Golang context.WithCancel函数代码示例

func WithDeadlineFraction(ctx context.Context, fraction float64) (context.Context, context.CancelFunc) {
	d, found := ctx.Deadline()
	if !found { // no deadline
		return context.WithCancel(ctx)
	}

	left := d.Sub(time.Now())
	if left < 0 { // already passed...
		return context.WithCancel(ctx)
	}

	left = time.Duration(float64(left) * fraction)
	return context.WithTimeout(ctx, left)
}

// InitializeKeyspace sets the ipns record for the given key to
// point to an empty directory.
func InitializeKeyspace(n *core.IpfsNode, key ci.PrivKey) error {
	emptyDir := &mdag.Node{Data: ft.FolderPBData()}
	nodek, err := n.DAG.Add(emptyDir)
	if err != nil {
		return err
	}

	ctx, cancel := context.WithCancel(n.Context())
	defer cancel()

	err = n.Pinning.Pin(ctx, emptyDir, false)
	if err != nil {
		return err
	}

	err = n.Pinning.Flush()
	if err != nil {
		return err
	}

	pub := nsys.NewRoutingPublisher(n.Routing, n.Repo.Datastore())
	if err := pub.Publish(ctx, key, path.FromKey(nodek)); err != nil {
		return err
	}

	return nil
}

func (i *cmdInvocation) SetupInterruptHandler(ctx context.Context) (io.Closer, context.Context) {

	intrh := NewIntrHandler()
	ctx, cancelFunc := context.WithCancel(ctx)

	handlerFunc := func(count int, ih *IntrHandler) {
		switch count {
		case 1:
			fmt.Println() // Prevent un-terminated ^C character in terminal

			ih.wg.Add(1)
			go func() {
				defer ih.wg.Done()
				cancelFunc()
			}()

		default:
			fmt.Println("Received another interrupt before graceful shutdown, terminating...")
			os.Exit(-1)
		}
	}

	intrh.Handle(handlerFunc, syscall.SIGHUP, syscall.SIGINT, syscall.SIGTERM)

	return intrh, ctx
}

func (rp *Republisher) republishEntries(p goprocess.Process) error {
	ctx, cancel := context.WithCancel(gpctx.OnClosingContext(p))
	defer cancel()

	for id, _ := range rp.entries {
		log.Debugf("republishing ipns entry for %s", id)
		priv := rp.ps.PrivKey(id)

		// Look for it locally only
		_, ipnskey := namesys.IpnsKeysForID(id)
		p, seq, err := rp.getLastVal(ipnskey)
		if err != nil {
			if err == errNoEntry {
				continue
			}
			return err
		}

		// update record with same sequence number
		eol := time.Now().Add(rp.RecordLifetime)
		err = namesys.PutRecordToRouting(ctx, priv, p, seq, eol, rp.r, id)
		if err != nil {
			return err
		}
	}

	return nil
}

func TestBasic(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	ds, rt := setupRoot(ctx, t)

	rootdir := rt.GetValue().(*Directory)

	// test making a basic dir
	_, err := rootdir.Mkdir("a")
	if err != nil {
		t.Fatal(err)
	}

	path := "a/b/c/d/e/f/g"
	d := mkdirP(t, rootdir, path)

	fi := getRandFile(t, ds, 1000)

	// test inserting that file
	err = d.AddChild("afile", fi)
	if err != nil {
		t.Fatal(err)
	}

	err = assertFileAtPath(ds, rootdir, fi, "a/b/c/d/e/f/g/afile")
	if err != nil {
		t.Fatal(err)
	}
}

func Unpin(n *core.IpfsNode, ctx context.Context, paths []string, recursive bool) ([]key.Key, error) {

	var unpinned []key.Key
	for _, p := range paths {
		p, err := path.ParsePath(p)
		if err != nil {
			return nil, err
		}

		k, err := core.ResolveToKey(ctx, n, p)
		if err != nil {
			return nil, err
		}

		ctx, cancel := context.WithCancel(ctx)
		defer cancel()
		err = n.Pinning.Unpin(ctx, k, recursive)
		if err != nil {
			return nil, err
		}
		unpinned = append(unpinned, k)
	}

	err := n.Pinning.Flush()
	if err != nil {
		return nil, err
	}
	return unpinned, nil
}

func (bs *Bitswap) connectToProviders(ctx context.Context, entries []wantlist.Entry) {

