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com.tangosol.net.partition
Class SimpleAssignmentStrategy

java.lang.Object
com.tangosol.net.partition.SimpleAssignmentStrategy

All Implemented Interfaces:

PartitionAssignmentStrategy, SimpleStrategyMBean

Direct Known Subclasses:

MirroringAssignmentStrategy

public class SimpleAssignmentStrategy

extends java.lang.Object

implements PartitionAssignmentStrategy, SimpleStrategyMBean

SimpleAssignmentStrategy is a PartitionAssignmentStrategy that attempts to balance the partition distribution based on the number of primary and backup partitions owned. The SimpleAssignmentStrategy will attempt to ensure machine-safety, but only if a balanced "safe" distribution is achievable.

The SimpleAssignmentStrategy is an extensible implementation of the internal distribution algorithm that was available prior to Coherence 3.7.

Since:

Coherence 3.7

Author:

rhl 2010.11.08

Nested Class Summary

protected class	SimpleAssignmentStrategy.AnalysisContext AnalysisContext holds the working view of the partition ownership that is used throughout the analysis and is used to reflect changes made during this analysis.
protected static class	SimpleAssignmentStrategy.BackupStrength BackupStrength represents a level of "strength" or "resiliency" between the primary and backup owners of a partition.
static interface	SimpleAssignmentStrategy.LoadCalculator LoadCalculator is used to calculate the scalar load (expressed as an integer) of a partition (or set of partitions).
static class	SimpleAssignmentStrategy.SimpleLoadCalculator SimpleLoadCalculator defines a "count-based" load (e.g. the load of each partition is defined to be 1).

Field Summary

protected SimpleAssignmentStrategy.AnalysisContext	m_ctxLast The last analysis context.
protected javax.management.NotificationBroadcasterSupport	m_emitter The notification emitter used for MBean notifications.
protected DistributionManager	m_manager The DistributionManager.
protected java.util.Map	m_mapSuggestLast The Map containing the last distribution suggested by this strategy.
protected java.util.Set	m_setOwnersLast The Set of ownership-enabled members at the time of the last analysis.
protected static java.util.Comparator	MEMBERID_COMPARATOR Comparator used to provide arbitrary (equals-compatible) comparisons between members.
protected static java.lang.String	MSG_NO_PENDING The message returned by SimpleStrategyMBean when all suggested distributions have completed and none are in-progress or pending.
protected static java.lang.String	MSG_NO_RESULT The message returned by SimpleStrategyMBean when the distribution coordinator has not done its first analysis yet.
static java.lang.String	NOTIFY_LOST Notification type for a "partitions are lost and needs to be recovered" event.

Constructor Summary

SimpleAssignmentStrategy()
Default constructor.

