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

Class SequentialBlockGroupIdGenerator

java.lang.Object
org.apache.hadoop.util.SequentialNumber
org.apache.hadoop.hdfs.server.blockmanagement.SequentialBlockGroupIdGenerator
All Implemented Interfaces:
org.apache.hadoop.util.IdGenerator
@Private public class SequentialBlockGroupIdGenerator extends org.apache.hadoop.util.SequentialNumber
Generate the next valid block group ID by incrementing the maximum block group ID allocated so far, with the first 2^10 block group IDs reserved. HDFS-EC introduces a hierarchical protocol to name blocks and groups: Contiguous: {reserved block IDs | flag | block ID} Striped: {reserved block IDs | flag | block group ID | index in group} Following n bits of reserved block IDs, The (n+1)th bit in an ID distinguishes contiguous (0) and striped (1) blocks. For a striped block, bits (n+2) to (64-m) represent the ID of its block group, while the last m bits represent its index of the group. The value m is determined by the maximum number of blocks in a group (MAX_BLOCKS_IN_GROUP). Note that the nextValue() methods requires external lock to guarantee IDs have no conflicts.

  • 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

  • Method Details

    • nextValue

      public long nextValue()
      Specified by:
      nextValue in interface org.apache.hadoop.util.IdGenerator
      Overrides:
      nextValue in class org.apache.hadoop.util.SequentialNumber