org.apache.hadoop.hbase.coprocessor.example

Class ZooKeeperScanPolicyObserver

java.lang.Object

org.apache.hadoop.hbase.coprocessor.BaseRegionObserver

org.apache.hadoop.hbase.coprocessor.example.ZooKeeperScanPolicyObserver

All Implemented Interfaces:

Coprocessor, RegionObserver

public class ZooKeeperScanPolicyObserver
extends BaseRegionObserver

This is an example showing how a RegionObserver could configured via ZooKeeper in order to control a Region compaction, flush, and scan policy. This also demonstrated the use of shared RegionObserver state. See RegionCoprocessorEnvironment.getSharedData(). This would be useful for an incremental backup tool, which would indicate the last time of a successful backup via ZK and instruct HBase to not delete data that was inserted since (based on wall clock time). This implements org.apache.zookeeper.Watcher directly instead of using ZooKeeperWatcher, because RegionObservers come and go and currently listeners registered with ZooKeeperWatcher cannot be removed.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.hadoop.hbase.coprocessor.RegionObserver

RegionObserver.MutationType

Nested classes/interfaces inherited from interface org.apache.hadoop.hbase.Coprocessor

Coprocessor.State

Field Summary

Fields

Modifier and Type	Field and Description
static String	node
static String	zkkey

Fields inherited from interface org.apache.hadoop.hbase.Coprocessor

PRIORITY_HIGHEST, PRIORITY_LOWEST, PRIORITY_SYSTEM, PRIORITY_USER, VERSION

Constructor Summary

Constructors

Constructor and Description
ZooKeeperScanPolicyObserver()

Method Summary

Methods

Modifier and Type	Method and Description
protected ScanInfo	getScanInfo(Store store, RegionCoprocessorEnvironment e)
InternalScanner	preCompactScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c, Store store, List<? extends KeyValueScanner> scanners, ScanType scanType, long earliestPutTs, InternalScanner s) Called prior to writing the StoreFiles selected for compaction into a new StoreFile and prior to creating the scanner used to read the input files.
InternalScanner	preFlushScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c, Store store, KeyValueScanner memstoreScanner, InternalScanner s) Called before a memstore is flushed to disk and prior to creating the scanner to read from the memstore.
KeyValueScanner	preStoreScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c, Store store, Scan scan, NavigableSet<byte[]> targetCols, KeyValueScanner s) Called before a store opens a new scanner.
void	start(CoprocessorEnvironment e)
void	stop(CoprocessorEnvironment e)

Methods inherited from class org.apache.hadoop.hbase.coprocessor.BaseRegionObserver

postAppend, postBatchMutate, postBatchMutateIndispensably, postBulkLoadHFile, postCheckAndDelete, postCheckAndPut, postClose, postCloseRegionOperation, postCompact, postCompact, postCompactSelection, postCompactSelection, postCompleteSplit, postDelete, postExists, postFlush, postFlush, postGetClosestRowBefore, postGetOp, postIncrement, postIncrementColumnValue, postInstantiateDeleteTracker, postLogReplay, postMutationBeforeWAL, postOpen, postPut, postRollBackSplit, postScannerClose, postScannerFilterRow, postScannerNext, postScannerOpen, postSplit, postStartRegionOperation, postStoreFileReaderOpen, postWALRestore, postWALRestore, preAppend, preAppendAfterRowLock, preBatchMutate, preBulkLoadHFile, preCheckAndDelete, preCheckAndDeleteAfterRowLock, preCheckAndPut, preCheckAndPutAfterRowLock, preClose, preCompact, preCompact, preCompactScannerOpen, preCompactSelection, preCompactSelection, preDelete, preExists, preFlush, preFlush, preGetClosestRowBefore, preGetOp, preIncrement, preIncrementAfterRowLock, preIncrementColumnValue, preOpen, prePrepareTimeStampForDeleteVersion, prePut, preRollBackSplit, preScannerClose, preScannerNext, preScannerOpen, preSplit, preSplit, preSplitAfterPONR, preSplitBeforePONR, preStoreFileReaderOpen, preWALRestore, preWALRestore

