ThomasandGitHub
aa559bf496
Go is not cgroup aware and by default will set GOMAXPROCS to the number of available threads, regardless of whether it is within the allocated quota. This behaviour causes high amount of CPU throttling and degraded application performance.
118 lines
2.8 KiB
Go
118 lines
2.8 KiB
Go
// Copyright (C) 2016 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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package main
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import (
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"context"
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"crypto/rand"
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"encoding/binary"
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"flag"
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"log"
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"strings"
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"time"
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"github.com/syncthing/syncthing/lib/beacon"
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"github.com/syncthing/syncthing/lib/discover"
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"github.com/syncthing/syncthing/lib/protocol"
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_ "go.uber.org/automaxprocs"
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)
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var (
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all = false // print all packets, not just first from each device/source
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fake = false // send fake packets to lure out other devices faster
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mc = "[ff12::8384]:21027"
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bc = 21027
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)
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var (
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// Static prefix that we use when generating fake device IDs, so that we
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// can recognize them ourselves. Also makes the device ID start with
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// "STPROBE-" which is humanly recognizable.
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randomPrefix = []byte{148, 223, 23, 4, 148}
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// Our random, fake, device ID that we use when sending announcements.
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myID = randomDeviceID()
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)
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func main() {
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flag.BoolVar(&all, "all", all, "Print all received announcements (not only first)")
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flag.BoolVar(&fake, "fake", fake, "Send fake announcements")
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flag.StringVar(&mc, "mc", mc, "IPv6 multicast address")
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flag.IntVar(&bc, "bc", bc, "IPv4 broadcast port number")
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flag.Parse()
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if fake {
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log.Println("My ID:", myID)
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}
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ctx := context.Background()
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runbeacon(ctx, beacon.NewMulticast(mc), fake)
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runbeacon(ctx, beacon.NewBroadcast(bc), fake)
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select {}
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}
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func runbeacon(ctx context.Context, bc beacon.Interface, fake bool) {
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go bc.Serve(ctx)
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go recv(bc)
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if fake {
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go send(bc)
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}
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}
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// receives and prints discovery announcements
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func recv(bc beacon.Interface) {
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seen := make(map[string]bool)
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for {
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data, src := bc.Recv()
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if m := binary.BigEndian.Uint32(data); m != discover.Magic {
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log.Printf("Incorrect magic %x in announcement from %v", m, src)
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continue
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}
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var ann discover.Announce
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ann.Unmarshal(data[4:])
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if ann.ID == myID {
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// This is one of our own fake packets, don't print it.
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continue
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}
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// Print announcement details for the first packet from a given
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// device ID and source address, or if -all was given.
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key := ann.ID.String() + src.String()
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if all || !seen[key] {
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log.Printf("Announcement from %v\n", src)
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log.Printf(" %v at %s\n", ann.ID, strings.Join(ann.Addresses, ", "))
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seen[key] = true
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}
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}
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}
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// sends fake discovery announcements once every second
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func send(bc beacon.Interface) {
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ann := discover.Announce{
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ID: myID,
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Addresses: []string{"tcp://fake.example.com:12345"},
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}
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bs, _ := ann.Marshal()
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for {
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bc.Send(bs)
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time.Sleep(time.Second)
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}
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}
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// returns a random but recognizable device ID
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func randomDeviceID() protocol.DeviceID {
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var id protocol.DeviceID
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copy(id[:], randomPrefix)
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rand.Read(id[len(randomPrefix):])
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return id
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}
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