org.apache.hadoop.fs.VectoredReadUtils Maven / Gradle / Ivy
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* 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.shaded.org.apache.hadoop.fs;
import java.io.EOFException;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.function.IntFunction;
import org.apache.hadoop.shaded.org.apache.hadoop.fs.impl.CombinedFileRange;
import org.apache.hadoop.shaded.org.apache.hadoop.util.Preconditions;
import org.apache.hadoop.shaded.org.apache.hadoop.util.functional.Function4RaisingIOE;
/**
* Utility class which implements helper methods used
* in vectored IO implementation.
*/
public final class VectoredReadUtils {
private static final int TMP_BUFFER_MAX_SIZE = 64 * 1024;
/**
* Validate a single range.
* @param range file range.
* @throws EOFException any EOF Exception.
*/
public static void validateRangeRequest(FileRange range)
throws EOFException {
Preconditions.checkArgument(range.getLength() >= 0, "length is negative");
if (range.getOffset() < 0) {
throw new EOFException("position is negative");
}
}
/**
* Validate a list of vectored read ranges.
* @param ranges list of ranges.
* @throws EOFException any EOF exception.
*/
public static void validateVectoredReadRanges(List ranges)
throws EOFException {
for (FileRange range : ranges) {
validateRangeRequest(range);
}
}
/**
* This is the default implementation which iterates through the ranges
* to read each synchronously, but the intent is that subclasses
* can make more efficient readers.
* The data or exceptions are pushed into {@link FileRange#getData()}.
* @param stream the stream to read the data from
* @param ranges the byte ranges to read
* @param allocate the byte buffer allocation
*/
public static void readVectored(PositionedReadable stream,
List ranges,
IntFunction allocate) {
for (FileRange range: ranges) {
range.setData(readRangeFrom(stream, range, allocate));
}
}
/**
* Synchronously reads a range from the stream dealing with the combinations
* of ByteBuffers buffers and PositionedReadable streams.
* @param stream the stream to read from
* @param range the range to read
* @param allocate the function to allocate ByteBuffers
* @return the CompletableFuture that contains the read data
*/
public static CompletableFuture readRangeFrom(PositionedReadable stream,
FileRange range,
IntFunction allocate) {
CompletableFuture result = new CompletableFuture<>();
try {
ByteBuffer buffer = allocate.apply(range.getLength());
if (stream instanceof ByteBufferPositionedReadable) {
((ByteBufferPositionedReadable) stream).readFully(range.getOffset(),
buffer);
buffer.flip();
} else {
readNonByteBufferPositionedReadable(stream, range, buffer);
}
result.complete(buffer);
} catch (IOException ioe) {
result.completeExceptionally(ioe);
}
return result;
}
private static void readNonByteBufferPositionedReadable(PositionedReadable stream,
FileRange range,
ByteBuffer buffer) throws IOException {
if (buffer.isDirect()) {
readInDirectBuffer(range.getLength(),
buffer,
(position, buffer1, offset, length) -> {
stream.readFully(position, buffer1, offset, length);
return null;
});
buffer.flip();
} else {
stream.readFully(range.getOffset(), buffer.array(),
buffer.arrayOffset(), range.getLength());
}
}
/**
* Read bytes from stream into a byte buffer using an
* intermediate byte array.
* @param length number of bytes to read.
* @param buffer buffer to fill.
* @param operation operation to use for reading data.
* @throws IOException any IOE.
*/
public static void readInDirectBuffer(int length,
ByteBuffer buffer,
Function4RaisingIOE operation) throws IOException {
if (length == 0) {
return;
}
int readBytes = 0;
int position = 0;
int tmpBufferMaxSize = Math.min(TMP_BUFFER_MAX_SIZE, length);
byte[] tmp = new byte[tmpBufferMaxSize];
while (readBytes < length) {
int currentLength = (readBytes + tmpBufferMaxSize) < length ?
tmpBufferMaxSize
: (length - readBytes);
operation.apply(position, tmp, 0, currentLength);
buffer.put(tmp, 0, currentLength);
position = position + currentLength;
readBytes = readBytes + currentLength;
}
}
/**
* Is the given input list.
*
* - already sorted by offset
* - each range is more than minimumSeek apart
* - the start and end of each range is a multiple of chunkSize
*
*
* @param input the list of input ranges.
