org.apache.hudi.org.apache.hadoop.hbase.coprocessor.MasterCoprocessorEnvironment Maven / Gradle / Ivy
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package org.apache.hadoop.hbase.coprocessor;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.CoprocessorEnvironment;
import org.apache.hadoop.hbase.HBaseInterfaceAudience;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.metrics.MetricRegistry;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.yetus.audience.InterfaceStability;
@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
@InterfaceStability.Evolving
public interface MasterCoprocessorEnvironment extends CoprocessorEnvironment {
/**
* @return Hosting Server's ServerName
*/
ServerName getServerName();
/**
* Returns the hosts' Connection to the Cluster. Do not close! This is a shared connection
* with the hosting server. Throws {@link 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 {@link org.apache.hadoop.hbase.client.ConnectionFactory} or
* {@link #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 {@link #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.
*
* @see #createConnection(Configuration)
* @return The host's Connection to the Cluster.
*/
Connection getConnection();
/**
* 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 {@link org.apache.hadoop.hbase.client.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.
* @return Connection created using the passed conf.
*/
Connection createConnection(Configuration conf) throws IOException;
/**
* Returns a MetricRegistry that can be used to track metrics at the master level.
*
*
See ExampleMasterObserverWithMetrics class in the hbase-examples modules for examples
* of how metrics can be instantiated and used.
* @return A MetricRegistry for the coprocessor class to track and export metrics.
*/
MetricRegistry getMetricRegistryForMaster();
}