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b2ddb1fcbf
This PR implements les.freeClientPool. It also adds a simulated clock in common/mclock, which enables time-sensitive tests to run quickly and still produce accurate results, and package common/prque which is a generalised variant of prque that enables removing elements other than the top one from the queue. les.freeClientPool implements a client database that limits the connection time of each client and manages accepting/rejecting incoming connections and even kicking out some connected clients. The pool calculates recent usage time for each known client (a value that increases linearly when the client is connected and decreases exponentially when not connected). Clients with lower recent usage are preferred, unknown nodes have the highest priority. Already connected nodes receive a small bias in their favor in order to avoid accepting and instantly kicking out clients. Note: the pool can use any string for client identification. Using signature keys for that purpose would not make sense when being known has a negative value for the client. Currently the LES protocol manager uses IP addresses (without port address) to identify clients.
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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