/**
*
* 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.wal;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.EOFException;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.WritableUtils;
/**
* A Key for an entry in the change log.
*
* The log intermingles edits to many tables and rows, so each log entry
* identifies the appropriate table and row. Within a table and row, they're
* also sorted.
*
* <p>Some Transactional edits (START, COMMIT, ABORT) will not have an
* associated row.
*/
@InterfaceAudience.Private
public class HLogKey implements WritableComparable<HLogKey> {
// should be < 0 (@see #readFields(DataInput))
// version 2 supports HLog compression
enum Version {
UNVERSIONED(0),
// Initial number we put on HLogKey when we introduced versioning.
INITIAL(-1),
// Version -2 introduced a dictionary compression facility. Only this
// dictionary-based compression is available in version -2.
COMPRESSED(-2);
final int code;
static final Version[] byCode;
static {
byCode = Version.values();
for (int i = 0; i < byCode.length; i++) {
if (byCode[i].code != -1 * i) {
throw new AssertionError("Values in this enum should be descending by one");
}
}
}
Version(int code) {
this.code = code;
}
boolean atLeast(Version other) {
return code <= other.code;
}
static Version fromCode(int code) {
return byCode[code * -1];
}
}
private static final Version VERSION = Version.COMPRESSED;
// The encoded region name.
private byte [] encodedRegionName;
private byte [] tablename;
private long logSeqNum;
// Time at which this edit was written.
private long writeTime;
private UUID clusterId;
private CompressionContext compressionContext;
/** Writable Constructor -- Do not use. */
public HLogKey() {
this(null, null, 0L, HConstants.LATEST_TIMESTAMP,
HConstants.DEFAULT_CLUSTER_ID);
}
/**
* Create the log key!
* We maintain the tablename mainly for debugging purposes.
* A regionName is always a sub-table object.
*
* @param encodedRegionName Encoded name of the region as returned by
* <code>HRegionInfo#getEncodedNameAsBytes()</code>.
* @param tablename - name of table
* @param logSeqNum - log sequence number
* @param now Time at which this edit was written.
* @param clusterId of the cluster (used in Replication)
*/
public HLogKey(final byte [] encodedRegionName, final byte [] tablename,
long logSeqNum, final long now, UUID clusterId) {
this.encodedRegionName = encodedRegionName;
this.tablename = tablename;
this.logSeqNum = logSeqNum;
this.writeTime = now;
this.clusterId = clusterId;
}
/**
* @param compressionContext Compression context to use
*/
public void setCompressionContext(CompressionContext compressionContext) {
this.compressionContext = compressionContext;
}
/** @return encoded region name */
public byte [] getEncodedRegionName() {
return encodedRegionName;
}
/** @return table name */
public byte [] getTablename() {
return tablename;
}
/** @return log sequence number */
public long getLogSeqNum() {
return logSeqNum;
}
void setLogSeqNum(long logSeqNum) {
this.logSeqNum = logSeqNum;
}
/**
* @return the write time
*/
public long getWriteTime() {
return this.writeTime;
}
/**
* Get the id of the original cluster
* @return Cluster id.
*/
public UUID getClusterId() {
return clusterId;
}
/**
* Set the cluster id of this key
* @param clusterId
*/
public void setClusterId(UUID clusterId) {
this.clusterId = clusterId;
}
@Override
public String toString() {
return Bytes.toString(tablename) + "/" + Bytes.toString(encodedRegionName) + "/" +
logSeqNum;
}
/**
* Produces a string map for this key. Useful for programmatic use and
* manipulation of the data stored in an HLogKey, for example, printing
* as JSON.
