Documentation
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Overview ¶
Package wait provides tools for polling or listening for changes to a condition.
Index ¶
- Variables
- func ExponentialBackoff(backoff Backoff, condition ConditionFunc) error
- func Forever(f func(), period time.Duration)
- func Jitter(duration time.Duration, maxFactor float64) time.Duration
- func JitterUntil(f func(), period time.Duration, jitterFactor float64, sliding bool, ...)
- func NonSlidingUntil(f func(), period time.Duration, stopCh <-chan struct{})
- func Poll(interval, timeout time.Duration, condition ConditionFunc) error
- func PollImmediate(interval, timeout time.Duration, condition ConditionFunc) error
- func PollImmediateInfinite(interval time.Duration, condition ConditionFunc) error
- func PollInfinite(interval time.Duration, condition ConditionFunc) error
- func PollUntil(interval time.Duration, condition ConditionFunc, stopCh <-chan struct{}) error
- func Until(f func(), period time.Duration, stopCh <-chan struct{})
- func WaitFor(wait WaitFunc, fn ConditionFunc, done <-chan struct{}) error
- type Backoff
- type ConditionFunc
- type WaitFunc
Constants ¶
This section is empty.
Variables ¶
var ErrWaitTimeout = errors.New("timed out waiting for the condition")
ErrWaitTimeout is returned when the condition exited without success
var ForeverTestTimeout = time.Second * 30
For any test of the style:
... <- time.After(timeout): t.Errorf("Timed out")
The value for timeout should effectively be "forever." Obviously we don't want our tests to truly lock up forever, but 30s is long enough that it is effectively forever for the things that can slow down a run on a heavily contended machine (GC, seeks, etc), but not so long as to make a developer ctrl-c a test run if they do happen to break that test.
var NeverStop <-chan struct{} = make(chan struct{})
NeverStop may be passed to Until to make it never stop.
Functions ¶
func ExponentialBackoff ¶ added in v1.2.0
func ExponentialBackoff(backoff Backoff, condition ConditionFunc) error
ExponentialBackoff repeats a condition check up to steps times, increasing the wait by multipling the previous duration by factor. If jitter is greater than zero, a random amount of each duration is added (between duration and duration*(1+jitter)). If the condition never returns true, ErrWaitTimeout is returned. All other errors terminate immediately.
func Jitter ¶
Jitter returns a time.Duration between duration and duration + maxFactor * duration, to allow clients to avoid converging on periodic behavior. If maxFactor is 0.0, a suggested default value will be chosen.
func JitterUntil ¶ added in v1.2.0
func JitterUntil(f func(), period time.Duration, jitterFactor float64, sliding bool, stopCh <-chan struct{})
JitterUntil loops until stop channel is closed, running f every period. If jitterFactor is positive, the period is jittered before every run of f. If jitterFactor is not positive, the period is unchanged. Catches any panics, and keeps going. f may not be invoked if stop channel is already closed. Pass NeverStop to Until if you don't want it stop.
func NonSlidingUntil ¶ added in v1.3.0
NonSlidingUntil loops until stop channel is closed, running f every period. NonSlidingUntil is syntactic sugar on top of JitterUntil with zero jitter factor, with sliding = false (meaning the timer for period starts at the same time as the function starts).
func Poll ¶
func Poll(interval, timeout time.Duration, condition ConditionFunc) error
Poll tries a condition func until it returns true, an error, or the timeout is reached. condition will always be invoked at least once but some intervals may be missed if the condition takes too long or the time window is too short. If you want to Poll something forever, see PollInfinite. Poll always waits the interval before the first check of the condition.
func PollImmediate ¶ added in v1.1.1
func PollImmediate(interval, timeout time.Duration, condition ConditionFunc) error
PollImmediate is identical to Poll, except that it performs the first check immediately, not waiting interval beforehand.
func PollImmediateInfinite ¶ added in v1.5.0
func PollImmediateInfinite(interval time.Duration, condition ConditionFunc) error
PollImmediateInfinite is identical to PollInfinite, except that it performs the first check immediately, not waiting interval beforehand.
func PollInfinite ¶ added in v1.1.0
func PollInfinite(interval time.Duration, condition ConditionFunc) error
PollInfinite polls forever.
func PollUntil ¶ added in v1.4.4
func PollUntil(interval time.Duration, condition ConditionFunc, stopCh <-chan struct{}) error
PollUntil is like Poll, but it takes a stop change instead of total duration
func Until ¶ added in v1.2.0
Until loops until stop channel is closed, running f every period. Until is syntactic sugar on top of JitterUntil with zero jitter factor, with sliding = true (which means the timer for period starts after the f completes).
func WaitFor ¶
func WaitFor(wait WaitFunc, fn ConditionFunc, done <-chan struct{}) error
WaitFor gets a channel from wait(), and then invokes fn once for every value placed on the channel and once more when the channel is closed. If fn returns an error the loop ends and that error is returned, and if fn returns true the loop ends and nil is returned. ErrWaitTimeout will be returned if the channel is closed without fn ever returning true.
Types ¶
type ConditionFunc ¶
ConditionFunc returns true if the condition is satisfied, or an error if the loop should be aborted.