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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.hdfs.util;
import org.apache.hadoop.thirdparty.com.google.common.annotations.VisibleForTesting;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.fs.StorageType;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.hdfs.protocol.LocatedStripedBlock;
import org.apache.hadoop.thirdparty.com.google.common.base.Preconditions;
import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
import org.apache.hadoop.hdfs.protocol.ErasureCodingPolicy;
import org.apache.hadoop.hdfs.DFSStripedOutputStream;
import org.apache.hadoop.security.token.Token;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.nio.ByteBuffer;
import java.util.*;
import java.io.IOException;
import java.util.concurrent.CancellationException;
import java.util.concurrent.CompletionService;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
/**
* When accessing a file in striped layout, operations on logical byte ranges
* in the file need to be mapped to physical byte ranges on block files stored
* on DataNodes. This utility class facilities this mapping by defining and
* exposing a number of striping-related concepts. The most basic ones are
* illustrated in the following diagram. Unless otherwise specified, all
* range-related calculations are inclusive (the end offset of the previous
* range should be 1 byte lower than the start offset of the next one).
*/
/*
* | <---- Block Group ----> | <- Block Group: logical unit composing
* | | striped HDFS files.
* blk_0 blk_1 blk_2 <- Internal Blocks: each internal block
* | | | represents a physically stored local
* v v v block file
* +------+ +------+ +------+
* |cell_0| |cell_1| |cell_2| <- {@link StripingCell} represents the
* +------+ +------+ +------+ logical order that a Block Group should
* |cell_3| |cell_4| |cell_5| be accessed: cell_0, cell_1, ...
* +------+ +------+ +------+
* |cell_6| |cell_7| |cell_8|
* +------+ +------+ +------+
* |cell_9|
* +------+ <- A cell contains cellSize bytes of data
*/
@InterfaceAudience.Private
public class StripedBlockUtil {
public static final Logger LOG =
LoggerFactory.getLogger(StripedBlockUtil.class);
/**
* Struct holding the read statistics. This is used when reads are done
* asynchronously, to allow the async threads return the read stats and let
* the main reading thread to update the stats. This is important for the
* ThreadLocal stats for the main reading thread to be correct.
*/
public static class BlockReadStats {
private final int bytesRead;
private final boolean isShortCircuit;
private final int networkDistance;
public BlockReadStats(int numBytesRead, boolean shortCircuit,
int distance) {
bytesRead = numBytesRead;
isShortCircuit = shortCircuit;
networkDistance = distance;
}
public int getBytesRead() {
return bytesRead;
}
public boolean isShortCircuit() {
return isShortCircuit;
}
public int getNetworkDistance() {
return networkDistance;
}
@Override
public String toString() {
final StringBuilder sb = new StringBuilder();
sb.append("bytesRead=").append(bytesRead)
.append(',')
.append("isShortCircuit=").append(isShortCircuit)
.append(',')
.append("networkDistance=").append(networkDistance);
return sb.toString();
}
}
/**
* This method parses a striped block group into individual blocks.
*
* @param bg The striped block group
* @param cellSize The size of a striping cell
* @param dataBlkNum The number of data blocks
* @return An array containing the blocks in the group
*/
public static LocatedBlock[] parseStripedBlockGroup(LocatedStripedBlock bg,
int cellSize, int dataBlkNum, int parityBlkNum) {
int locatedBGSize = bg.getBlockIndices().length;
LocatedBlock[] lbs = new LocatedBlock[dataBlkNum + parityBlkNum];
for (short i = 0; i < locatedBGSize; i++) {
final int idx = bg.getBlockIndices()[i];
// for now we do not use redundant replica of an internal block
if (idx < (dataBlkNum + parityBlkNum) && lbs[idx] == null) {
lbs[idx] = constructInternalBlock(bg, i, cellSize,
dataBlkNum, idx);
}
}
return lbs;
}
/**
* This method creates an internal block at the given index of a block group.
