hadoop BlockGrouper 源码
haddop BlockGrouper 代码
文件路径：/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/erasurecode/grouper/BlockGrouper.java
/**
* 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.grouper;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.io.erasurecode.ECBlock;
import org.apache.hadoop.io.erasurecode.ECBlockGroup;
import org.apache.hadoop.io.erasurecode.ECSchema;
/**
* As part of a codec, to handle how to form a block group for encoding
* and provide instructions on how to recover erased blocks from a block group
*/
@InterfaceAudience.Private
public class BlockGrouper {
private ECSchema schema;
/**
* Set EC schema.
* @param schema schema.
*/
public void setSchema(ECSchema schema) {
this.schema = schema;
}
/**
* Get EC schema.
* @return ECSchema.
*/
protected ECSchema getSchema() {
return schema;
}
/**
* Get required data blocks count in a BlockGroup.
* @return count of required data blocks
*/
public int getRequiredNumDataBlocks() {
return schema.getNumDataUnits();
}
/**
* Get required parity blocks count in a BlockGroup.
* @return count of required parity blocks
*/
public int getRequiredNumParityBlocks() {
return schema.getNumParityUnits();
}
/**
* Calculating and organizing BlockGroup, to be called by ECManager
* @param dataBlocks Data blocks to compute parity blocks against
* @param parityBlocks To be computed parity blocks
* @return ECBlockGroup.
*/
public ECBlockGroup makeBlockGroup(ECBlock[] dataBlocks,
ECBlock[] parityBlocks) {
ECBlockGroup blockGroup = new ECBlockGroup(dataBlocks, parityBlocks);
return blockGroup;
}
/**
* Given a BlockGroup, tell if any of the missing blocks can be recovered,
* to be called by ECManager
* @param blockGroup a blockGroup that may contain erased blocks but not sure
* recoverable or not
* @return true if any erased block recoverable, false otherwise
*/
public boolean anyRecoverable(ECBlockGroup blockGroup) {
int erasedCount = blockGroup.getErasedCount();
return erasedCount > 0 && erasedCount <= getRequiredNumParityBlocks();
}
}
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