hadoop BlockType 源码
haddop BlockType 代码
文件路径：/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/BlockType.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.hdfs.protocol;
/**
* Type of a block. Previously, all blocks were replicated (contiguous).
* Then Erasure Coded blocks (striped) were implemented.
*
* BlockTypes are currently defined by the highest bit in the block id. If
* this bit is set, then the block is striped.
*
* Further extensions may claim the second bit s.t. the highest two bits are
* set. e.g.
* 0b00 == contiguous
* 0b10 == striped
* 0b11 == possible further extension block type.
*/
public enum BlockType {
//! Replicated block.
CONTIGUOUS,
//! Erasure Coded Block
STRIPED;
// BLOCK_ID_MASK is the union of all masks.
static final long BLOCK_ID_MASK = 1L << 63;
// BLOCK_ID_MASK_STRIPED is the mask for striped blocks.
static final long BLOCK_ID_MASK_STRIPED = 1L << 63;
/**
* Parse a BlockId to find the BlockType
* Note: the old block id generation algorithm was based on a pseudo random
* number generator, so there may be legacy blocks that make this conversion
* unreliable.
*/
public static BlockType fromBlockId(long blockId) {
long blockType = blockId & BLOCK_ID_MASK;
if(blockType == BLOCK_ID_MASK_STRIPED) {
return STRIPED;
}
return CONTIGUOUS;
}
}
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