client/tso: organize the methods of TSO dispatcher (#8121)

ref #8047

Organize the methods of the TSO dispatcher.

Signed-off-by: JmPotato <[email protected]>

Co-authored-by: ti-chi-bot[bot] <108142056+ti-chi-bot[bot]@users.noreply.github.com>

client/tso_client.go

@@ -18,14 +18,22 @@ import (
 	"context"
 	"fmt"
 	"math/rand"
+	"runtime/trace"
 	"sync"
 	"time"
 
+	"github.com/opentracing/opentracing-go"
+	"github.com/pingcap/errors"
+	"github.com/pingcap/failpoint"
 	"github.com/pingcap/log"
 	"github.com/tikv/pd/client/errs"
+	"github.com/tikv/pd/client/grpcutil"
+	"github.com/tikv/pd/client/tsoutil"
 	"go.uber.org/zap"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
 	healthpb "google.golang.org/grpc/health/grpc_health_v1"
+	"google.golang.org/grpc/status"
 )
 
 // TSOClient is the client used to get timestamps.
@@ -127,18 +135,36 @@ func (c *tsoClient) Close() {
 	c.wg.Wait()
 
 	log.Info("close tso client")
-	c.tsoDispatcher.Range(func(_, dispatcherInterface any) bool {
-		if dispatcherInterface != nil {
-			dispatcher := dispatcherInterface.(*tsoDispatcher)
-			dispatcher.dispatcherCancel()
-			dispatcher.tsoBatchController.clear()
-		}
-		return true
-	})
-
+	c.closeTSODispatcher()
 	log.Info("tso client is closed")
 }
 
