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HDFS-2312. FSNamesystem javadoc incorrectly says its for DNs. (harsh) 

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1337761 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Harsh J 2012-05-13 03:33:19 +00:00
parent f22341ab1a
commit f1560d379d
2 changed files with 23 additions and 6 deletions
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2
hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
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@ -141,6 +141,8 @@ Trunk (unreleased changes)
HDFS-3243. TestParallelRead timing out on jenkins. (Henry Robinson via todd)
HDFS-3265. PowerPc Build error. (Kumar Ravi via mattf)
HDFS-2312. FSNamesystem javadoc incorrectly says its for DNs. (harsh)
Release 2.0.0 - UNRELEASED

27
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
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@ -197,18 +197,33 @@ import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
/***************************************************
* FSNamesystem does the actual bookkeeping work for the
* DataNode.
/**
* FSNamesystem is a container of both transient
* and persisted name-space state, and does all the book-keeping
* work on a NameNode.
*
* It tracks several important tables.
* Its roles are briefly described below:
*
* 1) valid fsname --> blocklist (kept on disk, logged)
* 1) Is the container for BlockManager, DatanodeManager,
* DelegationTokens, LeaseManager, etc. services.
* 2) RPC calls that modify or inspect the name-space
* should get delegated here.
* 3) Anything that touches only blocks (eg. block reports),
* it delegates to BlockManager.
* 4) Anything that touches only file information (eg. permissions, mkdirs),
* it delegates to FSDirectory.
* 5) Anything that crosses two of the above components should be
* coordinated here.
* 6) Logs mutations to FSEditLog.
*
* This class and its contents keep:
*
* 1) Valid fsname --> blocklist (kept on disk, logged)
* 2) Set of all valid blocks (inverted #1)
* 3) block --> machinelist (kept in memory, rebuilt dynamically from reports)
* 4) machine --> blocklist (inverted #2)
* 5) LRU cache of updated-heartbeat machines
***************************************************/
*/
@InterfaceAudience.Private
@Metrics(context="dfs")
public class FSNamesystem implements Namesystem, FSClusterStats,