*
* @param idxInReturnedLocs The index in the stored locations in the
* {@link LocatedStripedBlock} object
* @param idxInBlockGroup The logical index in the striped block group
* @return The constructed internal block
*/
public static LocatedBlock constructInternalBlock(LocatedStripedBlock bg,
int idxInReturnedLocs, int cellSize, int dataBlkNum,
int idxInBlockGroup) {
final ExtendedBlock blk = constructInternalBlock(
bg.getBlock(), cellSize, dataBlkNum, idxInBlockGroup);
final LocatedBlock locatedBlock;
if (idxInReturnedLocs < bg.getLocations().length) {
locatedBlock = new LocatedBlock(blk,
new DatanodeInfo[]{bg.getLocations()[idxInReturnedLocs]},
new String[]{bg.getStorageIDs()[idxInReturnedLocs]},
new StorageType[]{bg.getStorageTypes()[idxInReturnedLocs]},
bg.getStartOffset(), bg.isCorrupt(), null);
} else {
locatedBlock = new LocatedBlock(blk, null, null, null,
bg.getStartOffset(), bg.isCorrupt(), null);
}
Token[] blockTokens = bg.getBlockTokens();
if (idxInReturnedLocs < blockTokens.length) {
locatedBlock.setBlockToken(blockTokens[idxInReturnedLocs]);
}
return locatedBlock;
}
public static ExtendedBlock constructInternalBlock(
ExtendedBlock blockGroup, ErasureCodingPolicy ecPolicy,
int idxInBlockGroup) {
return constructInternalBlock(blockGroup, ecPolicy.getCellSize(),
ecPolicy.getNumDataUnits(), idxInBlockGroup);
}
/**
* This method creates an internal {@link ExtendedBlock} at the given index
* of a block group.
*/
public static ExtendedBlock constructInternalBlock(ExtendedBlock blockGroup,
int cellSize, int dataBlkNum, int idxInBlockGroup) {
ExtendedBlock block = new ExtendedBlock(blockGroup);
block.setBlockId(blockGroup.getBlockId() + idxInBlockGroup);
block.setNumBytes(getInternalBlockLength(blockGroup.getNumBytes(),
cellSize, dataBlkNum, idxInBlockGroup));
return block;
}
public static long getInternalBlockLength(long dataSize,
ErasureCodingPolicy ecPolicy,
int idxInBlockGroup) {
return getInternalBlockLength(dataSize, ecPolicy.getCellSize(),
ecPolicy.getNumDataUnits(), idxInBlockGroup);
}
/**
* Get the size of an internal block at the given index of a block group.
*
* @param dataSize Size of the block group only counting data blocks
* @param cellSize The size of a striping cell
* @param numDataBlocks The number of data blocks
* @param idxInBlockGroup The logical index in the striped block group
* @return The size of the internal block at the specified index
*/
public static long getInternalBlockLength(long dataSize,
int cellSize, int numDataBlocks, int idxInBlockGroup) {
Preconditions.checkArgument(dataSize >= 0);
Preconditions.checkArgument(cellSize > 0);
Preconditions.checkArgument(numDataBlocks > 0);
Preconditions.checkArgument(idxInBlockGroup >= 0);
// Size of each stripe (only counting data blocks)
final int stripeSize = cellSize * numDataBlocks;
// If block group ends at stripe boundary, each internal block has an equal
// share of the group
final int lastStripeDataLen = (int)(dataSize % stripeSize);
if (lastStripeDataLen == 0) {
return dataSize / numDataBlocks;
}
final int numStripes = (int) ((dataSize - 1) / stripeSize + 1);
return (numStripes - 1L)*cellSize
+ lastCellSize(lastStripeDataLen, cellSize,
numDataBlocks, idxInBlockGroup);
}
/**
* Compute the safe length given the internal block lengths.
*
* @param ecPolicy The EC policy used for the block group
* @param blockLens The lengths of internal blocks
* @return The safe length
*/
public static long getSafeLength(ErasureCodingPolicy ecPolicy,
long[] blockLens) {
final int cellSize = ecPolicy.getCellSize();
final int dataBlkNum = ecPolicy.getNumDataUnits();
Preconditions.checkArgument(blockLens.length >= dataBlkNum);
final int stripeSize = dataBlkNum * cellSize;
long[] cpy = Arrays.copyOf(blockLens, blockLens.length);
Arrays.sort(cpy);
// full stripe is a stripe has at least dataBlkNum full cells.
// lastFullStripeIdx is the index of the last full stripe.
int lastFullStripeIdx =
(int) (cpy[cpy.length - dataBlkNum] / cellSize);
return lastFullStripeIdx * stripeSize; // return the safeLength
// TODO: Include lastFullStripeIdx+1 stripe in safeLength, if there exists
// such a stripe (and it must be partial).
}
private static int lastCellSize(int size, int cellSize, int numDataBlocks,
int i) {
if (i < numDataBlocks) {
// parity block size (i.e. i >= numDataBlocks) is the same as
// the first data block size (i.e. i = 0).
size -= i*cellSize;
if (size < 0) {
size = 0;
}
}
return size > cellSize? cellSize: size;
}
/**
* Given a byte's offset in an internal block, calculate the offset in
* the block group.