+func (c *tsoClient) scheduleCheckTSDeadline() {
+	select {
+	case c.checkTSDeadlineCh <- struct{}{}:
+	default:
+	}
+}
+
+func (c *tsoClient) scheduleCheckTSODispatcher() {
+	select {
+	case c.checkTSODispatcherCh <- struct{}{}:
+	default:
+	}
+}
+
+func (c *tsoClient) scheduleUpdateTSOConnectionCtxs() {
+	select {
+	case c.updateTSOConnectionCtxsCh <- struct{}{}:
+	default:
+	}
+}
+
+// TSO Follower Proxy only supports the Global TSO proxy now.
+func (c *tsoClient) allowTSOFollowerProxy(dc string) bool {
+	return dc == globalDCLocation && c.option.getEnableTSOFollowerProxy()
+}
+
 func (c *tsoClient) getTSORequest(ctx context.Context, dcLocation string) *tsoRequest {
 	req := c.tsoReqPool.Get().(*tsoRequest)
 	// Set needed fields in the request before using it.
@@ -279,3 +305,293 @@ func (c *tsoClient) backupClientConn() (*grpc.ClientConn, string) {
 	}
 	return nil, ""
 }
+
+type tsoConnectionContext struct {
+	streamURL string
+	// Current stream to send gRPC requests, pdpb.PD_TsoClient for a leader/follower in the PD cluster,
+	// or tsopb.TSO_TsoClient for a primary/secondary in the TSO cluster
+	stream tsoStream
+	ctx    context.Context
+	cancel context.CancelFunc
+}
+
+func (c *tsoClient) updateTSOConnectionCtxs(updaterCtx context.Context, dc string, connectionCtxs *sync.Map) bool {
+	// Normal connection creating, it will be affected by the `enableForwarding`.
+	createTSOConnection := c.tryConnectToTSO
+	if c.allowTSOFollowerProxy(dc) {
+		createTSOConnection = c.tryConnectToTSOWithProxy
+	}
+	if err := createTSOConnection(updaterCtx, dc, connectionCtxs); err != nil {
+		log.Error("[tso] update connection contexts failed", zap.String("dc", dc), errs.ZapError(err))
+		return false
+	}
+	return true
+}
+
+// tryConnectToTSO will try to connect to the TSO allocator leader. If the connection becomes unreachable
+// and enableForwarding is true, it will create a new connection to a follower to do the forwarding,
+// while a new daemon will be created also to switch back to a normal leader connection ASAP the
+// connection comes back to normal.
+func (c *tsoClient) tryConnectToTSO(
+	dispatcherCtx context.Context,
+	dc string,
+	connectionCtxs *sync.Map,
+) error {
+	var (
+		networkErrNum uint64
+		err           error
+		stream        tsoStream
+		url           string
+		cc            *grpc.ClientConn
+	)
+	updateAndClear := func(newURL string, connectionCtx *tsoConnectionContext) {
+		if cc, loaded := connectionCtxs.LoadOrStore(newURL, connectionCtx); loaded {
+			// If the previous connection still exists, we should close it first.
+			cc.(*tsoConnectionContext).cancel()
+			connectionCtxs.Store(newURL, connectionCtx)
+		}
+		connectionCtxs.Range(func(url, cc any) bool {
+			if url.(string) != newURL {
+				cc.(*tsoConnectionContext).cancel()
+				connectionCtxs.Delete(url)
+			}
+			return true
+		})
+	}
+	// retry several times before falling back to the follower when the network problem happens
+
+	ticker := time.NewTicker(retryInterval)
+	defer ticker.Stop()
+	for i := 0; i < maxRetryTimes; i++ {
+		c.svcDiscovery.ScheduleCheckMemberChanged()
+		cc, url = c.GetTSOAllocatorClientConnByDCLocation(dc)
+		if cc != nil {
+			cctx, cancel := context.WithCancel(dispatcherCtx)
+			stream, err = c.tsoStreamBuilderFactory.makeBuilder(cc).build(cctx, cancel, c.option.timeout)
+			failpoint.Inject("unreachableNetwork", func() {
+				stream = nil
+				err = status.New(codes.Unavailable, "unavailable").Err()
+			})
+			if stream != nil && err == nil {
+				updateAndClear(url, &tsoConnectionContext{url, stream, cctx, cancel})
+				return nil
+			}
+
+			if err != nil && c.option.enableForwarding {
+				// The reason we need to judge if the error code is equal to "Canceled" here is that
+				// when we create a stream we use a goroutine to manually control the timeout of the connection.
+				// There is no need to wait for the transport layer timeout which can reduce the time of unavailability.
+				// But it conflicts with the retry mechanism since we use the error code to decide if it is caused by network error.
+				// And actually the `Canceled` error can be regarded as a kind of network error in some way.
