initialize the start block for the L1 synchronizer task

cmd/main.go

@@ -84,6 +84,12 @@ func start(cliCtx *cli.Context) error {
 	// derive address
 	selfAddr := crypto.PubkeyToAddress(pk.PublicKey)
 
+	// ensure synchro/reorg start block is set
+	err = synchronizer.InitStartBlock(storage, c.L1)
+	if err != nil {
+		log.Fatal(err)
+	}
+
 	var cancelFuncs []context.CancelFunc
 
 	sequencerTracker, err := synchronizer.NewSequencerTracker(c.L1, etherman)

synchronizer/init.go

@@ -0,0 +1,75 @@
+package synchronizer
+
+import (
+	"context"
+	"math/big"
+	"time"
+
+	"github.com/0xPolygon/cdk-data-availability/config"
+	"github.com/0xPolygon/cdk-data-availability/db"
+	"github.com/0xPolygon/cdk-data-availability/log"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/ethclient"
+)
+
+// InitStartBlock initializes the L1 sync task by finding the inception block for the CDKValidium contract
+func InitStartBlock(db *db.DB, l1 config.L1Config) error {
+	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Minute)
+	defer cancel()
+
+	current, err := getStartBlock(db)
+	if err != nil {
+		return err
+	}
+	if current > 0 {
+		// no need to resolve start block, it's already been set
+		return nil
+	}
+	log.Info("starting search for start block of contract", l1.CDKValidiumAddress)
+	startBlock, err := findContractDeploymentBlock(ctx, l1.RpcURL, common.HexToAddress(l1.CDKValidiumAddress))
+	if err != nil {
+		return err
+	}
+	err = setStartBlock(db, startBlock.Uint64())
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func findContractDeploymentBlock(ctx context.Context, url string, contract common.Address) (*big.Int, error) {
+	eth, err := ethclient.DialContext(ctx, url)
+	if err != nil {
+		return nil, err
+	}
+	latestBlock, err := eth.BlockByNumber(ctx, nil)
+	if err != nil {
+		return nil, err
+	}
+	b, err := findCode(ctx, eth, contract, 0, latestBlock.Number().Int64())
+	if err != nil {
+		return nil, err
+	}
+	return big.NewInt(b), nil
+}
+
+// findCode is an O(log(n)) search for the inception block of a contract at the given address
+func findCode(ctx context.Context, eth *ethclient.Client, address common.Address, startBlock, endBlock int64) (int64, error) {
+	if startBlock == endBlock {
+		return startBlock, nil
+	}
+	midBlock := (startBlock + endBlock) / 2
+	if codeLen := codeLen(ctx, eth, address, midBlock); codeLen > 2 {
+		return findCode(ctx, eth, address, startBlock, midBlock)
+	} else {
+		return findCode(ctx, eth, address, midBlock+1, endBlock)
+	}
+}
+
+func codeLen(ctx context.Context, eth *ethclient.Client, address common.Address, blockNumber int64) int64 {
+	data, err := eth.CodeAt(ctx, address, big.NewInt(blockNumber))
+	if err != nil {
+		return 0
+	}
+	return int64(len(data))
+}

test/Makefile

@@ -57,3 +57,12 @@ run-network: ## Runs the l1 network
 stop-network: ## Stops the l1 network
 	docker compose stop l1 && docker compose rm -f l1
 
+.PHONY: run-local
+run-local: run-network ## Run network and db for local instance
+	docker compose up -d cdk-data-availability-db
+
+.PHONY: stop-local
+stop-local: stop-network ## Run network and db for local instance
+	docker compose stop cdk-data-availability-db && docker compose rm -f cdk-data-availability-db
+
+