*/
public static long offsetInBlkToOffsetInBG(int cellSize, int dataBlkNum,
long offsetInBlk, int idxInBlockGroup) {
int cellIdxInBlk = (int) (offsetInBlk / cellSize);
return cellIdxInBlk * cellSize * dataBlkNum // n full stripes before offset
+ idxInBlockGroup * cellSize // m full cells before offset
+ offsetInBlk % cellSize; // partial cell
}
/**
* Get the next completed striped read task.
*
* @return {@link StripingChunkReadResult} indicating the status of the read
* task succeeded, and the block index of the task. If the method
* times out without getting any completed read tasks, -1 is
* returned as block index.
* @throws InterruptedException
*/
public static StripingChunkReadResult getNextCompletedStripedRead(
CompletionService readService,
Map, Integer> futures,
final long timeoutMillis) throws InterruptedException {
Preconditions.checkArgument(!futures.isEmpty());
Future future = null;
try {
if (timeoutMillis > 0) {
future = readService.poll(timeoutMillis, TimeUnit.MILLISECONDS);
} else {
future = readService.take();
}
if (future != null) {
final BlockReadStats stats = future.get();
return new StripingChunkReadResult(futures.remove(future),
StripingChunkReadResult.SUCCESSFUL, stats);
} else {
return new StripingChunkReadResult(StripingChunkReadResult.TIMEOUT);
}
} catch (ExecutionException e) {
LOG.debug("Exception during striped read task", e);
return new StripingChunkReadResult(futures.remove(future),
StripingChunkReadResult.FAILED);
} catch (CancellationException e) {
LOG.debug("Exception during striped read task", e);
return new StripingChunkReadResult(futures.remove(future),
StripingChunkReadResult.CANCELLED);
}
}
/**
* Get the total usage of the striped blocks, which is the total of data
* blocks and parity blocks.
*
* @param numDataBlkBytes
* Size of the block group only counting data blocks
* @param dataBlkNum
* The number of data blocks
* @param parityBlkNum
* The number of parity blocks
* @param cellSize
* The size of a striping cell
* @return The total usage of data blocks and parity blocks
*/
public static long spaceConsumedByStripedBlock(long numDataBlkBytes,
int dataBlkNum, int parityBlkNum, int cellSize) {
int parityIndex = dataBlkNum + 1;
long numParityBlkBytes = getInternalBlockLength(numDataBlkBytes, cellSize,
dataBlkNum, parityIndex) * parityBlkNum;
return numDataBlkBytes + numParityBlkBytes;
}
/**
* Similar functionality with {@link #divideByteRangeIntoStripes}, but is used
* by stateful read and uses ByteBuffer as reading target buffer. Besides the
* read range is within a single stripe thus the calculation logic is simpler.
*/
public static AlignedStripe[] divideOneStripe(ErasureCodingPolicy ecPolicy,
int cellSize, LocatedStripedBlock blockGroup, long rangeStartInBlockGroup,
long rangeEndInBlockGroup, ByteBuffer buf) {
final int dataBlkNum = ecPolicy.getNumDataUnits();
// Step 1: map the byte range to StripingCells
StripingCell[] cells = getStripingCellsOfByteRange(ecPolicy, cellSize,
blockGroup, rangeStartInBlockGroup, rangeEndInBlockGroup);
// Step 2: get the unmerged ranges on each internal block
VerticalRange[] ranges = getRangesForInternalBlocks(ecPolicy, cellSize,
cells);
// Step 3: merge into stripes
AlignedStripe[] stripes = mergeRangesForInternalBlocks(ecPolicy, ranges,
blockGroup, cellSize);
// Step 4: calculate each chunk's position in destination buffer. Since the
// whole read range is within a single stripe, the logic is simpler here.
int bufOffset =
(int) (rangeStartInBlockGroup % ((long) cellSize * dataBlkNum));
for (StripingCell cell : cells) {
long cellStart = cell.idxInInternalBlk * cellSize + cell.offset;
long cellEnd = cellStart + cell.size - 1;
for (AlignedStripe s : stripes) {
long stripeEnd = s.getOffsetInBlock() + s.getSpanInBlock() - 1;
long overlapStart = Math.max(cellStart, s.getOffsetInBlock());
long overlapEnd = Math.min(cellEnd, stripeEnd);
int overLapLen = (int) (overlapEnd - overlapStart + 1);
if (overLapLen > 0) {
Preconditions.checkState(s.chunks[cell.idxInStripe] == null);
final int pos = (int) (bufOffset + overlapStart - cellStart);
buf.position(pos);
buf.limit(pos + overLapLen);
s.chunks[cell.idxInStripe] = new StripingChunk(buf.slice());
}
}
bufOffset += cell.size;
}
// Step 5: prepare ALLZERO blocks
prepareAllZeroChunks(blockGroup, stripes, cellSize, dataBlkNum);
return stripes;
}
/**
* This method divides a requested byte range into an array of inclusive
* {@link AlignedStripe}.
