Adaptive sampling strategies not updated in certain situations

[black-adder]

Under certain conditions, the collector might not return adaptive sampling strategies for certain operations which in turn means the operation will continue to use the existing sampling strategy and not be updated.

https://github.com/uber/jaeger-client-go/blob/master/sampler.go#L361 doesn't update existing strategies that are not apart of the passed in strategies.

Issue exists in all clients

• Go Update default rate jaeger-client-go#413
• Java
• Node
• Python
• C#
• C++

[yurishkuro]

The expected outcome is that if the server did not return a strategy for operation X, the operation should fall back to the default sampler, even if it had its own strategy assigned previously.

Related issue: #1729

[yurishkuro]

Per #3362, we're sunsetting Jaeger clients.