WALProvider (Apache HBase 1.4.11 API)

All Known Implementing Classes:

DefaultWALProvider, RegionGroupingProvider
```
@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

Nested Classes
Modifier and Type	Interface and Description
`static interface`	`WALProvider.Writer`

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`close()` shutdown utstanding WALs and clean up any persisted state.
`long`	`getLogFileSize()` Get size of the log files this provider is managing
`long`	`getNumLogFiles()` Get number of the log files this provider is managing
`WAL`	`getWAL(byte[] identifier, byte[] namespace)`
`List<WAL>`	`getWALs()`
`void`	`init(WALFactory factory, org.apache.hadoop.conf.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,
        org.apache.hadoop.conf.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,
         byte[] namespace)
           throws IOException
```
    Parameters:
    identifier - may not be null. contents will not be altered.
    namespace - could be null, and will use default namespace if null
    
    Returns:
    a WAL for writing entries for the given region.
    
    Throws:
    
    IOException
  - getWALs
```
List<WAL> getWALs()
                  throws IOException
```
    Returns:
    the List of WALs that are used by this server
    
    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
  - getNumLogFiles
```
long getNumLogFiles()
```
    Get number of the log files this provider is managing
  - getLogFileSize
```
long getLogFileSize()
```
    Get size of the log files this provider is managing

Interface WALProvider

Nested Class Summary

Method Summary

Method Detail

init

getWAL

getWALs

shutdown

close

getNumLogFiles

getLogFileSize