/**
* Copyright 2010 The Apache Software Foundation
*
* 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 org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.filter.Filter.ReturnCode;
import org.apache.hadoop.hbase.io.TimeRange;
import org.apache.hadoop.hbase.util.Bytes;
import java.util.NavigableSet;
/**
* A query matcher that is specifically designed for the scan case.
*/
public class ScanQueryMatcher {
// Optimization so we can skip lots of compares when we decide to skip
// to the next row.
private boolean stickyNextRow;
private byte[] stopRow;
protected TimeRange tr;
protected Filter filter;
/** Keeps track of deletes */
protected DeleteTracker deletes;
protected boolean retainDeletesInOutput;
/** Keeps track of columns and versions */
protected ColumnTracker columns;
/** Key to seek to in memstore and StoreFiles */
protected KeyValue startKey;
/** Oldest allowed version stamp for TTL enforcement */
protected long oldestStamp;
/** Row comparator for the region this query is for */
KeyValue.KeyComparator rowComparator;
/** Row the query is on */
protected byte [] row;
/**
* Constructs a ScanQueryMatcher for a Scan.
* @param scan
* @param family
* @param columns
* @param ttl
* @param rowComparator
*/
public ScanQueryMatcher(Scan scan, byte [] family,
NavigableSet<byte[]> columns, long ttl,
KeyValue.KeyComparator rowComparator, int maxVersions,
boolean retainDeletesInOutput) {
this.tr = scan.getTimeRange();
this.oldestStamp = System.currentTimeMillis() - ttl;
this.rowComparator = rowComparator;
this.deletes = new ScanDeleteTracker();
this.stopRow = scan.getStopRow();
this.startKey = KeyValue.createFirstOnRow(scan.getStartRow());
this.filter = scan.getFilter();
this.retainDeletesInOutput = retainDeletesInOutput;
// Single branch to deal with two types of reads (columns vs all in family)
if (columns == null || columns.size() == 0) {
// use a specialized scan for wildcard column tracker.
this.columns = new ScanWildcardColumnTracker(maxVersions);
} else {
// We can share the ExplicitColumnTracker, diff is we reset
// between rows, not between storefiles.
this.columns = new ExplicitColumnTracker(columns,maxVersions);
}
}
public ScanQueryMatcher(Scan scan, byte [] family,
NavigableSet<byte[]> columns, long ttl,
KeyValue.KeyComparator rowComparator, int maxVersions) {
/* By default we will not include deletes */
/* deletes are included explicitly (for minor compaction) */
this(scan, family, columns, ttl, rowComparator, maxVersions, false);
}
/**
* Determines if the caller should do one of several things:
* - seek/skip to the next row (MatchCode.SEEK_NEXT_ROW)
* - seek/skip to the next column (MatchCode.SEEK_NEXT_COL)
* - include the current KeyValue (MatchCode.INCLUDE)
* - ignore the current KeyValue (MatchCode.SKIP)
* - got to the next row (MatchCode.DONE)
*
* @param kv KeyValue to check
* @return The match code instance.
*/
public MatchCode match(KeyValue kv) {
if (filter != null && filter.filterAllRemaining()) {
return MatchCode.DONE_SCAN;
}
byte [] bytes = kv.getBuffer();
int offset = kv.getOffset();
int initialOffset = offset;
int keyLength = Bytes.toInt(bytes, offset, Bytes.SIZEOF_INT);
offset += KeyValue.ROW_OFFSET;
short rowLength = Bytes.toShort(bytes, offset, Bytes.SIZEOF_SHORT);
offset += Bytes.SIZEOF_SHORT;
int ret = this.rowComparator.compareRows(row, 0, row.length,
bytes, offset, rowLength);
if (ret <= -1) {
return MatchCode.DONE;
} else if (ret >= 1) {
// could optimize this, if necessary?
// Could also be called SEEK_TO_CURRENT_ROW, but this
// should be rare/never happens.
return MatchCode.SEEK_NEXT_ROW;
}
// optimize case.
if (this.stickyNextRow)
return MatchCode.SEEK_NEXT_ROW;
if (this.columns.done()) {
stickyNextRow = true;
return MatchCode.SEEK_NEXT_ROW;
}
//Passing rowLength
offset += rowLength;
//Skipping family
byte familyLength = bytes [offset];
offset += familyLength + 1;
int qualLength = keyLength + KeyValue.ROW_OFFSET -
(offset - initialOffset) - KeyValue.TIMESTAMP_TYPE_SIZE;
long timestamp = kv.getTimestamp();
if (isExpired(timestamp)) {
// done, the rest of this column will also be expired as well.
return getNextRowOrNextColumn(bytes, offset, qualLength);
}
byte type = kv.getType();
if (isDelete(type)) {
if (tr.withinOrAfterTimeRange(timestamp)) {
this.deletes.add(bytes, offset, qualLength, timestamp, type);
// Can't early out now, because DelFam come before any other keys
}
if (retainDeletesInOutput) {
return MatchCode.INCLUDE;
}
else {
return MatchCode.SKIP;
}
}
if (!this.deletes.isEmpty() &&
deletes.isDeleted(bytes, offset, qualLength, timestamp)) {
// May be able to optimize the SKIP here, if we matched
// due to a DelFam, we can skip to next row
// due to a DelCol, we can skip to next col
// But it requires more info out of isDelete().