Method Summary

long	analyzeDistribution() Analyze the distribution and return the desired time interval before the next distribution analysis.
protected long	analyzeDistribution(SimpleAssignmentStrategy.AnalysisContext ctx) Analyze the distribution using the specified analysis context.
void	analyzeOrphans(java.util.Map mapConstraints) Analyze and suggest the assignment of orphaned partitions (partitions without an active primary or backup owner) subject to the specified constraints.
protected static java.util.Comparator	chainComparators(java.util.Comparator comp1, java.util.Comparator comp2) Helper method to return a Comparator chaining the specified comparators.
protected static java.util.Comparator	chainComparators(java.util.Comparator comp1, java.util.Comparator comp2, java.util.Comparator comp3) Helper method to return a Comparator chaining the specified comparators.
protected int	checkBackupBalance(SimpleAssignmentStrategy.AnalysisContext ctx) Check that the distribution of backup partitions is balanced.
protected int	checkBackupStrong(SimpleAssignmentStrategy.AnalysisContext ctx) Check that the backups are strong.
protected void	checkEndangered(SimpleAssignmentStrategy.AnalysisContext ctx) Check the distribution to ensure that backups are created for any "endangered" partitions.
protected void	checkLeaving(SimpleAssignmentStrategy.AnalysisContext ctx) Check for any service members that are leaving, and adjust the distribution plan accordingly.
protected void	checkPrimaryBalance(SimpleAssignmentStrategy.AnalysisContext ctx) Check the distribution to ensure that primary the partition load is balanced.
protected java.util.Map	collectPendingDistributions() Collect the pending partition distributions, grouped by the primary owner and storage index.
protected int	doBalancePrimary(SimpleAssignmentStrategy.AnalysisContext ctx, Member memberFrom, PartitionSet parts, Member[] aMembersTarget) Do balancing transfers for primary distribution.
protected void	emitLossNotification(PartitionSet partsLost) Emit a partition loss notification for given partitions.
protected static int	filterArray(java.lang.Object[] ao, Filter filter) Apply the specified filter to the elements of the specified array.
protected static int	filterArray(java.lang.Object[] ao, int cElems, Filter filter) Apply the specified filter to the specified array elements.
protected static int	filterSort(java.lang.Object[] ao, java.util.Comparator comparator, Filter filter) Filter the elements in the specified array and sort any matching elements using the specified comparator.
protected static int	filterSort(java.lang.Object[] ao, int cElems, java.util.Comparator comparator, Filter filter) Filter the specified array elements and sort any matching elements using the specified comparator.
int	getBackupCount() Get the configured number of backups.
int	getCoordinatorId() Get the node id of the ownership distribution coordinator.
java.lang.String	getDescription() Return a human-readable description of the state of the partition assignment.
int	getFairShareBackup() Get the number of backup partitions per storage-enabled service member that this strategy will currently attempt to maintain.
int	getFairSharePrimary() Get the number of primary partitions per storage-enabled service member that this strategy will currently attempt to maintain.
java.lang.String	getHAStatus() The High Availability status for the service.
java.lang.String	getHATarget() The High Availability status that this strategy attempts to achieve.
SimpleAssignmentStrategy.AnalysisContext	getLastAnalysisContext() Return the last AnalysisContext.
java.util.Date	getLastAnalysisTime() Get the last time a partition distribution analysis was performed.
java.util.Set	getLastOwnershipMembers() Return the set of ownership-enabled members present when the analysis was last considered.
DistributionManager	getManager() Return the DistributionManager.
protected Member	getMember(int nMemberId) Return the PartitionedService Member with the specified mini-id.
protected long	getMemberJoinDelay() Return the amount of time in ms to delay the analysis after a member has joined.
int	getPartitionCount() Get the configured number of partitions for the service.
int	getRemainingDistributionCount() Get the number of distributions (partition transfers) that remain to be completed before the service achieves the goals set by this strategy.
int	getServiceMachineCount() Get the number of machines that host storage-enabled nodes running this service.
int	getServiceNodeCount() Get the number of storage-enabled nodes running this service.
int	getServiceRackCount() Get the number of racks that host storage-enabled nodes running this service.
int	getServiceSiteCount() Get the number of sites that host storage-enabled nodes running this service.
java.lang.String	getStrategyName() Get name of the PartitionAssignmentStrategy in use.
protected long	getSuggestionCompletionDelay() Return the amount of time in ms to delay the analysis after a distribution suggestion has been made and before it is carried out.
protected PartitionSet	getUnownedPartitions(PartitionSet parts, int nMember) Calculate a subset of the PartitionSet consisting of partitions that are not owned (primary or backup) by the specified member.
protected int	getVariance(SimpleAssignmentStrategy.AnalysisContext ctx, boolean fPrimary) Return the maximum load variance in the partition assignments represented by the analysis context.
void	init(DistributionManager manager) Initialize the PartitionAssignmentStrategy and bind it to the specified DistributionManager.
SimpleAssignmentStrategy.AnalysisContext	instantiateAnalysisContext() Factory method.
SimpleAssignmentStrategy.LoadCalculator	instantiateLoadCalculator(boolean fPrimary) Instantiate the load calculator.
protected java.lang.String	makeMBeanName(PartitionedService service) Create a name for the MBean representing this strategy.
protected void	registerMBean() Register an MBean representing this SimpleAssignmentStrategy.
java.lang.String	reportPendingDistributions(boolean fVerbose) Report partitions that storage-enabled members are waiting to receive or still need to send in order to achieve distribution goal set by the strategy.
void	setLastAnalysisContext(SimpleAssignmentStrategy.AnalysisContext ctx) Set the last AnalysisContext.
protected void	setLastOwnershipMembers(java.util.Set setOwners) Record the set of ownership-enabled members present when the analysis was last considered.
protected java.util.SortedMap	splitByOwner(PartitionSet parts) Split the specified set of partitions pending distribution by the current primary owner (all transfers originate from the primary owner).
java.lang.String	toString()
protected void	unregisterMBean() Unregister the MBean representing this SimpleAssignmentStrategy.
protected void	validateBackups(SimpleAssignmentStrategy.AnalysisContext ctx) Check if there are enough ownership members to maintain the configured backup count, reducing the number of backups otherwise.

