jittered_ticker_test.go

// Copyright (c) 2016-2017, 2020 Tigera, Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package jitter

import (
	"fmt"
	"time"

	. "github.com/onsi/ginkgo"
	. "github.com/onsi/gomega"
	"github.com/sirupsen/logrus"
)

var _ = Describe("Real 20ms + 10ms Ticker", func() {
	var ticker *Ticker
	var startTime time.Time
	BeforeEach(func() {
		startTime = time.Now()
		ticker = NewTicker(20*time.Millisecond,
			10*time.Millisecond)
	})
	AfterEach(func() {
		ticker.Stop()
	})
	It("should never tick before minDelay", func() {
		<-ticker.Channel()
		now := time.Now()
		duration := now.Sub(startTime)
		Expect(duration).To(BeNumerically(">=", 20*time.Millisecond))
	}, 1)
	It("should produce longer and shorter ticks", func() {
		lastTime := startTime
		foundLT5 := false
		foundGT5 := false
		for i := 0; i < 40; i++ {
			<-ticker.Channel()
			now := time.Now()
			duration := time.Since(lastTime)
			logrus.WithField("duration", duration).Debug("Tick")
			if duration < 25*time.Millisecond {
				foundLT5 = true
			} else {
				foundGT5 = true
			}
			if foundLT5 && foundGT5 {
				break
			}
			lastTime = now
		}
		Expect(foundLT5).To(BeTrue())
		Expect(foundGT5).To(BeTrue())
	}, 1)
})

var _ = Describe("Delay calculation", func() {
	var ticker *Ticker
	BeforeEach(func() {
		ticker = NewTicker(20*time.Millisecond, 10*time.Millisecond)
		ticker.Stop()
	})
	for i := 0; i < 10; i++ {
		It(fmt.Sprintf("should tick before max delay, trial: %v", i), func() {
			duration := ticker.calculateDelay()
			Expect(duration).To(BeNumerically("<=", 30*time.Millisecond))
		})
		It(fmt.Sprintf("should never tick before min delay, trial: %v", i), func() {
			duration := ticker.calculateDelay()
			Expect(duration).To(BeNumerically(">=", 20*time.Millisecond))
		})
	}

	It("should produce longer and shorter ticks", func() {
		foundLT5 := false
		foundGT5 := false
		for i := 0; i < 40; i++ {
			duration := ticker.calculateDelay()
			logrus.WithField("duration", duration).Debug("Tick")
			if duration < 25*time.Millisecond {
				foundLT5 = true
			} else {
				foundGT5 = true
			}
			if foundLT5 && foundGT5 {
				break
			}
		}
		Expect(foundLT5).To(BeTrue())
		Expect(foundGT5).To(BeTrue())
	}, 1)
})

var _ = Describe("Ticker constructor", func() {
	It("should panic on negative duration", func() {
		Expect(func() { NewTicker(-1*time.Second, 0) }).To(Panic())
	})
	It("should panic on negative jitter", func() {
		Expect(func() { NewTicker(1*time.Second, -1*time.Second) }).To(Panic())
	})
})