Golang Bucket.Take方法代码示例

// NewTokenBucketThrottler returns an endpoint.Middleware that acts as a
// request throttler based on a token-bucket algorithm. Requests that would
// exceed the maximum request rate are delayed via the parameterized sleep
// function. By default you may pass time.Sleep.
func NewTokenBucketThrottler(tb *ratelimit.Bucket, sleep func(time.Duration)) endpoint.Middleware {
	return func(next endpoint.Endpoint) endpoint.Endpoint {
		return func() error {
			sleep(tb.Take(1))
			return next()
		}
	}
}

// NewTokenBucketThrottler returns an endpoint.Middleware that acts as a
// request throttler based on a token-bucket algorithm. Requests that would
// exceed the maximum request rate are delayed via the parameterized sleep
// function. By default you may pass time.Sleep.
func NewTokenBucketThrottler(tb *ratelimit.Bucket, sleep func(time.Duration)) endpoint.Middleware {
	return func(next endpoint.Endpoint) endpoint.Endpoint {
		return func(ctx context.Context, request interface{}) (interface{}, error) {
			sleep(tb.Take(1))
			return next(ctx, request)
		}
	}
}

func limit(b *ratelimit.Bucket, wait bool, errId string) func() error {
	return func() error {
		if wait {
			time.Sleep(b.Take(1))
		} else if b.TakeAvailable(1) == 0 {
			return errors.New(errId, "too many request", 429)
		}
		return nil
	}
}

func makeRateLimitFunc(sessionRateLimit, globalRateLimit *ratelimit.Bucket) func(int64) {
	// This may be a case of super duper premature optimization... We build an
	// optimized function to do the rate limiting here based on what we need
	// to do and then use it in the loop.

	if sessionRateLimit == nil && globalRateLimit == nil {
		// No limiting needed. We could equally well return a func(int64){} and
		// not do a nil check were we use it, but I think the nil check there
		// makes it clear that there will be no limiting if none is
		// configured...
		return nil
	}

	if sessionRateLimit == nil {
		// We only have a global limiter
		return func(bytes int64) {
			globalRateLimit.Wait(bytes)
		}
	}

	if globalRateLimit == nil {
		// We only have a session limiter
		return func(bytes int64) {
			sessionRateLimit.Wait(bytes)
		}
	}

	// We have both. Queue the bytes on both the global and session specific
	// rate limiters. Wait for both in parallell, so that the actual send
	// happens when both conditions are satisfied. In practice this just means
	// wait the longer of the two times.
	return func(bytes int64) {
		t0 := sessionRateLimit.Take(bytes)
		t1 := globalRateLimit.Take(bytes)
		if t0 > t1 {
			time.Sleep(t0)
		} else {
			time.Sleep(t1)
		}
	}
}