Package org.apache.bookkeeper.client

Class DefaultEnsemblePlacementPolicy

java.lang.Object

org.apache.bookkeeper.client.DefaultEnsemblePlacementPolicy

All Implemented Interfaces:

EnsemblePlacementPolicy

public class DefaultEnsemblePlacementPolicy
extends Object
implements EnsemblePlacementPolicy

Default Ensemble Placement Policy, which picks bookies randomly.

See Also:

• EnsemblePlacementPolicy

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.bookkeeper.client.EnsemblePlacementPolicy

EnsemblePlacementPolicy.PlacementPolicyAdherence, EnsemblePlacementPolicy.PlacementResult<T>

Field Summary

Fields

Modifier and Type	Field	Description
(package private) static final Set<BookieId>	EMPTY_SET
(package private) static final org.slf4j.Logger	LOG

Constructor Summary

Constructors

Constructor	Description
DefaultEnsemblePlacementPolicy()

Method Summary

Modifier and Type	Method	Description
EnsemblePlacementPolicy	initialize(ClientConfiguration conf, Optional<DNSToSwitchMapping> optionalDnsResolver, io.netty.util.HashedWheelTimer hashedWheelTimer, FeatureProvider featureProvider, StatsLogger statsLogger, BookieAddressResolver bookieAddressResolver)	Initialize the policy.
EnsemblePlacementPolicy.PlacementPolicyAdherence	isEnsembleAdheringToPlacementPolicy(List<BookieId> ensembleList, int writeQuorumSize, int ackQuorumSize)	returns AdherenceLevel if the Ensemble is strictly/softly/fails adhering to placement policy, like in the case of RackawareEnsemblePlacementPolicy, bookies in the writeset are from 'minNumRacksPerWriteQuorum' number of racks.
EnsemblePlacementPolicy.PlacementResult<List<BookieId>>	newEnsemble(int ensembleSize, int quorumSize, int ackQuorumSize, Map<String,byte[]> customMetadata, Set<BookieId> excludeBookies)	Choose numBookies bookies for ensemble.
Set<BookieId>	onClusterChanged(Set<BookieId> writableBookies, Set<BookieId> readOnlyBookies)	A consistent view of the cluster (what bookies are available as writable, what bookies are available as readonly) is updated when any changes happen in the cluster.
void	registerSlowBookie(BookieId bookieSocketAddress, long entryId)	Register a bookie as slow so that it is tried after available and read-only bookies.
DistributionSchedule.WriteSet	reorderReadLACSequence(List<BookieId> ensemble, BookiesHealthInfo bookiesHealthInfo, DistributionSchedule.WriteSet writeSet)	Reorder the read last add confirmed sequence of a given write quorum writeSet.
DistributionSchedule.WriteSet	reorderReadSequence(List<BookieId> ensemble, BookiesHealthInfo bookiesHealthInfo, DistributionSchedule.WriteSet writeSet)	Reorder the read sequence of a given write quorum writeSet.
EnsemblePlacementPolicy.PlacementResult<BookieId>	replaceBookie(int ensembleSize, int writeQuorumSize, int ackQuorumSize, Map<String,byte[]> customMetadata, List<BookieId> currentEnsemble, BookieId bookieToReplace, Set<BookieId> excludeBookies)	Choose a new bookie to replace bookieToReplace.
void	uninitalize()	Uninitialize the policy.
void	updateBookieInfo(Map<BookieId,BookieInfoReader.BookieInfo> bookieInfoMap)	Send the bookie info details.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.bookkeeper.client.EnsemblePlacementPolicy

areAckedBookiesAdheringToPlacementPolicy, getStickyReadBookieIndex, replaceToAdherePlacementPolicy

Field Details

LOG

static final org.slf4j.Logger LOG

EMPTY_SET

static final Set<BookieId> EMPTY_SET

Constructor Details

DefaultEnsemblePlacementPolicy

DefaultEnsemblePlacementPolicy()

Method Details

newEnsemble

public EnsemblePlacementPolicy.PlacementResult<List<BookieId>> newEnsemble(int ensembleSize,
 int quorumSize,
 int ackQuorumSize,
 Map<String,byte[]> customMetadata,
 Set<BookieId> excludeBookies)
                                                                    throws BKException.BKNotEnoughBookiesException

Description copied from interface: EnsemblePlacementPolicy

Choose numBookies bookies for ensemble. If the count is more than the number of available nodes, BKException.BKNotEnoughBookiesException is thrown.

