firewaldb: single implementation of BBolt DBExecutor

The `kvStores` and `privacyMapDB` types have very similar looking
`Update` and `View` methods. Instead of the duplication, here we let
things be more generic by defining a generic `kvdbExecutor` which has
Update and View methods defined.

firewalldb/kvdb_store.go

@@ -0,0 +1,44 @@
+package firewalldb
+
+import (
+	"context"
+
+	"go.etcd.io/bbolt"
+)
+
+// kvdbExecutor is a concrete implementation of the DBExecutor interface that
+// uses a bbolt database as its backing store.
+type kvdbExecutor[T any] struct {
+	db     *bbolt.DB
+	wrapTx func(tx *bbolt.Tx) T
+}
+
+// Update opens a database read/write transaction and executes the function f
+// with the transaction passed as a parameter. After f exits, if f did not
+// error, the transaction is committed. Otherwise, if f did error, the
+// transaction is rolled back. If the rollback fails, the original error
+// returned by f is still returned. If the commit fails, the commit error is
+// returned.
+//
+// NOTE: this is part of the DBExecutor interface.
+func (e *kvdbExecutor[T]) Update(ctx context.Context,
+	fn func(ctx context.Context, tx T) error) error {
+
+	return e.db.Update(func(tx *bbolt.Tx) error {
+		return fn(ctx, e.wrapTx(tx))
+	})
+}
+
+// View opens a database read transaction and executes the function f with the
+// transaction passed as a parameter. After f exits, the transaction is rolled
+// back. If f errors, its error is returned, not a rollback error (if any
+// occur).
+//
+// NOTE: this is part of the DBExecutor interface.
+func (e *kvdbExecutor[T]) View(ctx context.Context,
+	fn func(ctx context.Context, tx T) error) error {
+
+	return e.db.View(func(tx *bbolt.Tx) error {
+		return fn(ctx, e.wrapTx(tx))
+	})
+}

firewalldb/kvstores.go

@@ -107,62 +107,28 @@ type RulesDB interface {
 func (db *DB) GetKVStores(rule string, groupID session.ID,
 	feature string) KVStores {
 
-	return &kvStores{
-		db:          db.DB,
-		ruleName:    rule,
-		groupID:     groupID,
-		featureName: feature,
+	return &kvdbExecutor[KVStoreTx]{
+		db: db.DB,
+		wrapTx: func(tx *bbolt.Tx) KVStoreTx {
+			return &kvStoreTx{
+				boltTx: tx,
+				kvStores: &kvStores{
+					ruleName:    rule,
+					groupID:     groupID,
+					featureName: feature,
+				},
+			}
+		},
 	}
 }
 
 // kvStores implements the rules.KVStores interface.
 type kvStores struct {
-	db          *bbolt.DB
 	ruleName    string
 	groupID     session.ID
 	featureName string
 }
 
-// Update opens a database read/write transaction and executes the function f
-// with the transaction passed as a parameter. After f exits, if f did not
-// error, the transaction is committed. Otherwise, if f did error, the
-// transaction is rolled back. If the rollback fails, the original error
-// returned by f is still returned. If the commit fails, the commit error is
-// returned.
-//
-// NOTE: this is part of the KVStores interface.
-func (s *kvStores) Update(ctx context.Context, fn func(ctx context.Context,
-	tx KVStoreTx) error) error {
-
-	return s.db.Update(func(tx *bbolt.Tx) error {
-		boltTx := &kvStoreTx{
-			boltTx:   tx,
-			kvStores: s,
-		}
-
-		return fn(ctx, boltTx)
-	})
-}
-
-// View opens a database read transaction and executes the function f with the
-// transaction passed as a parameter. After f exits, the transaction is rolled
-// back. If f errors, its error is returned, not a rollback error (if any
-// occur).
-//
-// NOTE: this is part of the KVStores interface.
-func (s *kvStores) View(ctx context.Context, fn func(ctx context.Context,
-	tx KVStoreTx) error) error {
-
-	return s.db.View(func(tx *bbolt.Tx) error {
-		boltTx := &kvStoreTx{
-			boltTx:   tx,
-			kvStores: s,
-		}
-
-		return fn(ctx, boltTx)
-	})
-}
-
 // getBucketFunc defines the signature of the bucket creation/fetching function
 // required by kvStoreTx. If create is true, then all the bucket (and all
 // buckets leading up to the bucket) should be created if they do not already

firewalldb/privacy_mapper.go

@@ -42,9 +42,16 @@ type NewPrivacyMapDB func(groupID session.ID) PrivacyMapDB
 // PrivacyDB constructs a PrivacyMapDB that will be indexed under the given
 // group ID key.
 func (db *DB) PrivacyDB(groupID session.ID) PrivacyMapDB {
-	return &privacyMapDB{
-		db:      db,
-		groupID: groupID,
+	return &kvdbExecutor[PrivacyMapTx]{
+		db: db.DB,
+		wrapTx: func(tx *bbolt.Tx) PrivacyMapTx {
+			return &privacyMapTx{
+				boltTx: tx,
+				privacyMapDB: &privacyMapDB{
+					groupID: groupID,
+				},
+			}
+		},
 	}
 }
 
@@ -74,50 +81,9 @@ type PrivacyMapTx interface {
 
 // privacyMapDB is an implementation of PrivacyMapDB.
 type privacyMapDB struct {
-	db      *DB
 	groupID session.ID
 }
 
-// Update opens a database read/write transaction and executes the function f
-// with the transaction passed as a parameter. After f exits, if f did not
-// error, the transaction is committed. Otherwise, if f did error, the
-// transaction is rolled back. If the rollback fails, the original error
-// returned by f is still returned. If the commit fails, the commit error is
-// returned.
-//
-// NOTE: this is part of the PrivacyMapDB interface.
-func (p *privacyMapDB) Update(ctx context.Context, fn func(ctx context.Context,
-	tx PrivacyMapTx) error) error {
-
-	return p.db.Update(func(tx *bbolt.Tx) error {
-		boltTx := &privacyMapTx{
-			privacyMapDB: p,
-			boltTx:       tx,
-		}
-
-		return fn(ctx, boltTx)
-	})
-}
-
-// View opens a database read transaction and executes the function f with the
-// transaction passed as a parameter. After f exits, the transaction is rolled
-// back. If f errors, its error is returned, not a rollback error (if any
-// occur).
-//
-// NOTE: this is part of the PrivacyMapDB interface.
-func (p *privacyMapDB) View(ctx context.Context, fn func(ctx context.Context,
-	tx PrivacyMapTx) error) error {
-
-	return p.db.View(func(tx *bbolt.Tx) error {
-		boltTx := &privacyMapTx{
-			privacyMapDB: p,
-			boltTx:       tx,
-		}
-
-		return fn(ctx, boltTx)
-	})
-}
-
 // privacyMapTx is an implementation of PrivacyMapTx.
 type privacyMapTx struct {
 	*privacyMapDB