go-ethereum/p2p/dnsdisc/sync_test.go
Felix Lange 191364c350 p2p/dnsdisc: add enode.Iterator API (#20437)
* p2p/dnsdisc: add support for enode.Iterator

This changes the dnsdisc.Client API to support the enode.Iterator
interface.

* p2p/dnsdisc: rate-limit DNS requests

* p2p/dnsdisc: preserve linked trees across root updates

This improves the way links are handled when the link root changes.
Previously, sync would simply remove all links from the current tree and
garbage-collect all unreachable trees before syncing the new list of
links.

This behavior isn't great in certain cases: Consider a structure where
trees A, B, and C reference each other and D links to A. If D's link
root changed, the sync code would first remove trees A, B and C, only to
re-sync them later when the link to A was found again.

The fix for this problem is to track the current set of links in each
clientTree and removing old links only AFTER all links are synced.

* p2p/dnsdisc: deflake iterator test

* cmd/devp2p: adapt dnsClient to new p2p/dnsdisc API

* p2p/dnsdisc: tiny comment fix
2019-12-12 11:15:36 +02:00

84 lines
2.0 KiB
Go

// Copyright 2018 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 dnsdisc
import (
"math/rand"
"strconv"
"testing"
)
func TestLinkCache(t *testing.T) {
var lc linkCache
// Check adding links.
lc.addLink("1", "2")
if !lc.changed {
t.Error("changed flag not set")
}
lc.changed = false
lc.addLink("1", "2")
if lc.changed {
t.Error("changed flag set after adding link that's already present")
}
lc.addLink("2", "3")
lc.addLink("3", "1")
lc.addLink("2", "4")
lc.changed = false
if !lc.isReferenced("3") {
t.Error("3 not referenced")
}
if lc.isReferenced("6") {
t.Error("6 is referenced")
}
lc.resetLinks("1", nil)
if !lc.changed {
t.Error("changed flag not set")
}
if len(lc.backrefs) != 0 {
t.Logf("%+v", lc)
t.Error("reference maps should be empty")
}
}
func TestLinkCacheRandom(t *testing.T) {
tags := make([]string, 1000)
for i := range tags {
tags[i] = strconv.Itoa(i)
}
// Create random links.
var lc linkCache
var remove []string
for i := 0; i < 100; i++ {
a, b := tags[rand.Intn(len(tags))], tags[rand.Intn(len(tags))]
lc.addLink(a, b)
remove = append(remove, a)
}
// Remove all the links.
for _, s := range remove {
lc.resetLinks(s, nil)
}
if len(lc.backrefs) != 0 {
t.Logf("%+v", lc)
t.Error("reference maps should be empty")
}
}