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path: root/core/test/scheduler_test.go
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// Copyright 2018 The dexon-consensus-core Authors
// This file is part of the dexon-consensus-core library.
//
// The dexon-consensus-core library is free software: you can redistribute it
// and/or modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation, either version 3 of the License,
// or (at your option) any later version.
//
// The dexon-consensus-core library is distributed in the hope that it will be
// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
// General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the dexon-consensus-core library. If not, see
// <http://www.gnu.org/licenses/>.

package test

import (
    "sync"
    "testing"
    "time"

    "github.com/dexon-foundation/dexon-consensus-core/common"
    "github.com/dexon-foundation/dexon-consensus-core/core/types"
    "github.com/stretchr/testify/suite"
)

type SchedulerTestSuite struct {
    suite.Suite
}

type simpleStopper struct {
    lock         sync.Mutex
    touched      map[types.ValidatorID]int
    touchedCount int
}

func newSimpleStopper(
    validators []types.ValidatorID, touchedCount int) *simpleStopper {

    touched := make(map[types.ValidatorID]int)
    for _, vID := range validators {
        touched[vID] = 0
    }
    return &simpleStopper{
        touched:      touched,
        touchedCount: touchedCount,
    }
}

func (stopper *simpleStopper) ShouldStop(vID types.ValidatorID) bool {
    stopper.lock.Lock()
    defer stopper.lock.Unlock()

    stopper.touched[vID] = stopper.touched[vID] + 1
    for _, count := range stopper.touched {
        if count < stopper.touchedCount {
            return false
        }
    }
    return true
}

type simpleHandler struct {
    count int
    vID   types.ValidatorID
}

func (handler *simpleHandler) Handle(e *Event) (events []*Event) {
    if e.ValidatorID == handler.vID {
        handler.count++
    }
    return
}

type fixedLatencyHandler struct {
    vID types.ValidatorID
}

func (handler *fixedLatencyHandler) Handle(e *Event) (events []*Event) {
    // Simulate execution time.
    time.Sleep(500 * time.Millisecond)
    return []*Event{&Event{
        ValidatorID: handler.vID,
        Time:        e.Time.Add(800 * time.Millisecond),
    }}
}

func (s *SchedulerTestSuite) TestEventSequence() {
    // This test case makes sure the event sequence is correctly increment
    // by their timestamps in 'Time' field.
    var (
        sch = NewScheduler(nil)
        req = s.Require()
    )

    req.NotNil(sch)
    now := time.Now()
    req.Nil(sch.Seed(&Event{Time: now.Add(100 * time.Second), Payload: 1}))
    req.Nil(sch.Seed(&Event{Time: now.Add(99 * time.Second), Payload: 2}))
    req.Nil(sch.Seed(&Event{Time: now.Add(98 * time.Second), Payload: 3}))
    req.Nil(sch.Seed(&Event{Time: now.Add(97 * time.Second), Payload: 4}))
    req.Nil(sch.Seed(&Event{Time: now.Add(96 * time.Second), Payload: 5}))

    req.Equal(sch.nextTick().Payload.(int), 5)
    req.Equal(sch.nextTick().Payload.(int), 4)
    req.Equal(sch.nextTick().Payload.(int), 3)
    req.Equal(sch.nextTick().Payload.(int), 2)
    req.Equal(sch.nextTick().Payload.(int), 1)
    req.Nil(sch.nextTick())
}

func (s *SchedulerTestSuite) TestBasicRound() {
    // This test case makes sure these facts:
    //  - event is dispatched by validatorID attached to each handler.
    //  - stopper can stop the execution when condition is met.
    var (
        req        = s.Require()
        validators = GenerateRandomValidatorIDs(3)
        stopper    = newSimpleStopper(validators, 2)
        sch        = NewScheduler(stopper)
        handlers   = make(map[types.ValidatorID]*simpleHandler)
    )

    for _, vID := range validators {
        handler := &simpleHandler{vID: vID}
        handlers[vID] = handler
        sch.RegisterEventHandler(vID, handler)
        req.Nil(sch.Seed(&Event{ValidatorID: vID}))
        req.Nil(sch.Seed(&Event{ValidatorID: vID}))
    }
    sch.Run(10)
    // Verify result.
    for _, h := range handlers {
        req.Equal(h.count, 2)
    }
}

func (s *SchedulerTestSuite) TestChildEvent() {
    // This test case makes sure these fields of child events are
    // assigned correctly.
    var (
        req     = s.Require()
        vID     = types.ValidatorID{Hash: common.NewRandomHash()}
        stopper = newSimpleStopper(types.ValidatorIDs{vID}, 3)
        handler = &fixedLatencyHandler{vID: vID}
        sch     = NewScheduler(stopper)
    )

    sch.RegisterEventHandler(vID, handler)
    req.Nil(sch.Seed(&Event{
        ValidatorID: vID,
        Time:        time.Now().UTC(),
    }))
    sch.Run(1)
    // Verify result.
    history := sch.CloneExecutionHistory()
    req.Len(history, 3)
    curEvent := history[0]
    for _, e := range history[1:] {
        // Make sure the time difference between events are more than
        // 1.3 second.
        req.True(e.Time.Sub(curEvent.Time) >= 1300*time.Millisecond)
        // Make sure ParentTime field is set and is equal to parent event's
        // time.
        req.NotEqual(-1, e.ParentHistoryIndex)
        req.Equal(e.ParentHistoryIndex, curEvent.HistoryIndex)
        curEvent = e
    }
}

func TestScheduler(t *testing.T) {
    suite.Run(t, new(SchedulerTestSuite))
}