RegionStates (Hortonworks Data Platform Apache HBase Java API Reference)

java.lang.Object
- org.apache.hadoop.hbase.master.RegionStates

```
@InterfaceAudience.Private
public class RegionStates
extends Object
```
Region state accountant. It holds the states of all regions in the memory. In normal scenario, it should match the meta table and the true region states. This map is used by AssignmentManager to track region states.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`clearLastAssignment(HRegionInfo region)`
`RegionState`	`createRegionState(HRegionInfo hri)` Add a region to RegionStates.
`RegionState`	`createRegionState(HRegionInfo hri, RegionState.State newState, ServerName serverName, ServerName lastHost)` Add a region to RegionStates with the specified state.
`void`	`createRegionStates(List<HRegionInfo> hris)` Add a list of regions to RegionStates.
`void`	`deleteRegion(HRegionInfo hri)` Remove a region from all state maps.
`protected Map<TableName,Map<ServerName,List<HRegionInfo>>>`	`getAssignmentsByTable()` This is an EXPENSIVE clone.
`protected double`	`getAverageLoad()` Compute the average load across all region servers.
`Map<HRegionInfo,ServerName>`	`getRegionAssignments()`
`protected Map<ServerName,List<HRegionInfo>>`	`getRegionAssignmentsByServer()` Returns a clone of region assignments per server
`Map<RegionState.State,List<HRegionInfo>>`	`getRegionByStateOfTable(TableName tableName)` Gets current state of all regions of the table.
`protected HRegionInfo`	`getRegionInfo(byte[] regionName)` Get the HRegionInfo from cache, if not there, from the hbase:meta table
`ServerName`	`getRegionServerOfRegion(HRegionInfo hri)`
`Map<String,RegionState>`	`getRegionsInTransition()` Get regions in transition and their states
`List<HRegionInfo>`	`getRegionsOfTable(TableName tableName)` Gets the online regions of the specified table.
`protected RegionState`	`getRegionState(HRegionInfo hri)`
`protected RegionState`	`getRegionState(String encodedName)`
`RegionState`	`getRegionTransitionState(HRegionInfo hri)` Get region transition state
`RegionState`	`getRegionTransitionState(String encodedName)` Get region transition state
`Set<HRegionInfo>`	`getServerRegions(ServerName serverName)` Get a copy of all regions assigned to a server
`boolean`	`isMetaRegionInTransition()`
`boolean`	`isRegionInState(HRegionInfo hri, RegionState.State... states)`
`boolean`	`isRegionInState(String encodedName, RegionState.State... states)`
`boolean`	`isRegionInTransition(HRegionInfo hri)`
`boolean`	`isRegionInTransition(String encodedName)`
`boolean`	`isRegionOffline(HRegionInfo hri)`
`boolean`	`isRegionOnline(HRegionInfo hri)`
`boolean`	`isRegionsInTransition()`
`void`	`logSplit(HRegionInfo region)` Log split is done for a given region, so it is assignable now.
`void`	`logSplit(ServerName serverName)` A dead server's wals have been split so that all the regions used to be open on it can be safely assigned now.
`void`	`regionOffline(HRegionInfo hri)` A region is offline, won't be in transition any more.
`void`	`regionOffline(HRegionInfo hri, RegionState.State expectedState)` A region is offline, won't be in transition any more.
`void`	`regionOnline(HRegionInfo hri, ServerName serverName)`
`void`	`regionOnline(HRegionInfo hri, ServerName serverName, long openSeqNum)` A region is online, won't be in transition any more.
`List<HRegionInfo>`	`serverOffline(ZooKeeperWatcher watcher, ServerName sn)` A server is offline, all regions on it are dead.
`void`	`tableDeleted(TableName tableName)` A table is deleted.
`RegionState`	`transitionOpenFromPendingOpenOrOpeningOnServer(RegionTransition transition, RegionState fromState, ServerName sn)` Transition a region state to OPEN from OPENING/PENDING_OPEN
`RegionState`	`updateRegionState(HRegionInfo hri, RegionState.State state)` Update a region state.
`RegionState`	`updateRegionState(HRegionInfo hri, RegionState.State state, ServerName serverName)` Update a region state.
`RegionState`	`updateRegionState(RegionTransition transition, RegionState.State state)` Update a region state.
`void`	`waitForUpdate(long timeout)` Wait for the state map to be updated by assignment manager.
`void`	`waitOnRegionToClearRegionsInTransition(HRegionInfo hri)` Wait on region to clear regions-in-transition.

