Documentation
¶
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 PollImmediateUntil(interval time.Duration, condition ConditionFunc, stopCh <-chan struct{}) 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 Group
- 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 ¶
func ExponentialBackoff(backoff Backoff, condition ConditionFunc) error
ExponentialBackoff repeats a condition check with exponential backoff.
It checks the condition up to Steps times, increasing the wait by multiplying 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.
This allows clients to avoid converging on periodic behavior. If maxFactor is 0.0, a suggested default value will be chosen.
func JitterUntil ¶
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 and not jittered.
If sliding is true, the period is computed after f runs. If it is false then period includes the runtime for f.
Close stopCh to stop. f may not be invoked if stop channel is already closed. Pass NeverStop to if you don't want it stop.
func NonSlidingUntil ¶
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.
Poll always waits the interval before the run of 'condition'. 'condition' will always be invoked at least once.
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.
func PollImmediate ¶
func PollImmediate(interval, timeout time.Duration, condition ConditionFunc) error
PollImmediate tries a condition func until it returns true, an error, or the timeout is reached.
Poll always checks 'condition' before waiting for the interval. 'condition' will always be invoked at least once.
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.
func PollImmediateInfinite ¶
func PollImmediateInfinite(interval time.Duration, condition ConditionFunc) error
PollImmediateInfinite tries a condition func until it returns true or an error
PollImmediateInfinite runs the 'condition' before waiting for the interval.
Some intervals may be missed if the condition takes too long or the time window is too short.
func PollImmediateUntil ¶ added in v1.11.7
func PollImmediateUntil(interval time.Duration, condition ConditionFunc, stopCh <-chan struct{}) error
PollImmediateUntil tries a condition func until it returns true, an error or stopCh is closed.
PollImmediateUntil runs the 'condition' before waiting for the interval. 'condition' will always be invoked at least once.
func PollInfinite ¶
func PollInfinite(interval time.Duration, condition ConditionFunc) error
PollInfinite tries a condition func until it returns true or an error
PollInfinite always waits the interval before the run of 'condition'.
Some intervals may be missed if the condition takes too long or the time window is too short.
func PollUntil ¶
func PollUntil(interval time.Duration, condition ConditionFunc, stopCh <-chan struct{}) error
PollUntil tries a condition func until it returns true, an error or stopCh is closed.
PollUntil always waits interval before the first run of 'condition'. 'condition' will always be invoked at least once.
func Until ¶
Until loops until stop channel is closed, running f every period.
Until is syntactic sugar on top of JitterUntil with zero jitter factor and 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 continually checks 'fn' as driven by 'wait'.
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 Backoff ¶
type Backoff struct { Duration time.Duration // the base duration Factor float64 // Duration is multiplied by factor each iteration Jitter float64 // The amount of jitter applied each iteration Steps int // Exit with error after this many steps }
Backoff holds parameters applied to a Backoff function.
type ConditionFunc ¶
ConditionFunc returns true if the condition is satisfied, or an error if the loop should be aborted.
type Group ¶ added in v1.8.0
type Group struct {
// contains filtered or unexported fields
}
Group allows to start a group of goroutines and wait for their completion.
func (*Group) Start ¶ added in v1.8.0
func (g *Group) Start(f func())
Start starts f in a new goroutine in the group.
func (*Group) StartWithChannel ¶ added in v1.8.0
func (g *Group) StartWithChannel(stopCh <-chan struct{}, f func(stopCh <-chan struct{}))
StartWithChannel starts f in a new goroutine in the group. stopCh is passed to f as an argument. f should stop when stopCh is available.
func (*Group) StartWithContext ¶ added in v1.8.0
StartWithContext starts f in a new goroutine in the group. ctx is passed to f as an argument. f should stop when ctx.Done() is available.