org.apache.hadoop.hdfs.server.namenode

Class SequentialBlockIdGenerator

java.lang.Object

org.apache.hadoop.util.SequentialNumber

org.apache.hadoop.hdfs.server.namenode.SequentialBlockIdGenerator

@InterfaceAudience.Private
public class SequentialBlockIdGenerator
extends 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 and Description
static long	LAST_RESERVED_BLOCK_ID The last reserved block ID.

Method Summary

Methods

Modifier and Type	Method and Description
long	nextValue() Increment and then return the next value.

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

equals, getCurrentValue, hashCode, setCurrentValue, 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()

Description copied from class: SequentialNumber

Increment and then return the next value.

Overrides:

nextValue in class SequentialNumber