From 5a0ae55f6d355fcac82fcc6f8f7a91ce2ff22ae4 Mon Sep 17 00:00:00 2001
From: Tomasz Grabiec <tgrabiec@scylladb.com>
Date: Thu, 8 Jun 2017 13:45:56 +0200
Subject: [PATCH] Introduce schema_upgrader

---
 schema_upgrader.hh              | 68 +++++++++++++++++++++++++++++++++
 tests/streamed_mutation_test.cc | 20 ++++++++++
 2 files changed, 88 insertions(+)
 create mode 100644 schema_upgrader.hh

diff --git a/schema_upgrader.hh b/schema_upgrader.hh
new file mode 100644
index 0000000000..2683cec7dd
--- /dev/null
+++ b/schema_upgrader.hh
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2017 ScyllaDB
+ */
+
+/*
+ * This file is part of Scylla.
+ *
+ * Scylla is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Scylla is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Scylla.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "streamed_mutation.hh"
+#include "converting_mutation_partition_applier.hh"
+
+// A StreamedMutationTransformer which transforms the stream to a different schema
+class schema_upgrader {
+    schema_ptr _prev;
+    schema_ptr _new;
+private:
+    row transform(row&& r, column_kind kind) {
+        row new_row;
+        r.for_each_cell([&] (column_id id, atomic_cell_or_collection& cell) {
+            const column_definition& col = _prev->column_at(kind, id);
+            const column_definition* new_col = _new->get_column_definition(col.name());
+            if (new_col) {
+                converting_mutation_partition_applier::append_cell(new_row, kind, *new_col, col.type, std::move(cell));
+            }
+        });
+        return new_row;
+    }
+public:
+    schema_upgrader(schema_ptr s)
+        : _new(std::move(s))
+    { }
+    schema_ptr operator()(schema_ptr old) {
+        _prev = std::move(old);
+        return _new;
+    }
+    mutation_fragment consume(static_row&& row) {
+        return mutation_fragment(static_row(transform(std::move(row.cells()), column_kind::static_column)));
+    }
+    mutation_fragment consume(clustering_row&& row) {
+        return mutation_fragment(clustering_row(row.key(), row.tomb(), row.marker(),
+            transform(std::move(row.cells()), column_kind::regular_column)));
+    }
+    mutation_fragment consume(range_tombstone&& rt) {
+        return std::move(rt);
+    }
+    mutation_fragment operator()(mutation_fragment&& mf) {
+        return std::move(mf).consume(*this);
+    }
+};
+
+GCC6_CONCEPT(
+static_assert(StreamedMutationTranformer<schema_upgrader>());
+)
diff --git a/tests/streamed_mutation_test.cc b/tests/streamed_mutation_test.cc
index 3879f41edf..2ff294f817 100644
--- a/tests/streamed_mutation_test.cc
+++ b/tests/streamed_mutation_test.cc
@@ -29,8 +29,10 @@
 #include "tests/test_services.hh"
 #include "schema_builder.hh"
 #include "total_order_check.hh"
+#include "schema_upgrader.hh"
 
 #include "disk-error-handler.hh"
+#include "mutation_assertions.hh"
 
 thread_local disk_error_signal_type commit_error;
 thread_local disk_error_signal_type general_disk_error;
@@ -538,3 +540,21 @@ SEASTAR_TEST_CASE(test_ordering_of_position_in_partition_and_composite_view_in_a
             .check();
     });
 }
+
+SEASTAR_TEST_CASE(test_schema_upgrader_is_equivalent_with_mutation_upgrade) {
+    return seastar::async([] {
+        for_each_mutation_pair([](const mutation& m1, const mutation& m2, are_equal eq) {
+            if (m1.schema()->version() != m2.schema()->version()) {
+                // upgrade m1 to m2's schema
+
+                auto from_upgrader = mutation_from_streamed_mutation(
+                    transform(streamed_mutation_from_mutation(m1), schema_upgrader(m2.schema()))).get0();
+
+                auto regular = m1;
+                regular.upgrade(m2.schema());
+
+                assert_that(from_upgrader).has_mutation().is_equal_to(regular);
+            }
+        });
+    });
+}