package loadbalancer
This package implements client side load balancing algorithms.
As an end-user, see the Balancers API to create instances which can be used to configure a Finagle client with various load balancing strategies.
As an implementor, each algorithm gets its own subdirectory and is exposed via the Balancers object. Several convenient traits are provided which factor out common behavior and can be mixed in (i.e. Balancer, DistributorT, NodeT, and Updating).
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Type Members
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trait
EndpointFactory[Req, Rep] extends ServiceFactory[Req, Rep]
A specialized ServiceFactory which admits that it backs a concrete endpoint.
A specialized ServiceFactory which admits that it backs a concrete endpoint. The extra information and functionality provided here is used by Finagle's load balancers.
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abstract
class
LoadBalancerFactory extends AnyRef
A thin interface around a Balancer's constructor that allows Finagle to pass in context from the stack to the balancers at construction time.
A thin interface around a Balancer's constructor that allows Finagle to pass in context from the stack to the balancers at construction time.
- See also
The user guide for more details.
Balancers for a collection of available balancers.
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class
NoNodesOpenException extends RuntimeException with FailureFlags[NoNodesOpenException] with HasLogLevel with SourcedException
While this exception is safe to retry, the assumption used here is that the underlying situation will not change soon enough to make a retry worthwhile as retrying is most likely to eat up the entire budget.
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sealed
trait
WhenNoNodesOpen extends AnyRef
The behavior the load balancer should take when none of its nodes have a com.twitter.finagle.Status of Open.
The behavior the load balancer should take when none of its nodes have a com.twitter.finagle.Status of Open.
The default behavior is WhenNoNodesOpen.PickOne and can be customized on a client through LoadBalancerFactory.WhenNoNodesOpenParam:
import com.twitter.finagle.loadbalancer.LoadBalancerFactory.WhenNoNodesOpenParam import com.twitter.finagle.loadbalancer.WhenNoNodesOpen import com.twitter.finagle.Http Http.client .configured(WhenNoNodesOpenParam(WhenNoNodesOpen.FailFast))
- See also
WhenNoNodesOpens
for Java friendly API.the user guide.
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final
class
WhenNoNodesOpens extends AnyRef
Java API for
WhenNoNodesOpen
.
Value Members
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def
defaultAddressOrdering: Ordering[Address]
Returns the default process global Address ordering as set via
defaultAddressOrdering
.Returns the default process global Address ordering as set via
defaultAddressOrdering
. If no value is set, Address.OctetOrdering is used with the assumption that hosts resolved via Finagle provide the load balancer with resolved InetAddresses. If a separate resolution process is used, outside of Finagle, the default ordering should be overriden. -
def
defaultAddressOrdering(order: Ordering[Address]): Unit
Set the default Address ordering for the entire process (outside of clients which override it).
Set the default Address ordering for the entire process (outside of clients which override it).
- See also
LoadBalancerFactory.AddressOrdering for more info.
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def
defaultBalancerFactory: LoadBalancerFactory
Returns the default process global LoadBalancerFactory as set via
defaultBalancerFactory
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def
defaultBalancerFactory(factory: LoadBalancerFactory): Unit
Set the default LoadBalancerFactory for the entire process (outside of clients which override it).
Set the default LoadBalancerFactory for the entire process (outside of clients which override it).
- See also
LoadBalancerFactory.Param for more info.
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object
Balancers
Constructor methods for various load balancers.
Constructor methods for various load balancers. The methods take balancer specific parameters and return a LoadBalancerFactory that allows you to easily inject a balancer into the Finagle client stack via the
withLoadBalancer
method.configuring a client with a load balancer
$Protocol.client .withLoadBalancer(Balancers.aperture()) .newClient(...)
- See also
The user guide for more details.
Example: -
object
FlagBalancerFactory extends LoadBalancerFactory
A LoadBalancerFactory proxy which instantiates the underlying based on flags (see flags.scala for applicable flags).
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object
LoadBalancerFactory
Exposes a Stack.Module which composes load balancing into the respective Stack.
Exposes a Stack.Module which composes load balancing into the respective Stack. This is mixed in by default into Finagle's com.twitter.finagle.client.StackClient. The only necessary configuration is a LoadBalancerFactory.Dest which represents a changing collection of addresses that is load balanced over.
- object WhenNoNodesOpen
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object
defaultBalancer extends GlobalFlag[String]
A GlobalFlag that changes the default balancer for every client in the process.
A GlobalFlag that changes the default balancer for every client in the process. Valid choices are ['heap', 'choice', and 'aperture'].
To configure the load balancer on a per-client granularity instead, use the
withLoadBalancer
method like so:{{ val balancer = Balancers.aperture(...) $Protocol.client.withLoadBalancer(balancer) }}
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object
perHostStats extends GlobalFlag[Boolean]
A GlobalFlag which allows the configuration of per host (or endpoint) stats to be toggled.
A GlobalFlag which allows the configuration of per host (or endpoint) stats to be toggled. Note, these are off by default because they tend to be expensive, especially when the size of the destination cluster is large. However, they can be quite useful for debugging.
Deprecated Value Members
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object
DefaultBalancerFactory extends LoadBalancerFactory
- Annotations
- @deprecated
- Deprecated
(Since version 2017-11-28) Use com.twitter.finagle.loadbalancer.FlagBalancerFactory instead.