+				if rpcErr, ok := status.FromError(err); ok && (isNetworkError(rpcErr.Code()) || rpcErr.Code() == codes.Canceled) {
+					networkErrNum++
+				}
+			}
+			cancel()
+		} else {
+			networkErrNum++
+		}
+		select {
+		case <-dispatcherCtx.Done():
+			return err
+		case <-ticker.C:
+		}
+	}
+
+	if networkErrNum == maxRetryTimes {
+		// encounter the network error
+		backupClientConn, backupURL := c.backupClientConn()
+		if backupClientConn != nil {
+			log.Info("[tso] fall back to use follower to forward tso stream", zap.String("dc", dc), zap.String("follower-url", backupURL))
+			forwardedHost, ok := c.GetTSOAllocatorServingURLByDCLocation(dc)
+			if !ok {
+				return errors.Errorf("cannot find the allocator leader in %s", dc)
+			}
+
+			// create the follower stream
+			cctx, cancel := context.WithCancel(dispatcherCtx)
+			cctx = grpcutil.BuildForwardContext(cctx, forwardedHost)
+			stream, err = c.tsoStreamBuilderFactory.makeBuilder(backupClientConn).build(cctx, cancel, c.option.timeout)
+			if err == nil {
+				forwardedHostTrim := trimHTTPPrefix(forwardedHost)
+				addr := trimHTTPPrefix(backupURL)
+				// the goroutine is used to check the network and change back to the original stream
+				go c.checkAllocator(dispatcherCtx, cancel, dc, forwardedHostTrim, addr, url, updateAndClear)
+				requestForwarded.WithLabelValues(forwardedHostTrim, addr).Set(1)
+				updateAndClear(backupURL, &tsoConnectionContext{backupURL, stream, cctx, cancel})
+				return nil
+			}
+			cancel()
+		}
+	}
+	return err
+}
+
+// tryConnectToTSOWithProxy will create multiple streams to all the service endpoints to work as
+// a TSO proxy to reduce the pressure of the main serving service endpoint.
+func (c *tsoClient) tryConnectToTSOWithProxy(dispatcherCtx context.Context, dc string, connectionCtxs *sync.Map) error {
+	tsoStreamBuilders := c.getAllTSOStreamBuilders()
+	leaderAddr := c.svcDiscovery.GetServingURL()
+	forwardedHost, ok := c.GetTSOAllocatorServingURLByDCLocation(dc)
+	if !ok {
+		return errors.Errorf("cannot find the allocator leader in %s", dc)
+	}
+	// GC the stale one.
+	connectionCtxs.Range(func(addr, cc any) bool {
+		addrStr := addr.(string)
+		if _, ok := tsoStreamBuilders[addrStr]; !ok {
+			log.Info("[tso] remove the stale tso stream",
+				zap.String("dc", dc),
+				zap.String("addr", addrStr))
+			cc.(*tsoConnectionContext).cancel()
+			connectionCtxs.Delete(addr)
+		}
+		return true
+	})
+	// Update the missing one.
+	for addr, tsoStreamBuilder := range tsoStreamBuilders {
+		if _, ok = connectionCtxs.Load(addr); ok {
+			continue
+		}
+		log.Info("[tso] try to create tso stream",
+			zap.String("dc", dc), zap.String("addr", addr))
+		cctx, cancel := context.WithCancel(dispatcherCtx)
+		// Do not proxy the leader client.
+		if addr != leaderAddr {
+			log.Info("[tso] use follower to forward tso stream to do the proxy",
+				zap.String("dc", dc), zap.String("addr", addr))
+			cctx = grpcutil.BuildForwardContext(cctx, forwardedHost)
+		}
+		// Create the TSO stream.
+		stream, err := tsoStreamBuilder.build(cctx, cancel, c.option.timeout)
+		if err == nil {
+			if addr != leaderAddr {
+				forwardedHostTrim := trimHTTPPrefix(forwardedHost)
+				addrTrim := trimHTTPPrefix(addr)
+				requestForwarded.WithLabelValues(forwardedHostTrim, addrTrim).Set(1)
+			}
+			connectionCtxs.Store(addr, &tsoConnectionContext{addr, stream, cctx, cancel})
+			continue
+		}
+		log.Error("[tso] create the tso stream failed",
+			zap.String("dc", dc), zap.String("addr", addr), errs.ZapError(err))
+		cancel()
+	}
+	return nil
+}
+
+// getAllTSOStreamBuilders returns a TSO stream builder for every service endpoint of TSO leader/followers
+// or of keyspace group primary/secondaries.
+func (c *tsoClient) getAllTSOStreamBuilders() map[string]tsoStreamBuilder {
+	var (
+		addrs          = c.svcDiscovery.GetServiceURLs()
+		streamBuilders = make(map[string]tsoStreamBuilder, len(addrs))
+		cc             *grpc.ClientConn
+		err            error
+	)
+	for _, addr := range addrs {
+		if len(addrs) == 0 {
+			continue
+		}
+		if cc, err = c.svcDiscovery.GetOrCreateGRPCConn(addr); err != nil {
+			continue
+		}
+		healthCtx, healthCancel := context.WithTimeout(c.ctx, c.option.timeout)
+		resp, err := healthpb.NewHealthClient(cc).Check(healthCtx, &healthpb.HealthCheckRequest{Service: ""})
