Package org.apache.cassandra.locator

Class DynamicEndpointSnitch

java.lang.Object

org.apache.cassandra.locator.AbstractEndpointSnitch

org.apache.cassandra.locator.DynamicEndpointSnitch

All Implemented Interfaces:

DynamicEndpointSnitchMBean, IEndpointSnitch, LatencySubscribers.Subscriber

public class DynamicEndpointSnitch
extends AbstractEndpointSnitch
implements LatencySubscribers.Subscriber, DynamicEndpointSnitchMBean

A dynamic snitch that sorts endpoints by latency with an adapted phi failure detector

Field Summary

Fields

Modifier and Type	Field	Description
final IEndpointSnitch	subsnitch

Constructor Summary

Constructors

Constructor	Description
DynamicEndpointSnitch(IEndpointSnitch snitch)
DynamicEndpointSnitch(IEndpointSnitch snitch, String instance)

Method Summary

Modifier and Type	Method	Description
static void	addSeverity(double severity)
void	applyConfigChanges()	Update configuration from DatabaseDescriptor and estart the update-scheduler and reset-scheduler tasks if the configured rates for these tasks have changed.
void	close()
int	compareEndpoints(InetAddressAndPort target, Replica a1, Replica a2)	compares two endpoints in relation to the target endpoint, returning as Comparator.compare would
List<Double>	dumpTimings(String hostname)
double	getBadnessThreshold()
String	getDatacenter(InetAddressAndPort endpoint)	returns a String representing the datacenter the given endpoint belongs to
String	getRack(InetAddressAndPort endpoint)	returns a String representing the rack the given endpoint belongs to
int	getResetInterval()
Map<InetAddress,Double>	getScores()
Map<String,Double>	getScoresWithPort()
double	getSeverity()
static double	getSeverity(InetAddressAndPort endpoint)
String	getSubsnitchClassName()
int	getUpdateInterval()
void	gossiperStarting()	called after Gossiper instance exists immediately before it starts gossiping
boolean	isWorthMergingForRangeQuery(ReplicaCollection<?> merged, ReplicaCollection<?> l1, ReplicaCollection<?> l2)	Returns whether for a range query doing a query against merged is likely to be faster than 2 sequential queries, one against l1 followed by one against l2.
void	receiveTiming(InetAddressAndPort host, long latency, TimeUnit unit)
void	setSeverity(double severity)	Setting a Severity allows operators to inject preference information into the Dynamic Snitch replica selection.
<C extends ReplicaCollection<? extends C>> C	sortedByProximity(InetAddressAndPort address, C unsortedAddresses)	Sorts the Collection of node addresses by proximity to the given address
void	updateScores()
boolean	validate(Set<String> datacenters, Set<String> racks)	Determine if the datacenter or rack values in the current node's snitch conflict with those passed in parameters.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.cassandra.locator.IEndpointSnitch

getDatacenter, getDatacenter, getLocalDatacenter, getLocalRack

Field Details

subsnitch

public final IEndpointSnitch subsnitch

Constructor Details

DynamicEndpointSnitch

public DynamicEndpointSnitch(IEndpointSnitch snitch)

DynamicEndpointSnitch

public DynamicEndpointSnitch(IEndpointSnitch snitch,
 String instance)

Method Details

applyConfigChanges

public void applyConfigChanges()

Update configuration from DatabaseDescriptor and estart the update-scheduler and reset-scheduler tasks if the configured rates for these tasks have changed.

close

public void close()

gossiperStarting

public void gossiperStarting()

Description copied from interface: IEndpointSnitch

called after Gossiper instance exists immediately before it starts gossiping

Specified by:

gossiperStarting in interface IEndpointSnitch

Overrides:

gossiperStarting in class AbstractEndpointSnitch

getRack

public String getRack(InetAddressAndPort endpoint)

Description copied from interface: IEndpointSnitch

returns a String representing the rack the given endpoint belongs to

Specified by:

getRack in interface IEndpointSnitch

getDatacenter

public String getDatacenter(InetAddressAndPort endpoint)

