endpointsharding, lazy: Remove intermediary gracefulswitch balancers #8052
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## master #8052 +/- ##
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- Coverage 82.29% 82.17% -0.12%
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Files 384 387 +3
Lines 38926 38981 +55
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Hits 32034 32034
- Misses 5565 5610 +45
- Partials 1327 1337 +10
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| @@ -100,7 +99,7 @@ func (crr *customRoundRobin) UpdateClientConnState(state balancer.ClientConnStat | |||
| // is guaranteed to happen since the aggregator will always call | |||
| // UpdateChildState in its UpdateClientConnState. | |||
| return crr.Balancer.UpdateClientConnState(balancer.ClientConnState{ | |||
| BalancerConfig: gracefulSwitchPickFirst, | |||
| BalancerConfig: nil, // pickfirst can handle nil configs. | |||
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Delete the field entirely to remove complications from example?
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Removed throughout.
| @@ -236,7 +233,7 @@ func (b *wrrBalancer) UpdateClientConnState(ccs balancer.ClientConnState) error | |||
| // This causes child to update picker inline and will thus cause inline | |||
| // picker update. | |||
| return b.child.UpdateClientConnState(balancer.ClientConnState{ | |||
| BalancerConfig: endpointShardingLBConfig, | |||
| BalancerConfig: nil, // pickfirst can handle nil configs. | |||
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And then I'd delete it from all our code to avoid clutter. Most LB policies should handle not having configs, except some special xds things.
| // NewBalancer returns a load balancing policy that manages homogeneous child | ||
| // policies each owning a single endpoint. The endpointsharding balancer | ||
| // forwards the LoadBalancingConfig in ClientConn state updates to its children. | ||
| func NewBalancer(cc balancer.ClientConn, opts balancer.BuildOptions, childBuilder balancer.Builder, esOpts Options) balancer.Balancer { |
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I'm wondering about the signature here.
There's a lot of options:
- Keep this & make anyone wanting to use es+lazy wrap lazy in a Builder implementation.
- Keep this & implement a Builder in
lazy, still. - Create
type ChildBuilder interface { Build(..) .. }withoutName()and makelazyimplement that. - Accept a function matching the signature of
Buildhere.
None of these are great. I think I might like (4) the best for usability? But I dislike it for understandability. I suppose that could be helped with:
type ChildBuilder = func(...) ... // matching Build?
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Changed to use a type alias. Didn't export the ChildBuilder type since it's only an alias.
balancer/lazy/lazy.go
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| func (builder) Build(cc balancer.ClientConn, bOpts balancer.BuildOptions) balancer.Balancer { | ||
| // NewBalancer is the constructor for the lazy balancer. | ||
| func NewBalancer(cc balancer.ClientConn, bOpts balancer.BuildOptions, childBuilder balancer.Builder) balancer.Balancer { |
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The same concerns as above apply here, too.
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Changed, using an alias to the type of the balancer.Build method now.
Presently both
lazyandendpointshardingcreategracefulswtichbalancers to manage their children. Thegracefulswitchbalancer is unnecessary as the type of the child balancer in not expected to change in existing use cases. Having thegracefulswitchchild requires the child balancer's builder to be registered in the global LB registry. ThelazyLB is not a complete LB policy and should not be registered globally.This PR makes the constructors of
endpointpointshardingandlazyaccept the child balancer's builder to avoid using the global registry. This PR also removes theParseConfigfunctions/methods inlazyandendpointshardingas they will simply forward theLoadBalancingConfigs to their children. The children are responsible to parse theLoadBalancingConfigJSON. Sincepickfirstcan use anilLoadBalancingConfig, the existing users ofendpointshardingdon't need to provide aLoadBalancingConfig.RELEASE NOTES:
DisableAutoReconnectoption will not attempt to callExitIdleautomatically on their children when the children report idle.