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¶
Overview ¶
Package limit provides rate limiting policies.
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ( // ErrRejected signals that the operation was rejected by the Policy. ErrRejected = errors.New("limit: operation rejected") // ErrAbandoned signals that the operation was abandoned after being allowed by the Policy. ErrAbandoned = errors.New("limit: operation abandoned") )
Functions ¶
Types ¶
type MaxConcurrentOption ¶ added in v0.2.0
type MaxConcurrentOption interface {
// contains filtered or unexported methods
}
A MaxConcurrentOption provides optional configuration for a MaxConcurrent Policy.
func WithMaxConcurrentObserver ¶ added in v0.2.0
func WithMaxConcurrentObserver(observer Observer) MaxConcurrentOption
WithMaxConcurrentObserver returns a MaxConcurrentOption that sets an Observer.
type Observer ¶ added in v0.2.0
type Observer interface {
// ObserveAllow is called when an operation is allowed.
ObserveAllow(wait time.Duration)
// ObserveReport is called when the result of an operation is reported.
ObserveReport(latency time.Duration, err error)
// ObserveEnqueue is called when an operation can't currently be allowed
// and is parked until it's allowed or canceled in the future.
ObserveEnqueue()
// ObserveDequeue allow is called when an operation is unparked
// due to being allowed or canceled.
ObserveDequeue()
// ObserveCancel is called when an operation is canceled.
ObserveCancel()
// ObserveReject is called when an operation is rejected.
ObserveReject()
}
An Observer observes operation events.
type Policy ¶
type Policy interface {
// Allow returns a value indicating if an operation is currently allowed.
// If it is allowed, Report must be called with the operation's results.
Allow() bool
// Wait waits until an operation is allowed according to the policy.
// It returns an error if ctx is done or the Policy rejects the operation.
//
// If an error is not returned, Report must be called with the results of
// the operation.
//
// If ctx has a deadline and the policy provides a scheduled operation time
// after the deadline, it may return context.DeadlineExceeded preemptively.
Wait(ctx context.Context) error
// Report must be called with the results of an operation after it is allowed.
// Use ErrAbandoned to signal that the operation was abandoned after being allowed.
Report(latency time.Duration, err error)
}
A Policy is a policy for limiting operations.
func MaxConcurrent ¶
func MaxConcurrent(n int, options ...MaxConcurrentOption) Policy
MaxConcurrent returns a Policy that limits the maximum concurrent operations to n. It provides no fairness guarantees.
func RejectAll ¶ added in v0.3.0
func RejectAll() Policy
RejectAll returns a Policy that rejects everything.
func SerialPolicy ¶
SerialPolicy returns a Policy that serially combines the policies in the given order.
func TokenBucket ¶
func TokenBucket(size int, rate Rate, options ...TokenBucketOption) Policy
TokenBucket returns a token bucket Policy with the given bucket size and refill rate.
type TokenBucketOption ¶ added in v0.2.0
type TokenBucketOption interface {
// contains filtered or unexported methods
}
A TokenBucketOption provides optional configuration for a TokenBucket Policy.
func WithTokenBucketObserver ¶ added in v0.2.0
func WithTokenBucketObserver(observer Observer) TokenBucketOption
WithTokenBucketObserver returns a TokenBucketOption that sets an Observer.
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