From a638f1b95d69b710930c94533103f17e3a2d7b74 Mon Sep 17 00:00:00 2001
From: Ralph Pichler <pichler.ralph@gmail.com>
Date: Wed, 5 Feb 2020 15:21:55 +0100
Subject: [PATCH] state, swap: add batch support to state store (#2088)

---
 state/dbstore.go      | 33 +++++++++++++++++++++
 state/dbstore_test.go | 69 +++++++++++++++++++++++++++++++++++++++++++
 swap/swap.go          | 17 ++++++++---
 3 files changed, 115 insertions(+), 4 deletions(-)

diff --git a/state/dbstore.go b/state/dbstore.go
index 4d651e583b..5fa978675f 100644
--- a/state/dbstore.go
+++ b/state/dbstore.go
@@ -36,6 +36,7 @@ type Store interface {
 	Put(key string, i interface{}) (err error)
 	Delete(key string) (err error)
 	Iterate(prefix string, iterFunc iterFunction) (err error)
+	WriteBatch(batch *StoreBatch) (err error)
 	Close() error
 }
 
@@ -132,3 +133,35 @@ func (s *DBStore) Iterate(prefix string, iterFunc iterFunction) (err error) {
 func (s *DBStore) Close() error {
 	return s.db.Close()
 }
+
+// StoreBatch is a wrapper around a leveldb batch that takes care of the proper encoding.
+type StoreBatch struct {
+	leveldb.Batch
+}
+
+// Put encodes the value and puts a corresponding Put operation into the underlying batch.
+// This only returns an error if the encoding failed.
+func (b *StoreBatch) Put(key string, i interface{}) (err error) {
+	var bytes []byte
+	if marshaler, ok := i.(encoding.BinaryMarshaler); ok {
+		if bytes, err = marshaler.MarshalBinary(); err != nil {
+			return err
+		}
+	} else {
+		if bytes, err = json.Marshal(i); err != nil {
+			return err
+		}
+	}
+	b.Batch.Put([]byte(key), bytes)
+	return nil
+}
+
+// Delete adds a delete operation to the underlying batch.
+func (b *StoreBatch) Delete(key string) {
+	b.Batch.Delete([]byte(key))
+}
+
+// WriteBatch executes the batch on the underlying database.
+func (s *DBStore) WriteBatch(batch *StoreBatch) error {
+	return s.db.Write(&batch.Batch, nil)
+}
diff --git a/state/dbstore_test.go b/state/dbstore_test.go
index 1eddbe560e..27406c9371 100644
--- a/state/dbstore_test.go
+++ b/state/dbstore_test.go
@@ -86,6 +86,13 @@ func TestDBStore(t *testing.T) {
 	}
 
 	testStoreIterator(t, iteratedStore)
+
+	batchedStore, err := NewDBStore(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	testStoreBatch(t, batchedStore)
 }
 
 func testStore(t *testing.T, store Store) {
@@ -175,3 +182,65 @@ func testStoreIterator(t *testing.T, store Store) {
 		t.Fatalf("expected store entries to be %v, are %v instead", expectedEntries, entries)
 	}
 }
+
+func testStoreBatch(t *testing.T, store Store) {
+	defer store.Close()
+
+	batch := new(StoreBatch)
+
+	var val1 uint64 = 1
+	var val2 uint64 = 2
+
+	err := batch.Put("key1", val1)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = batch.Put("key2", val2)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = store.WriteBatch(batch)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var result uint64
+	err = store.Get("key1", &result)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if result != val1 {
+		t.Fatalf("expected key1 to be %d, was %d instead", val1, result)
+	}
+
+	err = store.Get("key2", &result)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if result != val2 {
+		t.Fatalf("expected key1 to be %d, was %d instead", val2, result)
+	}
+
+	batch = new(StoreBatch)
+	batch.Delete("key1")
+	batch.Delete("key2")
+
+	err = store.WriteBatch(batch)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = store.Get("key1", &result)
+	if err != ErrNotFound {
+		t.Fatal("expected key1 to be deleted")
+	}
+
+	err = store.Get("key2", &result)
+	if err != ErrNotFound {
+		t.Fatal("expected key2 to be deleted")
+	}
+}
diff --git a/swap/swap.go b/swap/swap.go
index 6218095358..bd2d5c8dd9 100644
--- a/swap/swap.go
+++ b/swap/swap.go
@@ -465,16 +465,25 @@ func (s *Swap) handleConfirmChequeMsg(ctx context.Context, p *Peer, msg *Confirm
 		return fmt.Errorf("ignoring confirm msg, unexpected cheque, confirm message cheque %s, expected %s", cheque, p.getPendingCheque())
 	}
 
-	err := p.setLastSentCheque(cheque)
+	batch := new(state.StoreBatch)
+	err := batch.Put(sentChequeKey(p.ID()), cheque)
 	if err != nil {
-		return protocols.Break(fmt.Errorf("setLastSentCheque failed: %w", err))
+		return protocols.Break(fmt.Errorf("encoding cheque failed: %w", err))
 	}
 
-	err = p.setPendingCheque(nil)
+	err = batch.Put(pendingChequeKey(p.ID()), nil)
 	if err != nil {
-		return protocols.Break(fmt.Errorf("setPendingCheque failed: %w", err))
+		return protocols.Break(fmt.Errorf("encoding pending cheque failed: %w", err))
 	}
 
+	err = s.store.WriteBatch(batch)
+	if err != nil {
+		return protocols.Break(fmt.Errorf("could not write cheque to database: %w", err))
+	}
+
+	p.lastSentCheque = cheque
+	p.pendingCheque = nil
+
 	return nil
 }