* @param ecPolicy The codec policy for the file, which carries the numbers
* of data / parity blocks
* @param cellSize Cell size of stripe
* @param blockGroup The striped block group
* @param rangeStartInBlockGroup The byte range's start offset in block group
* @param rangeEndInBlockGroup The byte range's end offset in block group
* @param buf Destination buffer of the read operation for the byte range
*
* At most 5 stripes will be generated from each logical range, as
* demonstrated in the header of {@link AlignedStripe}.
*/
public static AlignedStripe[] divideByteRangeIntoStripes(
ErasureCodingPolicy ecPolicy,
int cellSize, LocatedStripedBlock blockGroup,
long rangeStartInBlockGroup, long rangeEndInBlockGroup, ByteBuffer buf) {
// Step 0: analyze range and calculate basic parameters
final int dataBlkNum = ecPolicy.getNumDataUnits();
// Step 1: map the byte range to StripingCells
StripingCell[] cells = getStripingCellsOfByteRange(ecPolicy, cellSize,
blockGroup, rangeStartInBlockGroup, rangeEndInBlockGroup);
// Step 2: get the unmerged ranges on each internal block
VerticalRange[] ranges = getRangesForInternalBlocks(ecPolicy, cellSize,
cells);
// Step 3: merge into at most 5 stripes
AlignedStripe[] stripes = mergeRangesForInternalBlocks(ecPolicy, ranges,
blockGroup, cellSize);
// Step 4: calculate each chunk's position in destination buffer
calcualteChunkPositionsInBuf(cellSize, stripes, cells, buf);
// Step 5: prepare ALLZERO blocks
prepareAllZeroChunks(blockGroup, stripes, cellSize, dataBlkNum);
return stripes;
}
/**
* Map the logical byte range to a set of inclusive {@link StripingCell}
* instances, each representing the overlap of the byte range to a cell
* used by {@link DFSStripedOutputStream} in encoding.
*/
@VisibleForTesting
private static StripingCell[] getStripingCellsOfByteRange(
ErasureCodingPolicy ecPolicy,
int cellSize, LocatedStripedBlock blockGroup,
long rangeStartInBlockGroup, long rangeEndInBlockGroup) {
Preconditions.checkArgument(
rangeStartInBlockGroup <= rangeEndInBlockGroup &&
rangeEndInBlockGroup < blockGroup.getBlockSize(),
"start=%s end=%s blockSize=%s", rangeStartInBlockGroup,
rangeEndInBlockGroup, blockGroup.getBlockSize());
long len = rangeEndInBlockGroup - rangeStartInBlockGroup + 1;
int firstCellIdxInBG = (int) (rangeStartInBlockGroup / cellSize);
int lastCellIdxInBG = (int) (rangeEndInBlockGroup / cellSize);
int numCells = lastCellIdxInBG - firstCellIdxInBG + 1;
StripingCell[] cells = new StripingCell[numCells];
final int firstCellOffset = (int) (rangeStartInBlockGroup % cellSize);
final int firstCellSize =
(int) Math.min(cellSize - (rangeStartInBlockGroup % cellSize), len);
cells[0] = new StripingCell(ecPolicy, firstCellSize, firstCellIdxInBG,
firstCellOffset);
if (lastCellIdxInBG != firstCellIdxInBG) {
final int lastCellSize = (int) (rangeEndInBlockGroup % cellSize) + 1;
cells[numCells - 1] = new StripingCell(ecPolicy, lastCellSize,
lastCellIdxInBG, 0);
}
for (int i = 1; i < numCells - 1; i++) {
cells[i] = new StripingCell(ecPolicy, cellSize, i + firstCellIdxInBG, 0);
}
return cells;
}
/**
* Given a logical byte range, mapped to each {@link StripingCell}, calculate
* the physical byte range (inclusive) on each stored internal block.
