org.apache.hadoop.io.erasurecode.coder.ErasureEncoder Maven / Gradle / Ivy
/**
* 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.io.erasurecode.coder;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.io.erasurecode.ECBlock;
import org.apache.hadoop.io.erasurecode.ECBlockGroup;
import org.apache.hadoop.io.erasurecode.ErasureCoderOptions;
/**
* An abstract erasure encoder that's to be inherited by new encoders.
*
* It implements the {@link ErasureCoder} interface.
*/
@InterfaceAudience.Private
public abstract class ErasureEncoder extends Configured
implements ErasureCoder {
private final int numDataUnits;
private final int numParityUnits;
private final ErasureCoderOptions options;
public ErasureEncoder(ErasureCoderOptions options) {
this.options = options;
this.numDataUnits = options.getNumDataUnits();
this.numParityUnits = options.getNumParityUnits();
}
@Override
public ErasureCodingStep calculateCoding(ECBlockGroup blockGroup) {
// We may have more than this when considering complicate cases. HADOOP-11550
return prepareEncodingStep(blockGroup);
}
@Override
public int getNumDataUnits() {
return numDataUnits;
}
@Override
public int getNumParityUnits() {
return numParityUnits;
}
@Override
public ErasureCoderOptions getOptions() {
return options;
}
protected ECBlock[] getInputBlocks(ECBlockGroup blockGroup) {
return blockGroup.getDataBlocks();
}
protected ECBlock[] getOutputBlocks(ECBlockGroup blockGroup) {
return blockGroup.getParityBlocks();
}
@Override
public boolean preferDirectBuffer() {
return false;
}
@Override
public void release() {
// Nothing to do by default
}
/**
* Perform encoding against a block group.
* @param blockGroup
* @return encoding step for caller to do the real work
*/
protected abstract ErasureCodingStep prepareEncodingStep(
ECBlockGroup blockGroup);
}