DefaultWALProvider (Hortonworks Data Platform Apache HBase Java API Reference)

java.lang.Object
- org.apache.hadoop.hbase.wal.DefaultWALProvider

All Implemented Interfaces:

WALProvider
```
@InterfaceAudience.Private
 @InterfaceStability.Evolving
public class DefaultWALProvider
extends java.lang.Object
implements WALProvider
```
A WAL Provider that returns a single thread safe WAL that writes to Hadoop FS. By default, this implementation picks a directory in Hadoop FS based on a combination of
- the HBase root WAL directory
- HConstants.HREGION_LOGDIR_NAME
- the given factory's factoryId (usually identifying the regionserver by host:port)
It also uses the providerId to diffentiate among files.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static interface DefaultWALProvider.Reader

static interface DefaultWALProvider.Writer

Nested Classes
Modifier and Type	Class and Description
`static interface`	`DefaultWALProvider.Reader`
`static interface`	`DefaultWALProvider.Writer`

Field Summary

Fields
Modifier and Type	Field and Description
`protected FSHLog`	`log`
`static java.lang.String`	`META_WAL_PROVIDER_ID` The hbase:meta region's WAL filename extension
`static java.lang.String`	`SPLITTING_EXT` File Extension used while splitting an WAL into regions (HBASE-2312)
`static java.lang.String`	`WAL_FILE_NAME_DELIMITER`

Constructor Summary

Constructors
Constructor and Description

DefaultWALProvider()

Constructors
Constructor and Description
`DefaultWALProvider()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`close()` shutdown utstanding WALs and clean up any persisted state.
`static DefaultWALProvider.Writer`	`createWriter(Configuration conf, FileSystem fs, Path path, boolean overwritable)` public because of FSHLog.
`static long`	`extractFileNumFromWAL(Path walName)`
`static long`	`extractFileNumFromWAL(WAL wal)` It returns the file create timestamp from the file name.
`static Path`	`getCurrentFileName(WAL wal)` return the current filename from the current wal.
`static long`	`getLogFileSize(WALFactory walFactory)` iff the given WALFactory is using the DefaultWALProvider for meta and/or non-meta, count the size of files (rolled and active).
`static long`	`getNumLogFiles(WALFactory walFactory)` iff the given WALFactory is using the DefaultWALProvider for meta and/or non-meta, count the number of files (rolled and active).
`static int`	`getNumRolledLogFiles(WAL wal)` returns the number of rolled WAL files.
`static ServerName`	`getServerNameFromWALDirectoryName(Configuration conf, java.lang.String path)` Pulls a ServerName out of a Path generated according to our layout rules.
`static ServerName`	`getServerNameFromWALDirectoryName(Path logFile)` This function returns region server name from a log file name which is in one of the following formats: hdfs:///hbase/.logs/-splitting/...
`WAL`	`getWAL(byte[] identifier)`
`static java.lang.String`	`getWALDirectoryName(java.lang.String serverName)` Construct the directory name for all WALs on a given server.
`void`	`init(WALFactory factory, Configuration conf, java.util.List<WALActionsListener> listeners, java.lang.String providerId)` Set up the provider to create wals.
`static boolean`	`isMetaFile(Path p)`
`void`	`shutdown()` persist outstanding WALs to storage and stop accepting new appends.
`static boolean`	`validateWALFilename(java.lang.String filename)` A WAL file name is of the format: <wal-name>`WAL_FILE_NAME_DELIMITER`<file-creation-timestamp>[.meta].

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - log
```
protected FSHLog log
```
  - WAL_FILE_NAME_DELIMITER
```
public static final java.lang.String WAL_FILE_NAME_DELIMITER
```
    See Also:
    
    Constant Field Values
  - META_WAL_PROVIDER_ID
```
public static final java.lang.String META_WAL_PROVIDER_ID
```
    The hbase:meta region's WAL filename extension
    
    See Also:
    
    Constant Field Values
  - SPLITTING_EXT
```
public static final java.lang.String SPLITTING_EXT
```
    File Extension used while splitting an WAL into regions (HBASE-2312)
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - DefaultWALProvider
```
public DefaultWALProvider()
```
- Method Detail
  - init
```
public void init(WALFactory factory,
                 Configuration conf,
                 java.util.List<WALActionsListener> listeners,
                 java.lang.String providerId)
          throws java.io.IOException
```
    Description copied from interface: WALProvider
    
    Set up the provider to create wals. will only be called once per instance.
    
    Specified by:
    
    init in interface WALProvider
    
    Parameters:
    
    factory - factory that made us, identity used for FS layout. may not be null
    
    conf - may not be null
    
    listeners - may be null
    
    providerId - differentiate between providers from one facotry, used for FS layout. may be null
    
    Throws:
    
    java.io.IOException
  - getWAL
```
public WAL getWAL(byte[] identifier)
           throws java.io.IOException
```
    Specified by:
    
    getWAL in interface WALProvider
    
    Parameters:
    
    identifier - may not be null. contents will not be altered.
    