*/
@VisibleForTesting
private static VerticalRange[] getRangesForInternalBlocks(
ErasureCodingPolicy ecPolicy,
int cellSize, StripingCell[] cells) {
int dataBlkNum = ecPolicy.getNumDataUnits();
int parityBlkNum = ecPolicy.getNumParityUnits();
VerticalRange[] ranges = new VerticalRange[dataBlkNum + parityBlkNum];
long earliestStart = Long.MAX_VALUE;
long latestEnd = -1;
for (StripingCell cell : cells) {
// iterate through all cells and update the list of StripeRanges
if (ranges[cell.idxInStripe] == null) {
ranges[cell.idxInStripe] = new VerticalRange(
cell.idxInInternalBlk * cellSize + cell.offset, cell.size);
} else {
ranges[cell.idxInStripe].spanInBlock += cell.size;
}
VerticalRange range = ranges[cell.idxInStripe];
if (range.offsetInBlock < earliestStart) {
earliestStart = range.offsetInBlock;
}
if (range.offsetInBlock + range.spanInBlock - 1 > latestEnd) {
latestEnd = range.offsetInBlock + range.spanInBlock - 1;
}
}
// Each parity block should be fetched at maximum range of all data blocks
for (int i = dataBlkNum; i < dataBlkNum + parityBlkNum; i++) {
ranges[i] = new VerticalRange(earliestStart,
latestEnd - earliestStart + 1);
}
return ranges;
}
/**
* Merge byte ranges on each internal block into a set of inclusive
* {@link AlignedStripe} instances.
*/
private static AlignedStripe[] mergeRangesForInternalBlocks(
ErasureCodingPolicy ecPolicy, VerticalRange[] ranges,
LocatedStripedBlock blockGroup, int cellSize) {
int dataBlkNum = ecPolicy.getNumDataUnits();
int parityBlkNum = ecPolicy.getNumParityUnits();
List stripes = new ArrayList<>();
SortedSet stripePoints = new TreeSet<>();
for (VerticalRange r : ranges) {
if (r != null) {
stripePoints.add(r.offsetInBlock);
stripePoints.add(r.offsetInBlock + r.spanInBlock);
}
}
// Add block group last cell offset in stripePoints if it is fall in to read
// offset range.
int lastCellIdxInBG = (int) (blockGroup.getBlockSize() / cellSize);
int idxInInternalBlk = lastCellIdxInBG / ecPolicy.getNumDataUnits();
long lastCellEndOffset = (idxInInternalBlk * (long)cellSize)
+ (blockGroup.getBlockSize() % cellSize);
if (stripePoints.first() < lastCellEndOffset
&& stripePoints.last() > lastCellEndOffset) {
stripePoints.add(lastCellEndOffset);
}
long prev = -1;
for (long point : stripePoints) {
if (prev >= 0) {
stripes.add(new AlignedStripe(prev, point - prev,
dataBlkNum + parityBlkNum));
}
prev = point;
}
return stripes.toArray(new AlignedStripe[stripes.size()]);
}
/**
* Cell indexing convention defined in {@link StripingCell}.
*/
private static void calcualteChunkPositionsInBuf(int cellSize,
AlignedStripe[] stripes, StripingCell[] cells, ByteBuffer buf) {
/*
* | <--------------- AlignedStripe --------------->|
*
* |<- length_0 ->|<-- length_1 -->|<- length_2 ->|
* +------------------+------------------+----------------+
* | cell_0_0_0 | cell_3_1_0 | cell_6_2_0 | <- blk_0
* +------------------+------------------+----------------+
* _/ \_______________________
* | |
* v offset_0 v offset_1
* +----------------------------------------------------------+
* | cell_0_0_0 | cell_1_0_1 and cell_2_0_2 |cell_3_1_0 ...| <- buf
* | (partial) | (from blk_1 and blk_2) | |
* +----------------------------------------------------------+
*/
int done = 0;
for (StripingCell cell : cells) {
long cellStart = cell.idxInInternalBlk * cellSize + cell.offset;
long cellEnd = cellStart + cell.size - 1;
StripingChunk chunk;
for (AlignedStripe s : stripes) {
long stripeEnd = s.getOffsetInBlock() + s.getSpanInBlock() - 1;
long overlapStart = Math.max(cellStart, s.getOffsetInBlock());
long overlapEnd = Math.min(cellEnd, stripeEnd);
int overLapLen = (int) (overlapEnd - overlapStart + 1);
if (overLapLen <= 0) {
continue;
}
chunk = s.chunks[cell.idxInStripe];
if (chunk == null) {
chunk = new StripingChunk();
s.chunks[cell.idxInStripe] = chunk;
}
chunk.getChunkBuffer().addSlice(buf,
(int) (done + overlapStart - cellStart), overLapLen);
}
done += cell.size;
}
}
/**
* If a {@link StripingChunk} maps to a byte range beyond an internal block's
* size, the chunk should be treated as zero bytes in decoding.
