This adds in downgrade code for Database partitions work. We add an

extra field in the header.

3 files changed, 139 insertions, 0 deletions

diff --git a/src/couch/src/couch_bt_engine_header.erl b/src/couch/src/couch_bt_engine_header.erl
index 9c8e7adb3..619264a0d 100644
--- a/src/couch/src/couch_bt_engine_header.erl
+++ b/src/couch/src/couch_bt_engine_header.erl
@@ -26,6 +26,7 @@
 
 -export([
     disk_version/1,
+    latest_disk_version/0,
     update_seq/1,
     id_tree_state/1,
     seq_tree_state/1,
@@ -72,6 +73,9 @@
 }).
 
 
+-define(PARTITION_DISK_VERSION, 8).
+
+
 new() ->
     #db_header{
         uuid = couch_uuids:random(),
@@ -99,6 +103,7 @@ is_header(Header) ->
 
 upgrade(Header) ->
     Funs = [
+        fun downgrade_partition_header/1,
         fun upgrade_tuple/1,
         fun upgrade_disk_version/1,
         fun upgrade_uuid/1,
@@ -136,6 +141,10 @@ disk_version(Header) ->
     get_field(Header, disk_version).
 
 
+latest_disk_version() ->
+        ?LATEST_DISK_VERSION.
+
+
 update_seq(Header) ->
     get_field(Header, update_seq).
 
@@ -210,6 +219,50 @@ indexes() ->
     lists:zip(Fields, Indexes).
 
 
+downgrade_partition_header(Header) ->
+    DiskVersion = disk_version(Header),
+    Latest = latest_disk_version(),
+    case DiskVersion of
+        N when N =< Latest ->
+            Header;
+        ?PARTITION_DISK_VERSION ->
+            {
+                db_header,
+                _DiskVer,
+                UpSeq,
+                _Unused,
+                IdTreeState,
+                SeqTreeState,
+                LocalTreeState,
+                PurgeTreeState,
+                PurgeSeqTreeState,
+                SecurityPtr,
+                RevsLimit,
+                Uuid,
+                Epochs,
+                CompactedSeq,
+                PurgeInfosLimit,
+                _PropsPtr
+            } = Header,
+            
+            NewHeader = new(),
+            set(NewHeader, [
+                {update_seq, UpSeq},
+                {id_tree_state, IdTreeState},
+                {seq_tree_state, SeqTreeState},
+                {local_tree_state, LocalTreeState},
+                {purge_tree_state, PurgeTreeState},
+                {purge_seq_tree_state, PurgeSeqTreeState},
+                {security_ptr, SecurityPtr},
+                {revs_limit, RevsLimit},
+                {uuid, Uuid},
+                {epochs, Epochs},
+                {compacted_seq, CompactedSeq},
+                {purge_infos_limit, PurgeInfosLimit}
+            ])
+    end.
+
+
 upgrade_tuple(Old) when is_record(Old, db_header) ->
     Old;
 upgrade_tuple(Old) when is_tuple(Old) ->
diff --git a/src/couch/test/couch_bt_engine_partition_downgrade_tests.erl b/src/couch/test/couch_bt_engine_partition_downgrade_tests.erl
new file mode 100644
index 000000000..f0839a411
--- /dev/null
+++ b/src/couch/test/couch_bt_engine_partition_downgrade_tests.erl
@@ -0,0 +1,86 @@
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License. You may obtain a copy of
+% the License at
+%
+%   http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+-module(couch_bt_engine_partition_downgrade_tests).
+
+-include_lib("couch/include/couch_eunit.hrl").
+-include_lib("couch/include/couch_db.hrl").
+
+
+setup() ->
+    Ctx = test_util:start_couch(),
+    DbDir = config:get("couchdb", "database_dir"),
+    DbFileNames = [
+        "db_non_partitioned.couch"
+    ],
+    NewPaths = lists:map(fun(DbFileName) ->
+        OldDbFilePath = filename:join([?FIXTURESDIR, DbFileName]),
+        NewDbFilePath = filename:join([DbDir, DbFileName]),
+        ok = filelib:ensure_dir(NewDbFilePath),
+        file:delete(NewDbFilePath),
+        {ok, _} = file:copy(OldDbFilePath, NewDbFilePath),
+        NewDbFilePath
+    end, DbFileNames),
+    {Ctx, NewPaths}.
+
+
+teardown({Ctx, Paths}) ->
+    test_util:stop_couch(Ctx),
+    lists:foreach(fun(Path) ->
+        file:delete(Path)
+    end, Paths).
+
+
+downgrade_test_() ->
+    {
+        "Couch Bt Engine partition downgrade tests",
+        {
+            setup,
+            fun setup/0,
+            fun teardown/1,
+            [
+                t_downgrade_non_partitioned_db()
+            ]
+        }
+    }.
+
+
+t_downgrade_non_partitioned_db() ->
+    ?_test(begin
+        % There are 13 documents in the fixture with 1 conflicted
+        DbName = <<"db_non_partitioned">>,
+        ?assertEqual(8, get_disk_version_from_header(DbName)),
+
+        {ok, _} = save_doc(DbName, {[{<<"_id">>, <<"doc4">>}, {<<"v">>, 1}]}),
+        {ok, _} = save_doc(DbName, {[{<<"_id">>, <<"doc5">>}, {<<"v">>, 2}]}),
+
+        couch_util:with_db(DbName, fun(Db) ->
+            ?assertEqual(7, couch_db_engine:get_disk_version(Db))
+        end)
+    end).
+
+
+get_disk_version_from_header(DbFileName) ->
+    DbDir = config:get("couchdb", "database_dir"),
+    DbFilePath = filename:join([DbDir, ?l2b(?b2l(DbFileName) ++ ".couch")]),
+    {ok, Fd} = couch_file:open(DbFilePath, []),
+    {ok, Header} = couch_file:read_header(Fd),
+    DiskVerison = couch_bt_engine_header:disk_version(Header),
+    couch_file:close(Fd),
+    DiskVerison.
+
+
+save_doc(DbName, Json) ->
+    Doc = couch_doc:from_json_obj(Json),
+    couch_util:with_db(DbName, fun(Db) ->
+        couch_db:update_doc(Db, Doc, [])
+    end).
diff --git a/src/couch/test/fixtures/db_non_partitioned.couch b/src/couch/test/fixtures/db_non_partitioned.couch
new file mode 100644
index 000000000..327d9bb5d
--- /dev/null
+++ b/src/couch/test/fixtures/db_non_partitioned.couch