redis_rate

README

Rate limiting for go-redis

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This package is based on rwz/redis-gcra and implements GCRA (aka leaky bucket) for rate limiting based on Redis. The code requires Redis version 3.2 or newer since it relies on replicate_commands feature.

Installation

redis_rate supports 2 last Go versions and requires a Go version with modules support. So make sure to initialize a Go module:

go mod init github.com/my/repo

And then install redis_rate/v9 (note v9 in the import; omitting it is a popular mistake):

go get github.com/go-redis/redis_rate/v9

Example

package redis_rate_test

import (
	"context"
	"fmt"

	"github.com/go-redis/redis/v8"
	"github.com/go-redis/redis_rate/v9"
)

func ExampleNewLimiter() {
	ctx := context.Background()
	rdb := redis.NewClient(&redis.Options{
		Addr: "localhost:6379",
	})
	_ = rdb.FlushDB(ctx).Err()

	limiter := redis_rate.NewLimiter(rdb)
	res, err := limiter.Allow(ctx, "project:123", redis_rate.PerSecond(10))
	if err != nil {
		panic(err)
	}
	fmt.Println("allowed", res.Allowed, "remaining", res.Remaining)
	// Output: allowed 1 remaining 9
}

Documentation

Index

• type Limit
  • func PerHour(rate int) Limit
  • func PerMinute(rate int) Limit
  • func PerSecond(rate int) Limit
  • func (l Limit) IsZero() bool
  • func (l Limit) String() string
• type Limiter
  • func NewLimiter(rdb rediser) *Limiter
  • func (l Limiter) Allow(ctx context.Context, key string, limit Limit) (*Result, error)
  • func (l Limiter) AllowAtMost(ctx context.Context, key string, limit Limit, n int) (*Result, error)
  • func (l Limiter) AllowN(ctx context.Context, key string, limit Limit, n int) (*Result, error)
  • func (l *Limiter) Reset(ctx context.Context, key string) error
• type Result

Examples

• NewLimiter

Types

type Limit

type Limit struct {
	Rate   int
	Burst  int
	Period time.Duration
}

func PerHour

func PerHour(rate int) Limit

func PerMinute

func PerMinute(rate int) Limit

func PerSecond

func PerSecond(rate int) Limit

func (Limit) IsZero

func (l Limit) IsZero() bool

func (Limit) String

func (l Limit) String() string

type Limiter

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

Limiter controls how frequently events are allowed to happen.

func NewLimiter

func NewLimiter(rdb rediser) *Limiter

NewLimiter returns a new Limiter.

Example

ctx := context.Background()
rdb := redis.NewClient(&redis.Options{
	Addr: "localhost:6379",
})
_ = rdb.FlushDB(ctx).Err()

limiter := redis_rate.NewLimiter(rdb)
res, err := limiter.Allow(ctx, "project:123", redis_rate.PerSecond(10))
if err != nil {
	panic(err)
}
fmt.Println("allowed", res.Allowed, "remaining", res.Remaining)

Output:

allowed 1 remaining 9

func (Limiter) Allow

func (l Limiter) Allow(ctx context.Context, key string, limit Limit) (*Result, error)

Allow is a shortcut for AllowN(ctx, key, limit, 1).

func (Limiter) AllowAtMost

func (l Limiter) AllowAtMost(
	ctx context.Context,
	key string,
	limit Limit,
	n int,
) (*Result, error)

AllowAtMost reports whether at most n events may happen at time now. It returns number of allowed events that is less than or equal to n.

func (Limiter) AllowN

func (l Limiter) AllowN(
	ctx context.Context,
	key string,
	limit Limit,
	n int,
) (*Result, error)

AllowN reports whether n events may happen at time now.

func (*Limiter) Reset

func (l *Limiter) Reset(ctx context.Context, key string) error

Reset gets a key and reset all limitations and previous usages

type Result

type Result struct {
	// Limit is the limit that was used to obtain this result.
	Limit Limit

	// Allowed is the number of events that may happen at time now.
	Allowed int

	// Remaining is the maximum number of requests that could be
	// permitted instantaneously for this key given the current
	// state. For example, if a rate limiter allows 10 requests per
	// second and has already received 6 requests for this key this
	// second, Remaining would be 4.
	Remaining int

	// RetryAfter is the time until the next request will be permitted.
	// It should be -1 unless the rate limit has been exceeded.
	RetryAfter time.Duration

	// ResetAfter is the time until the RateLimiter returns to its
	// initial state for a given key. For example, if a rate limiter
	// manages requests per second and received one request 200ms ago,
	// Reset would return 800ms. You can also think of this as the time
	// until Limit and Remaining will be equal.
	ResetAfter time.Duration
}