    Returns:
    
    a WAL for writing entries for the given region.
    
    Throws:
    
    java.io.IOException
  - close
```
public void close()
           throws java.io.IOException
```
    Description copied from interface: WALProvider
    
    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.
    
    Specified by:
    
    close in interface WALProvider
    
    Throws:
    
    java.io.IOException
  - shutdown
```
public void shutdown()
              throws java.io.IOException
```
    Description copied from interface: WALProvider
    
    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.
    
    Specified by:
    
    shutdown in interface WALProvider
    
    Throws:
    
    java.io.IOException
  - getNumLogFiles
```
public static long getNumLogFiles(WALFactory walFactory)
```
    iff the given WALFactory is using the DefaultWALProvider for meta and/or non-meta, count the number of files (rolled and active). if either of them aren't, count 0 for that provider.
    
    Parameters:
    
    walFactory - may not be null.
  - getLogFileSize
```
public static long getLogFileSize(WALFactory walFactory)
```
    iff the given WALFactory is using the DefaultWALProvider for meta and/or non-meta, count the size of files (rolled and active). if either of them aren't, count 0 for that provider.
    
    Parameters:
    
    walFactory - may not be null.
  - getNumRolledLogFiles
```
public static int getNumRolledLogFiles(WAL wal)
```
    returns the number of rolled WAL files.
  - getCurrentFileName
```
public static Path getCurrentFileName(WAL wal)
```
    return the current filename from the current wal.
  - extractFileNumFromWAL
```
public static long extractFileNumFromWAL(WAL wal)
```
    It returns the file create timestamp from the file name. For name format see validateWALFilename(String) public until remaining tests move to o.a.h.h.wal
    
    Parameters:
    
    wal - must not be null
    
    Returns:
    
    the file number that is part of the WAL file name
  - extractFileNumFromWAL
```
public static long extractFileNumFromWAL(Path walName)
```
  - validateWALFilename
```
public static boolean validateWALFilename(java.lang.String filename)
```
    A WAL file name is of the format: <wal-name>WAL_FILE_NAME_DELIMITER<file-creation-timestamp>[.meta]. provider-name is usually made up of a server-name and a provider-id
    
    Parameters:
    
    filename - name of the file to validate
    
    Returns:
    
    true if the filename matches an WAL, false otherwise
  - getWALDirectoryName
```
public static java.lang.String getWALDirectoryName(java.lang.String serverName)
```
    Construct the directory name for all WALs on a given server.
    
    Parameters:
    
    serverName - Server name formatted as described in ServerName
    
    Returns:
    
    the relative WAL directory name, e.g. .logs/1.example.org,60030,12345 if serverName passed is 1.example.org,60030,12345
  - getServerNameFromWALDirectoryName
```
public static ServerName getServerNameFromWALDirectoryName(Configuration conf,
                                                           java.lang.String path)
                                                    throws java.io.IOException
```
    Pulls a ServerName out of a Path generated according to our layout rules. In the below layouts, this method ignores the format of the logfile component. Current format: [base directory for hbase]/hbase/.logs/ServerName/logfile or [base directory for hbase]/hbase/.logs/ServerName-splitting/logfile Expected to work for individual log files and server-specific directories.
    
    Returns:
    
    null if it's not a log file. Returns the ServerName of the region server that created this log file otherwise.
    
    Throws:
    
    java.io.IOException
  - getServerNameFromWALDirectoryName
```
public static ServerName getServerNameFromWALDirectoryName(Path logFile)
```
    This function returns region server name from a log file name which is in one of the following formats:
    - hdfs:///hbase/.logs/-splitting/...
    - hdfs:///hbase/.logs//...
    Parameters:
    
    logFile -
    
    Returns:
    
    null if the passed in logFile isn't a valid WAL file path
  - isMetaFile
```
public static boolean isMetaFile(Path p)
```
  - createWriter
```
public static DefaultWALProvider.Writer createWriter(Configuration conf,
                                                     FileSystem fs,
                                                     Path path,
                                                     boolean overwritable)
                                              throws java.io.IOException
```
    public because of FSHLog. Should be package-private
    
    Throws:
    
    java.io.IOException

Class DefaultWALProvider

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

log

WAL_FILE_NAME_DELIMITER

META_WAL_PROVIDER_ID

SPLITTING_EXT

Constructor Detail

DefaultWALProvider

Method Detail

init

getWAL

close

shutdown

getNumLogFiles

getLogFileSize

getNumRolledLogFiles

getCurrentFileName

extractFileNumFromWAL

extractFileNumFromWAL

validateWALFilename

getWALDirectoryName

getServerNameFromWALDirectoryName

getServerNameFromWALDirectoryName

isMetaFile

createWriter