rate

Documentation

Overview

Package rate defines Rate and provides basic interfaces for rate limiter driver implementations.

Index

• type BypassLimiter
  • func (b *BypassLimiter) Take(ctx context.Context, tag string, tokens float64) (remaining float64, ok bool, err error)
• type LeakyBucket
  • func NewLeakyBucket(at time.Time, r *Rate, burstLimit float64) *LeakyBucket
  • func (l *LeakyBucket) Refill(at time.Time, r *Rate, burstLimit float64)
  • func (l *LeakyBucket) Remaining() float64
  • func (l *LeakyBucket) Take(tokens float64) (remaining float64, ok bool)
  • func (l *LeakyBucket) Touched() time.Time
• type Limiter
  • func NewBypassLimiter(next Limiter, filter TagFilter) (Limiter, error)
  • func NewListBypassLimiter(next Limiter, skipTags ...string) (Limiter, error)
• type Rate
  • func New(limit float64, interval time.Duration) (*Rate, error)
  • func (r *Rate) Burst() float64
  • func (r *Rate) FasterThan(a *Rate) bool
  • func (r *Rate) Interval() time.Duration
  • func (r *Rate) LogValue() slog.Value
  • func (r *Rate) PerNanosecond() float64
  • func (r *Rate) ReplenishedTokens(from, to time.Time) float64
  • func (r *Rate) SlowerThan(a *Rate) bool
  • func (r *Rate) String() string
  • func (r *Rate) Validate() error
• type TagFilter

Types

type BypassLimiter

type BypassLimiter struct {
	Limiter
	// contains filtered or unexported fields
}

BypassLimiter uses a TagFilter to selectively apply a Limiter.

func (*BypassLimiter) Take

func (b *BypassLimiter) Take(
	ctx context.Context,
	tag string,
	tokens float64,
) (
	remaining float64,
	ok bool,
	err error,
)

Take consumes tokens, if they are available.

type LeakyBucket

type LeakyBucket struct {
	// contains filtered or unexported fields
}

LeakyBucket keeps track of available tokens according to a given Rate.

func NewLeakyBucket

func NewLeakyBucket(at time.Time, r *Rate, burstLimit float64) *LeakyBucket

NewLeakyBucket returns a full LeakyBucket.

func (*LeakyBucket) Refill

func (l *LeakyBucket) Refill(at time.Time, r *Rate, burstLimit float64)

Refill calculates and returns tokens since last update to given time at a Rate. Restored tokens will not exceed the burst limit.

func (*LeakyBucket) Remaining

func (l *LeakyBucket) Remaining() float64

Remaining returns the number of tokens in the bucket. Use only after running LeakyBucket.Refill.

func (*LeakyBucket) Take

func (l *LeakyBucket) Take(tokens float64) (remaining float64, ok bool)

Take removes tokens from the bucket, if that many are available. Use only after running LeakyBucket.Refill.

func (*LeakyBucket) Touched

func (l *LeakyBucket) Touched() time.Time

Touched returns the last time the bucket was updated.

type Limiter

type Limiter interface {
	Rate() *Rate
	Remaining(
		ctx context.Context,
		tag string,
	) (float64, error)
	Take(
		ctx context.Context,
		tag string,
		tokens float64,
	) (
		remaining float64,
		ok bool,
		err error,
	)
}

Limiter contrains the number of consumed tokens to a certain Rate.

func NewBypassLimiter

func NewBypassLimiter(next Limiter, filter TagFilter) (Limiter, error)

NewBypassLimiter attaches a TagFilter to a Limiter.

func NewListBypassLimiter

func NewListBypassLimiter(next Limiter, skipTags ...string) (Limiter, error)

NewListBypassLimiter creates a BypassLimiter that never limits request tags from a given list.

type Rate

type Rate struct {
	// contains filtered or unexported fields
}

Rate represents replenishment of tokens per interval of time. The original interval is preserved in order to calculate default burst.

func New

func New(limit float64, interval time.Duration) (*Rate, error)

New creates a Rate based on expected limit and a given time interval.

func (*Rate) Burst

func (r *Rate) Burst() float64

Burst returns the number of tokens replenished per original interval.

func (*Rate) FasterThan

func (r *Rate) FasterThan(a *Rate) bool

FasterThan returns true if this Rate replenishes more tokens per nanosecond than the other.

func (*Rate) Interval

func (r *Rate) Interval() time.Duration

Interval returns the duration of expected replenishment time.

func (*Rate) LogValue

func (r *Rate) LogValue() slog.Value

LogValue satisfies slog.Valuer in order to provide more information when logging.

func (*Rate) PerNanosecond

func (r *Rate) PerNanosecond() float64

PerNanosecond returns the amount of tokens replenished per nanosecond.

func (*Rate) ReplenishedTokens

func (r *Rate) ReplenishedTokens(from, to time.Time) float64

ReplenishedTokens returns fractional token amount based on time passed.

func (*Rate) SlowerThan

func (r *Rate) SlowerThan(a *Rate) bool

SlowerThan returns true if this Rate replenishes less tokens per nanosecond than the other.

func (*Rate) String

func (r *Rate) String() string

String expresses the Rate in format convenient for humans.

func (*Rate) Validate

func (r *Rate) Validate() error

Validate checks that the Rate is real and reasonable.

type TagFilter

type TagFilter func(tag string) bool

TagFilter directs a BypassLimiter to drop tags that return false.