MetaTableLocator (Apache HBase 1.2.12 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.

Field Summary

Fields
Modifier and Type Field and Description

private static org.apache.commons.logging.Log LOG

private boolean stopped

Fields
Modifier and Type	Field and Description
`private static org.apache.commons.logging.Log`	`LOG`
`private boolean`	`stopped`

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)`
`private static org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService.BlockingInterface`	`getCachedConnection(HConnection hConnection, ServerName sn)`
`private List<HRegionInfo>`	`getListOfHRegionInfos(List<Pair<HRegionInfo,ServerName>> pairs)`
`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.
`private org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService.BlockingInterface`	`getMetaServerConnection(HConnection hConnection, ZooKeeperWatcher zkw, long timeout, int replicaId)` Gets a connection to the server hosting meta, as reported by ZooKeeper, waiting up to the specified timeout for availability.
`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.
`private boolean`	`verifyRegionLocation(Connection connection, org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService.BlockingInterface hostingServer, ServerName address, byte[] regionName)` Verify we can connect to `hostingServer` and that its carrying `regionName`.
`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

Field Detail

LOG

private static final org.apache.commons.logging.Log LOG

stopped
```
private volatile boolean stopped
```

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

getListOfHRegionInfos

private List<HRegionInfo> getListOfHRegionInfos(List<Pair<HRegionInfo,ServerName>> pairs)

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

verifyRegionLocation
```
private boolean verifyRegionLocation(Connection connection,
                           org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService.BlockingInterface hostingServer,
                           ServerName address,
                           byte[] regionName)
                              throws IOException
```
Verify we can connect to hostingServer and that its carrying regionName.

Parameters:
hostingServer - Interface to the server hosting regionName
address - The servername that goes with the metaServer Interface. Used logging.
regionName - The regionname we are interested in.

Returns:
True if we were able to verify the region located at other side of the Interface.

Throws:

IOException

getMetaServerConnection

private org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService.BlockingInterface getMetaServerConnection(HConnection hConnection,
                                                                                                            ZooKeeperWatcher zkw,
                                                                                                            long timeout,
                                                                                                            int replicaId)
                                                                                                               throws InterruptedException,
                                                                                                                      NotAllMetaRegionsOnlineException,
                                                                                                                      IOException

Gets a connection to the server hosting meta, as reported by ZooKeeper, waiting up to the specified timeout for availability.

WARNING: Does not retry. Use an HTable instead.

Parameters:: hConnection -; zkw -; timeout - How long to wait on meta location; replicaId -
Returns:: connection to server hosting meta
Throws:: InterruptedException; NotAllMetaRegionsOnlineException - if timed out waiting; IOException

getCachedConnection

private static org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService.BlockingInterface getCachedConnection(HConnection hConnection,
                                                                                                        ServerName sn)
                                                                                                                  throws IOException

Parameters:: sn - ServerName to get a connection against.
Returns:: The AdminProtocol we got when we connected to sn May have come from cache, may not be good, may have been setup by this invocation, or may be null.
Throws:: 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

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

LOG

stopped

Constructor Detail

MetaTableLocator

Method Detail

isLocationAvailable

getMetaRegionsAndLocations

getMetaRegionsAndLocations

getMetaRegions

getMetaRegions

getListOfHRegionInfos

getMetaRegionLocation

getMetaRegionLocation

waitMetaRegionLocation

waitMetaRegionLocation

waitMetaRegionLocation

verifyMetaRegionLocation

verifyMetaRegionLocation

verifyRegionLocation

getMetaServerConnection

getCachedConnection

setMetaLocation

setMetaLocation

getMetaRegionState

getMetaRegionState

deleteMetaLocation

deleteMetaLocation

blockUntilAvailable

blockUntilAvailable

blockUntilAvailable

stop