rate

Documentation

Overview

Package rate contains rate limiting strategies for asynq.Handler(s).

Index

• type Semaphore
  • func NewSemaphore(rco asynq.RedisConnOpt, scope string, maxTokens int) *Semaphore
  • func (s *Semaphore) Acquire(ctx context.Context) (bool, error)
  • func (s *Semaphore) Close() error
  • func (s *Semaphore) Release(ctx context.Context) error

Types

type Semaphore

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

Semaphore is a distributed counting semaphore which can be used to set maxTokens across multiple asynq servers.

func NewSemaphore

func NewSemaphore(rco asynq.RedisConnOpt, scope string, maxTokens int) *Semaphore

NewSemaphore creates a counting Semaphore for the given scope with the given number of tokens.

func (*Semaphore) Acquire

func (s *Semaphore) Acquire(ctx context.Context) (bool, error)

Acquire attempts to acquire a token from the semaphore. - Returns (true, nil), iff semaphore key exists and current value is less than maxTokens - Returns (false, nil) when token cannot be acquired - Returns (false, error) otherwise

The context.Context passed to Acquire must have a deadline set, this ensures that token is released if the job goroutine crashes and does not call Release.

func (*Semaphore) Close

func (s *Semaphore) Close() error

Close closes the connection to redis.

func (*Semaphore) Release

func (s *Semaphore) Release(ctx context.Context) error

Release will release the token on the counting semaphore.