fix: update lego.

vendor/go.uber.org/ratelimit/ratelimit.go

@@ -0,0 +1,140 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package ratelimit // import "go.uber.org/ratelimit"
+
+import (
+	"sync"
+	"time"
+
+	"go.uber.org/ratelimit/internal/clock"
+)
+
+// Note: This file is inspired by:
+// https://github.com/prashantv/go-bench/blob/master/ratelimit
+
+// Limiter is used to rate-limit some process, possibly across goroutines.
+// The process is expected to call Take() before every iteration, which
+// may block to throttle the goroutine.
+type Limiter interface {
+	// Take should block to make sure that the RPS is met.
+	Take() time.Time
+}
+
+// Clock is the minimum necessary interface to instantiate a rate limiter with
+// a clock or mock clock, compatible with clocks created using
+// github.com/andres-erbsen/clock.
+type Clock interface {
+	Now() time.Time
+	Sleep(time.Duration)
+}
+
+type limiter struct {
+	sync.Mutex
+	last       time.Time
+	sleepFor   time.Duration
+	perRequest time.Duration
+	maxSlack   time.Duration
+	clock      Clock
+}
+
+// Option configures a Limiter.
+type Option func(l *limiter)
+
+// New returns a Limiter that will limit to the given RPS.
+func New(rate int, opts ...Option) Limiter {
+	l := &limiter{
+		perRequest: time.Second / time.Duration(rate),
+		maxSlack:   -10 * time.Second / time.Duration(rate),
+	}
+	for _, opt := range opts {
+		opt(l)
+	}
+	if l.clock == nil {
+		l.clock = clock.New()
+	}
+	return l
+}
+
+// WithClock returns an option for ratelimit.New that provides an alternate
+// Clock implementation, typically a mock Clock for testing.
+func WithClock(clock Clock) Option {
+	return func(l *limiter) {
+		l.clock = clock
+	}
+}
+
+// WithoutSlack is an option for ratelimit.New that initializes the limiter
+// without any initial tolerance for bursts of traffic.
+var WithoutSlack Option = withoutSlackOption
+
+func withoutSlackOption(l *limiter) {
+	l.maxSlack = 0
+}
+
+// Take blocks to ensure that the time spent between multiple
+// Take calls is on average time.Second/rate.
+func (t *limiter) Take() time.Time {
+	t.Lock()
+	defer t.Unlock()
+
+	now := t.clock.Now()
+
+	// If this is our first request, then we allow it.
+	if t.last.IsZero() {
+		t.last = now
+		return t.last
+	}
+
+	// sleepFor calculates how much time we should sleep based on
+	// the perRequest budget and how long the last request took.
+	// Since the request may take longer than the budget, this number
+	// can get negative, and is summed across requests.
+	t.sleepFor += t.perRequest - now.Sub(t.last)
+
+	// We shouldn't allow sleepFor to get too negative, since it would mean that
+	// a service that slowed down a lot for a short period of time would get
+	// a much higher RPS following that.
+	if t.sleepFor < t.maxSlack {
+		t.sleepFor = t.maxSlack
+	}
+
+	// If sleepFor is positive, then we should sleep now.
+	if t.sleepFor > 0 {
+		t.clock.Sleep(t.sleepFor)
+		t.last = now.Add(t.sleepFor)
+		t.sleepFor = 0
+	} else {
+		t.last = now
+	}
+
+	return t.last
+}
+
+type unlimited struct{}
+
+// NewUnlimited returns a RateLimiter that is not limited.
+func NewUnlimited() Limiter {
+	return unlimited{}
+}
+
+func (unlimited) Take() time.Time {
+	return time.Now()
+}