// needful -> million column challenge.
return MatchCode.SKIP;
}
int timestampComparison = tr.compare(timestamp);
if (timestampComparison >= 1) {
return MatchCode.SKIP;
} else if (timestampComparison <= -1) {
return getNextRowOrNextColumn(bytes, offset, qualLength);
}
/**
* Filters should be checked before checking column trackers. If we do
* otherwise, as was previously being done, ColumnTracker may increment its
* counter for even that KV which may be discarded later on by Filter. This
* would lead to incorrect results in certain cases.
*/
if (filter != null) {
ReturnCode filterResponse = filter.filterKeyValue(kv);
if (filterResponse == ReturnCode.SKIP) {
return MatchCode.SKIP;
} else if (filterResponse == ReturnCode.NEXT_COL) {
return getNextRowOrNextColumn(bytes, offset, qualLength);
} else if (filterResponse == ReturnCode.NEXT_ROW) {
stickyNextRow = true;
return MatchCode.SEEK_NEXT_ROW;
} else if (filterResponse == ReturnCode.SEEK_NEXT_USING_HINT) {
return MatchCode.SEEK_NEXT_USING_HINT;
}
}
MatchCode colChecker = columns.checkColumn(bytes, offset, qualLength, timestamp);
/*
* According to current implementation, colChecker can only be
* SEEK_NEXT_COL, SEEK_NEXT_ROW, SKIP or INCLUDE. Therefore, always return
* the MatchCode. If it is SEEK_NEXT_ROW, also set stickyNextRow.
*/
if (colChecker == MatchCode.SEEK_NEXT_ROW) {
stickyNextRow = true;
}
return colChecker;
}
public MatchCode getNextRowOrNextColumn(byte[] bytes, int offset,
int qualLength) {
if (columns instanceof ExplicitColumnTracker) {
//We only come here when we know that columns is an instance of
//ExplicitColumnTracker so we should never have a cast exception
((ExplicitColumnTracker)columns).doneWithColumn(bytes, offset,
qualLength);
if (columns.getColumnHint() == null) {
return MatchCode.SEEK_NEXT_ROW;
} else {
return MatchCode.SEEK_NEXT_COL;
}
} else {
return MatchCode.SEEK_NEXT_COL;
}
}
public boolean moreRowsMayExistAfter(KeyValue kv) {
if (!Bytes.equals(stopRow , HConstants.EMPTY_END_ROW) &&
rowComparator.compareRows(kv.getBuffer(),kv.getRowOffset(),
kv.getRowLength(), stopRow, 0, stopRow.length) >= 0) {
// KV >= STOPROW
// then NO there is nothing left.
return false;
} else {
return true;
}
}
/**
* Set current row
* @param row
*/
public void setRow(byte [] row) {
this.row = row;
reset();
}
public void reset() {
this.deletes.reset();
this.columns.reset();
stickyNextRow = false;
}
// should be in KeyValue.
protected boolean isDelete(byte type) {
return (type != KeyValue.Type.Put.getCode());
}
protected boolean isExpired(long timestamp) {
return (timestamp < oldestStamp);
}
/**
*
* @return the start key
*/
public KeyValue getStartKey() {
return this.startKey;
}
public KeyValue getNextKeyHint(KeyValue kv) {
if (filter == null) {
return null;
} else {
return filter.getNextKeyHint(kv);
}
}
public KeyValue getKeyForNextColumn(KeyValue kv) {
ColumnCount nextColumn = columns.getColumnHint();
if (nextColumn == null) {
return KeyValue.createLastOnRow(
kv.getBuffer(), kv.getRowOffset(), kv.getRowLength(),
kv.getBuffer(), kv.getFamilyOffset(), kv.getFamilyLength(),
kv.getBuffer(), kv.getQualifierOffset(), kv.getQualifierLength());
} else {
return KeyValue.createFirstOnRow(
kv.getBuffer(), kv.getRowOffset(), kv.getRowLength(),
kv.getBuffer(), kv.getFamilyOffset(), kv.getFamilyLength(),
nextColumn.getBuffer(), nextColumn.getOffset(), nextColumn.getLength());
}
}
public KeyValue getKeyForNextRow(KeyValue kv) {
return KeyValue.createLastOnRow(
kv.getBuffer(), kv.getRowOffset(), kv.getRowLength(),
null, 0, 0,
null, 0, 0);
}
/**
* {@link #match} return codes. These instruct the scanner moving through
* memstores and StoreFiles what to do with the current KeyValue.
* <p>
* Additionally, this contains "early-out" language to tell the scanner to
* move on to the next File (memstore or Storefile), or to return immediately.
*/
public static enum MatchCode {
/**
* Include KeyValue in the returned result
*/
INCLUDE,
/**
* Do not include KeyValue in the returned result
*/
SKIP,
/**
* Do not include, jump to next StoreFile or memstore (in time order)
*/
NEXT,
/**
* Do not include, return current result
*/
DONE,
/**
* These codes are used by the ScanQueryMatcher
*/
/**
* Done with the row, seek there.
*/
SEEK_NEXT_ROW,
/**
* Done with column, seek to next.
*/
SEEK_NEXT_COL,
/**
* Done with scan, thanks to the row filter.
*/
DONE_SCAN,
/*
* Seek to next key which is given as hint.
*/
SEEK_NEXT_USING_HINT,
}
}