MetaTableLocator (Apache HBase 1.4.11 API)

java.lang.Object
- org.apache.hadoop.hbase.zookeeper.MetaTableLocator

```
@InterfaceAudience.Private
public class MetaTableLocator
extends Object
```
Utility class to perform operation (get/wait for/verify/set/delete) on znode in ZooKeeper which keeps hbase:meta region server location. Stateless class with a bunch of static methods. Doesn't manage resources passed in (e.g. HConnection, ZooKeeperWatcher etc). Meta region location is set by RegionServerServices. This class doesn't use ZK watchers, rather accesses ZK directly. This class it stateless. The only reason it's not made a non-instantiable util class with a collection of static methods is that it'd be rather hard to mock properly in tests. TODO: rewrite using RPC calls to master to find out about hbase:meta.

Constructor Summary

Constructors
Constructor and Description

MetaTableLocator()

Constructors
Constructor and Description
`MetaTableLocator()`

Method Summary

Methods
Modifier and Type	Method and Description
`ServerName`	`blockUntilAvailable(ZooKeeperWatcher zkw, int replicaId, long timeout)` Wait until the meta region is available and is not in transition.
`ServerName`	`blockUntilAvailable(ZooKeeperWatcher zkw, long timeout)` Wait until the meta region is available and is not in transition.
`List<ServerName>`	`blockUntilAvailable(ZooKeeperWatcher zkw, long timeout, org.apache.hadoop.conf.Configuration conf)` Wait until the primary meta region is available.
`void`	`deleteMetaLocation(ZooKeeperWatcher zookeeper)` Deletes the location of `hbase:meta` in ZooKeeper.
`void`	`deleteMetaLocation(ZooKeeperWatcher zookeeper, int replicaId)`
`ServerName`	`getMetaRegionLocation(ZooKeeperWatcher zkw)` Gets the meta region location, if available.
`ServerName`	`getMetaRegionLocation(ZooKeeperWatcher zkw, int replicaId)` Gets the meta region location, if available.
`List<HRegionInfo>`	`getMetaRegions(ZooKeeperWatcher zkw)`
`List<HRegionInfo>`	`getMetaRegions(ZooKeeperWatcher zkw, int replicaId)`
`List<Pair<HRegionInfo,ServerName>>`	`getMetaRegionsAndLocations(ZooKeeperWatcher zkw)`
`List<Pair<HRegionInfo,ServerName>>`	`getMetaRegionsAndLocations(ZooKeeperWatcher zkw, int replicaId)`
`static RegionState`	`getMetaRegionState(ZooKeeperWatcher zkw)` Load the meta region state from the meta server ZNode.
`static RegionState`	`getMetaRegionState(ZooKeeperWatcher zkw, int replicaId)` Load the meta region state from the meta server ZNode.
`boolean`	`isLocationAvailable(ZooKeeperWatcher zkw)` Checks if the meta region location is available.
`static void`	`setMetaLocation(ZooKeeperWatcher zookeeper, ServerName serverName, int replicaId, RegionState.State state)` Sets the location of `hbase:meta` in ZooKeeper to the specified server address.
`static void`	`setMetaLocation(ZooKeeperWatcher zookeeper, ServerName serverName, RegionState.State state)` Sets the location of `hbase:meta` in ZooKeeper to the specified server address.
`void`	`stop()` Stop working.
`boolean`	`verifyMetaRegionLocation(HConnection hConnection, ZooKeeperWatcher zkw, long timeout)` Verify `hbase:meta` is deployed and accessible.
`boolean`	`verifyMetaRegionLocation(HConnection hConnection, ZooKeeperWatcher zkw, long timeout, int replicaId)` Verify `hbase:meta` is deployed and accessible.
`void`	`waitMetaRegionLocation(ZooKeeperWatcher zkw)` Waits indefinitely for availability of `hbase:meta`.
`ServerName`	`waitMetaRegionLocation(ZooKeeperWatcher zkw, int replicaId, long timeout)` Gets the meta region location, if available, and waits for up to the specified timeout if not immediately available.
`ServerName`	`waitMetaRegionLocation(ZooKeeperWatcher zkw, long timeout)` Gets the meta region location, if available, and waits for up to the specified timeout if not immediately available.

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

- Constructor Detail
  - MetaTableLocator
```
public MetaTableLocator()
```
- Method Detail
  - isLocationAvailable
```
public boolean isLocationAvailable(ZooKeeperWatcher zkw)
```
    Checks if the meta region location is available.
    
