org.apache.hadoop.hbase.coprocessor

Interface RegionCoprocessorEnvironment

All Superinterfaces:

CoprocessorEnvironment<RegionCoprocessor>

All Known Implementing Classes:

RegionCoprocessorHost.RegionEnvironment, RegionCoprocessorHost.RegionEnvironmentForCoreCoprocessors

@InterfaceAudience.LimitedPrivate(value="Coprocesssor")
 @InterfaceStability.Evolving
public interface RegionCoprocessorEnvironment
extends CoprocessorEnvironment<RegionCoprocessor>

Method Summary

Modifier and Type	Method and Description
Connection	createConnection(org.apache.hadoop.conf.Configuration conf) Creates a cluster connection using the passed Configuration.
RawCellBuilder	getCellBuilder() Returns a CellBuilder so that coprocessors can build cells.
Connection	getConnection() Returns the hosts' Connection to the Cluster.
MetricRegistry	getMetricRegistryForRegionServer() Returns a MetricRegistry that can be used to track metrics at the region server level.
OnlineRegions	getOnlineRegions() Returns Interface to Map of regions online on this RegionServer getServerName()}.
Region	getRegion() Returns the region associated with this coprocessor
RegionInfo	getRegionInfo() Returns region information for the region this coprocessor is running on
ServerName	getServerName() Returns Hosting Server's ServerName
ConcurrentMap<String,Object>	getSharedData() Returns shared data between all instances of this coprocessor

Methods inherited from interface org.apache.hadoop.hbase.CoprocessorEnvironment

getClassLoader, getConfiguration, getHBaseVersion, getInstance, getLoadSequence, getPriority, getVersion

Method Detail

getRegion

Region getRegion()

Returns the region associated with this coprocessor

getRegionInfo

RegionInfo getRegionInfo()

Returns region information for the region this coprocessor is running on

getOnlineRegions

OnlineRegions getOnlineRegions()

Returns Interface to Map of regions online on this RegionServer getServerName()}.

getSharedData

ConcurrentMap<String,Object> getSharedData()

Returns shared data between all instances of this coprocessor

getServerName

ServerName getServerName()

Returns Hosting Server's ServerName

getConnection

Connection getConnection()

Returns the hosts' Connection to the Cluster. Do not close! This is a shared connection with the hosting server. Throws UnsupportedOperationException if you try to close or abort it. For light-weight usage only. Heavy-duty usage will pull down the hosting RegionServer responsiveness as well as that of other Coprocessors making use of this Connection. Use to create table on start or to do administrative operations. Coprocessors should create their own Connections if heavy usage to avoid impinging on hosting Server operation. To create a Connection or if a Coprocessor requires a region with a particular Configuration, use ConnectionFactory or createConnection(Configuration)}.

Be aware that operations that make use of this Connection are executed as the RegionServer User, the hbase super user that started this server process. Exercise caution running operations as this User (See createConnection(Configuration)} to run as other than the RegionServer User).

Be careful RPC'ing from a Coprocessor context. RPC's will fail, stall, retry, and/or crawl because the remote side is not online, is struggling or it is on the other side of a network partition. Any use of Connection from inside a Coprocessor must be able to handle all such hiccups.

NOTE: the returned Connection is created using User.getCurrent(),so the Connection is as the System User who running the RegionServer, not the client User who initiate the RPC.

Returns:

The host's Connection to the Cluster.

See Also:

createConnection(Configuration)

createConnection

Connection createConnection(org.apache.hadoop.conf.Configuration conf)
                     throws IOException

Creates a cluster connection using the passed Configuration. Creating a Connection is a heavy-weight operation. The resultant Connection's cache of region locations will be empty. Therefore you should cache and reuse Connections rather than create a Connection on demand. Create on start of your Coprocessor. You will have to cast the CoprocessorEnvironment appropriately to get at this API at start time because Coprocessor start method is passed a subclass of this CoprocessorEnvironment or fetch Connection using a synchronized accessor initializing the Connection on first access. Close the returned Connection when done to free resources. Using this API rather than ConnectionFactory.createConnection(Configuration) returns a Connection that will short-circuit RPC if the target is a local resource. Use ConnectionFactory if you don't need this ability.

Be careful RPC'ing from a Coprocessor context. RPC's will fail, stall, retry, and/or crawl because the remote side is not online, is struggling or it is on the other side of a network partition. Any use of Connection from inside a Coprocessor must be able to handle all such hiccups.

NOTE: the returned Connection is created using User.getCurrent(),so the Connection is as the System User who running the RegionServer, not the client User who initiate the RPC.

Returns:

Connection created using the passed conf.

Throws:

IOException

getMetricRegistryForRegionServer

MetricRegistry getMetricRegistryForRegionServer()

Returns a MetricRegistry that can be used to track metrics at the region server level. All metrics tracked at this level will be shared by all the coprocessor instances of the same class in the same region server process. Note that there will be one region coprocessor environment per region in the server, but all of these instances will share the same MetricRegistry. The metric instances (like Counter, Timer, etc) will also be shared among all of the region coprocessor instances.

See ExampleRegionObserverWithMetrics class in the hbase-examples modules to see examples of how metrics can be instantiated and used.

Returns:

A MetricRegistry for the coprocessor class to track and export metrics.

getCellBuilder

RawCellBuilder getCellBuilder()

Returns a CellBuilder so that coprocessors can build cells. These cells can also include tags. Note that this builder does not support updating seqId of the cells

Returns:

the RawCellBuilder