• Felföldi Zsolt's avatar
    les: implement client connection logic (#16899) · b2ddb1fc
    Felföldi Zsolt authored
    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.
    b2ddb1fc
mclock.go 1.73 KB
// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// Package mclock is a wrapper for a monotonic clock source
package mclock

import (
	"time"

	"github.com/aristanetworks/goarista/monotime"
)

// AbsTime represents absolute monotonic time.
type AbsTime time.Duration

// Now returns the current absolute monotonic time.
func Now() AbsTime {
	return AbsTime(monotime.Now())
}

// Add returns t + d.
func (t AbsTime) Add(d time.Duration) AbsTime {
	return t + AbsTime(d)
}

// Clock interface makes it possible to replace the monotonic system clock with
// a simulated clock.
type Clock interface {
	Now() AbsTime
	Sleep(time.Duration)
	After(time.Duration) <-chan time.Time
}

// System implements Clock using the system clock.
type System struct{}

// Now implements Clock.
func (System) Now() AbsTime {
	return AbsTime(monotime.Now())
}

// Sleep implements Clock.
func (System) Sleep(d time.Duration) {
	time.Sleep(d)
}

// After implements Clock.
func (System) After(d time.Duration) <-chan time.Time {
	return time.After(d)
}