43 lines
1.3 KiB
Go
43 lines
1.3 KiB
Go
package ratelimit
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import (
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"context"
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"errors"
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"time"
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"github.com/juju/ratelimit"
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"github.com/go-kit/kit/endpoint"
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)
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// ErrLimited is returned in the request path when the rate limiter is
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// triggered and the request is rejected.
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var ErrLimited = errors.New("rate limit exceeded")
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// NewTokenBucketLimiter returns an endpoint.Middleware that acts as a rate
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// limiter based on a token-bucket algorithm. Requests that would exceed the
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// maximum request rate are simply rejected with an error.
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func NewTokenBucketLimiter(tb *ratelimit.Bucket) endpoint.Middleware {
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return func(next endpoint.Endpoint) endpoint.Endpoint {
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return func(ctx context.Context, request interface{}) (interface{}, error) {
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if tb.TakeAvailable(1) == 0 {
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return nil, ErrLimited
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}
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return next(ctx, request)
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}
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}
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}
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// NewTokenBucketThrottler returns an endpoint.Middleware that acts as a
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// request throttler based on a token-bucket algorithm. Requests that would
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// exceed the maximum request rate are delayed via the parameterized sleep
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// function. By default you may pass time.Sleep.
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func NewTokenBucketThrottler(tb *ratelimit.Bucket, sleep func(time.Duration)) endpoint.Middleware {
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return func(next endpoint.Endpoint) endpoint.Endpoint {
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return func(ctx context.Context, request interface{}) (interface{}, error) {
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sleep(tb.Take(1))
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return next(ctx, request)
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}
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}
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}
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