Golang Context.Err方法代码示例

func (m *EtcdManager) AcquireLease(ctx context.Context, network string, attrs *LeaseAttrs) (*Lease, error) {
	config, err := m.GetNetworkConfig(ctx, network)
	if err != nil {
		return nil, err
	}

	for {
		l, err := m.acquireLeaseOnce(ctx, network, config, attrs)
		switch {
		case err == nil:
			log.Info("Subnet lease acquired: ", l.Subnet)
			return l, nil

		case err == context.Canceled, err == context.DeadlineExceeded:
			return nil, err

		default:
			log.Error("Failed to acquire subnet: ", err)
		}

		select {
		case <-time.After(time.Second):

		case <-ctx.Done():
			return nil, ctx.Err()
		}
	}
}

func (msr *MockSubnetRegistry) watchNetworks(ctx context.Context, since uint64) (Event, uint64, error) {
	msr.mux.Lock()
	index := msr.index
	msr.mux.Unlock()

	for {
		if since < index {
			return Event{}, 0, etcd.Error{
				Code:    etcd.ErrorCodeEventIndexCleared,
				Cause:   "out of date",
				Message: "cursor is out of date",
				Index:   index,
			}
		}

		select {
		case <-ctx.Done():
			return Event{}, 0, ctx.Err()

		case e := <-msr.networkEvents:
			if e.index > since {
				return e.evt, e.index, nil
			}
		}
	}
}

func (msr *MockSubnetRegistry) watchSubnets(ctx context.Context, network string, since uint64) (Event, uint64, error) {
	n, ok := msr.networks[network]
	if !ok {
		return Event{}, msr.index, fmt.Errorf("Network %s not found", network)
	}

	for {
		if since < msr.index {
			return Event{}, msr.index, etcd.Error{
				Code:    etcd.ErrorCodeEventIndexCleared,
				Cause:   "out of date",
				Message: "cursor is out of date",
				Index:   msr.index,
			}
		}

		select {
		case <-ctx.Done():
			return Event{}, msr.index, ctx.Err()

		case e := <-n.subnetsEvents:
			if e.index <= since {
				continue
			}
			return e.evt, msr.index, nil
		}
	}
}

func (msr *MockSubnetRegistry) watchSubnet(ctx context.Context, network string, since uint64, sn ip.IP4Net) (Event, uint64, error) {
	msr.mux.Lock()
	n, ok := msr.networks[network]
	msr.mux.Unlock()

	if !ok {
		return Event{}, 0, fmt.Errorf("Network %s not found", network)
	}

	for {
		msr.mux.Lock()
		index := msr.index
		msr.mux.Unlock()

		if since < index {
			return Event{}, msr.index, etcd.Error{
				Code:    etcd.ErrorCodeEventIndexCleared,
				Cause:   "out of date",
				Message: "cursor is out of date",
				Index:   index,
			}
		}

		select {
		case <-ctx.Done():
			return Event{}, index, ctx.Err()

		case e := <-n.subnetEventsChan(sn):
			if e.index > since {
				return e.evt, index, nil
			}
		}
	}
}

func (esr *etcdSubnetRegistry) watchSubnets(ctx context.Context, network string, since uint64) (*etcd.Response, error) {
	stop := make(chan bool)
	respCh := make(chan watchResp)

	go func() {
		for {
			key := path.Join(esr.etcdCfg.Prefix, network, "subnets")
			rresp, err := esr.client().RawWatch(key, since, true, nil, stop)

			if err != nil {
				respCh <- watchResp{nil, err}
				return
			}

			if len(rresp.Body) == 0 {
				// etcd timed out, go back but recreate the client as the underlying
				// http transport gets hosed (http://code.google.com/p/go/issues/detail?id=8648)
				esr.resetClient()
				continue
			}

			resp, err := rresp.Unmarshal()
			respCh <- watchResp{resp, err}
		}
	}()

	select {
	case <-ctx.Done():
		close(stop)
		<-respCh // Wait for f to return.
		return nil, ctx.Err()
	case wr := <-respCh:
		return wr.resp, wr.err
	}
}

func (c *simpleHTTPClient) Do(ctx context.Context, act httpAction) (*http.Response, []byte, error) {
	req := act.HTTPRequest(c.endpoint)

	if err := printcURL(req); err != nil {
		return nil, nil, err
	}

	rtchan := make(chan roundTripResponse, 1)
	go func() {
		resp, err := c.transport.RoundTrip(req)
		rtchan <- roundTripResponse{resp: resp, err: err}
		close(rtchan)
	}()

	var resp *http.Response
	var err error

	select {
	case rtresp := <-rtchan:
		resp, err = rtresp.resp, rtresp.err
	case <-ctx.Done():
		// cancel and wait for request to actually exit before continuing
		c.transport.CancelRequest(req)
		rtresp := <-rtchan
		resp = rtresp.resp
		err = ctx.Err()
	}

