Package org.apache.accumulo.server.log

Class WalStateManager

java.lang.Object

org.apache.accumulo.server.log.WalStateManager

public class WalStateManager
extends Object

This class governs the space in Zookeeper that advertises the status of Write-Ahead Logs in use by tablet servers.

The Accumulo Manager needs to know the state of the WALs to mark tablets during recovery. The GC needs to know when a log is no longer needed so it can be removed.

The state of the WALs is kept in Zookeeper under /accumulo/<instanceid>/wals. For each server, there is a znode formatted like the TServerInstance.toString(): "host:port[sessionid]". Under the server znode, is a node for each log, using the UUID for the log. In each of the WAL znodes, is the current state of the log, and the full path to the log.

The state [OPEN, CLOSED, UNREFERENCED] is what the tablet server believes to be the state of the file.

In the event of a recovery, the log is identified as belonging to a dead server. The manager will update the tablets assigned to that server with log references. Once all tablets have been reassigned and the log references are removed, the log will be eligible for deletion.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	WalStateManager.WalMarkerException
static class	WalStateManager.WalState

Field Summary

Fields

Modifier and Type	Field	Description
static String	ZWALS

Constructor Summary

Constructors

Constructor	Description
WalStateManager(ServerContext context)

Method Summary

Modifier and Type	Method	Description
void	addNewWalMarker(TServerInstance tsi, org.apache.hadoop.fs.Path path)
void	closeWal(TServerInstance instance, org.apache.hadoop.fs.Path path)
void	forget(TServerInstance instance)
Map<TServerInstance,List<UUID>>	getAllMarkers()
Map<org.apache.hadoop.fs.Path,WalStateManager.WalState>	getAllState()
List<org.apache.hadoop.fs.Path>	getWalsInUse(TServerInstance tsi)
void	initWalMarker(TServerInstance tsi)
void	removeWalMarker(TServerInstance instance, UUID uuid)
Pair<WalStateManager.WalState,org.apache.hadoop.fs.Path>	state(TServerInstance instance, UUID uuid)
void	walUnreferenced(TServerInstance tsi, org.apache.hadoop.fs.Path path)

Methods inherited from class java.lang.Object

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

Field Detail

ZWALS

public static final String ZWALS

See Also:

Constant Field Values

Constructor Detail

WalStateManager

public WalStateManager(ServerContext context)

Method Detail

initWalMarker

public void initWalMarker(TServerInstance tsi)
                   throws WalStateManager.WalMarkerException

Throws:

WalStateManager.WalMarkerException

addNewWalMarker

public void addNewWalMarker(TServerInstance tsi,
                            org.apache.hadoop.fs.Path path)
                     throws WalStateManager.WalMarkerException

Throws:

WalStateManager.WalMarkerException

walUnreferenced

public void walUnreferenced(TServerInstance tsi,
                            org.apache.hadoop.fs.Path path)
                     throws WalStateManager.WalMarkerException

Throws:

WalStateManager.WalMarkerException

getWalsInUse

public List<org.apache.hadoop.fs.Path> getWalsInUse(TServerInstance tsi)
                                             throws WalStateManager.WalMarkerException

Throws:

WalStateManager.WalMarkerException

getAllMarkers

public Map<TServerInstance,List<UUID>> getAllMarkers()
                                                    throws WalStateManager.WalMarkerException

Throws:

WalStateManager.WalMarkerException

state

public Pair<WalStateManager.WalState,org.apache.hadoop.fs.Path> state(TServerInstance instance,
                                                                            UUID uuid)
                                                                     throws WalStateManager.WalMarkerException

Throws:

WalStateManager.WalMarkerException

getAllState

public Map<org.apache.hadoop.fs.Path,WalStateManager.WalState> getAllState()
                                                                          throws WalStateManager.WalMarkerException

Throws:

WalStateManager.WalMarkerException

removeWalMarker

public void removeWalMarker(TServerInstance instance,
                            UUID uuid)
                     throws WalStateManager.WalMarkerException

Throws:

WalStateManager.WalMarkerException

forget

public void forget(TServerInstance instance)
            throws WalStateManager.WalMarkerException

Throws:

WalStateManager.WalMarkerException

closeWal

public void closeWal(TServerInstance instance,
                     org.apache.hadoop.fs.Path path)
              throws WalStateManager.WalMarkerException

Throws:

WalStateManager.WalMarkerException