Package org.apache.accumulo.core.spi.balancer

Interface BalancerEnvironment

All Superinterfaces:

PluginEnvironment, ServiceEnvironment

public interface BalancerEnvironment
extends ServiceEnvironment

This interface is an extension of ServiceEnvironment that exposes system level information that is specific to tablet balancing.

Since:

2.1.0

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.accumulo.core.spi.common.ServiceEnvironment

ServiceEnvironment.Configuration

Method Summary

Modifier and Type	Method	Description
Map<String,TableId>	getTableIdMap()	Many Accumulo plugins are given table IDs as this is what Accumulo uses internally to identify tables.
boolean	isTableOnline(TableId tableId)	Accumulo plugins working with a table may need to know if the table is online or not before operating on it.
List<TabletStatistics>	listOnlineTabletsForTable(TabletServerId tabletServerId, TableId tableId)	Fetch the tablets for the given table by asking the tablet server.
Map<TabletId,TabletServerId>	listTabletLocations(TableId tableId)	Fetch the locations for each of tableId's tablets from the metadata table.
String	tableContext(TableId tableId)	Retrieve the classloader context that is configured for tableId, or null if none is configured.

Methods inherited from interface org.apache.accumulo.core.client.PluginEnvironment

getTableName, instantiate, instantiate

Methods inherited from interface org.apache.accumulo.core.spi.common.ServiceEnvironment

getConfiguration, getConfiguration

Method Detail

getTableIdMap

Map<String,TableId> getTableIdMap()

Many Accumulo plugins are given table IDs as this is what Accumulo uses internally to identify tables. This provides a mapping of table names to table IDs for the purposes of translating and/or enumerating the existing tables.

isTableOnline

boolean isTableOnline(TableId tableId)

Accumulo plugins working with a table may need to know if the table is online or not before operating on it.

Parameters:

tableId - The id of the table to check.

Returns:

true if the table is online and false if not

listTabletLocations

Map<TabletId,TabletServerId> listTabletLocations(TableId tableId)

Fetch the locations for each of tableId's tablets from the metadata table. If there is no location available for a given tablet, then the returned mapping will have a null value stored for the tablet id.

Parameters:

tableId - The id of the table for which to retrieve tablets.

Returns:

a mapping of TabletId to TabletServerId (or @null if no location is available) for each tablet belonging to tableId

listOnlineTabletsForTable

List<TabletStatistics> listOnlineTabletsForTable(TabletServerId tabletServerId,
                                                 TableId tableId)
                                          throws AccumuloException,
                                                 AccumuloSecurityException

Fetch the tablets for the given table by asking the tablet server. Useful if your balance strategy needs details at the tablet level to decide what tablets to move.

Parameters:

tabletServerId - The tablet server to ask.

tableId - The table id

Returns:

a list of tablet statistics

Throws:

AccumuloSecurityException - tablet server disapproves of your internal System password.

AccumuloException - any other problem

tableContext

String tableContext(TableId tableId)

Retrieve the classloader context that is configured for tableId, or null if none is configured.