org.apache.hadoop.hbase.client
Interface HConnection

All Superinterfaces:

Abortable

public interface HConnection
extends Abortable

Cluster connection. Hosts a connection to the ZooKeeper ensemble and thereafter into the HBase cluster. Knows how to locate regions out on the cluster, keeps a cache of locations and then knows how to recalibrate after they move. HConnectionManager manages instances of this class.

HConnections are used by HTable mostly but also by HBaseAdmin, CatalogTracker, and ZooKeeperWatcher. HConnection instances can be shared. Sharing is usually what you want because rather than each HConnection instance having to do its own discovery of regions out on the cluster, instead, all clients get to share the one cache of locations. Sharing makes cleanup of HConnections awkward. See HConnectionManager for cleanup discussion.

See Also:

HConnectionManager

Method Summary

void	clearRegionCache() Allows flushing the region cache.
void	clearRegionCache(byte[] tableName) Allows flushing the region cache of all locations that pertain to tableName
org.apache.hadoop.conf.Configuration	getConfiguration()
HRegionInterface	getHRegionConnection(HServerAddress regionServer) Establishes a connection to the region server at the specified address.
HRegionInterface	getHRegionConnection(HServerAddress regionServer, boolean getMaster) Establishes a connection to the region server at the specified address.
HTableDescriptor	getHTableDescriptor(byte[] tableName)
HMasterInterface	getMaster()
boolean	getRegionCachePrefetch(byte[] tableName) Check whether region cache prefetch is enabled or not.
HRegionLocation	getRegionLocation(byte[] tableName, byte[] row, boolean reload) Find region location hosting passed row
<T> T	getRegionServerWithoutRetries(ServerCallable<T> callable) Pass in a ServerCallable with your particular bit of logic defined and this method will pass it to the defined region server.
<T> T	getRegionServerWithRetries(ServerCallable<T> callable) Pass in a ServerCallable with your particular bit of logic defined and this method will manage the process of doing retries with timed waits and refinds of missing regions.
ZooKeeperWatcher	getZooKeeperWatcher() Retrieve ZooKeeperWatcher used by this connection.
boolean	isMasterRunning()
boolean	isTableAvailable(byte[] tableName)
boolean	isTableDisabled(byte[] tableName)
boolean	isTableEnabled(byte[] tableName) A table that isTableEnabled == false and isTableDisabled == false is possible.
HTableDescriptor[]	listTables() List all the userspace tables.
HRegionLocation	locateRegion(byte[] regionName) Gets the location of the region of regionName.
HRegionLocation	locateRegion(byte[] tableName, byte[] row) Find the location of the region of tableName that row lives in.
java.util.List<HRegionLocation>	locateRegions(byte[] tableName) Gets the locations of all regions in the specified table, tableName.
void	prewarmRegionCache(byte[] tableName, java.util.Map<HRegionInfo,HServerAddress> regions) Load the region map and warm up the global region cache for the table.
void	processBatch(java.util.List<Row> actions, byte[] tableName, java.util.concurrent.ExecutorService pool, java.lang.Object[] results) Process a mixed batch of Get, Put and Delete actions.
void	processBatchOfPuts(java.util.List<Put> list, byte[] tableName, java.util.concurrent.ExecutorService pool) Deprecated. Use HConnectionManager::processBatch instead.
HRegionLocation	relocateRegion(byte[] tableName, byte[] row) Find the location of the region of tableName that row lives in, ignoring any value that might be in the cache.
void	setRegionCachePrefetch(byte[] tableName, boolean enable) Enable or disable region cache prefetch for the table.

Methods inherited from interface org.apache.hadoop.hbase.Abortable

abort

Method Detail

getConfiguration

org.apache.hadoop.conf.Configuration getConfiguration()

Returns:

Configuration instance being used by this HConnection instance.

getZooKeeperWatcher

ZooKeeperWatcher getZooKeeperWatcher()
                                     throws java.io.IOException

Retrieve ZooKeeperWatcher used by this connection.

