path: root/p2p/discv5/topic_test.go

// 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 discv5

import (
    "encoding/binary"
    "testing"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/common/mclock"
)

func TestTopicRadius(t *testing.T) {
    now := mclock.Now()
    topic := Topic("qwerty")
    rad := newTopicRadius(topic)
    targetRad := (^uint64(0)) / 100

    waitFn := func(addr common.Hash) time.Duration {
        prefix := binary.BigEndian.Uint64(addr[0:8])
        dist := prefix ^ rad.topicHashPrefix
        relDist := float64(dist) / float64(targetRad)
        relTime := (1 - relDist/2) * 2
        if relTime < 0 {
            relTime = 0
        }
        return time.Duration(float64(targetWaitTime) * relTime)
    }

    bcnt := 0
    cnt := 0
    var sum float64
    for cnt < 100 {
        addr := rad.nextTarget(false).target
        wait := waitFn(addr)
        ticket := &ticket{
            topics:  []Topic{topic},
            regTime: []mclock.AbsTime{mclock.AbsTime(wait)},
            node:    &Node{nodeNetGuts: nodeNetGuts{sha: addr}},
        }
        rad.adjustWithTicket(now, addr, ticketRef{ticket, 0})
        if rad.radius != maxRadius {
            cnt++
            sum += float64(rad.radius)
        } else {
            bcnt++
            if bcnt > 500 {
                t.Errorf("Radius did not converge in 500 iterations")
            }
        }
    }
    avgRel := sum / float64(cnt) / float64(targetRad)
    if avgRel > 1.05 || avgRel < 0.95 {
        t.Errorf("Average/target ratio is too far from 1 (%v)", avgRel)
    }
}