* @param chunkSize the size of the chunks that the offset and end must align to.
* @param minimumSeek the minimum distance between ranges.
* @return true if we can use the input list as is.
*/
public static boolean isOrderedDisjoint(List input,
int chunkSize,
int minimumSeek) {
long previous = -minimumSeek;
for (FileRange range: input) {
long offset = range.getOffset();
long end = range.getOffset() + range.getLength();
if (offset % chunkSize != 0 ||
end % chunkSize != 0 ||
(offset - previous < minimumSeek)) {
return false;
}
previous = end;
}
return true;
}
/**
* Calculates floor value of offset based on chunk size.
* @param offset file offset.
* @param chunkSize file chunk size.
* @return floor value.
*/
public static long roundDown(long offset, int chunkSize) {
if (chunkSize > 1) {
return offset - (offset % chunkSize);
} else {
return offset;
}
}
/**
* Calculates the ceil value of offset based on chunk size.
* @param offset file offset.
* @param chunkSize file chunk size.
* @return ceil value.
*/
public static long roundUp(long offset, int chunkSize) {
if (chunkSize > 1) {
long next = offset + chunkSize - 1;
return next - (next % chunkSize);
} else {
return offset;
}
}
/**
* Check if the input ranges are overlapping in nature.
* We call two ranges to be overlapping when start offset
* of second is less than the end offset of first.
* End offset is calculated as start offset + length.
* @param input list if input ranges.
* @return true/false based on logic explained above.
*/
public static List validateNonOverlappingAndReturnSortedRanges(
List input) {
if (input.size() <= 1) {
return input;
}
FileRange[] sortedRanges = sortRanges(input);
FileRange prev = sortedRanges[0];
for (int i=1; i input) {
FileRange[] sortedRanges = input.toArray(new FileRange[0]);
Arrays.sort(sortedRanges, Comparator.comparingLong(FileRange::getOffset));
return sortedRanges;
}
/**
* Merge sorted ranges to optimize the access from the underlying file
* system.
* The motivations are that:
*
* - Upper layers want to pass down logical file ranges.
* - Fewer reads have better performance.
* - Applications want callbacks as ranges are read.
* - Some file systems want to round ranges to be at checksum boundaries.
*
*
* @param sortedRanges already sorted list of ranges based on offset.
* @param chunkSize round the start and end points to multiples of chunkSize
* @param minimumSeek the smallest gap that we should seek over in bytes
* @param maxSize the largest combined file range in bytes
* @return the list of sorted CombinedFileRanges that cover the input
*/
public static List mergeSortedRanges(List sortedRanges,
int chunkSize,
int minimumSeek,
int maxSize) {
CombinedFileRange current = null;
List result = new ArrayList<>(sortedRanges.size());
// now merge together the ones that merge
for (FileRange range: sortedRanges) {
long start = roundDown(range.getOffset(), chunkSize);
long end = roundUp(range.getOffset() + range.getLength(), chunkSize);
if (current == null || !current.merge(start, end, range, minimumSeek, maxSize)) {
current = new CombinedFileRange(start, end, range);
result.add(current);
}
}
return result;
}
/**
* Slice the data that was read to the user's request.
* This function assumes that the user's request is completely subsumed by the
* read data. This always creates a new buffer pointing to the same underlying
* data but with its own mark and position fields such that reading one buffer
* can't effect other's mark and position.
* @param readData the buffer with the readData
* @param readOffset the offset in the file for the readData
* @param request the user's request
* @return the readData buffer that is sliced to the user's request
*/
public static ByteBuffer sliceTo(ByteBuffer readData, long readOffset,
FileRange request) {
int offsetChange = (int) (request.getOffset() - readOffset);
int requestLength = request.getLength();
// Create a new buffer that is backed by the original contents
// The buffer will have position 0 and the same limit as the original one
readData = readData.slice();
// Change the offset and the limit of the buffer as the reader wants to see
// only relevant data
readData.position(offsetChange);
readData.limit(offsetChange + requestLength);
// Create a new buffer after the limit change so that only that portion of the data is
// returned to the reader.
readData = readData.slice();
return readData;
}
/**
* private constructor.
*/
private VectoredReadUtils() {
throw new UnsupportedOperationException();
}
}
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