make root generation a function

Author: bianyuanop

chain/block.go

@@ -9,15 +9,12 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/ava-labs/avalanchego/database"
-	"github.com/ava-labs/avalanchego/database/memdb"
 	"github.com/ava-labs/avalanchego/ids"
 	"github.com/ava-labs/avalanchego/snow/choices"
 	"github.com/ava-labs/avalanchego/snow/consensus/snowman"
 	"github.com/ava-labs/avalanchego/snow/engine/snowman/block"
 	"github.com/ava-labs/avalanchego/snow/validators"
 	"github.com/ava-labs/avalanchego/utils/set"
-	"github.com/ava-labs/avalanchego/utils/units"
 	"github.com/ava-labs/avalanchego/vms/platformvm/warp"
 	"github.com/ava-labs/avalanchego/x/merkledb"
 	"go.opentelemetry.io/otel/attribute"
@@ -296,43 +293,19 @@ func (b *StatelessBlock) initializeBuilt(
 	}
 
 	// transaction hash generation
-	db, err := merkledb.New(ctx, memdb.New(), merkledb.Config{
-		BranchFactor:              merkledb.BranchFactor16,
-		HistoryLength:             100,
-		EvictionBatchSize:         units.MiB,
-		IntermediateNodeCacheSize: units.MiB,
-		ValueNodeCacheSize:        units.MiB,
-		Tracer:                    b.vm.Tracer(),
-	})
-	if err != nil {
-		return err
-	}
-	// collect keys, values from transactions/results
-	var ops []database.BatchOp
+	var merkleItems [][]byte
 	for _, tx := range b.Txs {
-		key := utils.ToID(tx.Bytes())
-		ops = append(ops, database.BatchOp{
-			Key:   key[:],
-			Value: tx.Bytes(),
-		})
+		merkleItems = append(merkleItems, tx.Bytes())
 	}
 	for _, result := range b.results {
-		key := utils.ToID(result.Output)
-		ops = append(ops, database.BatchOp{
-			Key:   key[:],
-			Value: result.Output,
-		})
+		merkleItems = append(merkleItems, result.Output)
 	}
-	view, err = db.NewView(ctx, merkledb.ViewChanges{BatchOps: ops})
-	if err != nil {
-		return err
-	}
-	view.CommitToDB(ctx)
-	txsRoot, err := db.GetMerkleRoot(ctx)
+
+	root, _, err := utils.GenerateMerkleRoot(ctx, b.vm.Tracer(), merkleItems)
 	if err != nil {
 		return err
 	}
-	b.TxsRoot = txsRoot[:]
+	b.TxsRoot = root
 
 	return nil
 }

utils/utils.go

@@ -4,6 +4,7 @@
 package utils
 
 import (
+	"context"
 	"fmt"
 	"math"
 	"net"
@@ -13,9 +14,14 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/ava-labs/avalanchego/database"
+	"github.com/ava-labs/avalanchego/database/memdb"
 	"github.com/ava-labs/avalanchego/ids"
+	"github.com/ava-labs/avalanchego/trace"
 	"github.com/ava-labs/avalanchego/utils/hashing"
 	"github.com/ava-labs/avalanchego/utils/perms"
+	"github.com/ava-labs/avalanchego/utils/units"
+	"github.com/ava-labs/avalanchego/x/merkledb"
 	"github.com/ava-labs/hypersdk/consts"
 	formatter "github.com/onsi/ginkgo/v2/formatter"
 )
@@ -116,3 +122,44 @@ func LoadBytes(filename string, expectedSize int) ([]byte, error) {
 	}
 	return bytes, nil
 }
+
+// Generate merkle root for a set of items
+// this function does not take ownership of given bytes array
+func GenerateMerkleRoot(ctx context.Context, tracer trace.Tracer, merkleItems [][]byte) ([]byte, merkledb.MerkleDB, error) {
+	var batchOps []database.BatchOp
+
+	for _, item := range merkleItems {
+		key := ToID(item)
+		batchOps = append(batchOps, database.BatchOp{
+			Key:   key[:],
+			Value: item,
+		})
+	}
+
+	db, err := merkledb.New(ctx, memdb.New(), merkledb.Config{
+		BranchFactor:              merkledb.BranchFactor16,
+		HistoryLength:             100,
+		EvictionBatchSize:         units.MiB,
+		IntermediateNodeCacheSize: units.MiB,
+		ValueNodeCacheSize:        units.MiB,
+		Tracer:                    tracer,
+	})
+	if err != nil {
+		return nil, nil, err
+	}
+
+	view, err := db.NewView(ctx, merkledb.ViewChanges{BatchOps: batchOps})
+	if err != nil {
+		return nil, nil, err
+	}
+	if err := view.CommitToDB(ctx); err != nil {
+		return nil, nil, err
+	}
+
+	root, err := db.GetMerkleRoot(ctx)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return root[:], db, nil
+}