Package org.apache.hadoop.hbase.master.assignment

Class RegionStateNode

java.lang.Object

org.apache.hadoop.hbase.master.assignment.RegionStateNode

All Implemented Interfaces:

Comparable<RegionStateNode>

@Private
public class RegionStateNode
extends Object
implements Comparable<RegionStateNode>

Current Region State. Most fields are synchronized with meta region, i.e, we will update meta immediately after we modify this RegionStateNode, and usually under the lock. The only exception is lastHost, which should not be used for critical condition.

Typically, the only way to modify this class is through TransitRegionStateProcedure, and we will record the TRSP along with this RegionStateNode to make sure that there could at most one TRSP. For other operations, such as SCP, we will first get the lock, and then try to schedule a TRSP. If there is already one, then the solution will be different:

• For SCP, we will update the region state in meta to tell the TRSP to retry.
• For DisableTableProcedure, as we have the xlock, we can make sure that the TRSP has not been executed yet, so just unset it and attach a new one. The original one will quit immediately when executing.
• For split/merge, we will fail immediately as there is no actual operations yet so no harm.
• For EnableTableProcedure/TruncateTableProcedure, we can make sure that there will be no TRSP attached with the RSNs.
• For other procedures, you'd better use ReopenTableRegionsProcedure. The RTRP will take care of lots of corner cases when reopening regions.

Several fields are declared with volatile, which means you are free to get it without lock, but usually you should not use these fields without locking for critical condition, as it will be easily to introduce inconsistency. For example, you are free to dump the status and show it on web without locking, but if you want to change the state of the RegionStateNode by checking the current state, you'd better have the lock...

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static final class	RegionStateNode.AssignmentProcedureEvent

Field Summary

Fields

Modifier and Type	Field	Description
private final ProcedureEvent<?>	event
private ServerName	lastHost
private long	lastUpdate	Updated whenever a call to setRegionLocation(ServerName) or setState(RegionState.State, RegionState.State...).
(package private) final Lock	lock
private static final org.slf4j.Logger	LOG
private long	openSeqNum
private TransitRegionStateProcedure	procedure
private final RegionInfo	regionInfo
private ServerName	regionLocation
private final ConcurrentMap<RegionInfo,RegionStateNode>	ritMap
private RegionState.State	state	A Region-in-Transition (RIT) moves through states.

Constructor Summary

Constructors

Constructor	Description
RegionStateNode(RegionInfo regionInfo, ConcurrentMap<RegionInfo,RegionStateNode> ritMap)

Method Summary

Modifier and Type	Method	Description
void	checkOnline()
int	compareTo(RegionStateNode other)
boolean	equals(Object other)
int	getFormatVersion()
ServerName	getLastHost()
long	getLastUpdate()
long	getOpenSeqNum()
TransitRegionStateProcedure	getProcedure()
ProcedureEvent<?>	getProcedureEvent()
RegionInfo	getRegionInfo()
ServerName	getRegionLocation()
RegionState.State	getState()
TableName	getTable()
int	hashCode()
boolean	isInState(RegionState.State... expected)	Notice that, we will return true if expected is empty.
boolean	isInTransition()
boolean	isSplit()	Return whether the region has been split and not online.
boolean	isStuck()
boolean	isSystemTable()
void	lock()
ServerName	offline()	Put region into OFFLINE mode (set state and clear location).
void	setLastHost(ServerName serverName)
void	setOpenSeqNum(long seqId)
TransitRegionStateProcedure	setProcedure(TransitRegionStateProcedure proc)
ServerName	setRegionLocation(ServerName serverName)
boolean	setState(RegionState.State update, RegionState.State... expected)
String	toDescriptiveString()
RegionState	toRegionState()
String	toShortString()
String	toString()
void	transitionState(RegionState.State update, RegionState.State... expected)	Set new RegionState.State but only if currently in expected State (if not, throw UnexpectedStateException.
boolean	tryLock()
void	unlock()
void	unsetProcedure(TransitRegionStateProcedure proc)

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

LOG

private static final org.slf4j.Logger LOG

lock

final Lock lock

regionInfo

private final RegionInfo regionInfo

event

private final ProcedureEvent<?> event

ritMap

private final ConcurrentMap<RegionInfo,RegionStateNode> ritMap

procedure

private volatile TransitRegionStateProcedure procedure

regionLocation

private volatile ServerName regionLocation

lastHost

private volatile ServerName lastHost

state

private volatile RegionState.State state

A Region-in-Transition (RIT) moves through states. See RegionState.State for complete list. A Region that is opened moves from OFFLINE => OPENING => OPENED.

lastUpdate

private volatile long lastUpdate

Updated whenever a call to setRegionLocation(ServerName) or setState(RegionState.State, RegionState.State...).

openSeqNum

private volatile long openSeqNum

Constructor Details

RegionStateNode

RegionStateNode(RegionInfo regionInfo,
 ConcurrentMap<RegionInfo,RegionStateNode> ritMap)

Method Details

setState

public boolean setState(RegionState.State update,
 RegionState.State... expected)

Parameters:

update - new region state this node should be assigned.

expected - current state should be in this given list of expected states

Returns:

true, if current state is in expected list; otherwise false.

offline

public ServerName offline()

Put region into OFFLINE mode (set state and clear location).

Returns:

Last recorded server deploy

transitionState

public void transitionState(RegionState.State update,
 RegionState.State... expected)
                     throws UnexpectedStateException

Set new RegionState.State but only if currently in expected State (if not, throw UnexpectedStateException.

Throws:

UnexpectedStateException

isInState

public boolean isInState(RegionState.State... expected)

Notice that, we will return true if expected is empty.

This is a bit strange but we need this logic, for example, we can change the state to OPENING from any state, as in SCP we will not change the state to CLOSED before opening the region.

isStuck

public boolean isStuck()

isInTransition

public boolean isInTransition()

isSplit

public boolean isSplit()

Return whether the region has been split and not online.

In this method we will test both region info and state, and will return true if either of the test returns true. Please see the comments in AssignmentManager.markRegionAsSplit(RegionInfo, ServerName, RegionInfo, RegionInfo) for more details on why we need to test two conditions.

getLastUpdate

public long getLastUpdate()

setLastHost

public void setLastHost(ServerName serverName)

setOpenSeqNum

public void setOpenSeqNum(long seqId)

setRegionLocation

public ServerName setRegionLocation(ServerName serverName)

setProcedure

public TransitRegionStateProcedure setProcedure(TransitRegionStateProcedure proc)

unsetProcedure

public void unsetProcedure(TransitRegionStateProcedure proc)

getProcedure

public TransitRegionStateProcedure getProcedure()

getProcedureEvent

public ProcedureEvent<?> getProcedureEvent()

getRegionInfo

public RegionInfo getRegionInfo()

getTable

public TableName getTable()

isSystemTable

public boolean isSystemTable()

getLastHost

public ServerName getLastHost()

getRegionLocation

public ServerName getRegionLocation()

getState

public RegionState.State getState()

getOpenSeqNum

public long getOpenSeqNum()

getFormatVersion

public int getFormatVersion()

toRegionState

public RegionState toRegionState()

compareTo

public int compareTo(RegionStateNode other)

Specified by:

compareTo in interface Comparable<RegionStateNode>

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object other)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object

toShortString

public String toShortString()

toDescriptiveString

public String toDescriptiveString()

checkOnline

public void checkOnline()
                 throws DoNotRetryRegionException

Throws:

DoNotRetryRegionException

lock

public void lock()

tryLock

public boolean tryLock()

unlock

public void unlock()