+		healthCancel()
+		if err == nil && resp.GetStatus() == healthpb.HealthCheckResponse_SERVING {
+			streamBuilders[addr] = c.tsoStreamBuilderFactory.makeBuilder(cc)
+		}
+	}
+	return streamBuilders
+}
+
+type tsoInfo struct {
+	tsoServer           string
+	reqKeyspaceGroupID  uint32
+	respKeyspaceGroupID uint32
+	respReceivedAt      time.Time
+	physical            int64
+	logical             int64
+}
+
+func (c *tsoClient) processRequests(
+	stream tsoStream, dcLocation string, tbc *tsoBatchController,
+) error {
+	requests := tbc.getCollectedRequests()
+	// nolint
+	for _, req := range requests {
+		defer trace.StartRegion(req.requestCtx, "pdclient.tsoReqSend").End()
+		if span := opentracing.SpanFromContext(req.requestCtx); span != nil && span.Tracer() != nil {
+			span = span.Tracer().StartSpan("pdclient.processRequests", opentracing.ChildOf(span.Context()))
+			defer span.Finish()
+		}
+	}
+
+	count := int64(len(requests))
+	reqKeyspaceGroupID := c.svcDiscovery.GetKeyspaceGroupID()
+	respKeyspaceGroupID, physical, logical, suffixBits, err := stream.processRequests(
+		c.svcDiscovery.GetClusterID(), c.svcDiscovery.GetKeyspaceID(), reqKeyspaceGroupID,
+		dcLocation, count, tbc.batchStartTime)
+	if err != nil {
+		tbc.finishCollectedRequests(0, 0, 0, err)
+		return err
+	}
+	// `logical` is the largest ts's logical part here, we need to do the subtracting before we finish each TSO request.
+	firstLogical := tsoutil.AddLogical(logical, -count+1, suffixBits)
+	curTSOInfo := &tsoInfo{
+		tsoServer:           stream.getServerURL(),
+		reqKeyspaceGroupID:  reqKeyspaceGroupID,
+		respKeyspaceGroupID: respKeyspaceGroupID,
+		respReceivedAt:      time.Now(),
+		physical:            physical,
+		logical:             tsoutil.AddLogical(firstLogical, count-1, suffixBits),
+	}
+	c.compareAndSwapTS(dcLocation, curTSOInfo, physical, firstLogical)
+	tbc.finishCollectedRequests(physical, firstLogical, suffixBits, nil)
+	return nil
+}
+
+func (c *tsoClient) compareAndSwapTS(
+	dcLocation string,
+	curTSOInfo *tsoInfo,
+	physical, firstLogical int64,
+) {
+	val, loaded := c.lastTSOInfoMap.LoadOrStore(dcLocation, curTSOInfo)
+	if !loaded {
+		return
+	}
+	lastTSOInfo := val.(*tsoInfo)
+	if lastTSOInfo.respKeyspaceGroupID != curTSOInfo.respKeyspaceGroupID {
+		log.Info("[tso] keyspace group changed",
+			zap.String("dc-location", dcLocation),
+			zap.Uint32("old-group-id", lastTSOInfo.respKeyspaceGroupID),
+			zap.Uint32("new-group-id", curTSOInfo.respKeyspaceGroupID))
+	}
+
+	// The TSO we get is a range like [largestLogical-count+1, largestLogical], so we save the last TSO's largest logical
+	// to compare with the new TSO's first logical. For example, if we have a TSO resp with logical 10, count 5, then
+	// all TSOs we get will be [6, 7, 8, 9, 10]. lastTSOInfo.logical stores the logical part of the largest ts returned
+	// last time.
+	if tsoutil.TSLessEqual(physical, firstLogical, lastTSOInfo.physical, lastTSOInfo.logical) {
+		log.Panic("[tso] timestamp fallback",
+			zap.String("dc-location", dcLocation),
+			zap.Uint32("keyspace", c.svcDiscovery.GetKeyspaceID()),
+			zap.String("last-ts", fmt.Sprintf("(%d, %d)", lastTSOInfo.physical, lastTSOInfo.logical)),
+			zap.String("cur-ts", fmt.Sprintf("(%d, %d)", physical, firstLogical)),
+			zap.String("last-tso-server", lastTSOInfo.tsoServer),
+			zap.String("cur-tso-server", curTSOInfo.tsoServer),
+			zap.Uint32("last-keyspace-group-in-request", lastTSOInfo.reqKeyspaceGroupID),
+			zap.Uint32("cur-keyspace-group-in-request", curTSOInfo.reqKeyspaceGroupID),
+			zap.Uint32("last-keyspace-group-in-response", lastTSOInfo.respKeyspaceGroupID),
+			zap.Uint32("cur-keyspace-group-in-response", curTSOInfo.respKeyspaceGroupID),
+			zap.Time("last-response-received-at", lastTSOInfo.respReceivedAt),
+			zap.Time("cur-response-received-at", curTSOInfo.respReceivedAt))
+	}
+	lastTSOInfo.tsoServer = curTSOInfo.tsoServer
+	lastTSOInfo.reqKeyspaceGroupID = curTSOInfo.reqKeyspaceGroupID
+	lastTSOInfo.respKeyspaceGroupID = curTSOInfo.respKeyspaceGroupID
+	lastTSOInfo.respReceivedAt = curTSOInfo.respReceivedAt
+	lastTSOInfo.physical = curTSOInfo.physical
+	lastTSOInfo.logical = curTSOInfo.logical
+}