The implementation should respect to the replace settings. The size of the returned bookie list should be equal to the provide ensembleSize.

customMetadata is the same user defined data that user provides when BookKeeper.createLedger(int, int, int, BookKeeper.DigestType, byte[], Map).

If 'enforceMinNumRacksPerWriteQuorum' config is enabled then the bookies belonging to default faultzone (rack) will be excluded while selecting bookies.

Specified by:

newEnsemble in interface EnsemblePlacementPolicy

Parameters:

ensembleSize - Ensemble Size

quorumSize - Write Quorum Size

ackQuorumSize - the value of ackQuorumSize (added since 4.5)

customMetadata - the value of customMetadata. it is the same user defined metadata that user provides in BookKeeper.createLedger(int, int, int, BookKeeper.DigestType, byte[])

excludeBookies - Bookies that should not be considered as targets.

Returns:

a placement result containing list of bookie addresses for the ensemble.

Throws:

BKException.BKNotEnoughBookiesException - if not enough bookies available.

replaceBookie

public EnsemblePlacementPolicy.PlacementResult<BookieId> replaceBookie(int ensembleSize,
 int writeQuorumSize,
 int ackQuorumSize,
 Map<String,byte[]> customMetadata,
 List<BookieId> currentEnsemble,
 BookieId bookieToReplace,
 Set<BookieId> excludeBookies)
                                                                throws BKException.BKNotEnoughBookiesException

Description copied from interface: EnsemblePlacementPolicy

Choose a new bookie to replace bookieToReplace. If no bookie available in the cluster, BKException.BKNotEnoughBookiesException is thrown.

If 'enforceMinNumRacksPerWriteQuorum' config is enabled then the bookies belonging to default faultzone (rack) will be excluded while selecting bookies.

Specified by:

replaceBookie in interface EnsemblePlacementPolicy

Parameters:

ensembleSize - the value of ensembleSize

writeQuorumSize - the value of writeQuorumSize

ackQuorumSize - the value of ackQuorumSize (added since 4.5)

customMetadata - the value of customMetadata. it is the same user defined metadata that user provides in BookKeeper.createLedger(int, int, int, BookKeeper.DigestType, byte[])

currentEnsemble - the value of currentEnsemble

bookieToReplace - bookie to replace

excludeBookies - bookies that should not be considered as candidate.

Returns:

a placement result containing the new bookie address.

Throws:

BKException.BKNotEnoughBookiesException

onClusterChanged

public Set<BookieId> onClusterChanged(Set<BookieId> writableBookies,
 Set<BookieId> readOnlyBookies)

Description copied from interface: EnsemblePlacementPolicy

A consistent view of the cluster (what bookies are available as writable, what bookies are available as readonly) is updated when any changes happen in the cluster.

The implementation should take actions when the cluster view is changed. So subsequent EnsemblePlacementPolicy.newEnsemble(int, int, int, Map, Set) and EnsemblePlacementPolicy.replaceBookie(int, int, int, java.util.Map, java.util.List, BookieId, java.util.Set) can choose proper bookies.

Specified by:

onClusterChanged in interface EnsemblePlacementPolicy

Parameters:

writableBookies - All the bookies in the cluster available for write/read.

readOnlyBookies - All the bookies in the cluster available for readonly.

Returns:

the dead bookies during this cluster change.

registerSlowBookie

public void registerSlowBookie(BookieId bookieSocketAddress,
 long entryId)

Description copied from interface: EnsemblePlacementPolicy

Register a bookie as slow so that it is tried after available and read-only bookies.

