mirror of https://github.com/poanetwork/quorum.git
130 lines
3.1 KiB
Go
130 lines
3.1 KiB
Go
// Copyright 2018 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package mclock
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import (
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"sync"
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"time"
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)
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// Simulated implements a virtual Clock for reproducible time-sensitive tests. It
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// simulates a scheduler on a virtual timescale where actual processing takes zero time.
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//
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// The virtual clock doesn't advance on its own, call Run to advance it and execute timers.
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// Since there is no way to influence the Go scheduler, testing timeout behaviour involving
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// goroutines needs special care. A good way to test such timeouts is as follows: First
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// perform the action that is supposed to time out. Ensure that the timer you want to test
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// is created. Then run the clock until after the timeout. Finally observe the effect of
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// the timeout using a channel or semaphore.
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type Simulated struct {
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now AbsTime
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scheduled []event
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mu sync.RWMutex
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cond *sync.Cond
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}
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type event struct {
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do func()
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at AbsTime
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}
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// Run moves the clock by the given duration, executing all timers before that duration.
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func (s *Simulated) Run(d time.Duration) {
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s.mu.Lock()
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defer s.mu.Unlock()
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s.init()
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end := s.now + AbsTime(d)
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for len(s.scheduled) > 0 {
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ev := s.scheduled[0]
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if ev.at > end {
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break
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}
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s.now = ev.at
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ev.do()
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s.scheduled = s.scheduled[1:]
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}
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s.now = end
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}
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func (s *Simulated) ActiveTimers() int {
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s.mu.RLock()
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defer s.mu.RUnlock()
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return len(s.scheduled)
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}
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func (s *Simulated) WaitForTimers(n int) {
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s.mu.Lock()
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defer s.mu.Unlock()
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s.init()
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for len(s.scheduled) < n {
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s.cond.Wait()
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}
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}
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// Now implements Clock.
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func (s *Simulated) Now() AbsTime {
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s.mu.RLock()
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defer s.mu.RUnlock()
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return s.now
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}
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// Sleep implements Clock.
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func (s *Simulated) Sleep(d time.Duration) {
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<-s.After(d)
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}
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// After implements Clock.
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func (s *Simulated) After(d time.Duration) <-chan time.Time {
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after := make(chan time.Time, 1)
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s.insert(d, func() {
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after <- (time.Time{}).Add(time.Duration(s.now))
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})
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return after
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}
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func (s *Simulated) insert(d time.Duration, do func()) {
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s.mu.Lock()
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defer s.mu.Unlock()
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s.init()
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at := s.now + AbsTime(d)
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l, h := 0, len(s.scheduled)
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ll := h
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for l != h {
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m := (l + h) / 2
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if at < s.scheduled[m].at {
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h = m
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} else {
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l = m + 1
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}
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}
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s.scheduled = append(s.scheduled, event{})
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copy(s.scheduled[l+1:], s.scheduled[l:ll])
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s.scheduled[l] = event{do: do, at: at}
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s.cond.Broadcast()
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}
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func (s *Simulated) init() {
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if s.cond == nil {
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s.cond = sync.NewCond(&s.mu)
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}
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}
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