Field Detail

MEMBERID_COMPARATOR

protected static final java.util.Comparator MEMBERID_COMPARATOR

Comparator used to provide arbitrary (equals-compatible) comparisons between members.

MSG_NO_RESULT

protected static final java.lang.String MSG_NO_RESULT

The message returned by SimpleStrategyMBean when the distribution coordinator has not done its first analysis yet.

See Also:

Constant Field Values

MSG_NO_PENDING

protected static final java.lang.String MSG_NO_PENDING

The message returned by SimpleStrategyMBean when all suggested distributions have completed and none are in-progress or pending.

See Also:

Constant Field Values

NOTIFY_LOST

public static final java.lang.String NOTIFY_LOST

Notification type for a "partitions are lost and needs to be recovered" event.

See Also:

Constant Field Values

m_manager

protected DistributionManager m_manager

The DistributionManager.

m_ctxLast

protected SimpleAssignmentStrategy.AnalysisContext m_ctxLast

The last analysis context.

m_setOwnersLast

protected java.util.Set m_setOwnersLast

The Set of ownership-enabled members at the time of the last analysis.

m_mapSuggestLast

protected java.util.Map m_mapSuggestLast

The Map containing the last distribution suggested by this strategy.

m_emitter

protected javax.management.NotificationBroadcasterSupport m_emitter

The notification emitter used for MBean notifications.

Constructor Detail

SimpleAssignmentStrategy

public SimpleAssignmentStrategy()

Default constructor.

Method Detail

getManager

public DistributionManager getManager()

Return the DistributionManager.

Returns:

the DistributionManager

getLastAnalysisContext

public SimpleAssignmentStrategy.AnalysisContext getLastAnalysisContext()

Return the last AnalysisContext.

Returns:

the last AnalysisContext

setLastAnalysisContext

public void setLastAnalysisContext(SimpleAssignmentStrategy.AnalysisContext ctx)

Set the last AnalysisContext.

Parameters:

ctx - the AnalysisContext

getLastOwnershipMembers

public java.util.Set getLastOwnershipMembers()

Return the set of ownership-enabled members present when the analysis was last considered.

Returns:

the set of ownership-enabled members when analysis was last considered

setLastOwnershipMembers

protected void setLastOwnershipMembers(java.util.Set setOwners)

Record the set of ownership-enabled members present when the analysis was last considered.

Parameters:

setOwners - the set of ownership-enabled members

getMemberJoinDelay

protected long getMemberJoinDelay()

Return the amount of time in ms to delay the analysis after a member has joined. This delay could be used to "dampen" the reactivity of the strategy to membership changes.

Returns:

the amount of time in ms to delay the analysis after a member joins

getSuggestionCompletionDelay

protected long getSuggestionCompletionDelay()

Return the amount of time in ms to delay the analysis after a distribution suggestion has been made and before it is carried out. This delay could be used to "dampen" the volatility of the strategy by allowing sufficient time for in-flight transfers to complete prior to considering further recommendations.

Returns:

the amount of time in ms to delay the analysis after a suggestion is made

init

public void init(DistributionManager manager)

Initialize the PartitionAssignmentStrategy and bind it to the specified DistributionManager. This method is called only on the distribution coordinator, prior its first distribution analysis.

Specified by:

init in interface PartitionAssignmentStrategy

Parameters:

manager - the DistributionManager that this strategy is bound to

analyzeOrphans

public void analyzeOrphans(java.util.Map mapConstraints)

Analyze and suggest the assignment of orphaned partitions (partitions without an active primary or backup owner) subject to the specified constraints. For each partition, the supplied constraints specify the set of members which are eligible to be assigned the ownership.

The strategy must provide suggestions for all orphaned partitions which are consistent with the supplied constraints. Failure to provide a complete set of valid suggestions may result in the loss of partition data.

