RegionLocationFinder (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.master.balancer.RegionLocationFinder

```
@InterfaceAudience.Private
 class RegionLocationFinder
extends Object
```
This will find where data for a region is located in HDFS. It ranks ServerName's by the size of the store files they are holding for a given region.

Field Summary

Fields
Modifier and Type	Field and Description
`private com.google.common.cache.LoadingCache<HRegionInfo,HDFSBlocksDistribution>`	`cache`
`private static long`	`CACHE_TIME`
`private org.apache.hadoop.conf.Configuration`	`conf`
`private com.google.common.util.concurrent.ListeningExecutorService`	`executor`
`private long`	`lastFullRefresh`
`private com.google.common.cache.CacheLoader<HRegionInfo,HDFSBlocksDistribution>`	`loader`
`private static org.apache.commons.logging.Log`	`LOG`
`private MasterServices`	`services`
`private ClusterStatus`	`status`

Constructor Summary

Constructors
Constructor and Description

RegionLocationFinder()

Constructors
Constructor and Description
`RegionLocationFinder()`

Method Summary

Methods
Modifier and Type	Method and Description
`private com.google.common.cache.LoadingCache<HRegionInfo,HDFSBlocksDistribution>`	`createCache()` Create a cache for region to list of servers
`HDFSBlocksDistribution`	`getBlockDistribution(HRegionInfo hri)`
`org.apache.hadoop.conf.Configuration`	`getConf()`
`protected HTableDescriptor`	`getTableDescriptor(TableName tableName)` return HTableDescriptor for a given tableName
`protected List<ServerName>`	`getTopBlockLocations(HRegionInfo region)`
`protected HDFSBlocksDistribution`	`internalGetTopBlockLocation(HRegionInfo region)` Returns an ordered list of hosts that are hosting the blocks for this region.
`protected List<ServerName>`	`mapHostNameToServerName(List<String> hosts)` Map hostname to ServerName, The output ServerName list will have the same order as input hosts.
`private boolean`	`scheduleFullRefresh()` Refresh all the region locations.
`void`	`setClusterStatus(ClusterStatus status)`
`void`	`setConf(org.apache.hadoop.conf.Configuration conf)`
`void`	`setServices(MasterServices services)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOG

private static final org.apache.commons.logging.Log LOG

CACHE_TIME
```
private static final long CACHE_TIME
```
See Also:
Constant Field Values

conf

private org.apache.hadoop.conf.Configuration conf

status
```
private volatile ClusterStatus status
```

services
```
private MasterServices services
```

executor

private final com.google.common.util.concurrent.ListeningExecutorService executor

lastFullRefresh
```
private long lastFullRefresh
```

loader

private com.google.common.cache.CacheLoader<HRegionInfo,HDFSBlocksDistribution> loader

cache

private com.google.common.cache.LoadingCache<HRegionInfo,HDFSBlocksDistribution> cache

Constructor Detail
- RegionLocationFinder
```
RegionLocationFinder()
```

Method Detail
- createCache
```
private com.google.common.cache.LoadingCache<HRegionInfo,HDFSBlocksDistribution> createCache()
```
  Create a cache for region to list of servers
  
  Parameters:
  time - time to cache the locations
  
  Returns:
  A new Cache.
- getConf
```
public org.apache.hadoop.conf.Configuration getConf()
```
- setConf
```
public void setConf(org.apache.hadoop.conf.Configuration conf)
```
- setServices
```
public void setServices(MasterServices services)
```
- setClusterStatus
```
public void setClusterStatus(ClusterStatus status)
```
- scheduleFullRefresh
```
private boolean scheduleFullRefresh()
```
  Refresh all the region locations.
  
  Returns:
  true if user created regions got refreshed.
- getTopBlockLocations
```
protected List<ServerName> getTopBlockLocations(HRegionInfo region)
```
- internalGetTopBlockLocation
```
protected HDFSBlocksDistribution internalGetTopBlockLocation(HRegionInfo region)
```
  Returns an ordered list of hosts that are hosting the blocks for this region. The weight of each host is the sum of the block lengths of all files on that host, so the first host in the list is the server which holds the most bytes of the given region's HFiles.
  
  Parameters:
  region - region
  
  Returns:
  ordered list of hosts holding blocks of the specified region
- getTableDescriptor
```
protected HTableDescriptor getTableDescriptor(TableName tableName)
                                       throws IOException
```
  return HTableDescriptor for a given tableName
  
  Parameters:
  tableName - the table name
  
  Returns:
  HTableDescriptor
  
  Throws:
  
  IOException
- mapHostNameToServerName
```
protected List<ServerName> mapHostNameToServerName(List<String> hosts)
```
  Map hostname to ServerName, The output ServerName list will have the same order as input hosts.
  
  Parameters:
  hosts - the list of hosts
  
  Returns:
  ServerName list
- getBlockDistribution
```
public HDFSBlocksDistribution getBlockDistribution(HRegionInfo hri)
```

Class RegionLocationFinder

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

LOG

CACHE_TIME

conf

status

services

executor

lastFullRefresh

loader

cache

Constructor Detail

RegionLocationFinder

Method Detail

createCache

getConf

setConf

setServices

setClusterStatus

scheduleFullRefresh

getTopBlockLocations

internalGetTopBlockLocation

getTableDescriptor

mapHostNameToServerName

getBlockDistribution