org.apache.hadoop.hbase.wal

Interface WALProvider

All Known Implementing Classes:

BoundedRegionGroupingProvider, DefaultWALProvider

@InterfaceAudience.Private
public interface WALProvider

The Write Ahead Log (WAL) stores all durable edits to the HRegion. This interface provides the entry point for all WAL implementors.

See DefaultWALProvider for an example implementation. A single WALProvider will be used for retrieving multiple WALs in a particular region server and must be threadsafe.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	WALProvider.Writer

Method Summary

Modifier and Type	Method and Description
void	close() shutdown utstanding WALs and clean up any persisted state.
WAL	getWAL(byte[] identifier)
void	init(WALFactory factory, Configuration conf, List<WALActionsListener> listeners, String providerId) Set up the provider to create wals.
void	shutdown() persist outstanding WALs to storage and stop accepting new appends.

Method Detail

init

void init(WALFactory factory,
          Configuration conf,
          List<WALActionsListener> listeners,
          String providerId)
   throws IOException

Set up the provider to create wals. will only be called once per instance.

Parameters:

factory - factory that made us may not be null

conf - may not be null

listeners - may be null

providerId - differentiate between providers from one factory. may be null

Throws:

IOException

getWAL

WAL getWAL(byte[] identifier)
    throws IOException

Parameters:

identifier - may not be null. contents will not be altered.

Returns:

a WAL for writing entries for the given region.

Throws:

IOException

shutdown

void shutdown()
       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.

Throws:

IOException

close

void close()
    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.

Throws:

IOException