UmputunandGitHub
3520de768d
* add siteID to cache Get * indirect option setters * add mongo cache with tests, add Key and Flusher * lint: minor warns * workaround for cache parallel test * repeater in mongo cache * missing repeater vendor * fix nop cache * add cache mongo benchmark * wired mongo cache, single opts group for mongo * disable goconst * stop cache repeated on not found error * use local mongo for tests in travis
Repeater 
Repeater calls a function until it returns no error, up to some number of iterations and delays defined by strategy. It terminates immediately on err from the provided (optional) list of critical errors.
Install and update
go get -u github.com/go-pkgz/repeater
How to use
New Repeater created by New(strtg strategy.Interface) or shortcut for defaults - NewDefault(repeats int, delay time.Duration) *Repeater.
To activate invoke Do method. Do repeats func until no error returned. Predefined (optional) errors terminates the loop immediately.
func (r Repeater) Do(fun func() error, errors ...error) (err error)
Repeating strategy
User can provide his own strategy implementing the interface:
type Interface interface {
Start(ctx context.Context) chan struct{}
}
Returned channels used as "ticks," i.e., for each repeat or initial operation one read from this channel needed. Closing this channel indicates "done with retries." It is pretty much the same idea as time.Timer or time.Tick implements. Note - the first (technically not-repeated-yet) call won't happen until something sent to the channel. For this reason, the typical strategy sends first "tick" before the first wait/sleep.
Three most common strategies provided by package and ready to use:
- Fixed delay, up to max number of attempts -
NewFixedDelay(repeats int, delay time.Duration). It is the default strategy used byrepeater.NewDefaultconstructor - BackOff with jitter provides exponential backoff. It starts from 100ms interval and goes in steps with
last * math.Pow(factor, attempt). Optional jitter randomizes intervals a little bit. The strategy created byNewBackoff(repeats int, factor float64, jitter bool). Factor = 1 effectively makes this strategy fixed with 100ms delay. - Once strategy does not do any repeats and mainly used for tests/mocks -
NewOnce()