org.apache.hadoop.hbase.wal.WALProvider 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.wal;
import java.io.Closeable;
import java.io.IOException;
import java.util.List;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
// imports for things that haven't moved from regionserver.wal yet.
import org.apache.hadoop.hbase.regionserver.wal.WALActionsListener;
/**
* The Write Ahead Log (WAL) stores all durable edits to the HRegion.
* This interface provides the entry point for all WAL implementors.
*
* See {@link DefaultWALProvider} for an example implementation.
*
* A single WALProvider will be used for retrieving multiple WALs in a particular region server
* and must be threadsafe.
*/
@InterfaceAudience.Private
public interface WALProvider {
/**
* Set up the provider to create wals.
* will only be called once per instance.
* @param factory factory that made us may not be null
* @param conf may not be null
* @param listeners may be null
* @param providerId differentiate between providers from one factory. may be null
*/
void init(final WALFactory factory, final Configuration conf,
final List listeners, final String providerId) throws IOException;
/**
* @param identifier may not be null. contents will not be altered.
* @param namespace could be null, and will use default namespace if null
* @return a WAL for writing entries for the given region.
*/
WAL getWAL(final byte[] identifier, byte[] namespace) throws IOException;
/** @return the List of WALs that are used by this server
*/
List getWALs() throws IOException;
/**
* persist outstanding WALs to storage and stop accepting new appends.
* This method serves as shorthand for sending a sync to every WAL provided by a given
* implementation. Those WALs will also stop accepting new writes.
*/
void shutdown() throws IOException;
/**
* shutdown utstanding WALs and clean up any persisted state.
* Call this method only when you will not need to replay any of the edits to the WALs from
* this provider. After this call completes, the underlying resources should have been reclaimed.
*/
void close() throws IOException;
// Writers are used internally. Users outside of the WAL should be relying on the
// interface provided by WAL.
interface Writer extends Closeable {
/**
* @param forceSync Flag to force sync rather than flushing to the buffer. Example - Hadoop
* hflush vs hsync.
* @throws IOException
*/
void sync(boolean forceSync) throws IOException;
void append(WAL.Entry entry) throws IOException;
long getLength() throws IOException;
}
/**
* Get number of the log files this provider is managing
*/
long getNumLogFiles();
/**
* Get size of the log files this provider is managing
*/
long getLogFileSize();
}