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

- Method Detail
  - getRegionAssignments
```
public Map<HRegionInfo,ServerName> getRegionAssignments()
```
    Returns:
    
    an unmodifiable the region assignment map
  - getRegionServerOfRegion
```
public ServerName getRegionServerOfRegion(HRegionInfo hri)
```
  - getRegionsInTransition
```
public Map<String,RegionState> getRegionsInTransition()
```
    Get regions in transition and their states
  - isRegionInTransition
```
public boolean isRegionInTransition(HRegionInfo hri)
```
    Returns:
    
    True if specified region in transition.
  - isRegionInTransition
```
public boolean isRegionInTransition(String encodedName)
```
    Returns:
    
    True if specified region in transition.
  - isRegionsInTransition
```
public boolean isRegionsInTransition()
```
    Returns:
    
    True if any region in transition.
  - isMetaRegionInTransition
```
public boolean isMetaRegionInTransition()
```
    Returns:
    
    True if hbase:meta table region is in transition.
  - isRegionOnline
```
public boolean isRegionOnline(HRegionInfo hri)
```
    Returns:
    
    True if specified region assigned, and not in transition.
  - isRegionOffline
```
public boolean isRegionOffline(HRegionInfo hri)
```
    Returns:
    
    True if specified region offline/closed, but not in transition. If the region is not in the map, it is offline to us too.
  - isRegionInState
```
public boolean isRegionInState(HRegionInfo hri,
                               RegionState.State... states)
```
    Returns:
    
    True if specified region is in one of the specified states.
  - isRegionInState
```
public boolean isRegionInState(String encodedName,
                               RegionState.State... states)
```
    Returns:
    
    True if specified region is in one of the specified states.
  - waitForUpdate
```
public void waitForUpdate(long timeout)
                   throws InterruptedException
```
    Wait for the state map to be updated by assignment manager.
    
    Throws:
    
    InterruptedException
  - getRegionTransitionState
```
public RegionState getRegionTransitionState(HRegionInfo hri)
```
    Get region transition state
  - getRegionTransitionState
```
public RegionState getRegionTransitionState(String encodedName)
```
    Get region transition state
  - createRegionStates
```
public void createRegionStates(List<HRegionInfo> hris)
```
    Add a list of regions to RegionStates. If a region is split and offline, its state will be SPLIT. Otherwise, its state will be OFFLINE. Region already in RegionStates will be skipped.
  - createRegionState
```
public RegionState createRegionState(HRegionInfo hri)
```
    Add a region to RegionStates. If the region is split and offline, its state will be SPLIT. Otherwise, its state will be OFFLINE. If it is already in RegionStates, this call has no effect, and the original state is returned.
  - createRegionState
```
public RegionState createRegionState(HRegionInfo hri,
                                     RegionState.State newState,
                                     ServerName serverName,
                                     ServerName lastHost)
```
    Add a region to RegionStates with the specified state. If the region is already in RegionStates, this call has no effect, and the original state is returned.
    
    Parameters:
    
    hri - the region info to create a state for
    
    newState - the state to the region in set to
    
    serverName - the server the region is transitioning on
    
    lastHost - the last server that hosts the region
    
    Returns:
    
    the current state
  - updateRegionState
```
public RegionState updateRegionState(HRegionInfo hri,
                                     RegionState.State state)
```
    Update a region state. It will be put in transition if not already there.
  - updateRegionState
```
public RegionState updateRegionState(RegionTransition transition,
                                     RegionState.State state)
```
    Update a region state. It will be put in transition if not already there. If we can't find the region info based on the region name in the transition, log a warning and return null.
  - transitionOpenFromPendingOpenOrOpeningOnServer
```
public RegionState transitionOpenFromPendingOpenOrOpeningOnServer(RegionTransition transition,
                                                                  RegionState fromState,
                                                                  ServerName sn)
```
    Transition a region state to OPEN from OPENING/PENDING_OPEN
  - updateRegionState
```
public RegionState updateRegionState(HRegionInfo hri,
                                     RegionState.State state,
                                     ServerName serverName)
```
    Update a region state. It will be put in transition if not already there.
  - regionOnline
```
public void regionOnline(HRegionInfo hri,
                         ServerName serverName)
```
  - regionOnline
```
public void regionOnline(HRegionInfo hri,
                         ServerName serverName,
                         long openSeqNum)
```
    A region is online, won't be in transition any more. We can't confirm it is really online on specified region server because it hasn't been put in region server's online region list yet.
  - logSplit
```
public void logSplit(ServerName serverName)
```
    A dead server's wals have been split so that all the regions used to be open on it can be safely assigned now. Mark them assignable.
  - logSplit
```
public void logSplit(HRegionInfo region)
```
    Log split is done for a given region, so it is assignable now.
  - clearLastAssignment
```
public void clearLastAssignment(HRegionInfo region)
```
  - regionOffline
```
public void regionOffline(HRegionInfo hri)
```
    A region is offline, won't be in transition any more.
  - regionOffline
```
public void regionOffline(HRegionInfo hri,
                          RegionState.State expectedState)
```
    A region is offline, won't be in transition any more. Its state should be the specified expected state, which can only be Split/Merged/Offline/null(=Offline)/SplittingNew/MergingNew.
  - serverOffline
```
public List<HRegionInfo> serverOffline(ZooKeeperWatcher watcher,
                                       ServerName sn)
```
    A server is offline, all regions on it are dead.
  - getRegionsOfTable
```
public List<HRegionInfo> getRegionsOfTable(TableName tableName)
```
    Gets the online regions of the specified table. This method looks at the in-memory state. It does not go to hbase:meta. Only returns online regions. If a region on this table has been closed during a disable, etc., it will be included in the returned list. So, the returned list may not necessarily be ALL regions in this table, its all the ONLINE regions in the table.
    
