Placement service lock optimisations and race condition fix

pkg/actors/placement/client.go

@@ -48,7 +48,7 @@ type placementClient struct {
 
 // connectToServer initializes a new connection to the target server and if it succeeds replace the current
 // stream with the connected stream.
-func (c *placementClient) connectToServer(ctx context.Context, serverAddr string, apiLevel uint32) error {
+func (c *placementClient) connectToServer(ctx context.Context, serverAddr string) error {
 	opts, err := c.getGrpcOpts()
 	if err != nil {
 		return err

pkg/actors/placement/client_test.go

@@ -32,22 +32,22 @@ func TestConnectToServer(t *testing.T) {
 		client := newPlacementClient(func() ([]grpc.DialOption, error) {
 			return nil, errEstablishingTLSConn
 		})
-		assert.Equal(t, client.connectToServer(context.Background(), "", 1), errEstablishingTLSConn)
+		assert.Equal(t, client.connectToServer(context.Background(), ""), errEstablishingTLSConn)
 	})
 	t.Run("when grpc dial returns an error connectToServer should return an error", func(t *testing.T) {
 		client := newPlacementClient(func() ([]grpc.DialOption, error) {
 			return []grpc.DialOption{}, nil
 		})
 
-		require.Error(t, client.connectToServer(context.Background(), "", 1))
+		require.Error(t, client.connectToServer(context.Background(), ""))
 	})
 	t.Run("when new placement stream returns an error connectToServer should return an error", func(t *testing.T) {
 		client := newPlacementClient(func() ([]grpc.DialOption, error) {
 			return []grpc.DialOption{}, nil
 		})
 		conn, cleanup := newTestServerWithOpts() // do not register the placement stream server
 		defer cleanup()
-		require.Error(t, client.connectToServer(context.Background(), conn, 1))
+		require.Error(t, client.connectToServer(context.Background(), conn))
 	})
 	t.Run("when connectToServer succeeds it should broadcast that a new connection is alive", func(t *testing.T) {
 		conn, _, cleanup := newTestServer() // do not register the placement stream server
@@ -64,7 +64,7 @@ func TestConnectToServer(t *testing.T) {
 			ready.Done()
 		}()
 
-		require.NoError(t, client.connectToServer(context.Background(), conn, 1))
+		require.NoError(t, client.connectToServer(context.Background(), conn))
 		ready.Wait() // should not timeout
 		assert.True(t, client.streamConnAlive)
 	})
@@ -84,7 +84,7 @@ func TestConnectToServer(t *testing.T) {
 			ready.Done()
 		}()
 
-		err := client.connectToServer(context.Background(), conn, 10)
+		err := client.connectToServer(context.Background(), conn)
 		require.NoError(t, err)
 	})
 }
@@ -119,7 +119,7 @@ func TestDisconnect(t *testing.T) {
 		defer cleanup()
 
 		client := newPlacementClient(getGrpcOptsGetter([]string{conn}, testSecurity(t)))
-		require.NoError(t, client.connectToServer(context.Background(), conn, 1))
+		require.NoError(t, client.connectToServer(context.Background(), conn))
 
 		called := false
 		shouldBeCalled := func() {

pkg/actors/placement/placement.go

@@ -163,7 +163,7 @@
 	p.appHealthy.Store(true)
 	p.resetPlacementTables()
 
-	if !p.establishStreamConn(ctx, internal.ActorAPILevel) {
+	if !p.establishStreamConn(ctx) {
 		return nil
 	}
 
@@ -205,7 +205,7 @@
 			if !p.running.Load() {
 				break
 			}
-			p.establishStreamConn(ctx, internal.ActorAPILevel)
+			p.establishStreamConn(ctx)
 		}
 	}()
 
@@ -258,9 +258,7 @@
 				log.Debug("Disconnecting from placement service by the unhealthy app")
 
 				p.client.disconnect()
-				p.placementTableLock.Lock()
 				p.resetPlacementTables()
-				p.placementTableLock.Unlock()
 				if p.haltAllActorsFn != nil {
 					haltErr := p.haltAllActorsFn()
 					if haltErr != nil {
@@ -379,7 +377,7 @@
 }
 
 //nolint:nosnakecase
-func (p *actorPlacement) establishStreamConn(ctx context.Context, apiLevel uint32) (established bool) {
+func (p *actorPlacement) establishStreamConn(ctx context.Context) (established bool) {
 	// Backoff for reconnecting in case of errors
 	bo := backoff.NewExponentialBackOff()
 	bo.InitialInterval = placementReconnectMinInterval
@@ -414,7 +412,7 @@
 			log.Debug("try to connect to placement service: " + serverAddr)
 		}
 
