node/pkg/ethereum: poll for guardian set changes

The new set of Eth contracts no longer emits an event.

Change-Id: I6c3654c88960b08b5548ed72cf09e555b079ef3a

bridge/pkg/ethereum/watcher.go

@@ -42,11 +42,6 @@ var (
 			Name: "wormhole_eth_messages_confirmed_total",
 			Help: "Total number of Eth messages verified (post-confirmation)",
 		}, []string{"eth_network"})
-	guardianSetChangesConfirmed = promauto.NewCounterVec(
-		prometheus.CounterOpts{
-			Name: "wormhole_eth_guardian_set_changes_confirmed_total",
-			Help: "Total number of guardian set changes verified (we only see confirmed ones to begin with)",
-		}, []string{"eth_network"})
 	currentEthHeight = promauto.NewGaugeVec(
 		prometheus.GaugeOpts{
 			Name: "wormhole_eth_current_height",
@@ -155,34 +150,54 @@ func (e *EthBridgeWatcher) Run(ctx context.Context) error {
 		return fmt.Errorf("failed to subscribe to message publication events: %w", err)
 	}
 
-	// Subscribe to guardian set changes
-	guardianSetC := make(chan *abi.AbiGuardianSetAdded, 2)
-	guardianSetEvent, err := f.WatchGuardianSetAdded(&bind.WatchOpts{Context: timeout}, guardianSetC, nil)
-	if err != nil {
-		ethConnectionErrors.WithLabelValues(e.networkName, "subscribe_error").Inc()
-		p2p.DefaultRegistry.AddErrorCount(e.chainID, 1)
-		return fmt.Errorf("failed to subscribe to guardian set events: %w", err)
-	}
+	// 0 is a valid guardian set, so we need a nil value here
+	var currentGuardianSet *uint32
 
-	// Get initial validator set.
-	timeout, cancel = context.WithTimeout(ctx, 15*time.Second)
-	defer cancel()
-	idx, gs, err := FetchCurrentGuardianSet(timeout, e.url, e.bridge)
-	if err != nil {
-		ethConnectionErrors.WithLabelValues(e.networkName, "guardian_set_fetch_error").Inc()
-		p2p.DefaultRegistry.AddErrorCount(e.chainID, 1)
-		return fmt.Errorf("failed requesting guardian set from Ethereum: %w", err)
-	}
-	logger.Info("initial guardian set fetched",
-		zap.Any("value", gs), zap.Uint32("index", idx),
-		zap.String("eth_network", e.networkName))
+	// Poll for guardian set.
+	go func() {
+		t := time.NewTicker(15 * time.Second)
+		defer t.Stop()
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-t.C:
+				msm := time.Now()
+				logger.Info("fetching guardian set")
+				timeout, cancel = context.WithTimeout(ctx, 15*time.Second)
+				idx, gs, err := fetchCurrentGuardianSet(timeout, caller)
+				if err != nil {
+					ethConnectionErrors.WithLabelValues(e.networkName, "guardian_set_fetch_error").Inc()
+					p2p.DefaultRegistry.AddErrorCount(e.chainID, 1)
+					logger.Error("failed requesting guardian set",
+						zap.Error(err), zap.String("eth_network", e.networkName))
+					cancel()
+					continue
+				}
 
-	if e.setChan != nil {
-		e.setChan <- &common.GuardianSet{
-			Keys:  gs.Keys,
-			Index: idx,
+				queryLatency.WithLabelValues(e.networkName, "get_guardian_set").Observe(time.Since(msm).Seconds())
+
+				cancel()
+
+				if currentGuardianSet != nil && *currentGuardianSet == idx {
+					continue
+				}
+
+				logger.Info("updated guardian set found",
+					zap.Any("value", gs), zap.Uint32("index", idx),
+					zap.String("eth_network", e.networkName))
+
+				currentGuardianSet = &idx
+
+				if e.setChan != nil {
+					e.setChan <- &common.GuardianSet{
+						Keys:  gs.Keys,
+						Index: idx,
+					}
+				}
+			}
 		}
-	}
+	}()
 
 	errC := make(chan error)
 	go func() {
@@ -195,11 +210,6 @@ func (e *EthBridgeWatcher) Run(ctx context.Context) error {
 				errC <- fmt.Errorf("error while processing message publication subscription: %w", err)
 				p2p.DefaultRegistry.AddErrorCount(e.chainID, 1)
 				return
-			case err := <-guardianSetEvent.Err():
-				ethConnectionErrors.WithLabelValues(e.networkName, "subscription_error").Inc()
-				errC <- fmt.Errorf("error while processing guardian set subscription: %w", err)
-				p2p.DefaultRegistry.AddErrorCount(e.chainID, 1)
-				return
 			case ev := <-messageC:
 				// Request timestamp for block
 				msm := time.Now()
@@ -237,34 +247,6 @@ func (e *EthBridgeWatcher) Run(ctx context.Context) error {
 					height:  ev.Raw.BlockNumber,
 				}
 				e.pendingMu.Unlock()
-			case ev := <-guardianSetC:
-				logger.Info("guardian set has changed, fetching new value",
-					zap.Uint32("new_index", ev.Index), zap.String("eth_network", e.networkName))
-
-				guardianSetChangesConfirmed.WithLabelValues(e.networkName).Inc()
-
-				msm := time.Now()
-				timeout, cancel = context.WithTimeout(ctx, 15*time.Second)
-				gs, err := caller.GetGuardianSet(&bind.CallOpts{Context: timeout}, ev.Index)
-				cancel()
-				queryLatency.WithLabelValues(e.networkName, "get_guardian_set").Observe(time.Since(msm).Seconds())
-				if err != nil {
-					// We failed to process the guardian set update and are now out of sync with the chain.
-					// Recover by crashing the runnable, which causes the guardian set to be re-fetched.
-					errC <- fmt.Errorf("error requesting new guardian set value for %d: %w", ev.Index, err)
-					return
-				}
-
-				logger.Info("new guardian set fetched",
-					zap.Any("value", gs), zap.Uint32("index", ev.Index),
-					zap.String("eth_network", e.networkName))
-
-				if e.setChan != nil {
-					e.setChan <- &common.GuardianSet{
-						Keys:  gs.Keys,
-						Index: ev.Index,
-					}
-				}
 			}
 		}
 	}()
@@ -338,17 +320,7 @@ func (e *EthBridgeWatcher) Run(ctx context.Context) error {
 }
 
 // Fetch the current guardian set ID and guardian set from the chain.
-func FetchCurrentGuardianSet(ctx context.Context, rpcURL string, bridgeContract eth_common.Address) (uint32, *abi.StructsGuardianSet, error) {
-	c, err := ethclient.DialContext(ctx, rpcURL)
-	if err != nil {
-		return 0, nil, fmt.Errorf("dialing eth client failed: %w", err)
-	}
-
-	caller, err := abi.NewAbiCaller(bridgeContract, c)
-	if err != nil {
-		panic(err)
-	}
-
+func fetchCurrentGuardianSet(ctx context.Context, caller *abi.AbiCaller) (uint32, *abi.StructsGuardianSet, error) {
 	opts := &bind.CallOpts{Context: ctx}
 
 	currentIndex, err := caller.GetCurrentGuardianSetIndex(opts)