org.apache.hadoop.hbase.regionserver.wal

Class CombinedAsyncWriter

java.lang.Object

org.apache.hadoop.hbase.regionserver.wal.CombinedAsyncWriter

All Implemented Interfaces:

Closeable, AutoCloseable, WALProvider.AsyncWriter, WALProvider.WriterBase

@InterfaceAudience.Private
public final class CombinedAsyncWriter
extends Object
implements WALProvider.AsyncWriter

An WALProvider.AsyncWriter wrapper which writes data to a set of WALProvider.AsyncWriter instances.

Field Summary

Fields

Modifier and Type	Field and Description
private static org.slf4j.Logger	LOG
private org.apache.hbase.thirdparty.com.google.common.collect.ImmutableList<WALProvider.AsyncWriter>	writers

Constructor Summary

Constructors

Modifier	Constructor and Description
private	CombinedAsyncWriter(org.apache.hbase.thirdparty.com.google.common.collect.ImmutableList<WALProvider.AsyncWriter> writers)

Method Summary

Modifier and Type	Method and Description
void	append(WAL.Entry entry)
void	close()
static CombinedAsyncWriter	create(WALProvider.AsyncWriter writer, WALProvider.AsyncWriter... writers)
long	getLength()
long	getSyncedLength() NOTE: We add this method for WALFileLengthProvider used for replication, considering the case if we use AsyncFSWAL,we write to 3 DNs concurrently, according to the visibility guarantee of HDFS, the data will be available immediately when arriving at DN since all the DNs will be considered as the last one in pipeline.
CompletableFuture<Long>	sync(boolean forceSync)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOG

private static final org.slf4j.Logger LOG

writers

private final org.apache.hbase.thirdparty.com.google.common.collect.ImmutableList<WALProvider.AsyncWriter> writers

Constructor Detail

CombinedAsyncWriter

private CombinedAsyncWriter(org.apache.hbase.thirdparty.com.google.common.collect.ImmutableList<WALProvider.AsyncWriter> writers)

Method Detail

getLength

public long getLength()

Specified by:

getLength in interface WALProvider.WriterBase

getSyncedLength

public long getSyncedLength()

Description copied from interface: WALProvider.WriterBase

NOTE: We add this method for WALFileLengthProvider used for replication, considering the case if we use AsyncFSWAL,we write to 3 DNs concurrently, according to the visibility guarantee of HDFS, the data will be available immediately when arriving at DN since all the DNs will be considered as the last one in pipeline. This means replication may read uncommitted data and replicate it to the remote cluster and cause data inconsistency. The method WALProvider.WriterBase.getLength() may return length which just in hdfs client buffer and not successfully synced to HDFS, so we use this method to return the length successfully synced to HDFS and replication thread could only read writing WAL file limited by this length. see also HBASE-14004 and this document for more details: https://docs.google.com/document/d/11AyWtGhItQs6vsLRIx32PwTxmBY3libXwGXI25obVEY/edit#

Specified by:

getSyncedLength in interface WALProvider.WriterBase

Returns:

byteSize successfully synced to underlying filesystem.

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

append

public void append(WAL.Entry entry)

Specified by:

append in interface WALProvider.AsyncWriter

sync

public CompletableFuture<Long> sync(boolean forceSync)

Specified by:

sync in interface WALProvider.AsyncWriter

create

public static CombinedAsyncWriter create(WALProvider.AsyncWriter writer,
                                         WALProvider.AsyncWriter... writers)