*
* @param offset
* @return the byte value at the given index.
*/
public abstract byte getByteAfterPosition(int offset);
/**
* Writes a byte to this ByteBuff at the current position and increments the position
* @param b
* @return this object
*/
public abstract ByteBuff put(byte b);
/**
* Writes a byte to this ByteBuff at the given index
* @param index
* @param b
* @return this object
*/
public abstract ByteBuff put(int index, byte b);
/**
* Copies the specified number of bytes from this ByteBuff's current position to
* the byte[]'s offset. Also advances the position of the ByteBuff by the given length.
* @param dst
* @param offset within the current array
* @param length upto which the bytes to be copied
*/
public abstract void get(byte[] dst, int offset, int length);
/**
* Copies the specified number of bytes from this ByteBuff's given position to
* the byte[]'s offset. The position of the ByteBuff remains in the current position only
* @param sourceOffset the offset in this ByteBuff from where the copy should happen
* @param dst the byte[] to which the ByteBuff's content is to be copied
* @param offset within the current array
* @param length upto which the bytes to be copied
*/
public abstract void get(int sourceOffset, byte[] dst, int offset, int length);
/**
* Copies the content from this ByteBuff's current position to the byte array and fills it. Also
* advances the position of the ByteBuff by the length of the byte[].
* @param dst
*/
public abstract void get(byte[] dst);
/**
* Copies from the given byte[] to this ByteBuff
* @param src
* @param offset the position in the byte array from which the copy should be done
* @param length the length upto which the copy should happen
* @return this ByteBuff
*/
public abstract ByteBuff put(byte[] src, int offset, int length);
/**
* Copies from the given byte[] to this ByteBuff
* @param src
* @return this ByteBuff
*/
public abstract ByteBuff put(byte[] src);
/**
* @return true or false if the underlying BB support hasArray
*/
public abstract boolean hasArray();
/**
* @return the byte[] if the underlying BB has single BB and hasArray true
*/
public abstract byte[] array();
/**
* @return the arrayOffset of the byte[] incase of a single BB backed ByteBuff
*/
public abstract int arrayOffset();
/**
* Returns the short value at the current position. Also advances the position by the size
* of short
*
* @return the short value at the current position
*/
public abstract short getShort();
/**
* Fetches the short value at the given index. Does not change position of the
* underlying ByteBuffers. The caller is sure that the index will be after
* the current position of this ByteBuff. So even if the current short does not fit in the
* current item we can safely move to the next item and fetch the remaining bytes forming
* the short
*
* @param index
* @return the short value at the given index
*/
public abstract short getShort(int index);
/**
* Fetches the short value at the given offset from current position. Does not change position
* of the underlying ByteBuffers.
*
* @param offset
* @return the short value at the given index.
*/
public abstract short getShortAfterPosition(int offset);
/**
* Returns the int value at the current position. Also advances the position by the size of int
*
* @return the int value at the current position
*/
public abstract int getInt();
/**
* Writes an int to this ByteBuff at its current position. Also advances the position
* by size of int
* @param value Int value to write
* @return this object
*/
public abstract ByteBuff putInt(int value);
/**
* Fetches the int at the given index. Does not change position of the underlying ByteBuffers.
* Even if the current int does not fit in the
* current item we can safely move to the next item and fetch the remaining bytes forming
* the int
*
* @param index
* @return the int value at the given index
*/
public abstract int getInt(int index);
/**
* Fetches the int value at the given offset from current position. Does not change position
* of the underlying ByteBuffers.
*
* @param offset
* @return the int value at the given index.
*/
public abstract int getIntAfterPosition(int offset);
/**
* Returns the long value at the current position. Also advances the position by the size of long
*
* @return the long value at the current position
*/
public abstract long getLong();
/**
* Writes a long to this ByteBuff at its current position.