Returns:

ZooKeeperWatcher handle being used by the connection.

Throws:

java.io.IOException - if a remote or network exception occurs

getMaster

HMasterInterface getMaster()
                           throws MasterNotRunningException,
                                  ZooKeeperConnectionException

Returns:

proxy connection to master server for this instance

Throws:

MasterNotRunningException - if the master is not running

ZooKeeperConnectionException - if unable to connect to zookeeper

isMasterRunning

boolean isMasterRunning()
                        throws MasterNotRunningException,
                               ZooKeeperConnectionException

Returns:

- true if the master server is running

Throws:

MasterNotRunningException

ZooKeeperConnectionException

isTableEnabled

boolean isTableEnabled(byte[] tableName)
                       throws java.io.IOException

A table that isTableEnabled == false and isTableDisabled == false is possible. This happens when a table has a lot of regions that must be processed.

Parameters:

tableName - table name

Returns:

true if the table is enabled, false otherwise

Throws:

java.io.IOException - if a remote or network exception occurs

isTableDisabled

boolean isTableDisabled(byte[] tableName)
                        throws java.io.IOException

Parameters:

tableName - table name

Returns:

true if the table is disabled, false otherwise

Throws:

java.io.IOException - if a remote or network exception occurs

isTableAvailable

boolean isTableAvailable(byte[] tableName)
                         throws java.io.IOException

Parameters:

tableName - table name

Returns:

true if all regions of the table are available, false otherwise

Throws:

java.io.IOException - if a remote or network exception occurs

listTables

HTableDescriptor[] listTables()
                              throws java.io.IOException

List all the userspace tables. In other words, scan the META table. If we wanted this to be really fast, we could implement a special catalog table that just contains table names and their descriptors. Right now, it only exists as part of the META table's region info.

Returns:

- returns an array of HTableDescriptors

Throws:

java.io.IOException - if a remote or network exception occurs

getHTableDescriptor

HTableDescriptor getHTableDescriptor(byte[] tableName)
                                     throws java.io.IOException

Parameters:

tableName - table name

Returns:

table metadata

Throws:

java.io.IOException - if a remote or network exception occurs

locateRegion

HRegionLocation locateRegion(byte[] tableName,
                             byte[] row)
                             throws java.io.IOException

Find the location of the region of tableName that row lives in.

Parameters:

tableName - name of the table row is in

row - row key you're trying to find the region of

Returns:

HRegionLocation that describes where to find the region in question

Throws:

java.io.IOException - if a remote or network exception occurs

clearRegionCache

void clearRegionCache()

Allows flushing the region cache.

clearRegionCache

void clearRegionCache(byte[] tableName)

Allows flushing the region cache of all locations that pertain to tableName

Parameters:

tableName - Name of the table whose regions we are to remove from cache.

relocateRegion

HRegionLocation relocateRegion(byte[] tableName,
                               byte[] row)
                               throws java.io.IOException

Find the location of the region of tableName that row lives in, ignoring any value that might be in the cache.

Parameters:

tableName - name of the table row is in

row - row key you're trying to find the region of

Returns:

HRegionLocation that describes where to find the region in question

Throws:

java.io.IOException - if a remote or network exception occurs

locateRegion

HRegionLocation locateRegion(byte[] regionName)
                             throws java.io.IOException

Gets the location of the region of regionName.

Parameters:

regionName - name of the region to locate

Returns:

HRegionLocation that describes where to find the region in question

Throws:

java.io.IOException - if a remote or network exception occurs

locateRegions

java.util.List<HRegionLocation> locateRegions(byte[] tableName)
                                              throws java.io.IOException

Gets the locations of all regions in the specified table, tableName.

Parameters:

tableName - table to get regions of

Returns:

list of region locations for all regions of table

Throws:

java.io.IOException

getHRegionConnection

HRegionInterface getHRegionConnection(HServerAddress regionServer)
                                      throws java.io.IOException

Establishes a connection to the region server at the specified address.

