fix: block_event dedupe using linked list

.gitignore

@@ -9,3 +9,5 @@ coverage.out
 *.swo
 
 wallets.json
+
+*.key

p2p/protocol.go

@@ -41,6 +41,9 @@ type conn struct {
 	requests   *list.List
 	requestNum uint64
 
+	// Linked list of seen block hashes with timestamps
+	blockHashes *list.List
+
 	// oldestBlock stores the first block the sensor has seen so when fetching
 	// parent blocks, it does not request blocks older than this.
 	oldestBlock *types.Header
@@ -72,6 +75,14 @@ type HeadBlock struct {
 	Time            uint64
 }
 
+type BlockHashEntry struct {
+	hash common.Hash
+	time time.Time
+}
+
+// blockHashTTL defines the time-to-live for block hash entries in blockHashes list.
+var blockHashTTL = 10 * time.Minute
+
 // NewEthProctocol creates the new eth protocol. This will handle writing the
 // status exchange, message handling, and writing blocks/txs to the database.
 func NewEthProtocol(version uint, opts EthProtocolOptions) ethp2p.Protocol {
@@ -81,17 +92,18 @@ func NewEthProtocol(version uint, opts EthProtocolOptions) ethp2p.Protocol {
 		Length:  17,
 		Run: func(p *ethp2p.Peer, rw ethp2p.MsgReadWriter) error {
 			c := conn{
-				sensorID:   opts.SensorID,
-				node:       p.Node(),
-				logger:     log.With().Str("peer", p.Node().URLv4()).Logger(),
-				rw:         rw,
-				db:         opts.Database,
-				requests:   list.New(),
-				requestNum: 0,
-				head:       opts.Head,
-				headMutex:  opts.HeadMutex,
-				counter:    opts.MsgCounter,
-				name:       p.Fullname(),
+				sensorID:    opts.SensorID,
+				node:        p.Node(),
+				logger:      log.With().Str("peer", p.Node().URLv4()).Logger(),
+				rw:          rw,
+				db:          opts.Database,
+				requests:    list.New(),
+				requestNum:  0,
+				head:        opts.Head,
+				headMutex:   opts.HeadMutex,
+				counter:     opts.MsgCounter,
+				name:        p.Fullname(),
+				blockHashes: list.New(),
 			}
 
 			c.headMutex.RLock()
@@ -304,19 +316,69 @@ func (c *conn) handleNewBlockHashes(ctx context.Context, msg ethp2p.Msg) error {
 
 	c.counter.WithLabelValues(packet.Name(), c.node.URLv4(), c.name).Add(float64(len(packet)))
 
-	hashes := make([]common.Hash, 0, len(packet))
-	for _, hash := range packet {
-		hashes = append(hashes, hash.Hash)
-		if err := c.getBlockData(hash.Hash); err != nil {
+	// Collect unique hashes for database write.
+	uniqueHashes := make([]common.Hash, 0, len(packet))
+
+	for _, entry := range packet {
+		hash := entry.Hash
+		if c.hasSeenBlockHash(hash) {
+			c.logger.Info().Str("hash", hash.Hex()).Msg("Skipping duplicate block hash")
+			continue
+		}
+
+		// **Attempt to fetch block data first**
+		if err := c.getBlockData(hash); err != nil {
 			return err
 		}
+
+		// **Now that we've successfully fetched, record the new block hash**
+		c.addBlockHash(hash)
+		uniqueHashes = append(uniqueHashes, hash)
 	}
 
-	c.db.WriteBlockHashes(ctx, c.node, hashes, tfs)
+	// Write only unique hashes to the database.
+	if len(uniqueHashes) > 0 {
+		c.db.WriteBlockHashes(ctx, c.node, uniqueHashes, tfs)
+	}
 
 	return nil
 }
 
+// addBlockHash adds a new block hash with a timestamp to the blockHashes list.
+func (c *conn) addBlockHash(hash common.Hash) {
+	now := time.Now()
+
+	// Remove all entries older than blockHashTTL
+	for e := c.blockHashes.Front(); e != nil; {
+		next := e.Next() // Save the next element
+		entry := e.Value.(BlockHashEntry)
+
+		if now.Sub(entry.time) <= blockHashTTL {
+			break
+		}
+
+		c.blockHashes.Remove(e)
+		e = next
+	}
+
+	// Add the new block hash entry to the list.
+	c.blockHashes.PushBack(BlockHashEntry{
+		hash: hash,
+		time: now,
+	})
+}
+
+// Helper method to check if a block hash is already in blockHashes.
+func (c *conn) hasSeenBlockHash(hash common.Hash) bool {
+	for e := c.blockHashes.Front(); e != nil; e = e.Next() {
+		entry := e.Value.(BlockHashEntry)
+		if entry.hash.Cmp(hash) == 0 {
+			return true
+		}
+	}
+	return false
+}
+
 func (c *conn) handleTransactions(ctx context.Context, msg ethp2p.Msg) error {
 	var txs eth.TransactionsPacket
 	if err := msg.Decode(&txs); err != nil {