org.apache.hadoop.hbase.master

Class CachedClusterId

java.lang.Object

org.apache.hadoop.hbase.master.CachedClusterId

@InterfaceAudience.Private
public class CachedClusterId
extends Object

Caches the cluster ID of the cluster. For standby masters, this is used to serve the client RPCs that fetch the cluster ID. ClusterID is only created by an active master if one does not already exist. Standby masters just read the information from the file system. This class is thread-safe. TODO: Make it a singleton without affecting concurrent junit tests.

Field Summary

Fields

Modifier and Type	Field and Description
static org.slf4j.Logger	LOG

Constructor Summary

Constructors

Constructor and Description
CachedClusterId(Server server, org.apache.hadoop.conf.Configuration conf)

Method Summary

Modifier and Type	Method and Description
int	getCacheStats()
String	getFromCacheOrFetch() Fetches the ClusterId from FS if it is not cached locally.

Methods inherited from class java.lang.Object

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

Field Detail

LOG

public static final org.slf4j.Logger LOG

Constructor Detail

CachedClusterId

public CachedClusterId(Server server,
                       org.apache.hadoop.conf.Configuration conf)
                throws IOException

Throws:

IOException

Method Detail

getFromCacheOrFetch

public String getFromCacheOrFetch()

Fetches the ClusterId from FS if it is not cached locally. Atomically updates the cached copy and is thread-safe. Optimized to do a single fetch when there are multiple threads are trying get from a clean cache.

Returns:

ClusterId by reading from FileSystem or null in any error case or cluster ID does not exist on the file system or if the server initiated a tear down.

getCacheStats

public int getCacheStats()