Package com.yahoo.search.dispatch

Class LoadBalancer

java.lang.Object

com.yahoo.search.dispatch.LoadBalancer

public class LoadBalancer
extends Object

LoadBalancer determines which group of content nodes should be accessed next for each search query when the internal java dispatcher is used. The implementation here is a simplistic least queries in flight + round-robin load balancer

Author:

ollivir

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	LoadBalancer.Policy

Constructor Summary

Constructors

Constructor	Description
LoadBalancer(Collection<Group> groups, LoadBalancer.Policy policy)

Method Summary

Modifier and Type	Method	Description
void	releaseGroup(Group group, boolean success, com.yahoo.search.dispatch.RequestDuration searchTime)	Release an allocation given by takeGroup(java.util.Set<java.lang.Integer>).
Optional<Group>	takeGroup(Set<Integer> rejectedGroups)	Select and allocate the search cluster group which is to be used for the next search query.

Methods inherited from class java.lang.Object

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

Constructor Details

LoadBalancer

public LoadBalancer(Collection<Group> groups,
 LoadBalancer.Policy policy)

Method Details

takeGroup

public Optional<Group> takeGroup(Set<Integer> rejectedGroups)

Select and allocate the search cluster group which is to be used for the next search query. Callers must call releaseGroup(com.yahoo.search.dispatch.searchcluster.Group, boolean, com.yahoo.search.dispatch.RequestDuration) symmetrically for each taken allocation.

Parameters:

rejectedGroups - if not null, the load balancer will only return groups with IDs not in the set

Returns:

the node group to target, or empty if the internal dispatch logic cannot be used

releaseGroup

public void releaseGroup(Group group,
 boolean success,
 com.yahoo.search.dispatch.RequestDuration searchTime)

Release an allocation given by takeGroup(java.util.Set<java.lang.Integer>). The release must be done exactly once for each allocation.

Parameters:

group - previously allocated group

success - was the query successful

searchTime - query execution time, used for adaptive load balancing