Extract tower-load from tower-balance #285
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The tower-balance crate includes the `Load` and `Instrument` traits, which are likely useful outside of balancers; and certainly have no tight coulping with any specific balancer implementation. This change extracts these protocol-agnostic traits into a dedicated crate. The `Load` trait includes a latency-aware _PeakEWMA_ load strategy as well as a simple _PendingRequests_ strategy for latency-agnostic applications. The `Instrument` trait is used by both of these strategies to track in-flight requests without knowing protocol details. It is expected that protocol-specific crates will provide, for instance, HTTP time-to-first-byte latency strategies. A default `NoInstrument` implementation tracks the a request until its response future is satisfied. This crate should only be published once tower-balance is published.
carllerche
approved these changes
May 29, 2019
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The tower-balance crate includes the
LoadandInstrumenttraits,which are likely useful outside of balancers; and certainly have no
tight coulping with any specific balancer implementation. This change
extracts these protocol-agnostic traits into a dedicated crate.
The
Loadtrait includes a latency-aware PeakEWMA load strategy aswell as a simple PendingRequests strategy for latency-agnostic
applications.
The
Instrumenttrait is used by both of these strategies to trackin-flight requests without knowing protocol details. It is expected that
protocol-specific crates will provide, for instance, HTTP
time-to-first-byte latency strategies.
A default
NoInstrumentimplementation tracks the a request until itsresponse future is satisfied.
This crate should only be published once tower-balance is published.