Specified by:

analyzeOrphans in interface PartitionAssignmentStrategy

Parameters:

mapConstraints - the map of assignment constraints associating members with the set of partitions that they could be assigned ownership of

analyzeDistribution

public long analyzeDistribution()

Analyze the distribution and return the desired time interval before the next distribution analysis. This method may or may not make distribution suggestions through the distribution manager. The strategy can influence (but not guarantee) the frequency with which it is analyzed by returning the desired interval before the next call, or -1 if the strategy has no preference and will rely on the PartitionedService to decide.

As a result of failover, partitions may become 'endangered', meaning that the necessary number of backups do not exist. Failure to suggest a distribution recovery plan for those partitions may result in the partition remaining in the endangered state. Additionally, ownership-enabled service members that are in the process of shutting down will wait until all owned partitions are transferred out. Failure to suggest a distribution plan may delay the exit of these leaving members.

The statistics and ownership information exposed by the DistributionManager will not mutate for the duration of this method call.

Specified by:

analyzeDistribution in interface PartitionAssignmentStrategy

Returns:

the time interval before the next desired analysis, or -1

analyzeDistribution

protected long analyzeDistribution(SimpleAssignmentStrategy.AnalysisContext ctx)

Analyze the distribution using the specified analysis context.

Parameters:

ctx - the analysis context

Returns:

the time interval before the next desired analysis, or -1

See Also:

analyzeDistribution()

getDescription

public java.lang.String getDescription()

Return a human-readable description of the state of the partition assignment.

Specified by:

getDescription in interface PartitionAssignmentStrategy

Returns:

a human-readable description

toString

public java.lang.String toString()

checkLeaving

protected void checkLeaving(SimpleAssignmentStrategy.AnalysisContext ctx)

Check for any service members that are leaving, and adjust the distribution plan accordingly.

Partitions owned by leaving members must be transferred to other members before the departing members are able to shutdown.

Parameters:

ctx - the AnalysisContext

validateBackups

protected void validateBackups(SimpleAssignmentStrategy.AnalysisContext ctx)

Check if there are enough ownership members to maintain the configured backup count, reducing the number of backups otherwise.

Parameters:

ctx - the AnalysisContext

checkPrimaryBalance

protected void checkPrimaryBalance(SimpleAssignmentStrategy.AnalysisContext ctx)

Check the distribution to ensure that primary the partition load is balanced.

Parameters:

ctx - the analysis context

doBalancePrimary

protected int doBalancePrimary(SimpleAssignmentStrategy.AnalysisContext ctx,
                               Member memberFrom,
                               PartitionSet parts,
                               Member[] aMembersTarget)

Do balancing transfers for primary distribution.

Parameters:

ctx - the analysis context

memberFrom - the member to transfer partitions from

parts - the set of partitions from which to transfer

aMembersTarget - the (unordered) array of members

Returns:

the number of changes (transfers) that were made

checkEndangered

protected void checkEndangered(SimpleAssignmentStrategy.AnalysisContext ctx)

Check the distribution to ensure that backups are created for any "endangered" partitions.

A partition is "endangered" if it is incompletely backed up (e.g. some backup copies do not exist).

Parameters:

ctx - the analysis context

checkBackupStrong

protected int checkBackupStrong(SimpleAssignmentStrategy.AnalysisContext ctx)

Check that the backups are strong.

Parameters:

ctx - the analysis context

Returns:

the number of changes (transfers) that were made

checkBackupBalance

protected int checkBackupBalance(SimpleAssignmentStrategy.AnalysisContext ctx)

Check that the distribution of backup partitions is balanced.

Parameters:

ctx - the analysis context

Returns:

the number of changes (transfers) that were made

getMember

protected Member getMember(int nMemberId)

Return the PartitionedService Member with the specified mini-id.

Parameters:

nMemberId - the mini-id

Returns:

the PartitionedService Member with the specified mini-id, or null

getVariance

protected int getVariance(SimpleAssignmentStrategy.AnalysisContext ctx,
                          boolean fPrimary)

Return the maximum load variance in the partition assignments represented by the analysis context. The maximum variance is the difference in load between the 'lightest' and 'heaviest' members.

