org.apache.hadoop.hbase.master

Class DeadServer

java.lang.Object

org.apache.hadoop.hbase.master.DeadServer

@InterfaceAudience.Private
public class DeadServer
extends Object

Class to hold dead servers list and utility querying dead server list. Servers are added when they expire or when we find them in filesystem on startup. When a server crash procedure is queued, it will populate the processing list and then remove the server from processing list when done. Servers are removed from dead server list when a new instance is started over the old on same hostname and port or when new Master comes online tidying up after all initialization. Processing list and deadserver list are not tied together (you don't have to be in deadservers list to be processing and vice versa).

Field Summary

Fields

Modifier and Type	Field and Description
private Map<ServerName,Long>	deadServers Set of known dead servers.
private static org.slf4j.Logger	LOG
private Set<ServerName>	processingServers Set of dead servers currently being processed by a SCP.

Constructor Summary

Constructors

Constructor and Description
DeadServer()

Method Summary

Modifier and Type	Method and Description
(package private) boolean	areDeadServersInProgress() Checks if there are currently any dead servers being processed by the master.
(package private) void	cleanAllPreviousInstances(ServerName newServerName)
private boolean	cleanOldServerName(ServerName newServerName, Iterator<ServerName> deadServerIterator)
(package private) boolean	cleanPreviousInstance(ServerName newServerName) Handles restart of a server.
(package private) List<Pair<ServerName,Long>>	copyDeadServersSince(long ts) Extract all the servers dead since a given time, and sort them.
Set<ServerName>	copyServerNames()
void	finish(ServerName sn) Complete processing for this dead server.
Date	getTimeOfDeath(ServerName deadServerName) Get the time when a server died
boolean	isDeadServer(ServerName serverName)
(package private) boolean	isEmpty()
void	processing(ServerName sn) Add sn< to set of processing deadservers.
(package private) void	putIfAbsent(ServerName sn) Adds the server to the dead server list if it's not there already.
boolean	removeDeadServer(ServerName deadServerName) Called from rpc by operator cleaning up deadserver list.
int	size()
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

LOG

private static final org.slf4j.Logger LOG

deadServers

private final Map<ServerName,Long> deadServers

Set of known dead servers. On znode expiration, servers are added here. This is needed in case of a network partitioning where the server's lease expires, but the server is still running. After the network is healed, and it's server logs are recovered, it will be told to call server startup because by then, its regions have probably been reassigned.

processingServers

private final Set<ServerName> processingServers

Set of dead servers currently being processed by a SCP. Added to this list at the start of SCP and removed after it is done processing the crash.

Constructor Detail

DeadServer

public DeadServer()

Method Detail

isDeadServer

public boolean isDeadServer(ServerName serverName)

Parameters:

serverName - server name.

Returns:

true if this server is on the dead servers list false otherwise

areDeadServersInProgress

boolean areDeadServersInProgress()

Checks if there are currently any dead servers being processed by the master. Returns true if at least one region server is currently being processed as dead.

Returns:

true if any RS are being processed as dead

copyServerNames

public Set<ServerName> copyServerNames()

putIfAbsent

void putIfAbsent(ServerName sn)

Adds the server to the dead server list if it's not there already.

processing

public void processing(ServerName sn)

Add sn< to set of processing deadservers.

See Also:

finish(ServerName)

finish

public void finish(ServerName sn)

Complete processing for this dead server.

Parameters:

sn - ServerName for the dead server.

See Also:

processing(ServerName)

size

public int size()

isEmpty

boolean isEmpty()

cleanPreviousInstance

boolean cleanPreviousInstance(ServerName newServerName)

Handles restart of a server. The new server instance has a different start code. The new start code should be greater than the old one. We don't check that here. Removes the old server from deadserver list.

Parameters:

newServerName - Servername as either host:port or host,port,startcode.

Returns:

true if this server was dead before and coming back alive again

cleanAllPreviousInstances

void cleanAllPreviousInstances(ServerName newServerName)

cleanOldServerName

private boolean cleanOldServerName(ServerName newServerName,
                                   Iterator<ServerName> deadServerIterator)

Parameters:

newServerName - Server to match port and hostname against.

deadServerIterator - Iterator primed so can call 'next' on it.

Returns:

True if newServerName and current primed iterator ServerName have same host and port and we removed old server from iterator and from processing list.

toString

public String toString()

Overrides:

toString in class Object

copyDeadServersSince

List<Pair<ServerName,Long>> copyDeadServersSince(long ts)

Extract all the servers dead since a given time, and sort them.

Parameters:

ts - the time, 0 for all

Returns:

a sorted array list, by death time, lowest values first.

getTimeOfDeath

public Date getTimeOfDeath(ServerName deadServerName)

Get the time when a server died

Parameters:

deadServerName - the dead server name

Returns:

the date when the server died

removeDeadServer

public boolean removeDeadServer(ServerName deadServerName)

Called from rpc by operator cleaning up deadserver list.

Parameters:

deadServerName - the dead server name

Returns:

true if this server was removed