org.apache.hadoop.hbase.client.Connection Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hbase.client;
import java.io.Closeable;
import java.io.IOException;
import java.util.concurrent.ExecutorService;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Abortable;
import org.apache.hadoop.hbase.HBaseInterfaceAudience;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.TableName;
import org.apache.yetus.audience.InterfaceAudience;
/**
* A cluster connection encapsulating lower level individual connections to actual servers and a
* connection to zookeeper. Connections are instantiated through the {@link ConnectionFactory}
* class. The lifecycle of the connection is managed by the caller, who has to {@link #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 {@link Table}
* and {@link 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. {@link Table}
* and {@link 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 {@link Table} and {@link Admin} is not
* recommended.
* @see ConnectionFactory
* @since 0.99.0
*/
@InterfaceAudience.Public
public interface Connection extends Abortable, Closeable {
/*
* Implementation notes: - Only allow new style of interfaces: -- All table names are passed as
* TableName. No more byte[] and string arguments -- Most of the classes with names H is
* deprecated in favor of non-H versions (Table, Connection, etc) -- Only real client-facing
* public methods are allowed - Connection should contain only getTable(), getAdmin() kind of
* general methods.
*/
/** Returns Configuration instance being used by this Connection instance. */
Configuration getConfiguration();
/**
* 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.
*
* The caller is responsible for calling {@link Table#close()} on the returned table instance.
*
* Since 0.98.1 this method no longer checks table existence. An exception will be thrown if the
* table does not exist only when the first operation is attempted.
* @param tableName the name of the table
* @return a Table to use for interactions with this table
*/
default Table getTable(TableName tableName) throws IOException {
return getTable(tableName, null);
}
/**
* 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.
*
* The caller is responsible for calling {@link Table#close()} on the returned table instance.
*
* Since 0.98.1 this method no longer checks table existence. An exception will be thrown if the
* table does not exist only when the first operation is attempted.
* @param tableName the name of the table
* @param pool The thread pool to use for batch operations, null to use a default pool.
* @return a Table to use for interactions with this table
*/
default Table getTable(TableName tableName, ExecutorService pool) throws IOException {
return getTableBuilder(tableName, pool).build();
}
/**
*
* Retrieve a {@link BufferedMutator} for performing client-side buffering of writes. The
* {@link BufferedMutator} returned by this method is thread-safe. This accessor will create a new
* ThreadPoolExecutor and will be shutdown once we close the BufferedMutator. This object can be
* used for long lived operations.
*
*
* The caller is responsible for calling {@link BufferedMutator#close()} on the returned
* {@link BufferedMutator} instance.
*
*
* @param tableName the name of the table
* @return a {@link BufferedMutator} for the supplied tableName.
*/
BufferedMutator getBufferedMutator(TableName tableName) throws IOException;
/**
* Retrieve a {@link BufferedMutator} for performing client-side buffering of writes. The
* {@link BufferedMutator} returned by this method is thread-safe. This object can be used for
* long lived table operations. If user passes ThreadPool in BufferedMutatorParams then we will
* use that otherwise we will create for the user. For user specified ThreadPool, it is the user's
* responsibility to shutdown. For ThreadPool created by us, we will shutdown when user calls
* {@link BufferedMutator#close()}. The caller is responsible for calling
* {@link BufferedMutator#close()} on the returned {@link BufferedMutator} instance.
* @param params details on how to instantiate the {@code BufferedMutator}.
* @return a {@link BufferedMutator} for the supplied tableName.
*/
BufferedMutator getBufferedMutator(BufferedMutatorParams params) 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.
* The caller is responsible for calling {@link RegionLocator#close()} on the returned
* RegionLocator instance. RegionLocator needs to be unmanaged
* @param tableName Name of the table who's region is to be examined
* @return A RegionLocator instance
*/
RegionLocator getRegionLocator(TableName tableName) throws IOException;
/**
* Clear all the entries in the region location cache, for all the tables.
*
* If you only want to clear the cache for a specific table, use
* {@link RegionLocator#clearRegionLocationCache()}.
*
* This may cause performance issue so use it with caution.
*/
void clearRegionLocationCache();
/**
* 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.
* The caller is responsible for calling {@link Admin#close()} on the returned Admin instance.
* @return an Admin instance for cluster administration
*/
Admin getAdmin() throws IOException;
@Override
void close() throws IOException;
/**
* Returns whether the connection is closed or not.
* @return true if this connection is closed
*/
boolean isClosed();
/**
* Returns an {@link TableBuilder} for creating {@link Table}.
* @param tableName the name of the table
* @param pool the thread pool to use for requests like batch and scan
*/
TableBuilder getTableBuilder(TableName tableName, ExecutorService pool);
/**
* Returns the cluster ID unique to this HBase cluster.
* The default implementation is added to keep client compatibility.
*/
default String getClusterId() {
return null;
}
/**
* Retrieve an Hbck implementation to fix an HBase cluster. The returned Hbck is not guaranteed to
* be thread-safe. A new instance should be created by each thread. This is a lightweight
* operation. Pooling or caching of the returned Hbck instance is not recommended.
* The caller is responsible for calling {@link Hbck#close()} on the returned Hbck instance.
* This will be used mostly by hbck tool.
* @return an Hbck instance for active master. Active master is fetched from the zookeeper.
*/
@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.HBCK)
default Hbck getHbck() throws IOException {
throw new UnsupportedOperationException("Not implemented");
}
/**
* Retrieve an Hbck implementation to fix an HBase cluster. The returned Hbck is not guaranteed to
* be thread-safe. A new instance should be created by each thread. This is a lightweight
* operation. Pooling or caching of the returned Hbck instance is not recommended.
* The caller is responsible for calling {@link Hbck#close()} on the returned Hbck instance.
* This will be used mostly by hbck tool. This may only be used to by pass getting registered
* master from ZK. In situations where ZK is not available or active master is not registered with
* ZK and user can get master address by other means, master can be explicitly specified.
* @param masterServer explicit {@link ServerName} for master server
* @return an Hbck instance for a specified master server
*/
@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.HBCK)
default Hbck getHbck(ServerName masterServer) throws IOException {
throw new UnsupportedOperationException("Not implemented");
}
}