Parameters:

ctx - the analysis context

fPrimary - true iff the "primary" load variance should be computed

Returns:

the maximum variance

chainComparators

protected static java.util.Comparator chainComparators(java.util.Comparator comp1,
                                                       java.util.Comparator comp2)

Helper method to return a Comparator chaining the specified comparators.

Parameters:

comp1 - the first comparator

comp2 - the second comparator

Returns:

a chained comparator

chainComparators

protected static java.util.Comparator chainComparators(java.util.Comparator comp1,
                                                       java.util.Comparator comp2,
                                                       java.util.Comparator comp3)

Helper method to return a Comparator chaining the specified comparators.

Parameters:

comp1 - the first comparator

comp2 - the second comparator

comp3 - the third comparator

Returns:

a chained comparator

filterSort

protected static int filterSort(java.lang.Object[] ao,
                                java.util.Comparator comparator,
                                Filter filter)

Filter the elements in the specified array and sort any matching elements using the specified comparator. All matching results will be compacted to the front of the array. The order of results not matching the filter is undefined.

Parameters:

ao - the object array to sort and filter

comparator - the comparator to order the elements

filter - the filter to use to filter the results

Returns:

the number of elements matching the specified filter

filterSort

protected static int filterSort(java.lang.Object[] ao,
                                int cElems,
                                java.util.Comparator comparator,
                                Filter filter)

Filter the specified array elements and sort any matching elements using the specified comparator. All matching results will be compacted to the front of the array. The order of results not matching the filter is undefined.

Parameters:

ao - the object array to sort and filter

cElems - the number of elements to filter and sort

comparator - the comparator to order the elements

filter - the filter to use to filter the results

Returns:

the number of elements matching the specified filter

filterArray

protected static int filterArray(java.lang.Object[] ao,
                                 Filter filter)

Apply the specified filter to the elements of the specified array. All matching results will be compacted to the front of the array in a "stable" manner. The order of results not matching the filter may not be preserved.

Parameters:

ao - the object array to apply the filter to

filter - the filter to apply

Returns:

the number of elements matching the specified filter

filterArray

protected static int filterArray(java.lang.Object[] ao,
                                 int cElems,
                                 Filter filter)

Apply the specified filter to the specified array elements. All matching results will be compacted to the front of the array in a "stable" manner. The order of results not matching the filter may not be preserved.

Parameters:

ao - the object array to apply the filter to

cElems - the number of elements to filter

filter - the filter to apply

Returns:

the number of elements matching the specified filter

getPartitionCount

public int getPartitionCount()

Get the configured number of partitions for the service.

Specified by:

getPartitionCount in interface SimpleStrategyMBean

Returns:

the partition count

getBackupCount

public int getBackupCount()

Get the configured number of backups.

Specified by:

getBackupCount in interface SimpleStrategyMBean

Returns:

the backup count

getServiceNodeCount

public int getServiceNodeCount()

Get the number of storage-enabled nodes running this service.

Specified by:

getServiceNodeCount in interface SimpleStrategyMBean

Returns:

the number of storage-enabled nodes

getServiceMachineCount

public int getServiceMachineCount()

Get the number of machines that host storage-enabled nodes running this service.

Specified by:

getServiceMachineCount in interface SimpleStrategyMBean

Returns:

the number of machines with storage-enabled nodes

getServiceRackCount

public int getServiceRackCount()

Get the number of racks that host storage-enabled nodes running this service.

Specified by:

getServiceRackCount in interface SimpleStrategyMBean

Returns:

the number of racks with storage-enabled nodes

getServiceSiteCount

public int getServiceSiteCount()

Get the number of sites that host storage-enabled nodes running this service.

Specified by:

getServiceSiteCount in interface SimpleStrategyMBean

Returns:

the number of sites with storage-enabled nodes

getHAStatus

public java.lang.String getHAStatus()

The High Availability status for the service.

Specified by:

getHAStatus in interface SimpleStrategyMBean

Returns:

one of the following values: ENDANGERED, NODE-SAFE, MACHINE-SAFE, RACK-SAFE, SITE-SAFE

getHATarget

public java.lang.String getHATarget()

The High Availability status that this strategy attempts to achieve. Values are the same as for HAStatus attribute.