	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	// Get providers for all entries in wantlist (could take a while)
	wg := sync.WaitGroup{}
	for _, e := range entries {
		wg.Add(1)
		go func(k key.Key) {
			defer wg.Done()

			child, cancel := context.WithTimeout(ctx, providerRequestTimeout)
			defer cancel()
			providers := bs.network.FindProvidersAsync(child, k, maxProvidersPerRequest)
			for prov := range providers {
				go func(p peer.ID) {
					bs.network.ConnectTo(ctx, p)
				}(prov)
			}
		}(e.Key)
	}

	wg.Wait() // make sure all our children do finish.
}

func (dm *DagModifier) readPrep() error {
	err := dm.Sync()
	if err != nil {
		return err
	}

	if dm.read == nil {
		ctx, cancel := context.WithCancel(dm.ctx)
		dr, err := uio.NewDagReader(ctx, dm.curNode, dm.dagserv)
		if err != nil {
			return err
		}

		i, err := dr.Seek(int64(dm.curWrOff), os.SEEK_SET)
		if err != nil {
			return err
		}

		if i != int64(dm.curWrOff) {
			return ErrSeekFail
		}

		dm.readCancel = cancel
		dm.read = dr
	}

	return nil
}

func Unpin(n *core.IpfsNode, ctx context.Context, paths []string, recursive bool) ([]key.Key, error) {

	dagnodes := make([]*merkledag.Node, 0)
	for _, fpath := range paths {
		dagnode, err := core.Resolve(ctx, n, path.Path(fpath))
		if err != nil {
			return nil, err
		}
		dagnodes = append(dagnodes, dagnode)
	}

	var unpinned []key.Key
	for _, dagnode := range dagnodes {
		k, _ := dagnode.Key()

		ctx, cancel := context.WithCancel(ctx)
		defer cancel()
		err := n.Pinning.Unpin(ctx, k, recursive)
		if err != nil {
			return nil, err
		}
		unpinned = append(unpinned, k)
	}

	err := n.Pinning.Flush()
	if err != nil {
		return nil, err
	}
	return unpinned, nil
}

func RunSupernodePutRecordGetRecord(conf testutil.LatencyConfig) error {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	servers, clients, err := InitializeSupernodeNetwork(ctx, 2, 2, conf)
	if err != nil {
		return err
	}
	for _, n := range append(servers, clients...) {
		defer n.Close()
	}

	putter := clients[0]
	getter := clients[1]

	k := key.Key("key")
	note := []byte("a note from putter")

	if err := putter.Routing.PutValue(ctx, k, note); err != nil {
		return fmt.Errorf("failed to put value: %s", err)
	}

	received, err := getter.Routing.GetValue(ctx, k)
	if err != nil {
		return fmt.Errorf("failed to get value: %s", err)
	}

	if 0 != bytes.Compare(note, received) {
		return errors.New("record doesn't match")
	}
	return nil
}

func TestDoesNotDeadLockIfContextCancelledBeforePublish(t *testing.T) {

	g := blocksutil.NewBlockGenerator()
	ctx, cancel := context.WithCancel(context.Background())
	n := New()
	defer n.Shutdown()

	t.Log("generate a large number of blocks. exceed default buffer")
	bs := g.Blocks(1000)
	ks := func() []key.Key {
		var keys []key.Key
		for _, b := range bs {
			keys = append(keys, b.Key())
		}
		return keys
	}()

	_ = n.Subscribe(ctx, ks...) // ignore received channel

	t.Log("cancel context before any blocks published")
	cancel()
	for _, b := range bs {
		n.Publish(b)
	}

	t.Log("publishing the large number of blocks to the ignored channel must not deadlock")
}

// newKeyRoot creates a new KeyRoot for the given key, and starts up a republisher routine
// for it
func (fs *Filesystem) newKeyRoot(parent context.Context, k ci.PrivKey) (*KeyRoot, error) {
	hash, err := k.GetPublic().Hash()
	if err != nil {
		return nil, err
	}

	name := "/ipns/" + key.Key(hash).String()

	root := new(KeyRoot)
	root.key = k
	root.fs = fs
	root.name = name

	ctx, cancel := context.WithCancel(parent)
	defer cancel()

	pointsTo, err := fs.nsys.Resolve(ctx, name)
	if err != nil {
		err = namesys.InitializeKeyspace(ctx, fs.dserv, fs.nsys, fs.pins, k)
		if err != nil {
			return nil, err
		}

		pointsTo, err = fs.nsys.Resolve(ctx, name)
		if err != nil {
			return nil, err
		}
	}

	mnode, err := fs.resolver.ResolvePath(ctx, pointsTo)
	if err != nil {
		log.Errorf("Failed to retrieve value '%s' for ipns entry: %s\n", pointsTo, err)
		return nil, err
	}

	root.node = mnode

	root.repub = NewRepublisher(root, time.Millisecond*300, time.Second*3)
	go root.repub.Run(parent)

