SWR

A non-keyed cache using the SWR (stale-while-revalidate) pattern.

Usage

package main

import (
  "time"

  "github.com/angablue/swr"
)

func main() {
  c, err := swr.New(func() (string, error) {
    return "hello", nil
  }, time.Second*30)
}

Behaviour

Initial Fetch

• The initial fetch is blocking and triggered by the first call to Get().
• All other calls to Get() before the initial fetch returns will also block until the initial fetch returns.
• If the initial fetch errors, all calls to Get() prior to the return will also error.
• The following call to Get() will behave as if it was the first call, performing a blocking fetch.

Subsequent Fetches

• Once a fetch has succeeded, the value will be cached and subsequent calls to Get() will always return the cached value.
• Once the value becomes stale, the cache will keep returning the stale value while fetching a new value in the background.
• If the background refresh errors, the cache will not be updated and the following call to Get() will trigger another background refresh.
• If the background refresh succeeds, the value is cached and all subsequent calls to Get() will yield the fresh value.