*
* @return a Map containing data from this key
*/
public Map<String, Object> toStringMap() {
Map<String, Object> stringMap = new HashMap<String, Object>();
stringMap.put("table", Bytes.toStringBinary(tablename));
stringMap.put("region", Bytes.toStringBinary(encodedRegionName));
stringMap.put("sequence", logSeqNum);
return stringMap;
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
return compareTo((HLogKey)obj) == 0;
}
@Override
public int hashCode() {
int result = Bytes.hashCode(this.encodedRegionName);
result ^= this.logSeqNum;
result ^= this.writeTime;
result ^= this.clusterId.hashCode();
return result;
}
public int compareTo(HLogKey o) {
int result = Bytes.compareTo(this.encodedRegionName, o.encodedRegionName);
if (result == 0) {
if (this.logSeqNum < o.logSeqNum) {
result = -1;
} else if (this.logSeqNum > o.logSeqNum) {
result = 1;
}
if (result == 0) {
if (this.writeTime < o.writeTime) {
result = -1;
} else if (this.writeTime > o.writeTime) {
return 1;
}
}
}
// why isn't cluster id accounted for?
return result;
}
/**
* Drop this instance's tablename byte array and instead
* hold a reference to the provided tablename. This is not
* meant to be a general purpose setter - it's only used
* to collapse references to conserve memory.
*/
void internTableName(byte []tablename) {
// We should not use this as a setter - only to swap
// in a new reference to the same table name.
assert Bytes.equals(tablename, this.tablename);
this.tablename = tablename;
}
/**
* Drop this instance's region name byte array and instead
* hold a reference to the provided region name. This is not
* meant to be a general purpose setter - it's only used
* to collapse references to conserve memory.
*/
void internEncodedRegionName(byte []encodedRegionName) {
// We should not use this as a setter - only to swap
// in a new reference to the same table name.
assert Bytes.equals(this.encodedRegionName, encodedRegionName);
this.encodedRegionName = encodedRegionName;
}
@Override
public void write(DataOutput out) throws IOException {
WritableUtils.writeVInt(out, VERSION.code);
if (compressionContext == null) {
Bytes.writeByteArray(out, this.encodedRegionName);
Bytes.writeByteArray(out, this.tablename);
} else {
Compressor.writeCompressed(this.encodedRegionName, 0,
this.encodedRegionName.length, out,
compressionContext.regionDict);
Compressor.writeCompressed(this.tablename, 0, this.tablename.length, out,
compressionContext.tableDict);
}
out.writeLong(this.logSeqNum);
out.writeLong(this.writeTime);
// avoid storing 16 bytes when replication is not enabled
if (this.clusterId == HConstants.DEFAULT_CLUSTER_ID) {
out.writeBoolean(false);
} else {
out.writeBoolean(true);
out.writeLong(this.clusterId.getMostSignificantBits());
out.writeLong(this.clusterId.getLeastSignificantBits());
}
}
@Override
public void readFields(DataInput in) throws IOException {
Version version = Version.UNVERSIONED;
// HLogKey was not versioned in the beginning.
// In order to introduce it now, we make use of the fact
// that encodedRegionName was written with Bytes.writeByteArray,
// which encodes the array length as a vint which is >= 0.
// Hence if the vint is >= 0 we have an old version and the vint
// encodes the length of encodedRegionName.
// If < 0 we just read the version and the next vint is the length.
// @see Bytes#readByteArray(DataInput)
int len = WritableUtils.readVInt(in);
if (len < 0) {
// what we just read was the version
version = Version.fromCode(len);
// We only compress V2 of HLogkey.
// If compression is on, the length is handled by the dictionary
if (compressionContext == null || !version.atLeast(Version.COMPRESSED)) {
len = WritableUtils.readVInt(in);
}
}
if (compressionContext == null || !version.atLeast(Version.COMPRESSED)) {
this.encodedRegionName = new byte[len];
in.readFully(this.encodedRegionName);
this.tablename = Bytes.readByteArray(in);
} else {
this.encodedRegionName = Compressor.readCompressed(in, compressionContext.regionDict);
this.tablename = Compressor.readCompressed(in, compressionContext.tableDict);
}
this.logSeqNum = in.readLong();
this.writeTime = in.readLong();
this.clusterId = HConstants.DEFAULT_CLUSTER_ID;
if (version.atLeast(Version.INITIAL)) {
if (in.readBoolean()) {
this.clusterId = new UUID(in.readLong(), in.readLong());
}
} else {
try {
// dummy read (former byte cluster id)
in.readByte();
} catch(EOFException e) {
// Means it's a very old key, just continue
}
}
}
}