* Also advances the position by size of long
* @param value Long value to write
* @return this object
*/
public abstract ByteBuff putLong(long value);
/**
* Fetches the long at the given index. Does not change position of the
* underlying ByteBuffers. The caller is sure that the index will be after
* the current position of this ByteBuff. So even if the current long does not fit in the
* current item we can safely move to the next item and fetch the remaining bytes forming
* the long
*
* @param index
* @return the long value at the given index
*/
public abstract long getLong(int index);
/**
* Fetches the long value at the given offset from current position. Does not change position
* of the underlying ByteBuffers.
*
* @param offset
* @return the long value at the given index.
*/
public abstract long getLongAfterPosition(int offset);
/**
* Copy the content from this ByteBuff to a byte[].
* @return byte[] with the copied contents from this ByteBuff.
*/
public byte[] toBytes() {
return toBytes(0, this.limit());
}
/**
* Copy the content from this ByteBuff to a byte[] based on the given offset and
* length
*
* @param offset
* the position from where the copy should start
* @param length
* the length upto which the copy has to be done
* @return byte[] with the copied contents from this ByteBuff.
*/
public abstract byte[] toBytes(int offset, int length);
/**
* Copies the content from this ByteBuff to a ByteBuffer
* Note : This will advance the position marker of {@code out} but not change the position maker
* for this ByteBuff
* @param out the ByteBuffer to which the copy has to happen
* @param sourceOffset the offset in the ByteBuff from which the elements has
* to be copied
* @param length the length in this ByteBuff upto which the elements has to be copied
*/
public abstract void get(ByteBuffer out, int sourceOffset, int length);
/**
* Copies the contents from the src ByteBuff to this ByteBuff. This will be
* absolute positional copying and
* won't affect the position of any of the buffers.
* @param offset the position in this ByteBuff to which the copy should happen
* @param src the src ByteBuff
* @param srcOffset the offset in the src ByteBuff from where the elements should be read
* @param length the length up to which the copy should happen
*/
public abstract ByteBuff put(int offset, ByteBuff src, int srcOffset, int length);
/**
* Reads bytes from the given channel into this ByteBuff
* @param channel
* @return The number of bytes read from the channel
* @throws IOException
*/
public abstract int read(ReadableByteChannel channel) throws IOException;
/**
* Reads bytes from FileChannel into this ByteBuff
*/
public abstract int read(FileChannel channel, long offset) throws IOException;
/**
* Write this ByteBuff's data into target file
*/
public abstract int write(FileChannel channel, long offset) throws IOException;
/**
* function interface for Channel read
*/
@FunctionalInterface
interface ChannelReader {
int read(ReadableByteChannel channel, ByteBuffer buf, long offset) throws IOException;
}
static final ChannelReader CHANNEL_READER = (channel, buf, offset) -> {
return channel.read(buf);
};
static final ChannelReader FILE_READER = (channel, buf, offset) -> {
return ((FileChannel)channel).read(buf, offset);
};
// static helper methods
public static int read(ReadableByteChannel channel, ByteBuffer buf, long offset,
ChannelReader reader) throws IOException {
if (buf.remaining() <= NIO_BUFFER_LIMIT) {
return reader.read(channel, buf, offset);
}
int originalLimit = buf.limit();
int initialRemaining = buf.remaining();
int ret = 0;
while (buf.remaining() > 0) {
try {
int ioSize = Math.min(buf.remaining(), NIO_BUFFER_LIMIT);
buf.limit(buf.position() + ioSize);
offset += ret;
ret = reader.read(channel, buf, offset);
if (ret < ioSize) {
break;
}
} finally {
buf.limit(originalLimit);
}
}
int nBytes = initialRemaining - buf.remaining();
return (nBytes > 0) ? nBytes : ret;
}
/**
* Read integer from ByteBuff coded in 7 bits and increment position.
* @return Read integer.