*/
private static void prepareAllZeroChunks(LocatedStripedBlock blockGroup,
AlignedStripe[] stripes, int cellSize, int dataBlkNum) {
for (AlignedStripe s : stripes) {
for (int i = 0; i < dataBlkNum; i++) {
long internalBlkLen = getInternalBlockLength(blockGroup.getBlockSize(),
cellSize, dataBlkNum, i);
if (internalBlkLen <= s.getOffsetInBlock()) {
Preconditions.checkState(s.chunks[i] == null);
s.chunks[i] = new StripingChunk(StripingChunk.ALLZERO);
}
}
}
}
/**
* Cell is the unit of encoding used in {@link DFSStripedOutputStream}. This
* size impacts how a logical offset in the file or block group translates
* to physical byte offset in a stored internal block. The StripingCell util
* class facilitates this calculation. Each StripingCell is inclusive with
* its start and end offsets -- e.g., the end logical offset of cell_0_0_0
* should be 1 byte lower than the start logical offset of cell_1_0_1.
*
* A StripingCell is a special instance of {@link StripingChunk} whose offset
* and size align with the cell used when writing data.
* TODO: consider parity cells
*/
/* | <------- Striped Block Group -------> |
* blk_0 blk_1 blk_2
* | | |
* v v v
* +----------+ +----------+ +----------+
* |cell_0_0_0| |cell_1_0_1| |cell_2_0_2|
* +----------+ +----------+ +----------+
* |cell_3_1_0| |cell_4_1_1| |cell_5_1_2| <- {@link #idxInBlkGroup} = 5
* +----------+ +----------+ +----------+ {@link #idxInInternalBlk} = 1
* {@link #idxInStripe} = 2
*/
@VisibleForTesting
public static class StripingCell {
final ErasureCodingPolicy ecPolicy;
/** Logical order in a block group, used when doing I/O to a block group. */
private final long idxInBlkGroup;
private final long idxInInternalBlk;
private final int idxInStripe;
/**
* When a logical byte range is mapped to a set of cells, it might
* partially overlap with the first and last cells. This field and the
* {@link #size} variable represent the start offset and size of the
* overlap.
*/
private final long offset;
private final int size;
StripingCell(ErasureCodingPolicy ecPolicy, int cellSize, long idxInBlkGroup,
long offset) {
this.ecPolicy = ecPolicy;
this.idxInBlkGroup = idxInBlkGroup;
this.idxInInternalBlk = idxInBlkGroup / ecPolicy.getNumDataUnits();
this.idxInStripe = (int)(idxInBlkGroup -
this.idxInInternalBlk * ecPolicy.getNumDataUnits());
this.offset = offset;
this.size = cellSize;
}
int getIdxInStripe() {
return idxInStripe;
}
@Override
public String toString() {
return String.format("StripingCell(idxInBlkGroup=%d, " +
"idxInInternalBlk=%d, idxInStrip=%d, offset=%d, size=%d)",
idxInBlkGroup, idxInInternalBlk, idxInStripe, offset, size);
}
}
/**
* Given a requested byte range on a striped block group, an AlignedStripe
* represents an inclusive {@link VerticalRange} that is aligned with both
* the byte range and boundaries of all internal blocks. As illustrated in
* the diagram, any given byte range on a block group leads to 1~5
* AlignedStripe's.
*
* An AlignedStripe is the basic unit of reading from a striped block group,
* because within the AlignedStripe, all internal blocks can be processed in
* a uniform manner.
*
* The coverage of an AlignedStripe on an internal block is represented as a
* {@link StripingChunk}.
*
* To simplify the logic of reading a logical byte range from a block group,
* a StripingChunk is either completely in the requested byte range or
* completely outside the requested byte range.