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

node

public static final String node

See Also:

Constant Field Values

zkkey

public static final String zkkey

See Also:

Constant Field Values

Constructor Detail

ZooKeeperScanPolicyObserver

public ZooKeeperScanPolicyObserver()

Method Detail

start

public void start(CoprocessorEnvironment e)
           throws IOException

Specified by:

start in interface Coprocessor

Overrides:

start in class BaseRegionObserver

Throws:

IOException

stop

public void stop(CoprocessorEnvironment e)
          throws IOException

Specified by:

stop in interface Coprocessor

Overrides:

stop in class BaseRegionObserver

Throws:

IOException

getScanInfo

protected ScanInfo getScanInfo(Store store,
                   RegionCoprocessorEnvironment e)

preFlushScannerOpen

public InternalScanner preFlushScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c,
                                  Store store,
                                  KeyValueScanner memstoreScanner,
                                  InternalScanner s)
                                    throws IOException

Description copied from interface: RegionObserver

Called before a memstore is flushed to disk and prior to creating the scanner to read from the memstore. To override or modify how a memstore is flushed, implementing classes can return a new scanner to provide the KeyValues to be stored into the new StoreFile or null to perform the default processing. Calling ObserverContext.bypass() has no effect in this hook.

Specified by:

preFlushScannerOpen in interface RegionObserver

Overrides:

preFlushScannerOpen in class BaseRegionObserver

Parameters:

c - the environment provided by the region server

store - the store being flushed

memstoreScanner - the scanner for the memstore that is flushed

s - the base scanner, if not null, from previous RegionObserver in the chain

Returns:

the scanner to use during the flush. null if the default implementation is to be used.

Throws:

IOException - if an error occurred on the coprocessor

preCompactScannerOpen

public InternalScanner preCompactScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c,
                                    Store store,
                                    List<? extends KeyValueScanner> scanners,
                                    ScanType scanType,
                                    long earliestPutTs,
                                    InternalScanner s)
                                      throws IOException

Description copied from interface: RegionObserver

Called prior to writing the StoreFiles selected for compaction into a new StoreFile and prior to creating the scanner used to read the input files. To override or modify the compaction process, implementing classes can return a new scanner to provide the KeyValues to be stored into the new StoreFile or null to perform the default processing. Calling ObserverContext.bypass() has no effect in this hook.

Specified by:

preCompactScannerOpen in interface RegionObserver

Overrides:

preCompactScannerOpen in class BaseRegionObserver

Parameters:

c - the environment provided by the region server

store - the store being compacted

scanners - the list StoreFileScanners to be read from

scanType - the ScanType indicating whether this is a major or minor compaction

earliestPutTs - timestamp of the earliest put that was found in any of the involved store files

s - the base scanner, if not null, from previous RegionObserver in the chain

Returns:

the scanner to use during compaction. null if the default implementation is to be used.

Throws:

IOException - if an error occurred on the coprocessor

preStoreScannerOpen

public KeyValueScanner preStoreScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c,
                                  Store store,
                                  Scan scan,
                                  NavigableSet<byte[]> targetCols,
                                  KeyValueScanner s)
                                    throws IOException

Description copied from interface: RegionObserver

Called before a store opens a new scanner. This hook is called when a "user" scanner is opened.

See RegionObserver.preFlushScannerOpen(ObserverContext, Store, KeyValueScanner, InternalScanner) and RegionObserver.preCompactScannerOpen(ObserverContext, Store, List, ScanType, long, InternalScanner) to override scanners created for flushes or compactions, resp.

Call CoprocessorEnvironment#complete to skip any subsequent chained coprocessors. Calling ObserverContext.bypass() has no effect in this hook.

Specified by:

preStoreScannerOpen in interface RegionObserver

Overrides:

preStoreScannerOpen in class BaseRegionObserver

Parameters:

c - the environment provided by the region server

store - the store being scanned

scan - the Scan specification

targetCols - columns to be used in the scanner

s - the base scanner, if not null, from previous RegionObserver in the chain

Returns:

a KeyValueScanner instance to use or null to use the default implementation

Throws:

IOException - if an error occurred on the coprocessor