From 73c102235a3bd8ecd2504423f8c544e92a0b4257 Mon Sep 17 00:00:00 2001
From: gupadhyaya <ganeshrvce@gmail.com>
Date: Fri, 2 Aug 2024 10:09:59 +0400
Subject: [PATCH] use pointers to batch

---
 go.mod                  |  2 +-
 go.sum                  |  4 ++--
 sequencing/sequencer.go | 20 ++++++++++++++++----
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/go.mod b/go.mod
index 4866df2..c42f8c3 100644
--- a/go.mod
+++ b/go.mod
@@ -8,7 +8,7 @@ require (
 	github.com/gogo/protobuf v1.3.2
 	github.com/ipfs/go-log/v2 v2.5.1
 	github.com/rollkit/go-da v0.5.0
-	github.com/rollkit/go-sequencing v0.0.0-20240719145307-0166b8267e96
+	github.com/rollkit/go-sequencing v0.0.0-20240802060839-c195453f5eac
 	github.com/rollkit/rollkit v0.13.6
 )
 
diff --git a/go.sum b/go.sum
index d672ede..d0daef3 100644
--- a/go.sum
+++ b/go.sum
@@ -316,8 +316,8 @@ github.com/rogpeppe/go-internal v1.11.0 h1:cWPaGQEPrBb5/AsnsZesgZZ9yb1OQ+GOISoDN
 github.com/rogpeppe/go-internal v1.11.0/go.mod h1:ddIwULY96R17DhadqLgMfk9H9tvdUzkipdSkR5nkCZA=
 github.com/rollkit/go-da v0.5.0 h1:sQpZricNS+2TLx3HMjNWhtRfqtvVC/U4pWHpfUz3eN4=
 github.com/rollkit/go-da v0.5.0/go.mod h1:VsUeAoPvKl4Y8wWguu/VibscYiFFePkkrvZWyTjZHww=
-github.com/rollkit/go-sequencing v0.0.0-20240719145307-0166b8267e96 h1:5PDb1OkVhhe+FQdw6qX9agShN4bxH5Iz+bRrRmeMrZs=
-github.com/rollkit/go-sequencing v0.0.0-20240719145307-0166b8267e96/go.mod h1:J6E6NR7tNJ0cKBxtVHnby0hQ+S7RTayuDfG1Llwv800=
+github.com/rollkit/go-sequencing v0.0.0-20240802060839-c195453f5eac h1:tawGnkr4zMiGQDPlFOZupsw1HzGbbT9dHQNUcXyRmW4=
+github.com/rollkit/go-sequencing v0.0.0-20240802060839-c195453f5eac/go.mod h1:J6E6NR7tNJ0cKBxtVHnby0hQ+S7RTayuDfG1Llwv800=
 github.com/rollkit/rollkit v0.13.6 h1:ZdIBG5D5RuQvnnJSY8s3m46dR3A3F6jHN+01zX+Avt0=
 github.com/rollkit/rollkit v0.13.6/go.mod h1:clM4aPsWDJk/IN/SqCBsA+ab0/8gdh+5O4hRkLWKB7s=
 github.com/russross/blackfriday v1.5.2/go.mod h1:JO/DiYxRf+HjHt06OyowR9PTA263kcR/rfWxYHBV53g=
diff --git a/sequencing/sequencer.go b/sequencing/sequencer.go
index 6fbc5ec..748babb 100644
--- a/sequencing/sequencer.go
+++ b/sequencing/sequencer.go
@@ -289,19 +289,31 @@ func (c *Sequencer) SubmitRollupTransaction(ctx context.Context, rollupId []byte
 }
 
 // GetNextBatch implements sequencing.Sequencer.
-func (c *Sequencer) GetNextBatch(ctx context.Context, lastBatch sequencing.Batch) (sequencing.Batch, error) {
+func (c *Sequencer) GetNextBatch(ctx context.Context, lastBatch *sequencing.Batch) (*sequencing.Batch, error) {
+	// check the lastBatchHash to match the hash of the supplied lastBatch
+	if lastBatch == nil && c.lastBatchHash != nil {
+		return nil, errors.New("lastBatch is not supposed to be nil")
+	}
+	lastBatchBytes, err := lastBatch.Marshal()
+	if err != nil {
+		return nil, err
+	}
+	lastBatchHash := hashSHA256(lastBatchBytes)
+	if !bytes.Equal(c.lastBatchHash, lastBatchHash) {
+		return nil, errors.New("supplied lastBatch does not match with sequencer last batch")
+	}
 	batch := c.bq.Next()
 	batchBytes, err := batch.Marshal()
 	if err != nil {
-		return sequencing.Batch{}, err
+		return nil, err
 	}
 	c.lastBatchHash = hashSHA256(batchBytes)
 	c.seenBatches[string(c.lastBatchHash)] = struct{}{}
-	return *batch, nil
+	return batch, nil
 }
 
 // VerifyBatch implements sequencing.Sequencer.
-func (c *Sequencer) VerifyBatch(ctx context.Context, batch sequencing.Batch) (bool, error) {
+func (c *Sequencer) VerifyBatch(ctx context.Context, batch *sequencing.Batch) (bool, error) {
 	//TODO: need to add DA verification
 	batchBytes, err := batch.Marshal()
 	if err != nil {