*/
/*
* |<-------- Striped Block Group -------->|
* blk_0 blk_1 blk_2 blk_3 blk_4
* +----+ | +----+ +----+
* |full| | | | | | <- AlignedStripe0:
* +----+ |~~~~| | |~~~~| |~~~~| 1st cell is partial
* |part| | | | | | | | <- AlignedStripe1: byte range
* +----+ +----+ +----+ | |~~~~| |~~~~| doesn't start at 1st block
* |full| |full| |full| | | | | |
* |cell| |cell| |cell| | | | | | <- AlignedStripe2 (full stripe)
* | | | | | | | | | | |
* +----+ +----+ +----+ | |~~~~| |~~~~|
* |full| |part| | | | | | <- AlignedStripe3: byte range
* |~~~~| +----+ | |~~~~| |~~~~| doesn't end at last block
* | | | | | | | <- AlignedStripe4:
* +----+ | +----+ +----+ last cell is partial
* |
* <---- data blocks ----> | <--- parity -->
*/
public static class AlignedStripe {
public VerticalRange range;
/** status of each chunk in the stripe. */
public final StripingChunk[] chunks;
public int fetchedChunksNum = 0;
public int missingChunksNum = 0;
public AlignedStripe(long offsetInBlock, long length, int width) {
Preconditions.checkArgument(offsetInBlock >= 0 && length >= 0,
"OffsetInBlock(%s) and length(%s) must be non-negative",
offsetInBlock, length);
this.range = new VerticalRange(offsetInBlock, length);
this.chunks = new StripingChunk[width];
}
public boolean include(long pos) {
return range.include(pos);
}
public long getOffsetInBlock() {
return range.offsetInBlock;
}
public long getSpanInBlock() {
return range.spanInBlock;
}
@Override
public String toString() {
return "AlignedStripe(Offset=" + range.offsetInBlock + ", length=" +
range.spanInBlock + ", fetchedChunksNum=" + fetchedChunksNum +
", missingChunksNum=" + missingChunksNum + ")";
}
}
/**
* A simple utility class representing an arbitrary vertical inclusive range
* starting at {@link #offsetInBlock} and lasting for {@link #spanInBlock}
* bytes in an internal block. Note that VerticalRange doesn't necessarily
* align with {@link StripingCell}.
*/
/*
* |<- Striped Block Group ->|
* blk_0
* |
* v
* +-----+
* |~~~~~| <-- {@link #offsetInBlock}
* | | ^
* | | |
* | | | {@link #spanInBlock}
* | | v
* |~~~~~| ---
* | |
* +-----+
*/
public static class VerticalRange {
/** start offset in the block group (inclusive). */
public long offsetInBlock;
/** length of the stripe range. */
public long spanInBlock;
public VerticalRange(long offsetInBlock, long length) {
Preconditions.checkArgument(offsetInBlock >= 0 && length >= 0,
"OffsetInBlock(%s) and length(%s) must be non-negative",
offsetInBlock, length);
this.offsetInBlock = offsetInBlock;
this.spanInBlock = length;
}
/** whether a position is in the range. */
public boolean include(long pos) {
return pos >= offsetInBlock && pos < offsetInBlock + spanInBlock;
}
@Override
public String toString() {
return String.format("VerticalRange(offsetInBlock=%d, spanInBlock=%d)",
this.offsetInBlock, this.spanInBlock);
}
}
/**
* Indicates the coverage of an {@link AlignedStripe} on an internal block,
* and the state of the chunk in the context of the read request.
*/
/* |<---------------- Striped Block Group --------------->|
* blk_0 blk_1 blk_2 blk_3 blk_4
* +---------+ | +----+ +----+
* null null |REQUESTED| | |null| |null| <- AlignedStripe0
* +---------+ |---------| | |----| |----|
* null |REQUESTED| |REQUESTED| | |null| |null| <- AlignedStripe1
* +---------+ +---------+ +---------+ | +----+ +----+
* |REQUESTED| |REQUESTED| ALLZERO | |null| |null| <- AlignedStripe2
* +---------+ +---------+ | +----+ +----+
* <----------- data blocks ------------> | <--- parity -->
*/
public static class StripingChunk {
/** Chunk has been successfully fetched */
public static final int FETCHED = 0x01;
/** Chunk has encountered failed when being fetched */
public static final int MISSING = 0x02;
/** Chunk being fetched (fetching task is in-flight) */
public static final int PENDING = 0x04;
/**
* Chunk is requested either by application or for decoding, need to
* schedule read task
*/
public static final int REQUESTED = 0X08;
/**
* Internal block is short and has no overlap with chunk. Chunk considered
* all-zero bytes in codec calculations.
*/
public static final int ALLZERO = 0X0f;
/**
* If a chunk is completely in requested range, the state transition is:
* REQUESTED (when AlignedStripe created) -> PENDING ->
* {FETCHED | MISSING}
* If a chunk is completely outside requested range (including parity
* chunks), state transition is:
* null (AlignedStripe created) ->REQUESTED (upon failure) ->
* PENDING ...