    Returns:
    true if meta region location is available, false if not
  - getMetaRegionsAndLocations
```
public List<Pair<HRegionInfo,ServerName>> getMetaRegionsAndLocations(ZooKeeperWatcher zkw)
```
    Parameters:
    zkw - ZooKeeper watcher to be used
    
    Returns:
    meta table regions and their locations.
  - getMetaRegionsAndLocations
```
public List<Pair<HRegionInfo,ServerName>> getMetaRegionsAndLocations(ZooKeeperWatcher zkw,
                                                            int replicaId)
```
    Parameters:
    zkw -
    replicaId -
    
    Returns:
    meta table regions and their locations.
  - getMetaRegions
```
public List<HRegionInfo> getMetaRegions(ZooKeeperWatcher zkw)
```
    Parameters:
    zkw - ZooKeeper watcher to be used
    
    Returns:
    List of meta regions
  - getMetaRegions
```
public List<HRegionInfo> getMetaRegions(ZooKeeperWatcher zkw,
                               int replicaId)
```
    Parameters:
    zkw -
    replicaId -
    
    Returns:
    List of meta regions
  - getMetaRegionLocation
```
public ServerName getMetaRegionLocation(ZooKeeperWatcher zkw)
```
    Gets the meta region location, if available. Does not block.
    
    Parameters:
    zkw - zookeeper connection to use
    
    Returns:
    server name or null if we failed to get the data.
  - getMetaRegionLocation
```
public ServerName getMetaRegionLocation(ZooKeeperWatcher zkw,
                               int replicaId)
```
    Gets the meta region location, if available. Does not block.
    
    Parameters:
    zkw -
    replicaId -
    
    Returns:
    server name
  - waitMetaRegionLocation
```
public ServerName waitMetaRegionLocation(ZooKeeperWatcher zkw,
                                long timeout)
                                  throws InterruptedException,
                                         NotAllMetaRegionsOnlineException
```
    Gets the meta region location, if available, and waits for up to the specified timeout if not immediately available. Given the zookeeper notification could be delayed, we will try to get the latest data.
    
    Parameters:
    zkw -
    timeout - maximum time to wait, in millis
    
    Returns:
    server name for server hosting meta region formatted as per ServerName, or null if none available
    
    Throws:
    
    InterruptedException - if interrupted while waiting
    
    NotAllMetaRegionsOnlineException
  - waitMetaRegionLocation
```
public ServerName waitMetaRegionLocation(ZooKeeperWatcher zkw,
                                int replicaId,
                                long timeout)
                                  throws InterruptedException,
                                         NotAllMetaRegionsOnlineException
```
    Gets the meta region location, if available, and waits for up to the specified timeout if not immediately available. Given the zookeeper notification could be delayed, we will try to get the latest data.
    
    Parameters:
    zkw -
    replicaId -
    timeout - maximum time to wait, in millis
    
    Returns:
    server name for server hosting meta region formatted as per ServerName, or null if none available
    
    Throws:
    
    InterruptedException
    
    NotAllMetaRegionsOnlineException
  - waitMetaRegionLocation
```
public void waitMetaRegionLocation(ZooKeeperWatcher zkw)
                            throws InterruptedException
```
    Waits indefinitely for availability of hbase:meta. Used during cluster startup. Does not verify meta, just that something has been set up in zk.
    
    Throws:
    
    InterruptedException - if interrupted while waiting
    See Also:
    waitMetaRegionLocation(org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher, long)
  - verifyMetaRegionLocation
```
public boolean verifyMetaRegionLocation(HConnection hConnection,
                               ZooKeeperWatcher zkw,
                               long timeout)
                                 throws InterruptedException,
                                        IOException
```
    Verify hbase:meta is deployed and accessible.
    
    Parameters:
    hConnection -
    zkw -
    timeout - How long to wait on zk for meta address (passed through to the internal call to getMetaServerConnection(org.apache.hadoop.hbase.client.HConnection, org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher, long, int).
    
    Returns:
    True if the hbase:meta location is healthy.
    
    Throws:
    
    IOException
    
    InterruptedException
  - verifyMetaRegionLocation
```
public boolean verifyMetaRegionLocation(HConnection hConnection,
                               ZooKeeperWatcher zkw,
                               long timeout,
                               int replicaId)
                                 throws InterruptedException,
                                        IOException
```
    Verify hbase:meta is deployed and accessible.
    
    Parameters:
    hConnection -
    zkw -
    timeout - How long to wait on zk for meta address (passed through to
    replicaId -
    
    Returns:
    True if the hbase:meta location is healthy.
    
