BaseWALObserver (Apache HBase 1.4.11 API)

java.lang.Object
- org.apache.hadoop.hbase.coprocessor.BaseWALObserver

All Implemented Interfaces:

Coprocessor, WALObserver
```
@InterfaceAudience.LimitedPrivate(value="Coprocesssor")
@InterfaceStability.Evolving
public class BaseWALObserver
extends Object
implements WALObserver
```
An abstract class that implements WALObserver. By extending it, you can create your own WAL observer without overriding all abstract methods of WALObserver.

Nested Class Summary
- Nested classes/interfaces inherited from interface org.apache.hadoop.hbase.Coprocessor
  Coprocessor.State

Field Summary
- Fields inherited from interface org.apache.hadoop.hbase.Coprocessor
  PRIORITY_HIGHEST, PRIORITY_LOWEST, PRIORITY_SYSTEM, PRIORITY_USER, VERSION

Constructor Summary

Constructors
Constructor and Description

BaseWALObserver()

Constructors
Constructor and Description
`BaseWALObserver()`

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`postWALRoll(ObserverContext<? extends WALCoprocessorEnvironment> ctx, org.apache.hadoop.fs.Path oldPath, org.apache.hadoop.fs.Path newPath)` Called after rolling the current WAL
`void`	`postWALWrite(ObserverContext<? extends WALCoprocessorEnvironment> ctx, HRegionInfo info, WALKey logKey, WALEdit logEdit)` Implementers should override this method and leave the deprecated version as-is.
`void`	`postWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx, HRegionInfo info, HLogKey logKey, WALEdit logEdit)` Called after a `WALEdit` is writen to WAL.
`void`	`preWALRoll(ObserverContext<? extends WALCoprocessorEnvironment> ctx, org.apache.hadoop.fs.Path oldPath, org.apache.hadoop.fs.Path newPath)` Called before rolling the current WAL
`boolean`	`preWALWrite(ObserverContext<? extends WALCoprocessorEnvironment> ctx, HRegionInfo info, WALKey logKey, WALEdit logEdit)` Implementers should override this method and leave the deprecated version as-is.
`boolean`	`preWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx, HRegionInfo info, HLogKey logKey, WALEdit logEdit)` Called before a `WALEdit` is writen to WAL.
`void`	`start(CoprocessorEnvironment e)`
`void`	`stop(CoprocessorEnvironment e)`

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

- Constructor Detail
  - BaseWALObserver
```
public BaseWALObserver()
```
- Method Detail
  - start
```
public void start(CoprocessorEnvironment e)
           throws IOException
```
    Specified by:
    
    start in interface Coprocessor
    
    Throws:
    
    IOException
  - stop
```
public void stop(CoprocessorEnvironment e)
          throws IOException
```
    Specified by:
    
    stop in interface Coprocessor
    
    Throws:
    
    IOException
  - preWALWrite
```
public boolean preWALWrite(ObserverContext<? extends WALCoprocessorEnvironment> ctx,
                  HRegionInfo info,
                  WALKey logKey,
                  WALEdit logEdit)
                    throws IOException
```
    Implementers should override this method and leave the deprecated version as-is.
    
    Specified by:
    
    preWALWrite in interface WALObserver
    
    Returns:
    true if default behavior should be bypassed, false otherwise
    
    Throws:
    
    IOException
  - preWALWrite
```
public boolean preWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx,
                  HRegionInfo info,
                  HLogKey logKey,
                  WALEdit logEdit)
                    throws IOException
```
    Description copied from interface: WALObserver
    
    Called before a WALEdit is writen to WAL. This method is left in place to maintain binary compatibility with older WALObservers. If an implementation directly overrides WALObserver.preWALWrite(ObserverContext, HRegionInfo, WALKey, WALEdit) then this version won't be called at all, barring problems with the Security Manager. To work correctly in the presence of a strict Security Manager, or in the case of an implementation that relies on a parent class to implement preWALWrite, you should implement this method as a call to the non-deprecated version. Users of this method will see all edits that can be treated as HLogKey. If there are edits that can't be treated as HLogKey they won't be offered to coprocessors that rely on this method. If a coprocessor gets skipped because of this mechanism, a log message at ERROR will be generated per coprocessor on the logger for CoprocessorHost once per classloader.
    
    Specified by:
    
    preWALWrite in interface WALObserver
    
    Returns:
    true if default behavior should be bypassed, false otherwise
    
    Throws:
    
    IOException
  - postWALWrite
```
public void postWALWrite(ObserverContext<? extends WALCoprocessorEnvironment> ctx,
                HRegionInfo info,
                WALKey logKey,
                WALEdit logEdit)
                  throws IOException
```
    Implementers should override this method and leave the deprecated version as-is.
    
    Specified by:
    
    postWALWrite in interface WALObserver
    
    Throws:
    
    IOException
  - postWALWrite
```
public void postWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx,
                HRegionInfo info,
                HLogKey logKey,
                WALEdit logEdit)
                  throws IOException
```
    Description copied from interface: WALObserver
    
    Called after a WALEdit is writen to WAL. This method is left in place to maintain binary compatibility with older WALObservers. If an implementation directly overrides WALObserver.postWALWrite(ObserverContext, HRegionInfo, WALKey, WALEdit) then this version won't be called at all, barring problems with the Security Manager. To work correctly in the presence of a strict Security Manager, or in the case of an implementation that relies on a parent class to implement preWALWrite, you should implement this method as a call to the non-deprecated version. Users of this method will see all edits that can be treated as HLogKey. If there are edits that can't be treated as HLogKey they won't be offered to coprocessors that rely on this method. If a coprocessor gets skipped because of this mechanism, a log message at ERROR will be generated per coprocessor on the logger for CoprocessorHost once per classloader.
    
    Specified by:
    
    postWALWrite in interface WALObserver
    
    Throws:
    
    IOException
  - preWALRoll
```
public void preWALRoll(ObserverContext<? extends WALCoprocessorEnvironment> ctx,
              org.apache.hadoop.fs.Path oldPath,
              org.apache.hadoop.fs.Path newPath)
                throws IOException
```
    Description copied from interface: WALObserver
    
    Called before rolling the current WAL
    
    Specified by:
    
    preWALRoll in interface WALObserver
    
    oldPath - the path of the current wal that we are replacing
    newPath - the path of the wal we are going to create
    
    Throws:
    
    IOException
  - postWALRoll
```
public void postWALRoll(ObserverContext<? extends WALCoprocessorEnvironment> ctx,
               org.apache.hadoop.fs.Path oldPath,
               org.apache.hadoop.fs.Path newPath)
                 throws IOException
```
    Description copied from interface: WALObserver
    
    Called after rolling the current WAL
    
    Specified by:
    
    postWALRoll in interface WALObserver
    
    oldPath - the path of the wal that we replaced
    newPath - the path of the wal we have created and now is the current
    
    Throws:
    
    IOException

Class BaseWALObserver

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.hadoop.hbase.Coprocessor

Field Summary

Fields inherited from interface org.apache.hadoop.hbase.Coprocessor

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

BaseWALObserver

Method Detail

start

stop

preWALWrite

preWALWrite

postWALWrite

postWALWrite

preWALRoll

postWALRoll