Description copied from interface: IEndpointSnitch

returns a String representing the datacenter the given endpoint belongs to

Specified by:

getDatacenter in interface IEndpointSnitch

sortedByProximity

public <C extends ReplicaCollection<? extends C>> C sortedByProximity(InetAddressAndPort address,
 C unsortedAddresses)

Description copied from class: AbstractEndpointSnitch

Sorts the Collection of node addresses by proximity to the given address

Specified by:

sortedByProximity in interface IEndpointSnitch

Overrides:

sortedByProximity in class AbstractEndpointSnitch

Parameters:

address - the address to sort by proximity to

unsortedAddresses - the nodes to sort

Returns:

a new sorted List

compareEndpoints

public int compareEndpoints(InetAddressAndPort target,
 Replica a1,
 Replica a2)

Description copied from interface: IEndpointSnitch

compares two endpoints in relation to the target endpoint, returning as Comparator.compare would

Specified by:

compareEndpoints in interface IEndpointSnitch

Specified by:

compareEndpoints in class AbstractEndpointSnitch

receiveTiming

public void receiveTiming(InetAddressAndPort host,
 long latency,
 TimeUnit unit)

Specified by:

receiveTiming in interface LatencySubscribers.Subscriber

updateScores

public void updateScores()

getScores

public Map<InetAddress,Double> getScores()

Specified by:

getScores in interface DynamicEndpointSnitchMBean

getScoresWithPort

public Map<String,Double> getScoresWithPort()

Specified by:

getScoresWithPort in interface DynamicEndpointSnitchMBean

getUpdateInterval

public int getUpdateInterval()

Specified by:

getUpdateInterval in interface DynamicEndpointSnitchMBean

getResetInterval

public int getResetInterval()

Specified by:

getResetInterval in interface DynamicEndpointSnitchMBean

getBadnessThreshold

public double getBadnessThreshold()

Specified by:

getBadnessThreshold in interface DynamicEndpointSnitchMBean

getSubsnitchClassName

public String getSubsnitchClassName()

Specified by:

getSubsnitchClassName in interface DynamicEndpointSnitchMBean

dumpTimings

public List<Double> dumpTimings(String hostname)
                         throws UnknownHostException

Specified by:

dumpTimings in interface DynamicEndpointSnitchMBean

Throws:

UnknownHostException

setSeverity

public void setSeverity(double severity)

Description copied from interface: DynamicEndpointSnitchMBean

Setting a Severity allows operators to inject preference information into the Dynamic Snitch replica selection. When choosing which replicas to participate in a read request, the DSnitch sorts replicas by response latency, and selects the fastest replicas. Latencies are normalized to a score from 0 to 1, with lower scores being faster. The Severity injected here will be added to the normalized score. Thus, adding a Severity greater than 1 will mean the replica will never be contacted (unless needed for ALL or if it is added later for rapid read protection). Conversely, adding a negative Severity means the replica will *always* be contacted. (The "Severity" term is historical and dates to when this was used to represent how badly background tasks like compaction were affecting a replica's performance. See CASSANDRA-3722 for when this was introduced and CASSANDRA-11738 for why it was removed.)

Specified by:

setSeverity in interface DynamicEndpointSnitchMBean

addSeverity

public static void addSeverity(double severity)

getSeverity

public static double getSeverity(InetAddressAndPort endpoint)

getSeverity

public double getSeverity()

Specified by:

getSeverity in interface DynamicEndpointSnitchMBean

Returns:

the current manually injected Severity.

isWorthMergingForRangeQuery

public boolean isWorthMergingForRangeQuery(ReplicaCollection<?> merged,
 ReplicaCollection<?> l1,
 ReplicaCollection<?> l2)

Description copied from interface: IEndpointSnitch

Returns whether for a range query doing a query against merged is likely to be faster than 2 sequential queries, one against l1 followed by one against l2.

Specified by:

isWorthMergingForRangeQuery in interface IEndpointSnitch

Overrides:

isWorthMergingForRangeQuery in class AbstractEndpointSnitch

validate

public boolean validate(Set<String> datacenters,
 Set<String> racks)

Description copied from interface: IEndpointSnitch

Determine if the datacenter or rack values in the current node's snitch conflict with those passed in parameters.

Specified by:

validate in interface IEndpointSnitch