org.apache.hadoop.hbase.client

Interface Connection

All Superinterfaces:

Abortable, AutoCloseable, Closeable

All Known Subinterfaces:

ClusterConnection, HConnection

@InterfaceAudience.Public
@InterfaceStability.Evolving
public interface Connection
extends Abortable, Closeable

A cluster connection encapsulating lower level individual connections to actual servers and a connection to zookeeper. Connections are instantiated through the ConnectionFactory class. The lifecycle of the connection is managed by the caller, who has to close() the connection to release the resources.

The connection object contains logic to find the master, locate regions out on the cluster, keeps a cache of locations and then knows how to re-calibrate after they move. The individual connections to servers, meta cache, zookeeper connection, etc are all shared by the Table and Admin instances obtained from this connection.

Connection creation is a heavy-weight operation. Connection implementations are thread-safe, so that the client can create a connection once, and share it with different threads. Table and Admin instances, on the other hand, are light-weight and are not thread-safe. Typically, a single connection per client application is instantiated and every thread will obtain its own Table instance. Caching or pooling of Table and Admin is not recommended.

This class replaces HConnection, which is now deprecated.

See Also:

ConnectionFactory

Method Summary

Methods

Modifier and Type	Method and Description
void	close()
Admin	getAdmin() Retrieve an Admin implementation to administer an HBase cluster.
org.apache.hadoop.conf.Configuration	getConfiguration()
RegionLocator	getRegionLocator(TableName tableName) Retrieve a RegionLocator implementation to inspect region information on a table.
Table	getTable(TableName tableName) Retrieve a Table implementation for accessing a table.
Table	getTable(TableName tableName, ExecutorService pool) Retrieve a Table implementation for accessing a table.
boolean	isClosed() Returns whether the connection is closed or not.

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

abort, isAborted

Method Detail

getConfiguration

org.apache.hadoop.conf.Configuration getConfiguration()

Returns:

Configuration instance being used by this HConnection instance.

getTable

Table getTable(TableName tableName)
               throws IOException

Retrieve a Table implementation for accessing a table. The returned Table is not thread safe, a new instance should be created for each using thread. This is a lightweight operation, pooling or caching of the returned Table is neither required nor desired.

Parameters:

tableName - the name of the table

Returns:

a Table to use for interactions with this table

Throws:

IOException

getTable

Table getTable(TableName tableName,
             ExecutorService pool)
               throws IOException

Retrieve a Table implementation for accessing a table. The returned Table is not thread safe, a new instance should be created for each using thread. This is a lightweight operation, pooling or caching of the returned Table is neither required nor desired.

Parameters:

tableName - the name of the table

pool - The thread pool to use for batch operations, null to use a default pool.

Returns:

a Table to use for interactions with this table

Throws:

IOException

getRegionLocator

RegionLocator getRegionLocator(TableName tableName)
                               throws IOException

Retrieve a RegionLocator implementation to inspect region information on a table. The returned RegionLocator is not thread-safe, so a new instance should be created for each using thread. This is a lightweight operation. Pooling or caching of the returned RegionLocator is neither required nor desired. RegionLocator needs to be unmanaged

Parameters:

tableName - Name of the table who's region is to be examined

Returns:

A RegionLocator instance

Throws:

IOException

getAdmin

Admin getAdmin()
               throws IOException

Retrieve an Admin implementation to administer an HBase cluster. The returned Admin is not guaranteed to be thread-safe. A new instance should be created for each using thread. This is a lightweight operation. Pooling or caching of the returned Admin is not recommended.

Returns:

an Admin instance for cluster administration

Throws:

IOException

close

void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException

isClosed

boolean isClosed()

Returns whether the connection is closed or not.

Returns:

true if this connection is closed