Specified by:

registerSlowBookie in interface EnsemblePlacementPolicy

Parameters:

bookieSocketAddress - Address of bookie host

entryId - Entry ID that caused a speculative timeout on the bookie.

reorderReadSequence

public DistributionSchedule.WriteSet reorderReadSequence(List<BookieId> ensemble,
 BookiesHealthInfo bookiesHealthInfo,
 DistributionSchedule.WriteSet writeSet)

Description copied from interface: EnsemblePlacementPolicy

Reorder the read sequence of a given write quorum writeSet.

Specified by:

reorderReadSequence in interface EnsemblePlacementPolicy

Parameters:

ensemble - Ensemble to read entries.

bookiesHealthInfo - Health info for bookies

writeSet - Write quorum to read entries. This will be modified, rather than allocating a new WriteSet.

Returns:

The read sequence. This will be the same object as the passed in writeSet.

reorderReadLACSequence

public DistributionSchedule.WriteSet reorderReadLACSequence(List<BookieId> ensemble,
 BookiesHealthInfo bookiesHealthInfo,
 DistributionSchedule.WriteSet writeSet)

Description copied from interface: EnsemblePlacementPolicy

Reorder the read last add confirmed sequence of a given write quorum writeSet.

Specified by:

reorderReadLACSequence in interface EnsemblePlacementPolicy

Parameters:

ensemble - Ensemble to read entries.

bookiesHealthInfo - Health info for bookies

writeSet - Write quorum to read entries. This will be modified, rather than allocating a new WriteSet.

Returns:

The read sequence. This will be the same object as the passed in writeSet.

initialize

public EnsemblePlacementPolicy initialize(ClientConfiguration conf,
 Optional<DNSToSwitchMapping> optionalDnsResolver,
 io.netty.util.HashedWheelTimer hashedWheelTimer,
 FeatureProvider featureProvider,
 StatsLogger statsLogger,
 BookieAddressResolver bookieAddressResolver)

Description copied from interface: EnsemblePlacementPolicy

Initialize the policy.

Specified by:

initialize in interface EnsemblePlacementPolicy

Parameters:

conf - client configuration

optionalDnsResolver - dns resolver

hashedWheelTimer - timer

featureProvider - feature provider

statsLogger - stats logger

updateBookieInfo

public void updateBookieInfo(Map<BookieId,BookieInfoReader.BookieInfo> bookieInfoMap)

Description copied from interface: EnsemblePlacementPolicy

Send the bookie info details.

Specified by:

updateBookieInfo in interface EnsemblePlacementPolicy

Parameters:

bookieInfoMap - A map that has the bookie to BookieInfo

uninitalize

public void uninitalize()

Description copied from interface: EnsemblePlacementPolicy

Uninitialize the policy.

Specified by:

uninitalize in interface EnsemblePlacementPolicy

isEnsembleAdheringToPlacementPolicy

public EnsemblePlacementPolicy.PlacementPolicyAdherence isEnsembleAdheringToPlacementPolicy(List<BookieId> ensembleList,
 int writeQuorumSize,
 int ackQuorumSize)

Description copied from interface: EnsemblePlacementPolicy

returns AdherenceLevel if the Ensemble is strictly/softly/fails adhering to placement policy, like in the case of RackawareEnsemblePlacementPolicy, bookies in the writeset are from 'minNumRacksPerWriteQuorum' number of racks. And in the case of RegionawareEnsemblePlacementPolicy, check for minimumRegionsForDurability, reppRegionsToWrite, rack distribution within a region and other parameters of RegionAwareEnsemblePlacementPolicy. In ZoneAwareEnsemblePlacementPolicy if bookies in the writeset are from 'desiredNumOfZones' then it is considered as MEETS_STRICT if they are from 'minNumOfZones' then it is considered as MEETS_SOFT otherwise considered as FAIL.

Specified by:

isEnsembleAdheringToPlacementPolicy in interface EnsemblePlacementPolicy

Parameters:

ensembleList - list of BookieId of bookies in the ensemble

writeQuorumSize - writeQuorumSize of the ensemble

ackQuorumSize - ackQuorumSize of the ensemble

Returns: