Basic streaming plugin support (#31940)

This pull request migrates testdata to coreplugin streaming capabilities, this is mostly a working concept of streaming plugins at the moment, the work will continue in the following pull requests.
2021-03-23 20:24:08 +03:00
parent 1cd8981be4
commit 336bc559a3
31 changed files with 1204 additions and 290 deletions
@@ -0,0 +1,122 @@
+package features
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/centrifugal/centrifuge"
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/grafana/grafana/pkg/models"
+)
+
+//go:generate mockgen -destination=mock.go -package=features github.com/grafana/grafana/pkg/services/live/features ChannelPublisher,PresenceGetter,PluginContextGetter,StreamRunner
+
+type ChannelPublisher interface {
+	Publish(channel string, data []byte) error
+}
+
+type PresenceGetter interface {
+	GetNumSubscribers(channel string) (int, error)
+}
+
+type PluginContextGetter interface {
+	GetPluginContext(ctx context.Context, pluginID string, datasourceUID string) (backend.PluginContext, bool, error)
+}
+
+type StreamRunner interface {
+	RunStream(ctx context.Context, request *backend.RunStreamRequest, sender backend.StreamPacketSender) error
+}
+
+type streamSender struct {
+	channel          string
+	channelPublisher ChannelPublisher
+}
+
+func newStreamSender(channel string, publisher ChannelPublisher) *streamSender {
+	return &streamSender{channel: channel, channelPublisher: publisher}
+}
+
+func (p *streamSender) Send(packet *backend.StreamPacket) error {
+	return p.channelPublisher.Publish(p.channel, packet.Payload)
+}
+
+// PluginRunner can handle streaming operations for channels belonging to plugins.
+type PluginRunner struct {
+	pluginID            string
+	datasourceUID       string
+	pluginContextGetter PluginContextGetter
+	handler             backend.StreamHandler
+	streamManager       *StreamManager
+}
+
+// NewPluginRunner creates new PluginRunner.
+func NewPluginRunner(pluginID string, datasourceUID string, streamManager *StreamManager, pluginContextGetter PluginContextGetter, handler backend.StreamHandler) *PluginRunner {
+	return &PluginRunner{
+		pluginID:            pluginID,
+		datasourceUID:       datasourceUID,
+		pluginContextGetter: pluginContextGetter,
+		handler:             handler,
+		streamManager:       streamManager,
+	}
+}
+
+// GetHandlerForPath gets the handler for a path.
+func (m *PluginRunner) GetHandlerForPath(path string) (models.ChannelHandler, error) {
+	return &PluginPathRunner{
+		path:                path,
+		pluginID:            m.pluginID,
+		datasourceUID:       m.datasourceUID,
+		streamManager:       m.streamManager,
+		handler:             m.handler,
+		pluginContextGetter: m.pluginContextGetter,
+	}, nil
+}
+
+// PluginPathRunner can handle streaming operations for channels belonging to plugin specific path.
+type PluginPathRunner struct {
+	path                string
+	pluginID            string
+	datasourceUID       string
+	streamManager       *StreamManager
+	handler             backend.StreamHandler
+	pluginContextGetter PluginContextGetter
+}
+
+// OnSubscribe passes control to a plugin.
+func (r *PluginPathRunner) OnSubscribe(client *centrifuge.Client, e centrifuge.SubscribeEvent) (centrifuge.SubscribeReply, error) {
+	pCtx, found, err := r.pluginContextGetter.GetPluginContext(client.Context(), r.pluginID, r.datasourceUID)
+	if err != nil {
+		logger.Error("Get plugin context error", "error", err, "path", r.path)
+		return centrifuge.SubscribeReply{}, err
+	}
+	if !found {
+		logger.Error("Plugin context not found", "path", r.path)
+		return centrifuge.SubscribeReply{}, centrifuge.ErrorInternal
+	}
+	resp, err := r.handler.CanSubscribeToStream(client.Context(), &backend.SubscribeToStreamRequest{
+		PluginContext: pCtx,
+		Path:          r.path,
+	})
+	if err != nil {
+		logger.Error("Plugin CanSubscribeToStream call error", "error", err, "path", r.path)
+		return centrifuge.SubscribeReply{}, err
+	}
+	if !resp.OK {
+		return centrifuge.SubscribeReply{}, centrifuge.ErrorPermissionDenied
+	}
+	err = r.streamManager.SubmitStream(e.Channel, r.path, pCtx, r.handler)
+	if err != nil {
+		logger.Error("Error submitting stream to manager", "error", err, "path", r.path)
+		return centrifuge.SubscribeReply{}, centrifuge.ErrorInternal
+	}
+	return centrifuge.SubscribeReply{
+		Options: centrifuge.SubscribeOptions{
+			Presence: true,
+		},
+	}, nil
+}
+
+// OnPublish passes control to a plugin.
+func (r *PluginPathRunner) OnPublish(_ *centrifuge.Client, _ centrifuge.PublishEvent) (centrifuge.PublishReply, error) {
+	return centrifuge.PublishReply{}, fmt.Errorf("not implemented yet")
+}