Package org.apache.hadoop.hdfs.server.blockmanagement

Class SequentialBlockIdGenerator

java.lang.Object

org.apache.hadoop.util.SequentialNumber

org.apache.hadoop.hdfs.server.blockmanagement.SequentialBlockIdGenerator

All Implemented Interfaces:

org.apache.hadoop.util.IdGenerator

@Private
public class SequentialBlockIdGenerator
extends org.apache.hadoop.util.SequentialNumber

Generate the next valid block ID by incrementing the maximum block ID allocated so far, starting at 2^30+1. Block IDs used to be allocated randomly in the past. Hence we may find some conflicts while stepping through the ID space sequentially. However given the sparsity of the ID space, conflicts should be rare and can be skipped over when detected.

Field Summary

Fields

Modifier and Type	Field	Description
static long	LAST_RESERVED_BLOCK_ID	The last reserved block ID.

Method Summary

Modifier and Type	Method	Description
long	nextValue()

Methods inherited from class org.apache.hadoop.util.SequentialNumber

equals, getCurrentValue, hashCode, setCurrentValue, setIfGreater, skipTo

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

LAST_RESERVED_BLOCK_ID

public static final long LAST_RESERVED_BLOCK_ID

The last reserved block ID.

See Also:

Constant Field Values

Method Detail

nextValue

public long nextValue()

Specified by:

nextValue in interface org.apache.hadoop.util.IdGenerator

Overrides:

nextValue in class org.apache.hadoop.util.SequentialNumber