/**
*
* 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.regionserver;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.SortedSet;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
import org.apache.commons.logging.Log;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellComparator;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.KeyValueUtil;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.ClassSize;
import com.google.common.annotations.VisibleForTesting;
/**
* This is an abstraction of a segment maintained in a memstore, e.g., the active
* cell set or its snapshot.
*
* This abstraction facilitates the management of the compaction pipeline and the shifts of these
* segments from active set to snapshot set in the default implementation.
*/
@InterfaceAudience.Private
public abstract class Segment {
public final static long FIXED_OVERHEAD = ClassSize.align(ClassSize.OBJECT
+ 6 * ClassSize.REFERENCE // cellSet, comparator, memStoreLAB, dataSize,
// heapSize, and timeRangeTracker
+ Bytes.SIZEOF_LONG // minSequenceId
+ Bytes.SIZEOF_BOOLEAN); // tagsPresent
public final static long DEEP_OVERHEAD = FIXED_OVERHEAD + ClassSize.ATOMIC_REFERENCE
+ ClassSize.CELL_SET + 2 * ClassSize.ATOMIC_LONG + ClassSize.TIMERANGE_TRACKER;
private AtomicReference<CellSet> cellSet= new AtomicReference<>();
private final CellComparator comparator;
protected long minSequenceId;
private MemStoreLAB memStoreLAB;
// Sum of sizes of all Cells added to this Segment. Cell's heapSize is considered. This is not
// including the heap overhead of this class.
protected final AtomicLong dataSize;
protected final AtomicLong heapSize;
protected final TimeRangeTracker timeRangeTracker;
protected volatile boolean tagsPresent;
// Empty constructor to be used when Segment is used as interface,
// and there is no need in true Segments state
protected Segment(CellComparator comparator) {
this.comparator = comparator;
this.dataSize = new AtomicLong(0);
this.heapSize = new AtomicLong(0);
this.timeRangeTracker = new TimeRangeTracker();
}
// This constructor is used to create empty Segments.
protected Segment(CellSet cellSet, CellComparator comparator, MemStoreLAB memStoreLAB) {
this.cellSet.set(cellSet);
this.comparator = comparator;
this.minSequenceId = Long.MAX_VALUE;
this.memStoreLAB = memStoreLAB;
this.dataSize = new AtomicLong(0);
this.heapSize = new AtomicLong(0);
this.tagsPresent = false;
this.timeRangeTracker = new TimeRangeTracker();
}
protected Segment(Segment segment) {
this.cellSet.set(segment.getCellSet());
this.comparator = segment.getComparator();
this.minSequenceId = segment.getMinSequenceId();
this.memStoreLAB = segment.getMemStoreLAB();
this.dataSize = new AtomicLong(segment.keySize());
this.heapSize = new AtomicLong(segment.heapSize.get());
this.tagsPresent = segment.isTagsPresent();
this.timeRangeTracker = segment.getTimeRangeTracker();
}
/**
* Creates the scanner for the given read point
* @return a scanner for the given read point
*/
protected KeyValueScanner getScanner(long readPoint) {
return new SegmentScanner(this, readPoint);
}
/**
* Creates the scanner for the given read point, and a specific order in a list
* @return a scanner for the given read point
*/
public KeyValueScanner getScanner(long readPoint, long order) {
return new SegmentScanner(this, readPoint, order);
}
public List<KeyValueScanner> getScanners(long readPoint, long order) {
return Collections.singletonList(new SegmentScanner(this, readPoint, order));
}
/**
* @return whether the segment has any cells
*/
public boolean isEmpty() {
return getCellSet().isEmpty();
}
/**
* @return number of cells in segment
*/
public int getCellsCount() {
return getCellSet().size();
}
/**
* @return the first cell in the segment that has equal or greater key than the given cell
*/
public Cell getFirstAfter(Cell cell) {
SortedSet<Cell> snTailSet = tailSet(cell);
if (!snTailSet.isEmpty()) {
return snTailSet.first();
}
return null;
}
/**
* Closing a segment before it is being discarded
*/
public void close() {
if (this.memStoreLAB != null) {
this.memStoreLAB.close();
}
// do not set MSLab to null as scanners may still be reading the data here and need to decrease
// the counter when they finish
}
/**
* If the segment has a memory allocator the cell is being cloned to this space, and returned;
* otherwise the given cell is returned
* @return either the given cell or its clone
*/
public Cell maybeCloneWithAllocator(Cell cell) {
if (this.memStoreLAB == null) {
return cell;
}
Cell cellFromMslab = this.memStoreLAB.copyCellInto(cell);
return (cellFromMslab != null) ? cellFromMslab : cell;
}
/**
* Get cell length after serialized in {@link KeyValue}
*/
@VisibleForTesting
static int getCellLength(Cell cell) {
return KeyValueUtil.length(cell);
}
public abstract boolean shouldSeek(Scan scan, long oldestUnexpiredTS);
public abstract long getMinTimestamp();
public boolean isTagsPresent() {
return tagsPresent;
}
public void incScannerCount() {
if (this.memStoreLAB != null) {
this.memStoreLAB.incScannerCount();
}
}
public void decScannerCount() {
if (this.memStoreLAB != null) {
this.memStoreLAB.decScannerCount();
}
}
/**
* Setting the CellSet of the segment - used only for flat immutable segment for setting
* immutable CellSet after its creation in immutable segment constructor
* @return this object
*/
protected Segment setCellSet(CellSet cellSetOld, CellSet cellSetNew) {
this.cellSet.compareAndSet(cellSetOld, cellSetNew);
return this;
}
/**
* @return Sum of all cell's size.