-		err := p.client.connectToServer(ctx, serverAddr, apiLevel)
+		err := p.client.connectToServer(ctx, serverAddr)
 		if err == errEstablishingTLSConn {
 			return false
 		}
@@ -516,6 +514,9 @@
 // Resets the placement tables.
 // Note that this method should be invoked by a caller that owns a lock.
 func (p *actorPlacement) resetPlacementTables() {
+	p.placementTableLock.Lock()
+	defer p.placementTableLock.Unlock()
+
 	if p.hasPlacementTablesCh != nil {
 		close(p.hasPlacementTablesCh)
 	}
@@ -528,20 +529,20 @@
 	updated := false
 	var updatedAPILevel *uint32
 	func() {
-		p.placementTableLock.Lock()
-		defer p.placementTableLock.Unlock()
-
+		p.placementTableLock.RLock()
 		if in.GetVersion() == p.placementTables.Version {
+			p.placementTableLock.RUnlock()
 			return
 		}
+		p.placementTableLock.RUnlock()
 
 		if in.GetApiLevel() != p.apiLevel {
 			p.apiLevel = in.GetApiLevel()
 			updatedAPILevel = ptr.Of(in.GetApiLevel())
 		}
 
-		maps.Clear(p.placementTables.Entries)
-		p.placementTables.Version = in.GetVersion()
+		entries := map[string]*hashing.Consistent{}
+
 		for k, v := range in.GetEntries() {
 			loadMap := make(map[string]*hashing.Host, len(v.GetLoadMap()))
 			for lk, lv := range v.GetLoadMap() {
@@ -551,12 +552,27 @@
 			// TODO: @elena in v1.15 remove the check for versions < 1.13
 			// only keep `hashing.NewFromExisting`
 			if p.apiLevel < placement.NoVirtualNodesInPlacementTablesAPILevel {
-				p.placementTables.Entries[k] = hashing.NewFromExistingWithVirtNodes(v.GetHosts(), v.GetSortedSet(), loadMap)
+				entries[k] = hashing.NewFromExistingWithVirtNodes(v.GetHosts(), v.GetSortedSet(), loadMap)
 			} else {
-				p.placementTables.Entries[k] = hashing.NewFromExisting(loadMap, int(in.GetReplicationFactor()), p.virtualNodesCache)
+				entries[k] = hashing.NewFromExisting(loadMap, int(in.GetReplicationFactor()), p.virtualNodesCache)
 			}
 		}
 
+		p.placementTableLock.Lock()
+		defer p.placementTableLock.Unlock()
+
+		// Check if the table was updated in the meantime
+		// This is not needed atm, because the placement leader is the only one sending updates,
+		// but it might be needed soon because there's plans to allow other nodes to send updates
+		// This is a very cheap check, so it's a good idea to keep it
+		if in.GetVersion() == p.placementTables.Version {
+			return
+		}
+
+		maps.Clear(p.placementTables.Entries)
+		p.placementTables.Version = in.GetVersion()
+		p.placementTables.Entries = entries
+
 		updated = true
 		if p.hasPlacementTablesCh != nil {
 			close(p.hasPlacementTablesCh)

pkg/placement/hashing/consistent_hash.go

@@ -212,7 +212,7 @@
 	// in 1.13, and the API level was increased to 20, but we still have to support sidecars
 	// running on 1.12 with placement services on 1.13. That's why we are keeping the
 	// vhosts in the store in v1.13.
-	// This should be removed in 1.14.
+	// This should be removed in 1.15.
 	// --Start remove--
 	for i := 0; i < c.replicationFactor; i++ {
 		h := hash(host + strconv.Itoa(i))
@@ -234,15 +234,20 @@
 //
 // It returns ErrNoHosts if the ring has no hosts in it.
 func (c *Consistent) Get(key string) (string, error) {
+	// Do a cheap check first for an early return
 	c.RLock()
-	defer c.RUnlock()
-
 	if len(c.hosts) == 0 {
 		return "", ErrNoHosts
 	}
+	c.RUnlock()
 
 	h := hash(key)
+	c.RLock()
+	if len(c.hosts) == 0 {
+		return "", ErrNoHosts
+	}
 	idx := c.search(h)
+	c.RUnlock()
 	return c.hosts[c.sortedSet[idx]], nil
 }
 

tests/integration/suite/placement/quorum/insecure.go

@@ -18,12 +18,9 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
-	"strconv"
 	"testing"
 	"time"
 
-	"google.golang.org/grpc/metadata"
-
 	"github.com/spiffe/go-spiffe/v2/spiffeid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -122,7 +119,6 @@ func (i *insecure) Run(t *testing.T, ctx context.Context) {
 		}
 		t.Cleanup(func() { require.NoError(t, conn.Close()) })
 		client := v1pb.NewPlacementClient(conn)
-		ctx = metadata.AppendToOutgoingContext(ctx, "dapr-placement-api-level", strconv.Itoa(i.places[j].CurrentActorsAPILevel()))
 
 		stream, err = client.ReportDaprStatus(ctx)
 		if err != nil {