/*
* 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.util;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.util.zip.Checksum;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Checksum types. The Checksum type is a one byte number
* that stores a representation of the checksum algorithm
* used to encode a hfile. The ordinal of these cannot
* change or else you risk breaking all existing HFiles out there.
*/
public enum ChecksumType {
NULL((byte)0) {
@Override
public String getName() {
return "NULL";
}
@Override
public void initialize() {
// do nothing
}
@Override
public Checksum getChecksumObject() throws IOException {
return null; // checksums not used
}
},
CRC32((byte)1) {
private volatile Constructor<?> ctor;
@Override
public String getName() {
return "CRC32";
}
@Override
public void initialize() {
final String PURECRC32 = "org.apache.hadoop.util.PureJavaCrc32";
final String JDKCRC = "java.util.zip.CRC32";
LOG = LogFactory.getLog(ChecksumType.class);
// check if hadoop library is available
try {
ctor = ChecksumFactory.newConstructor(PURECRC32);
LOG.info("Checksum using " + PURECRC32);
} catch (Exception e) {
LOG.trace(PURECRC32 + " not available.");
}
try {
// The default checksum class name is java.util.zip.CRC32.
// This is available on all JVMs.
if (ctor == null) {
ctor = ChecksumFactory.newConstructor(JDKCRC);
LOG.info("Checksum can use " + JDKCRC);
}
} catch (Exception e) {
LOG.trace(JDKCRC + " not available.");
}
}
@Override
public Checksum getChecksumObject() throws IOException {
if (ctor == null) {
throw new IOException("Bad constructor for " + getName());
}
try {
return (Checksum)ctor.newInstance();
} catch (Exception e) {
throw new IOException(e);
}
}
},
CRC32C((byte)2) {
private transient Constructor<?> ctor;
@Override
public String getName() {
return "CRC32C";
}
@Override
public void initialize() {
final String PURECRC32C = "org.apache.hadoop.util.PureJavaCrc32C";
LOG = LogFactory.getLog(ChecksumType.class);
try {
ctor = ChecksumFactory.newConstructor(PURECRC32C);
LOG.info("Checksum can use " + PURECRC32C);
} catch (Exception e) {
LOG.trace(PURECRC32C + " not available.");
}
}
@Override
public Checksum getChecksumObject() throws IOException {
if (ctor == null) {
throw new IOException("Bad constructor for " + getName());
}
try {
return (Checksum)ctor.newInstance();
} catch (Exception e) {
throw new IOException(e);
}
}
};
private final byte code;
protected Log LOG;
/** initializes the relevant checksum class object */
abstract void initialize();
/** returns the name of this checksum type */
public abstract String getName();
private ChecksumType(final byte c) {
this.code = c;
initialize();
}
/** returns a object that can be used to generate/validate checksums */
public abstract Checksum getChecksumObject() throws IOException;
public byte getCode() {
return this.code;
}
/**
* Cannot rely on enum ordinals . They change if item is removed or moved.
* Do our own codes.
* @param b
* @return Type associated with passed code.
*/
public static ChecksumType codeToType(final byte b) {
for (ChecksumType t : ChecksumType.values()) {
if (t.getCode() == b) {
return t;
}
}
throw new RuntimeException("Unknown checksum type code " + b);
}
/**
* Map a checksum name to a specific type.
* Do our own names.
* @param b
* @return Type associated with passed code.
*/
public static ChecksumType nameToType(final String name) {
for (ChecksumType t : ChecksumType.values()) {
if (t.getName().equals(name)) {
return t;
}
}
throw new RuntimeException("Unknown checksum type name " + name);
}
}