org.apache.hadoop.hbase.wal

Class WALFactory

java.lang.Object

org.apache.hadoop.hbase.wal.WALFactory

@InterfaceAudience.Private
public class WALFactory
extends Object

Entry point for users of the Write Ahead Log. Acts as the shim between internal use and the particular WALProvider we use to handle wal requests. Configure which provider gets used with the configuration setting "hbase.wal.provider". Available implementations:

• defaultProvider : whatever provider is standard for the hbase version. Currently "asyncfs"
• asyncfs : a provider that will run on top of an implementation of the Hadoop FileSystem interface via an asynchronous client.
• filesystem : a provider that will run on top of an implementation of the Hadoop FileSystem interface via HDFS's synchronous DFSClient.
• multiwal : a provider that will use multiple "filesystem" wal instances per region server.

Alternatively, you may provide a custom implementation of WALProvider by class name.

Field Summary

Fields

Modifier and Type	Field and Description
static String	META_WAL_PROVIDER
static String	WAL_PROVIDER

Constructor Summary

Constructors

Constructor and Description
WALFactory(org.apache.hadoop.conf.Configuration conf, String factoryId)

Method Summary

Modifier and Type	Method and Description
void	close() Shutdown all WALs and clean up any underlying storage.
WAL.Reader	createReader(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path path)
WAL.Reader	createReader(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path path, CancelableProgressable reporter) Create a reader for the WAL.
WAL.Reader	createReader(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path path, CancelableProgressable reporter, boolean allowCustom)
static WAL.Reader	createReader(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path path, org.apache.hadoop.conf.Configuration configuration) Create a reader for the given path, accept custom reader classes from conf.
static WAL.Reader	createReaderIgnoreCustomClass(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path path, org.apache.hadoop.conf.Configuration configuration) Create a reader for the given path, ignore custom reader classes from conf.
WALProvider.Writer	createRecoveredEditsWriter(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path path) Should be package-private, visible for recovery testing.
WALProvider.Writer	createWALWriter(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path path) Create a writer for the WAL.
static WALProvider.Writer	createWALWriter(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path path, org.apache.hadoop.conf.Configuration configuration) If you already have a WALFactory, you should favor the instance method.
static WALFactory	getInstance(org.apache.hadoop.conf.Configuration configuration)
WALProvider	getMetaWALProvider()
Class<? extends WALProvider>	getProviderClass(String key, String defaultValue)
WAL	getWAL(RegionInfo region)
WALProvider	getWALProvider()
List<WAL>	getWALs()
void	shutdown() Tell the underlying WAL providers to shut down, but do not clean up underlying storage.

Methods inherited from class java.lang.Object

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

Field Detail

WAL_PROVIDER

public static final String WAL_PROVIDER

See Also:

Constant Field Values

META_WAL_PROVIDER

public static final String META_WAL_PROVIDER

See Also:

Constant Field Values

Constructor Detail

WALFactory

public WALFactory(org.apache.hadoop.conf.Configuration conf,
                  String factoryId)
           throws IOException

Parameters:

conf - must not be null, will keep a reference to read params in later reader/writer instances.

factoryId - a unique identifier for this factory. used i.e. by filesystem implementations to make a directory

Throws:

IOException

Method Detail

getProviderClass

public Class<? extends WALProvider> getProviderClass(String key,
                                                     String defaultValue)

close

public void close()
           throws IOException

Shutdown all WALs and clean up any underlying storage. Use only when you will not need to replay and edits that have gone to any wals from this factory.

Throws:

IOException

shutdown

public void shutdown()
              throws IOException

Tell the underlying WAL providers to shut down, but do not clean up underlying storage. If you are not ending cleanly and will need to replay edits from this factory's wals, use this method if you can as it will try to leave things as tidy as possible.

Throws:

IOException

getWALs

public List<WAL> getWALs()

getWAL

public WAL getWAL(RegionInfo region)
           throws IOException

Parameters:

region - the region which we want to get a WAL for it. Could be null.

Throws:

IOException

createReader

public WAL.Reader createReader(org.apache.hadoop.fs.FileSystem fs,
                               org.apache.hadoop.fs.Path path)
                        throws IOException

Throws:

IOException

createReader

public WAL.Reader createReader(org.apache.hadoop.fs.FileSystem fs,
                               org.apache.hadoop.fs.Path path,
                               CancelableProgressable reporter)
                        throws IOException

Create a reader for the WAL. If you are reading from a file that's being written to and need to reopen it multiple times, use WAL.Reader.reset() instead of this method then just seek back to the last known good position.

Returns:

A WAL reader. Close when done with it.

Throws:

IOException

createReader

public WAL.Reader createReader(org.apache.hadoop.fs.FileSystem fs,
                               org.apache.hadoop.fs.Path path,
                               CancelableProgressable reporter,
                               boolean allowCustom)
                        throws IOException

Throws:

IOException

createWALWriter

public WALProvider.Writer createWALWriter(org.apache.hadoop.fs.FileSystem fs,
                                          org.apache.hadoop.fs.Path path)
                                   throws IOException

Create a writer for the WAL. Uses defaults.

Should be package-private. public only for tests and Compressor

Returns:

A WAL writer. Close when done with it.

Throws:

IOException

createRecoveredEditsWriter

public WALProvider.Writer createRecoveredEditsWriter(org.apache.hadoop.fs.FileSystem fs,
                                                     org.apache.hadoop.fs.Path path)
                                              throws IOException

Should be package-private, visible for recovery testing. Uses defaults.

Returns:

an overwritable writer for recovered edits. caller should close.

Throws:

IOException

getInstance

public static WALFactory getInstance(org.apache.hadoop.conf.Configuration configuration)

createReader

public static WAL.Reader createReader(org.apache.hadoop.fs.FileSystem fs,
                                      org.apache.hadoop.fs.Path path,
                                      org.apache.hadoop.conf.Configuration configuration)
                               throws IOException

Create a reader for the given path, accept custom reader classes from conf. If you already have a WALFactory, you should favor the instance method.

Returns:

a WAL Reader, caller must close.

Throws:

IOException

createReaderIgnoreCustomClass

public static WAL.Reader createReaderIgnoreCustomClass(org.apache.hadoop.fs.FileSystem fs,
                                                       org.apache.hadoop.fs.Path path,
                                                       org.apache.hadoop.conf.Configuration configuration)
                                                throws IOException

Create a reader for the given path, ignore custom reader classes from conf. If you already have a WALFactory, you should favor the instance method. only public pending move of Compressor

Returns:

a WAL Reader, caller must close.

Throws:

IOException

createWALWriter

public static WALProvider.Writer createWALWriter(org.apache.hadoop.fs.FileSystem fs,
                                                 org.apache.hadoop.fs.Path path,
                                                 org.apache.hadoop.conf.Configuration configuration)
                                          throws IOException

If you already have a WALFactory, you should favor the instance method. Uses defaults.

Returns:

a writer that won't overwrite files. Caller must close.

Throws:

IOException

getWALProvider

public final WALProvider getWALProvider()

getMetaWALProvider

public final WALProvider getMetaWALProvider()