	pbn, err := ft.FromBytes(mnode.Data)
	if err != nil {
		log.Error("IPNS pointer was not unixfs node")
		return nil, err
	}

	switch pbn.GetType() {
	case ft.TDirectory:
		root.val = NewDirectory(ctx, pointsTo.String(), mnode, root, fs)
	case ft.TFile, ft.TMetadata, ft.TRaw:
		fi, err := NewFile(pointsTo.String(), mnode, root, fs)
		if err != nil {
			return nil, err
		}
		root.val = fi
	default:
		panic("unrecognized! (NYI)")
	}
	return root, nil
}

func (bs *Bitswap) rebroadcastWorker(parent context.Context) {
	ctx, cancel := context.WithCancel(parent)
	defer cancel()

	broadcastSignal := time.NewTicker(rebroadcastDelay.Get())
	defer broadcastSignal.Stop()

	tick := time.NewTicker(10 * time.Second)
	defer tick.Stop()

	for {
		log.Event(ctx, "Bitswap.Rebroadcast.idle")
		select {
		case <-tick.C:
			n := bs.wm.wl.Len()
			if n > 0 {
				log.Debug(n, "keys in bitswap wantlist")
			}
		case <-broadcastSignal.C: // resend unfulfilled wantlist keys
			log.Event(ctx, "Bitswap.Rebroadcast.active")
			entries := bs.wm.wl.Entries()
			if len(entries) > 0 {
				bs.connectToProviders(ctx, entries)
			}
		case <-parent.Done():
			return
		}
	}
}

func TestConsistentAccounting(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	sender := newEngine(ctx, "Ernie")
	receiver := newEngine(ctx, "Bert")

	// Send messages from Ernie to Bert
	for i := 0; i < 1000; i++ {

		m := message.New(false)
		content := []string{"this", "is", "message", "i"}
		m.AddBlock(blocks.NewBlock([]byte(strings.Join(content, " "))))

		sender.Engine.MessageSent(receiver.Peer, m)
		receiver.Engine.MessageReceived(sender.Peer, m)
	}

	// Ensure sender records the change
	if sender.Engine.numBytesSentTo(receiver.Peer) == 0 {
		t.Fatal("Sent bytes were not recorded")
	}

	// Ensure sender and receiver have the same values
	if sender.Engine.numBytesSentTo(receiver.Peer) != receiver.Engine.numBytesReceivedFrom(sender.Peer) {
		t.Fatal("Inconsistent book-keeping. Strategies don't agree")
	}

	// Ensure sender didn't record receving anything. And that the receiver
	// didn't record sending anything
	if receiver.Engine.numBytesSentTo(sender.Peer) != 0 || sender.Engine.numBytesReceivedFrom(receiver.Peer) != 0 {
		t.Fatal("Bert didn't send bytes to Ernie")
	}
}

func DirectAddCat(data []byte, conf testutil.LatencyConfig) error {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	const numPeers = 2

	// create network
	mn, err := mocknet.FullMeshLinked(ctx, numPeers)
	if err != nil {
		return err
	}
	mn.SetLinkDefaults(mocknet.LinkOptions{
		Latency: conf.NetworkLatency,
		// TODO add to conf. This is tricky because we want 0 values to be functional.
		Bandwidth: math.MaxInt32,
	})

	peers := mn.Peers()
	if len(peers) < numPeers {
		return errors.New("test initialization error")
	}

	adder, err := core.NewIPFSNode(ctx, core.ConfigOption(MocknetTestRepo(peers[0], mn.Host(peers[0]), conf, core.DHTOption)))
	if err != nil {
		return err
	}
	defer adder.Close()
	catter, err := core.NewIPFSNode(ctx, core.ConfigOption(MocknetTestRepo(peers[1], mn.Host(peers[1]), conf, core.DHTOption)))
	if err != nil {
		return err
	}
	defer catter.Close()

	bs1 := []peer.PeerInfo{adder.Peerstore.PeerInfo(adder.Identity)}
	bs2 := []peer.PeerInfo{catter.Peerstore.PeerInfo(catter.Identity)}

	if err := catter.Bootstrap(core.BootstrapConfigWithPeers(bs1)); err != nil {
		return err
	}
	if err := adder.Bootstrap(core.BootstrapConfigWithPeers(bs2)); err != nil {
		return err
	}

	added, err := coreunix.Add(adder, bytes.NewReader(data))
	if err != nil {
		return err
	}

	readerCatted, err := coreunix.Cat(catter, added)
	if err != nil {
		return err
	}

	// verify
	bufout := new(bytes.Buffer)
	io.Copy(bufout, readerCatted)
	if 0 != bytes.Compare(bufout.Bytes(), data) {
		return errors.New("catted data does not match added data")
	}
	return nil
}