Parameters:

regionServer - - the server to connect to

Returns:

proxy for HRegionServer

Throws:

java.io.IOException - if a remote or network exception occurs

getHRegionConnection

HRegionInterface getHRegionConnection(HServerAddress regionServer,
                                      boolean getMaster)
                                      throws java.io.IOException

Establishes a connection to the region server at the specified address.

Parameters:

regionServer - - the server to connect to

getMaster - - do we check if master is alive

Returns:

proxy for HRegionServer

Throws:

java.io.IOException - if a remote or network exception occurs

getRegionLocation

HRegionLocation getRegionLocation(byte[] tableName,
                                  byte[] row,
                                  boolean reload)
                                  throws java.io.IOException

Find region location hosting passed row

Parameters:

tableName - table name

row - Row to find.

reload - If true do not use cache, otherwise bypass.

Returns:

Location of row.

Throws:

java.io.IOException - if a remote or network exception occurs

getRegionServerWithRetries

<T> T getRegionServerWithRetries(ServerCallable<T> callable)
                             throws java.io.IOException,
                                    java.lang.RuntimeException

Pass in a ServerCallable with your particular bit of logic defined and this method will manage the process of doing retries with timed waits and refinds of missing regions.

Type Parameters:

T - the type of the return value

Parameters:

callable - callable to run

Returns:

an object of type T

Throws:

java.io.IOException - if a remote or network exception occurs

java.lang.RuntimeException - other unspecified error

getRegionServerWithoutRetries

<T> T getRegionServerWithoutRetries(ServerCallable<T> callable)
                                throws java.io.IOException,
                                       java.lang.RuntimeException

Pass in a ServerCallable with your particular bit of logic defined and this method will pass it to the defined region server.

Type Parameters:

T - the type of the return value

Parameters:

callable - callable to run

Returns:

an object of type T

Throws:

java.io.IOException - if a remote or network exception occurs

java.lang.RuntimeException - other unspecified error

processBatch

void processBatch(java.util.List<Row> actions,
                  byte[] tableName,
                  java.util.concurrent.ExecutorService pool,
                  java.lang.Object[] results)
                  throws java.io.IOException,
                         java.lang.InterruptedException

Process a mixed batch of Get, Put and Delete actions. All actions for a RegionServer are forwarded in one RPC call.

Parameters:

actions - The collection of actions.

tableName - Name of the hbase table

pool - thread pool for parallel execution

results - An empty array, same size as list. If an exception is thrown, you can test here for partial results, and to determine which actions processed successfully.

Throws:

java.io.IOException - if there are problems talking to META. Per-item exceptions are stored in the results array.

java.lang.InterruptedException

processBatchOfPuts

void processBatchOfPuts(java.util.List<Put> list,
                        byte[] tableName,
                        java.util.concurrent.ExecutorService pool)
                        throws java.io.IOException

Deprecated. Use HConnectionManager::processBatch instead.

Process a batch of Puts.

Parameters:

list - The collection of actions. The list is mutated: all successful Puts are removed from the list.

tableName - Name of the hbase table

pool - Thread pool for parallel execution

Throws:

java.io.IOException

setRegionCachePrefetch

void setRegionCachePrefetch(byte[] tableName,
                            boolean enable)

Enable or disable region cache prefetch for the table. It will be applied for the given table's all HTable instances within this connection. By default, the cache prefetch is enabled.

Parameters:

tableName - name of table to configure.

enable - Set to true to enable region cache prefetch.

getRegionCachePrefetch

boolean getRegionCachePrefetch(byte[] tableName)

Check whether region cache prefetch is enabled or not.

Parameters:

tableName - name of table to check

Returns:

true if table's region cache prefetch is enabled. Otherwise it is disabled.

prewarmRegionCache

void prewarmRegionCache(byte[] tableName,
                        java.util.Map<HRegionInfo,HServerAddress> regions)

Load the region map and warm up the global region cache for the table.

Parameters:

tableName - name of the table to perform region cache prewarm.

regions - a region map.