*/
public long keySize() {
return this.dataSize.get();
}
/**
* @return The heap size of this segment.
*/
public long heapSize() {
return this.heapSize.get();
}
/**
* Updates the size counters of the segment by the given delta
*/
//TODO
protected void incSize(long delta, long heapOverhead) {
this.dataSize.addAndGet(delta);
this.heapSize.addAndGet(heapOverhead);
}
public long getMinSequenceId() {
return minSequenceId;
}
public TimeRangeTracker getTimeRangeTracker() {
return this.timeRangeTracker;
}
//*** Methods for SegmentsScanner
public Cell last() {
return getCellSet().last();
}
public Iterator<Cell> iterator() {
return getCellSet().iterator();
}
public SortedSet<Cell> headSet(Cell firstKeyOnRow) {
return getCellSet().headSet(firstKeyOnRow);
}
public int compare(Cell left, Cell right) {
return getComparator().compare(left, right);
}
public int compareRows(Cell left, Cell right) {
return getComparator().compareRows(left, right);
}
/**
* @return a set of all cells in the segment
*/
protected CellSet getCellSet() {
return cellSet.get();
}
/**
* Returns the Cell comparator used by this segment
* @return the Cell comparator used by this segment
*/
protected CellComparator getComparator() {
return comparator;
}
protected void internalAdd(Cell cell, boolean mslabUsed, MemstoreSize memstoreSize) {
boolean succ = getCellSet().add(cell);
updateMetaInfo(cell, succ, mslabUsed, memstoreSize);
}
protected void updateMetaInfo(Cell cellToAdd, boolean succ, boolean mslabUsed,
MemstoreSize memstoreSize) {
long cellSize = 0;
// If there's already a same cell in the CellSet and we are using MSLAB, we must count in the
// MSLAB allocation size as well, or else there will be memory leak (occupied heap size larger
// than the counted number)
if (succ || mslabUsed) {
cellSize = getCellLength(cellToAdd);
}
long heapSize = heapSizeChange(cellToAdd, succ);
incSize(cellSize, heapSize);
if (memstoreSize != null) {
memstoreSize.incMemstoreSize(cellSize, heapSize);
}
getTimeRangeTracker().includeTimestamp(cellToAdd);
minSequenceId = Math.min(minSequenceId, cellToAdd.getSequenceId());
// In no tags case this NoTagsKeyValue.getTagsLength() is a cheap call.
// When we use ACL CP or Visibility CP which deals with Tags during
// mutation, the TagRewriteCell.getTagsLength() is a cheaper call. We do not
// parse the byte[] to identify the tags length.
if (cellToAdd.getTagsLength() > 0) {
tagsPresent = true;
}
}
/**
* @return The increase in heap size because of this cell addition. This includes this cell POJO's
* heap size itself and additional overhead because of addition on to CSLM.
*/
protected long heapSizeChange(Cell cell, boolean succ) {
if (succ) {
return ClassSize
.align(ClassSize.CONCURRENT_SKIPLISTMAP_ENTRY + CellUtil.estimatedHeapSizeOf(cell));
}
return 0;
}
/**
* Returns a subset of the segment cell set, which starts with the given cell
* @param firstCell a cell in the segment
* @return a subset of the segment cell set, which starts with the given cell
*/
protected SortedSet<Cell> tailSet(Cell firstCell) {
return getCellSet().tailSet(firstCell);
}
@VisibleForTesting
MemStoreLAB getMemStoreLAB() {
return memStoreLAB;
}
// Debug methods
/**
* Dumps all cells of the segment into the given log
*/
void dump(Log log) {
for (Cell cell: getCellSet()) {
log.debug(cell);
}
}
@Override
public String toString() {
String res = "Store segment of type "+this.getClass().getName()+"; ";
res += "isEmpty "+(isEmpty()?"yes":"no")+"; ";
res += "cellsCount "+getCellsCount()+"; ";
res += "cellsSize "+keySize()+"; ";
res += "totalHeapSize "+heapSize()+"; ";
res += "Min ts "+getMinTimestamp()+"; ";
return res;
}
}