*/
public static int readCompressedInt(ByteBuff buf) {
byte b = buf.get();
if ((b & ByteBufferUtils.NEXT_BIT_MASK) != 0) {
return (b & ByteBufferUtils.VALUE_MASK)
+ (readCompressedInt(buf) << ByteBufferUtils.NEXT_BIT_SHIFT);
}
return b & ByteBufferUtils.VALUE_MASK;
}
/**
* Compares two ByteBuffs
*
* @param buf1 the first ByteBuff
* @param o1 the offset in the first ByteBuff from where the compare has to happen
* @param len1 the length in the first ByteBuff upto which the compare has to happen
* @param buf2 the second ByteBuff
* @param o2 the offset in the second ByteBuff from where the compare has to happen
* @param len2 the length in the second ByteBuff upto which the compare has to happen
* @return Positive if buf1 is bigger than buf2, 0 if they are equal, and negative if buf1 is
* smaller than buf2.
*/
public static int compareTo(ByteBuff buf1, int o1, int len1, ByteBuff buf2,
int o2, int len2) {
if (buf1.hasArray() && buf2.hasArray()) {
return Bytes.compareTo(buf1.array(), buf1.arrayOffset() + o1, len1, buf2.array(),
buf2.arrayOffset() + o2, len2);
}
int end1 = o1 + len1;
int end2 = o2 + len2;
for (int i = o1, j = o2; i < end1 && j < end2; i++, j++) {
int a = buf1.get(i) & 0xFF;
int b = buf2.get(j) & 0xFF;
if (a != b) {
return a - b;
}
}
return len1 - len2;
}
/**
* Read long which was written to fitInBytes bytes and increment position.
* @param fitInBytes In how many bytes given long is stored.
* @return The value of parsed long.
*/
public static long readLong(ByteBuff in, final int fitInBytes) {
long tmpLength = 0;
for (int i = 0; i < fitInBytes; ++i) {
tmpLength |= (in.get() & 0xffl) << (8l * i);
}
return tmpLength;
}
public abstract ByteBuffer[] nioByteBuffers();
@Override
public String toString() {
return this.getClass().getSimpleName() + "[pos=" + position() + ", lim=" + limit() +
", cap= " + capacity() + "]";
}
/********************************* ByteBuff wrapper methods ***********************************/
/**
* In theory, the upstream should never construct an ByteBuff by passing an given refCnt, so
* please don't use this public method in other place. Make the method public here because the
* BucketEntry#wrapAsCacheable in hbase-server module will use its own refCnt and ByteBuffers from
* IOEngine to composite an HFileBlock's ByteBuff, we didn't find a better way so keep the public
* way here.
*/
public static ByteBuff wrap(ByteBuffer[] buffers, RefCnt refCnt) {
if (buffers == null || buffers.length == 0) {
throw new IllegalArgumentException("buffers shouldn't be null or empty");
}
return buffers.length == 1 ? new SingleByteBuff(refCnt, buffers[0])
: new MultiByteBuff(refCnt, buffers);
}
public static ByteBuff wrap(ByteBuffer[] buffers, Recycler recycler) {
return wrap(buffers, RefCnt.create(recycler));
}
public static ByteBuff wrap(ByteBuffer[] buffers) {
return wrap(buffers, RefCnt.create());
}
public static ByteBuff wrap(List buffers, Recycler recycler) {
return wrap(buffers, RefCnt.create(recycler));
}
public static ByteBuff wrap(List buffers) {
return wrap(buffers, RefCnt.create());
}
public static ByteBuff wrap(ByteBuffer buffer) {
return wrap(buffer, RefCnt.create());
}
/**
* Make this private because we don't want to expose the refCnt related wrap method to upstream.
*/
private static ByteBuff wrap(List buffers, RefCnt refCnt) {
if (buffers == null || buffers.size() == 0) {
throw new IllegalArgumentException("buffers shouldn't be null or empty");
}
return buffers.size() == 1 ? new SingleByteBuff(refCnt, buffers.get(0))
: new MultiByteBuff(refCnt, buffers.toArray(new ByteBuffer[0]));
}
/**
* Make this private because we don't want to expose the refCnt related wrap method to upstream.
*/
private static ByteBuff wrap(ByteBuffer buffer, RefCnt refCnt) {
return new SingleByteBuff(refCnt, buffer);
}
}
