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caffeine cache for loadbalancer Fix gh 638 (#643)

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* Add Caffeine-based loadBalancerCacheManager.

* Add more tests.

* Fix test.

* Only enable loadBalancer caching if caffeine is on classpath. Warn if
caffeine is not on classpath.

* Add javadocs.

* Add docs. Change property name.

* Fix configuration.

* Fix after code review. Add another constructor to CaffeineBasedLoadBalancerCacheManager,
allowing to pass cache name, in order to support alternative ServiceInstanceListSupplierImplementations.
This commit is contained in:
Olga Maciaszek-Sharma
2019-11-22 15:53:57 +01:00
committed by GitHub
parent d4cc825aa0
commit bf6b31ee8a
8 changed files with 334 additions and 57 deletions
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29
docs/src/main/asciidoc/spring-cloud-commons.adoc
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@@ -801,6 +801,28 @@ in the following sections:
* <<webclinet-loadbalancer-client, Spring WebClient as a Load Balancer Client>>
* <<webflux-with-reactive-loadbalancer,Spring WebFlux WebClient with `ReactorLoadBalancerExchangeFilterFunction`>>
=== Spring Cloud LoadBalancer Caching
Apart from the basic `ServiceInstanceListSupplier` implementation that retrieves instances
via `DiscoveryClient` each time it has to choose an instance, we provide a https://github.com/ben-manes/caffeine[Caffeine-backed]
implementation.
To make use of it, you need to have `com.github.ben-manes.caffeine:caffeine` in the classpath.
The default setup includes `expireAfterWrite` set to 30 seconds and records set to soft references.
You can set your own `TTL` value (the time after write after which entries should be expired), expressed as `Duration`, by passing a `String` compliant with the https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/time/Duration.html#parse(java.lang.CharSequence)[`Duration` API]
as the value of `spring.cloud.loadbalancer.cache.ttl` property.
You can also override the default Caffeine Cache setup for the LoadBalancer by passing your own https://static.javadoc.io/com.github.ben-manes.caffeine/caffeine/2.2.2/com/github/benmanes/caffeine/cache/CaffeineSpec.html[Caffeine Specification]
in the `spring.cloud.loadbalancer.cache.caffeine.spec` property.
WARN: Passing your own Caffeine specification will override any other LoadBalancerCache settings, including `TTL`.
You can also altogether disable loadBalancer caching by setting the value of `spring.cloud.loadbalancer.cache.enabled`
to `false`.
WARNING: Although the basic, non-cached, implementation is useful for prototyping and testing, it's much less efficient
than the cached versions, so we recommend always using the cached version in production.
[[spring-cloud-loadbalancer-starter]]
=== Spring Cloud LoadBalancer starter
@@ -808,11 +830,8 @@ We also provide a starter that allows you to easily add Spring Cloud LoadBalance
In order to use it, just add `org.springframework.cloud:spring-cloud-starter-loadbalancer` to your Spring
Cloud dependencies in your build file.
WARNING: In order to make use of the more efficient cached version of `ServiceInstanceListSupplier`,
`spring-cloud-starter-loadbalancer` will *enable caching* by default.
https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-caching.html[Spring Boot Caching]
mechanism will be used under the hood. If you don't want caching to be used, you can set
the value of `spring.cache.type` to `none`.
NOTE: Spring Cloud LoadBalancer starter includes
https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-caching.html[Spring Boot Caching].
WARNING: If you have both Ribbon and Spring Cloud LoadBalancer int the classpath, in order to maintain
backward compatibility, Ribbon-based implementations will be used by default. In order