    Parameters:
    
    tableName -
    
    Returns:
    
    Online regions from tableName
  - getRegionByStateOfTable
```
public Map<RegionState.State,List<HRegionInfo>> getRegionByStateOfTable(TableName tableName)
```
    Gets current state of all regions of the table. This method looks at the in-memory state. It does not go to hbase:meta. Method guaranteed to return keys for all states in RegionState.State
    
    Parameters:
    
    tableName -
    
    Returns:
    
    Online regions from tableName
  - waitOnRegionToClearRegionsInTransition
```
public void waitOnRegionToClearRegionsInTransition(HRegionInfo hri)
                                            throws InterruptedException
```
    Wait on region to clear regions-in-transition.
    If the region isn't in transition, returns immediately. Otherwise, method blocks until the region is out of transition.
    
    Throws:
    
    InterruptedException
  - tableDeleted
```
public void tableDeleted(TableName tableName)
```
    A table is deleted. Remove its regions from all internal maps. We loop through all regions assuming we don't delete tables too much.
  - getServerRegions
```
public Set<HRegionInfo> getServerRegions(ServerName serverName)
```
    Get a copy of all regions assigned to a server
  - deleteRegion
```
public void deleteRegion(HRegionInfo hri)
```
    Remove a region from all state maps.
  - getAverageLoad
```
protected double getAverageLoad()
```
    Compute the average load across all region servers. Currently, this uses a very naive computation - just uses the number of regions being served, ignoring stats about number of requests.
    
    Returns:
    
    the average load
  - getAssignmentsByTable
```
protected Map<TableName,Map<ServerName,List<HRegionInfo>>> getAssignmentsByTable()
```
    This is an EXPENSIVE clone. Cloning though is the safest thing to do. Can't let out original since it can change and at least the load balancer wants to iterate this exported list. We need to synchronize on regions since all access to this.servers is under a lock on this.regions.
    
    Returns:
    
    A clone of current assignments by table.
  - getRegionState
```
protected RegionState getRegionState(HRegionInfo hri)
```
  - getRegionAssignmentsByServer
```
protected Map<ServerName,List<HRegionInfo>> getRegionAssignmentsByServer()
```
    Returns a clone of region assignments per server
    
    Returns:
    
    a Map of ServerName to a List of HRegionInfo's
  - getRegionState
```
protected RegionState getRegionState(String encodedName)
```
  - getRegionInfo
```
protected HRegionInfo getRegionInfo(byte[] regionName)
```
    Get the HRegionInfo from cache, if not there, from the hbase:meta table
    
    Parameters:
    
    regionName -
    
    Returns:
    
    HRegionInfo for the region

Class RegionStates

Method Summary

Methods inherited from class java.lang.Object

Method Detail

getRegionAssignments

getRegionServerOfRegion

getRegionsInTransition

isRegionInTransition

isRegionInTransition

isRegionsInTransition

isMetaRegionInTransition

isRegionOnline

isRegionOffline

isRegionInState

isRegionInState

waitForUpdate

getRegionTransitionState

getRegionTransitionState

createRegionStates

createRegionState

createRegionState

updateRegionState

updateRegionState

transitionOpenFromPendingOpenOrOpeningOnServer

updateRegionState

regionOnline

regionOnline

logSplit

logSplit

clearLastAssignment

regionOffline

regionOffline

serverOffline

getRegionsOfTable

getRegionByStateOfTable

waitOnRegionToClearRegionsInTransition

tableDeleted

getServerRegions

deleteRegion

getAverageLoad

getAssignmentsByTable

getRegionState

getRegionAssignmentsByServer

getRegionState

getRegionInfo