feat(ffi-iterator): Benchmarking for Iterator (4/4)

ffi/firewood.go

@@ -152,8 +152,7 @@ func (db *Database) Propose(keys, vals [][]byte) (*Proposal, error) {
 		return nil, err
 	}
 
-	val := C.fwd_propose_on_db(db.handle, kvp)
-	return newProposal(db.handle, &val)
+	return getProposalFromProposalResult(C.fwd_propose_on_db(db.handle, kvp), db)
 }
 
 // Get retrieves the value for the given key. It always returns a nil error.
@@ -199,6 +198,28 @@ func (db *Database) GetFromRoot(root, key []byte) ([]byte, error) {
 	))
 }
 
+// IterLatest creates and iterator starting from the provided key on the latest root hash.
+// pass empty slice to start from beginning
+func (db *Database) IterLatest(key []byte) (*Iterator, error) {
+	return db.IterOnRoot(nil, key)
+}
+
+// IterOnRoot creates and iterator starting from the provided key on a specific root hash.
+// If the root is not found, it returns as an error.
+// pass empty slice to start from beginning
+func (db *Database) IterOnRoot(root, key []byte) (*Iterator, error) {
+	if db.handle == nil {
+		return nil, errDBClosed
+	}
+
+	var pinner runtime.Pinner
+	defer pinner.Unpin()
+
+	itResult := C.fwd_iter_on_root(db.handle, newBorrowedBytes(root, &pinner), newBorrowedBytes(key, &pinner))
+
+	return getIteratorFromIteratorResult(itResult, db)
+}
+
 // Root returns the current root hash of the trie.
 // Empty trie must return common.Hash{}.
 func (db *Database) Root() ([]byte, error) {