proxyd: emit event on consensus broken

proxyd/proxyd/cache.go

@@ -12,6 +12,7 @@ import (
 type Cache interface {
 	Get(ctx context.Context, key string) (string, error)
 	Put(ctx context.Context, key string, value string) error
+	Clear(ctx context.Context) error
 }
 
 const (
@@ -42,6 +43,11 @@ func (c *cache) Put(ctx context.Context, key string, value string) error {
 	return nil
 }
 
+func (c *cache) Clear(ctx context.Context) error {
+	c.lru.Purge()
+	return nil
+}
+
 type redisCache struct {
 	rdb *redis.Client
 }
@@ -75,6 +81,29 @@ func (c *redisCache) Put(ctx context.Context, key string, value string) error {
 	return err
 }
 
+func (c *redisCache) Clear(ctx context.Context) error {
+	patterns := []string{"lvc:*", "method:*"}
+
+	for _, p := range patterns {
+		scmd := c.rdb.Keys(ctx, p)
+		err := scmd.Err()
+		if err != nil {
+			RecordRedisError("CacheClear")
+			return err
+		}
+		keys, _ := scmd.Result()
+
+		icmd := c.rdb.Del(ctx, keys...)
+		err = icmd.Err()
+		if err != nil {
+			RecordRedisError("CacheClear")
+			return err
+		}
+	}
+
+	return nil
+}
+
 type cacheWithCompression struct {
 	cache Cache
 }
@@ -103,6 +132,10 @@ func (c *cacheWithCompression) Put(ctx context.Context, key string, value string
 	return c.cache.Put(ctx, key, string(encodedVal))
 }
 
+func (c *cacheWithCompression) Clear(ctx context.Context) error {
+	return c.cache.Clear(ctx)
+}
+
 type GetLatestBlockNumFn func(ctx context.Context) (uint64, error)
 type GetLatestGasPriceFn func(ctx context.Context) (uint64, error)
 

proxyd/proxyd/consensus_poller.go

@@ -17,11 +17,14 @@ const (
 	PollerInterval = 1 * time.Second
 )
 
+type OnConsensusBroken func()
+
 // ConsensusPoller checks the consensus state for each member of a BackendGroup
 // resolves the highest common block for multiple nodes, and reconciles the consensus
 // in case of block hash divergence to minimize re-orgs
 type ConsensusPoller struct {
 	cancelFunc context.CancelFunc
+	listeners  []OnConsensusBroken
 
 	backendGroup      *BackendGroup
 	backendState      map[*Backend]*backendState
@@ -149,6 +152,16 @@ func WithAsyncHandler(asyncHandler ConsensusAsyncHandler) ConsensusOpt {
 	}
 }
 
+func WithListener(listener OnConsensusBroken) ConsensusOpt {
+	return func(cp *ConsensusPoller) {
+		cp.AddListener(listener)
+	}
+}
+
+func (cp *ConsensusPoller) AddListener(listener OnConsensusBroken) {
+	cp.listeners = append(cp.listeners, listener)
+}
+
 func WithBanPeriod(banPeriod time.Duration) ConsensusOpt {
 	return func(cp *ConsensusPoller) {
 		cp.banPeriod = banPeriod
@@ -349,6 +362,7 @@ func (cp *ConsensusPoller) UpdateBackendGroupConsensus(ctx context.Context) {
 				- with minimum peer count
 				- updated recently
 				- not lagging
+			    - in sync
 			*/
 
 			peerCount, latestBlockNumber, _, lastUpdate, bannedUntil := cp.getBackendState(be)
@@ -392,7 +406,9 @@ func (cp *ConsensusPoller) UpdateBackendGroupConsensus(ctx context.Context) {
 	}
 
 	if broken {
-		// propagate event to other interested parts, such as cache invalidator
+		for _, l := range cp.listeners {
+			l()
+		}
 		log.Info("consensus broken", "currentConsensusBlockNumber", currentConsensusBlockNumber, "proposedBlock", proposedBlock, "proposedBlockHash", proposedBlockHash)
 	}
 

proxyd/proxyd/integration_tests/consensus_test.go

@@ -286,6 +286,11 @@ func TestConsensus(t *testing.T) {
 		h2.ResetOverrides()
 		bg.Consensus.Unban()
 
+		listenerCalled := false
+		bg.Consensus.AddListener(func() {
+			listenerCalled = true
+		})
+
 		for _, be := range bg.Backends {
 			bg.Consensus.UpdateBackend(ctx, be)
 		}
@@ -331,7 +336,7 @@ func TestConsensus(t *testing.T) {
 		// should resolve to 0x1, since 0x2 is out of consensus at the moment
 		require.Equal(t, "0x1", bg.Consensus.GetConsensusBlockNumber().String())
 
-		// later, when impl events, listen to broken consensus event
+		require.True(t, listenerCalled)
 	})
 
 	t.Run("broken consensus with depth 2", func(t *testing.T) {