nickva commented on a change in pull request #2666: soft-deletion for database
URL: https://github.com/apache/couchdb/pull/2666#discussion_r401724116
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File path: src/fabric/src/fabric2_fdb.erl
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@@ -346,12 +351,97 @@ delete(#{} = Db) ->
} = ensure_current(Db),
DbKey = erlfdb_tuple:pack({?ALL_DBS, DbName}, LayerPrefix),
- erlfdb:clear(Tx, DbKey),
- erlfdb:clear_range_startswith(Tx, DbPrefix),
+ DoRecovery = fabric2_util:do_recovery(),
+ case DoRecovery of
+ true ->
+ Timestamp = list_to_binary(fabric2_util:iso8601_timestamp()),
+ DeletedDbKey = erlfdb_tuple:pack({?DELETED_DBS, DbName, Timestamp},
+ LayerPrefix),
+ case erlfdb:wait(erlfdb:get(Tx, DeletedDbKey)) of
+ not_found ->
+ erlfdb:set(Tx, DeletedDbKey, DbPrefix),
+ erlfdb:clear(Tx, DbKey);
+ _Val ->
+ erlang:error({deleted_database_exists, DbName})
+ end;
+ false ->
+ erlfdb:clear(Tx, DbKey),
+ erlfdb:clear_range_startswith(Tx, DbPrefix)
+ end,
bump_metadata_version(Tx),
ok.
+deleted_dbs_info(#{} = Db0) ->
+ #{
+ name := DbName,
+ tx := Tx,
+ layer_prefix := LayerPrefix
+ } = ensure_current(Db0, false),
+
+ DeletedDbKey = erlfdb_tuple:pack({?DELETED_DBS, DbName}, LayerPrefix),
+ DeletedDbs = erlfdb:wait(erlfdb:get_range_startswith(Tx, DeletedDbKey)),
+ lists:foldl(fun({DbKey, DbPrefix}, Acc) ->
+ DBInfo = get_info_wait(get_info_future(Tx, DbPrefix)),
+ {?DELETED_DBS, DbName, DeletedTS} =
+ erlfdb_tuple:unpack(DbKey, LayerPrefix),
+ [{DeletedTS, DBInfo}| Acc]
+ end, [], DeletedDbs).
+
+
+undelete(#{} = Db0, TgtDbName, TimeStamp) ->
+ #{
+ name := DbName,
+ tx := Tx,
+ layer_prefix := LayerPrefix
+ } = ensure_current(Db0, false),
+ DbKey = erlfdb_tuple:pack({?ALL_DBS, TgtDbName}, LayerPrefix),
+ case erlfdb:wait(erlfdb:get(Tx, DbKey)) of
+ Bin when is_binary(Bin) ->
+ {error, file_exists};
+ not_found ->
+ DeletedDbTupleKey = {
+ ?DELETED_DBS,
+ DbName,
+ TimeStamp
+ },
+ DeleteDbKey = erlfdb_tuple:pack(DeletedDbTupleKey, LayerPrefix),
+ case erlfdb:wait(erlfdb:get(Tx, DeleteDbKey)) of
+ not_found ->
+ erlang:error({not_found, invalid_timestamp});
+ DbPrefix ->
+ erlfdb:set(Tx, DbKey, DbPrefix),
+ erlfdb:clear(Tx, DeleteDbKey),
+ bump_metadata_version(Tx),
+ ok
+ end
+ end.
+
+
+delete_deleted(#{} = Db0, TimeStamp) ->
+ #{
+ name := DbName,
+ tx := Tx,
+ layer_prefix := LayerPrefix
+ } = ensure_current(Db0),
+
+ DeletedDbTupleKey = {
+ ?DELETED_DBS,
+ DbName,
+ TimeStamp
+ },
+ DeleteDbKey = erlfdb_tuple:pack(DeletedDbTupleKey, LayerPrefix),
+ case erlfdb:wait(erlfdb:get(Tx, DeleteDbKey)) of
+ not_found ->
+ erlang:error({not_found});
+ DbPrefix ->
+ erlfdb:clear(Tx, DeleteDbKey),
+ erlfdb:clear_range_startswith(Tx, DbPrefix),
+ bump_metadata_version(Tx)
Review comment:
Actually I was wrong about the `db soft deleted and undeleted`. Thanks,
@jiangphcn for pointing it out. It seems in that case the old handle will be
usable because:
1) we bumped the db version only
2) old handle would notice metadata and db version being out of date
3) it would automatically re-open
4) it would continue to be used
We could assert that in the test perhaps then. Good catch @jiangphcn !
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