Specified by:

getHATarget in interface SimpleStrategyMBean

Returns:

the target High Availability status

getFairShareBackup

public int getFairShareBackup()

Get the number of backup partitions per storage-enabled service member that this strategy will currently attempt to maintain.

Specified by:

getFairShareBackup in interface SimpleStrategyMBean

Returns:

the number of backup partitions per storage-enabled member

getFairSharePrimary

public int getFairSharePrimary()

Get the number of primary partitions per storage-enabled service member that this strategy will currently attempt to maintain.

Specified by:

getFairSharePrimary in interface SimpleStrategyMBean

Returns:

the number of primary partitions per storage-enabled member

getStrategyName

public java.lang.String getStrategyName()

Get name of the PartitionAssignmentStrategy in use.

Specified by:

getStrategyName in interface SimpleStrategyMBean

Returns:

partitioning strategy name

getLastAnalysisTime

public java.util.Date getLastAnalysisTime()

Get the last time a partition distribution analysis was performed.

Specified by:

getLastAnalysisTime in interface SimpleStrategyMBean

Returns:

the time of the last analysis

getCoordinatorId

public int getCoordinatorId()

Get the node id of the ownership distribution coordinator.

Specified by:

getCoordinatorId in interface SimpleStrategyMBean

Returns:

current distribution coordinator node id

getRemainingDistributionCount

public int getRemainingDistributionCount()

Get the number of distributions (partition transfers) that remain to be completed before the service achieves the goals set by this strategy.

Specified by:

getRemainingDistributionCount in interface SimpleStrategyMBean

Returns:

the number of remaining partition transfers

reportPendingDistributions

public java.lang.String reportPendingDistributions(boolean fVerbose)

Report partitions that storage-enabled members are waiting to receive or still need to send in order to achieve distribution goal set by the strategy.

Specified by:

reportPendingDistributions in interface SimpleStrategyMBean

Parameters:

fVerbose - if true, the report includes partition numbers for each pending transfer

Returns:

a description of pending distributions for the service

registerMBean

protected void registerMBean()

Register an MBean representing this SimpleAssignmentStrategy.

This implementation creates and registers a SimpleStrategyMBean.

makeMBeanName

protected java.lang.String makeMBeanName(PartitionedService service)

Create a name for the MBean representing this strategy.

The name must be globally unique, but not contain the nodeId property. This allows us to re-bind the same JMX name to the MBean on a different node when the distribution coordinator migrates.

Parameters:

service - partitioned service that uses this strategy

Returns:

the name for the MBean

unregisterMBean

protected void unregisterMBean()

Unregister the MBean representing this SimpleAssignmentStrategy.

emitLossNotification

protected void emitLossNotification(PartitionSet partsLost)

Emit a partition loss notification for given partitions.

Parameters:

partsLost - the partition id that has been lost

collectPendingDistributions

protected java.util.Map collectPendingDistributions()

Collect the pending partition distributions, grouped by the primary owner and storage index. A partition distribution (either primary or backup) is considered to be pending if the distribution has been suggested but the ownership change has not yet occurred.

Returns:

a Map associating the sets of partitions still pending distribution with the primary owner

getUnownedPartitions

protected PartitionSet getUnownedPartitions(PartitionSet parts,
                                            int nMember)

Calculate a subset of the PartitionSet consisting of partitions that are not owned (primary or backup) by the specified member.

Parameters:

parts - set of partitions to check the ownership of

nMember - the member-id

Returns:

the subset of partitions that are not owned by the specified member

splitByOwner

protected java.util.SortedMap splitByOwner(PartitionSet parts)

Split the specified set of partitions pending distribution by the current primary owner (all transfers originate from the primary owner).

Parameters:

parts - a set of partitions not yet transferred

Returns:

the partitions pending distribution, associated with their primary owners

instantiateLoadCalculator

public SimpleAssignmentStrategy.LoadCalculator instantiateLoadCalculator(boolean fPrimary)

Instantiate the load calculator.

Parameters:

fPrimary - true iff the load calculator will be used for primary partition load; backup otherwise

Returns:

a load calculator

instantiateAnalysisContext

public SimpleAssignmentStrategy.AnalysisContext instantiateAnalysisContext()

Factory method.

Returns:

a new AnalysisContext

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