    Throws:
    
    InterruptedException
    
    IOException
  - setMetaLocation
```
public static void setMetaLocation(ZooKeeperWatcher zookeeper,
                   ServerName serverName,
                   RegionState.State state)
                            throws org.apache.zookeeper.KeeperException
```
    Sets the location of hbase:meta in ZooKeeper to the specified server address.
    
    Parameters:
    zookeeper - zookeeper reference
    serverName - The server hosting hbase:meta
    state - The region transition state
    
    Throws:
    
    org.apache.zookeeper.KeeperException - unexpected zookeeper exception
  - setMetaLocation
```
public static void setMetaLocation(ZooKeeperWatcher zookeeper,
                   ServerName serverName,
                   int replicaId,
                   RegionState.State state)
                            throws org.apache.zookeeper.KeeperException
```
    Sets the location of hbase:meta in ZooKeeper to the specified server address.
    
    Parameters:
    zookeeper -
    serverName -
    replicaId -
    state -
    
    Throws:
    
    org.apache.zookeeper.KeeperException
  - getMetaRegionState
```
public static RegionState getMetaRegionState(ZooKeeperWatcher zkw)
                                      throws org.apache.zookeeper.KeeperException
```
    Load the meta region state from the meta server ZNode.
    
    Throws:
    
    org.apache.zookeeper.KeeperException
  - getMetaRegionState
```
public static RegionState getMetaRegionState(ZooKeeperWatcher zkw,
                             int replicaId)
                                      throws org.apache.zookeeper.KeeperException
```
    Load the meta region state from the meta server ZNode.
    
    Parameters:
    zkw -
    replicaId -
    
    Returns:
    regionstate
    
    Throws:
    
    org.apache.zookeeper.KeeperException
  - deleteMetaLocation
```
public void deleteMetaLocation(ZooKeeperWatcher zookeeper)
                        throws org.apache.zookeeper.KeeperException
```
    Deletes the location of hbase:meta in ZooKeeper.
    
    Parameters:
    zookeeper - zookeeper reference
    
    Throws:
    
    org.apache.zookeeper.KeeperException - unexpected zookeeper exception
  - deleteMetaLocation
```
public void deleteMetaLocation(ZooKeeperWatcher zookeeper,
                      int replicaId)
                        throws org.apache.zookeeper.KeeperException
```
    Throws:
    
    org.apache.zookeeper.KeeperException
  - blockUntilAvailable
```
public List<ServerName> blockUntilAvailable(ZooKeeperWatcher zkw,
                                   long timeout,
                                   org.apache.hadoop.conf.Configuration conf)
                                     throws InterruptedException
```
    Wait until the primary meta region is available. Get the secondary locations as well but don't block for those.
    
    Parameters:
    zkw -
    timeout -
    conf -
    
    Returns:
    ServerName or null if we timed out.
    
    Throws:
    
    InterruptedException
  - blockUntilAvailable
```
public ServerName blockUntilAvailable(ZooKeeperWatcher zkw,
                             long timeout)
                               throws InterruptedException
```
    Wait until the meta region is available and is not in transition.
    
    Parameters:
    zkw - zookeeper connection to use
    timeout - maximum time to wait, in millis
    
    Returns:
    ServerName or null if we timed out.
    
    Throws:
    
    InterruptedException
  - blockUntilAvailable
```
public ServerName blockUntilAvailable(ZooKeeperWatcher zkw,
                             int replicaId,
                             long timeout)
                               throws InterruptedException
```
    Wait until the meta region is available and is not in transition.
    
    Parameters:
    zkw -
    replicaId -
    timeout -
    
    Returns:
    ServerName or null if we timed out.
    
    Throws:
    
    InterruptedException
  - stop
```
public void stop()
```
    Stop working. Interrupts any ongoing waits.

Class MetaTableLocator

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

MetaTableLocator

Method Detail

isLocationAvailable

getMetaRegionsAndLocations

getMetaRegionsAndLocations

getMetaRegions

getMetaRegions

getMetaRegionLocation

getMetaRegionLocation

waitMetaRegionLocation

waitMetaRegionLocation

waitMetaRegionLocation

verifyMetaRegionLocation

verifyMetaRegionLocation

setMetaLocation

setMetaLocation

getMetaRegionState

getMetaRegionState

deleteMetaLocation

deleteMetaLocation

blockUntilAvailable

blockUntilAvailable

blockUntilAvailable

stop