*/
public int state = REQUESTED;
private final ChunkByteBuffer chunkBuffer;
private final ByteBuffer byteBuffer;
public StripingChunk() {
this.chunkBuffer = new ChunkByteBuffer();
byteBuffer = null;
}
public StripingChunk(ByteBuffer buf) {
this.chunkBuffer = null;
this.byteBuffer = buf;
}
public StripingChunk(int state) {
this.chunkBuffer = null;
this.byteBuffer = null;
this.state = state;
}
public boolean useByteBuffer(){
return byteBuffer != null;
}
public boolean useChunkBuffer() {
return chunkBuffer != null;
}
public ByteBuffer getByteBuffer() {
assert byteBuffer != null;
return byteBuffer;
}
public ChunkByteBuffer getChunkBuffer() {
assert chunkBuffer != null;
return chunkBuffer;
}
}
/**
* A utility to manage ByteBuffer slices for a reader.
*/
public static class ChunkByteBuffer {
private final List slices;
ChunkByteBuffer() {
this.slices = new ArrayList<>();
}
public void addSlice(ByteBuffer buffer, int offset, int len) {
ByteBuffer tmp = buffer.duplicate();
tmp.position(buffer.position() + offset);
tmp.limit(buffer.position() + offset + len);
slices.add(tmp.slice());
}
public ByteBuffer getSlice(int i) {
return slices.get(i);
}
public List getSlices() {
return slices;
}
/**
* Note: target will be ready-to-read state after the call.
*/
public void copyTo(ByteBuffer target) {
for (ByteBuffer slice : slices) {
slice.flip();
target.put(slice);
}
target.flip();
}
public void copyFrom(ByteBuffer src) {
ByteBuffer tmp;
int len;
for (ByteBuffer slice : slices) {
len = slice.remaining();
tmp = src.duplicate();
tmp.limit(tmp.position() + len);
slice.put(tmp);
src.position(src.position() + len);
}
}
}
/**
* This class represents result from a striped read request.
* If the task was successful or the internal computation failed,
* an index is also returned.
*/
public static class StripingChunkReadResult {
public static final int SUCCESSFUL = 0x01;
public static final int FAILED = 0x02;
public static final int TIMEOUT = 0x04;
public static final int CANCELLED = 0x08;
public final int index;
public final int state;
private final BlockReadStats readStats;
public StripingChunkReadResult(int state) {
Preconditions.checkArgument(state == TIMEOUT,
"Only timeout result should return negative index.");
this.index = -1;
this.state = state;
this.readStats = null;
}
public StripingChunkReadResult(int index, int state) {
this(index, state, null);
}
public StripingChunkReadResult(int index, int state, BlockReadStats stats) {
Preconditions.checkArgument(state != TIMEOUT,
"Timeout result should return negative index.");
this.index = index;
this.state = state;
this.readStats = stats;
}
public BlockReadStats getReadStats() {
return readStats;
}
@Override
public String toString() {
return "(index=" + index + ", state =" + state + ", readStats ="
+ readStats + ")";
}
}
/** Used to indicate the buffered data's range in the block group. */
public static class StripeRange {
/** start offset in the block group (inclusive). */
final long offsetInBlock;
/** length of the stripe range. */
final long length;
public StripeRange(long offsetInBlock, long length) {
Preconditions.checkArgument(offsetInBlock >= 0 && length >= 0,
"Offset(%s) and length(%s) must be non-negative", offsetInBlock,
length);
this.offsetInBlock = offsetInBlock;
this.length = length;
}
public boolean include(long pos) {
return pos >= offsetInBlock && pos < offsetInBlock + length;
}
public long getLength() {
return length;
}
@Override
public String toString() {
return String.format("StripeRange(offsetInBlock=%d, length=%d)",
offsetInBlock, length);
}
}
/**
* Check if the information such as IDs and generation stamps in block-i
* match the block group.
*/
public static void checkBlocks(ExtendedBlock blockGroup,
int i, ExtendedBlock blocki) throws IOException {
if (!blocki.getBlockPoolId().equals(blockGroup.getBlockPoolId())) {
throw new IOException("Block pool IDs mismatched: block" + i + "="
+ blocki + ", expected block group=" + blockGroup);
}
if (blocki.getBlockId() - i != blockGroup.getBlockId()) {
throw new IOException("Block IDs mismatched: block" + i + "="
+ blocki + ", expected block group=" + blockGroup);
}
if (blocki.getGenerationStamp() != blockGroup.getGenerationStamp()) {
throw new IOException("Generation stamps mismatched: block" + i + "="
+ blocki + ", expected block group=" + blockGroup);
}
}
public static int getBlockIndex(Block reportedBlock) {
long BLOCK_GROUP_INDEX_MASK = 15;
return (int) (reportedBlock.getBlockId() &
BLOCK_GROUP_INDEX_MASK);
}
}
