From 77c5fc944a9e5e3da24cee6fe64da7b73acee76e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marcin=20G=C3=B3rzy=C5=84ski?= <marcin@gorzynski.me>
Date: Fri, 5 Apr 2024 22:43:27 +0200
Subject: [PATCH] Lazy ethmonitor & ethreceipts initialization (#117)

---
 ethmonitor/ethmonitor.go   | 27 +++++++++++++-------
 ethreceipts/ethreceipts.go | 50 ++++++++++++++++++++++++--------------
 2 files changed, 50 insertions(+), 27 deletions(-)

diff --git a/ethmonitor/ethmonitor.go b/ethmonitor/ethmonitor.go
index ebd75be5..b9b22af8 100644
--- a/ethmonitor/ethmonitor.go
+++ b/ethmonitor/ethmonitor.go
@@ -150,11 +150,7 @@ func NewMonitor(provider ethrpc.RawInterface, options ...Options) (*Monitor, err
 		}
 	}
 
-	chainID, err := getChainID(provider)
-	if err != nil {
-		return nil, err
-	}
-
+	var err error
 	var cache cachestore.Store[[]byte]
 	if opts.CacheBackend != nil {
 		cache, err = cachestorectl.Open[[]byte](opts.CacheBackend, cachestore.WithLockExpiry(5*time.Second))
@@ -173,7 +169,7 @@ func NewMonitor(provider ethrpc.RawInterface, options ...Options) (*Monitor, err
 		alert:        opts.Alerter,
 		provider:     provider,
 		chain:        newChain(opts.BlockRetentionLimit, opts.Bootstrap),
-		chainID:      chainID,
+		chainID:      nil,
 		cache:        cache,
 		publishCh:    make(chan Blocks),
 		publishQueue: newQueue(opts.BlockRetentionLimit * 2),
@@ -181,6 +177,15 @@ func NewMonitor(provider ethrpc.RawInterface, options ...Options) (*Monitor, err
 	}, nil
 }
 
+func (m *Monitor) lazyInit(ctx context.Context) error {
+	var err error
+	m.chainID, err = getChainID(ctx, m.provider)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
 func (m *Monitor) Run(ctx context.Context) error {
 	if m.IsRunning() {
 		return fmt.Errorf("ethmonitor: already running")
@@ -191,6 +196,10 @@ func (m *Monitor) Run(ctx context.Context) error {
 	atomic.StoreInt32(&m.running, 1)
 	defer atomic.StoreInt32(&m.running, 0)
 
+	if err := m.lazyInit(ctx); err != nil {
+		return err
+	}
+
 	// Check if in bootstrap mode -- in which case we expect nextBlockNumber
 	// to already be set.
 	if m.options.Bootstrap && m.chain.blocks == nil {
@@ -1022,10 +1031,10 @@ func (m *Monitor) setPayload(value []byte) []byte {
 	}
 }
 
-func getChainID(provider ethrpc.Interface) (*big.Int, error) {
+func getChainID(ctx context.Context, provider ethrpc.Interface) (*big.Int, error) {
 	var chainID *big.Int
-	err := breaker.Do(context.Background(), func() error {
-		ctx, cancel := context.WithTimeout(context.Background(), 4*time.Second)
+	err := breaker.Do(ctx, func() error {
+		ctx, cancel := context.WithTimeout(ctx, 4*time.Second)
 		defer cancel()
 
 		id, err := provider.ChainID(ctx)
diff --git a/ethreceipts/ethreceipts.go b/ethreceipts/ethreceipts.go
index e0d740a5..61137656 100644
--- a/ethreceipts/ethreceipts.go
+++ b/ethreceipts/ethreceipts.go
@@ -134,20 +134,6 @@ func NewReceiptsListener(log logger.Logger, provider ethrpc.Interface, monitor *
 		return nil, err
 	}
 
-	if opts.NumBlocksToFinality <= 0 {
-		chainID, err := getChainID(provider)
-		if err != nil {
-			chainID = big.NewInt(1) // assume mainnet in case of unlikely error
-		}
-		network, ok := ethrpc.Networks[chainID.Uint64()]
-		if ok {
-			opts.NumBlocksToFinality = network.NumBlocksToFinality
-		}
-	}
-	if opts.NumBlocksToFinality <= 0 {
-		opts.NumBlocksToFinality = 1 // absolute min is 1
-	}
-
 	return &ReceiptsListener{
 		options:           opts,
 		log:               log,
@@ -164,6 +150,25 @@ func NewReceiptsListener(log logger.Logger, provider ethrpc.Interface, monitor *
 	}, nil
 }
 
+func (l *ReceiptsListener) lazyInit(ctx context.Context) error {
+	if l.options.NumBlocksToFinality <= 0 {
+		chainID, err := getChainID(ctx, l.provider)
+		if err != nil {
+			chainID = big.NewInt(1) // assume mainnet in case of unlikely error
+		}
+		network, ok := ethrpc.Networks[chainID.Uint64()]
+		if ok {
+			l.options.NumBlocksToFinality = network.NumBlocksToFinality
+		}
+	}
+
+	if l.options.NumBlocksToFinality <= 0 {
+		l.options.NumBlocksToFinality = 1 // absolute min is 1
+	}
+
+	return nil
+}
+
 func (l *ReceiptsListener) Run(ctx context.Context) error {
 	if l.IsRunning() {
 		return fmt.Errorf("ethreceipts: already running")
@@ -174,6 +179,10 @@ func (l *ReceiptsListener) Run(ctx context.Context) error {
 	atomic.StoreInt32(&l.running, 1)
 	defer atomic.StoreInt32(&l.running, 0)
 
+	if err := l.lazyInit(ctx); err != nil {
+		return err
+	}
+
 	l.log.Info("ethreceipts: running")
 
 	return l.listener()
@@ -801,19 +810,24 @@ func (l *ReceiptsListener) latestBlockNum() *big.Int {
 	return latestBlockNum
 }
 
-func getChainID(provider ethrpc.Interface) (*big.Int, error) {
+func getChainID(ctx context.Context, provider ethrpc.Interface) (*big.Int, error) {
 	var chainID *big.Int
-	err := breaker.Do(context.Background(), func() error {
-		id, err := provider.ChainID(context.Background())
+	err := breaker.Do(ctx, func() error {
+		ctx, cancel := context.WithTimeout(ctx, 4*time.Second)
+		defer cancel()
+
+		id, err := provider.ChainID(ctx)
 		if err != nil {
 			return err
 		}
 		chainID = id
 		return nil
-	}, nil, 1*time.Second, 2, 20)
+	}, nil, 1*time.Second, 2, 3)
+
 	if err != nil {
 		return nil, err
 	}
+
 	return chainID, nil
 }