	// always check for resp nil-ness to deal with possible
	// race conditions between channels above
	defer func() {
		if resp != nil {
			resp.Body.Close()
		}
	}()

	if err != nil {
		return nil, nil, err
	}

	var body []byte
	done := make(chan struct{})
	go func() {
		body, err = ioutil.ReadAll(resp.Body)
		done <- struct{}{}
	}()

	select {
	case <-ctx.Done():
		err = resp.Body.Close()
		<-done
		if err == nil {
			err = ctx.Err()
		}
	case <-done:
	}

	return resp, body, err
}

func (msr *mockSubnetRegistry) watchSubnets(ctx context.Context, network string, since uint64) (*etcd.Response, error) {
	for {
		select {
		case <-ctx.Done():
			return nil, ctx.Err()

		case r := <-msr.events:
			if r.Node.ModifiedIndex <= since {
				continue
			}
			return r, nil
		}
	}
}

func (c *httpClusterClient) AutoSync(ctx context.Context, interval time.Duration) error {
	ticker := time.NewTicker(interval)
	defer ticker.Stop()
	for {
		err := c.Sync(ctx)
		if err != nil {
			return err
		}
		select {
		case <-ctx.Done():
			return ctx.Err()
		case <-ticker.C:
		}
	}
}

func (m *RemoteManager) httpDo(ctx context.Context, req *http.Request) (*http.Response, error) {
	// Run the HTTP request in a goroutine (so it can be canceled) and pass
	// the result via the channel c
	client := &http.Client{Transport: m.transport}
	c := make(chan httpRespErr, 1)
	go func() {
		resp, err := client.Do(req)
		c <- httpRespErr{resp, err}
	}()

	select {
	case <-ctx.Done():
		m.transport.CancelRequest(req)
		<-c // Wait for f to return.
		return nil, ctx.Err()
	case r := <-c:
		return r.resp, r.err
	}
}

func (m *EtcdManager) acquireLeaseOnce(ctx context.Context, network string, config *Config, attrs *LeaseAttrs) (*Lease, error) {
	for i := 0; i < registerRetries; i++ {
		l, err := m.tryAcquireLease(ctx, network, config, attrs.PublicIP, attrs)
		switch {
		case err != nil:
			return nil, err
		case l != nil:
			return l, nil
		}

		// before moving on, check for cancel
		// TODO(eyakubovich): propogate ctx deeper into registry
		select {
		case <-ctx.Done():
			return nil, ctx.Err()
		default:
		}
	}

	return nil, errors.New("Max retries reached trying to acquire a subnet")
}

func (msr *MockSubnetRegistry) watch(ctx context.Context, network string, since uint64) (*etcd.Response, error) {
	for {
		if since < msr.index {
			return nil, etcd.Error{
				Code:    etcd.ErrorCodeEventIndexCleared,
				Cause:   "out of date",
				Message: "cursor is out of date",
				Index:   msr.index,
			}
		}

		select {
		case <-ctx.Done():
			return nil, ctx.Err()

		case r := <-msr.events:
			if r.Node.ModifiedIndex <= since {
				continue
			}
			return r, nil
		}
	}
}

func (msr *MockSubnetRegistry) watchNetworks(ctx context.Context, since uint64) (Event, uint64, error) {
	for {
		if since < msr.index {
			return Event{}, msr.index, etcd.Error{
				Code:    etcd.ErrorCodeEventIndexCleared,
				Cause:   "out of date",
				Message: "cursor is out of date",
				Index:   msr.index,
			}
		}

		select {
		case <-ctx.Done():
			return Event{}, msr.index, ctx.Err()

		case e := <-msr.networkEvents:
			if e.index <= since {
				continue
			}
			return e.evt, msr.index, nil
		}
	}
}

func (c *simpleHTTPClient) Do(ctx context.Context, act httpAction) (*http.Response, []byte, error) {
	req := act.HTTPRequest(c.endpoint)

	if err := printcURL(req); err != nil {
		return nil, nil, err
	}

	hctx, hcancel := context.WithCancel(ctx)
	if c.headerTimeout > 0 {
		hctx, hcancel = context.WithTimeout(ctx, c.headerTimeout)
	}
	defer hcancel()

	reqcancel := requestCanceler(c.transport, req)

	rtchan := make(chan roundTripResponse, 1)
	go func() {
		resp, err := c.transport.RoundTrip(req)
		rtchan <- roundTripResponse{resp: resp, err: err}
		close(rtchan)
	}()

	var resp *http.Response
	var err error

	select {
	case rtresp := <-rtchan:
		resp, err = rtresp.resp, rtresp.err
	case <-hctx.Done():
		// cancel and wait for request to actually exit before continuing
		reqcancel()
		rtresp := <-rtchan
		resp = rtresp.resp
		switch {
		case ctx.Err() != nil:
			err = ctx.Err()
		case hctx.Err() != nil:
			err = fmt.Errorf("client: endpoint %s exceeded header timeout", c.endpoint.String())
		default:
			panic("failed to get error from context")
		}
	}

	// always check for resp nil-ness to deal with possible
	// race conditions between channels above
	defer func() {
		if resp != nil {
			resp.Body.Close()
		}
	}()

	if err != nil {
		return nil, nil, err
	}

	var body []byte
	done := make(chan struct{})
	go func() {
		body, err = ioutil.ReadAll(resp.Body)
		done <- struct{}{}
	}()

	select {
	case <-ctx.Done():
		resp.Body.Close()
		<-done
		return nil, nil, ctx.Err()
	case <-done:
	}

	return resp, body, err
}