Merge pull request #3390 from esl/wdbm-mongoose_rdbms

With the changes done in #3386, this turned out to be really easy. Before that, I tried to make mongoose_rdbms_backend expose its API with HostTypes, but it was a bit messy. I think it's better to do it in a separate PR (after the whole without-dynamic-backend-modules branch is merged), to keep this already big diff smaller and more focused. Other issue is that mongoose_rdbms has many functions exported, which seem to be not used, mainly for escaping different types. This could be revisited, but, in similar fashion, I left this as is for now. What's left to do is remove dynamic mongoose_rdbms_type, but it will be done in a separate PR.
esl · Nov 9, 2021 · d856ba0 · d856ba0
2 parents d21eb5d + 6ce5112
commit d856ba0
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diff --git a/rebar.config b/rebar.config
@@ -19,7 +19,6 @@
 {xref_ignores, [
     eldap_filter_yecc, 'XmppAddr', mongoose_xmpp_errors,
     %% *_backend
-    mongoose_rdbms_backend,
     mod_bosh_backend,
     mod_global_distrib_mapping_backend,
     mod_mam_cassandra_arch_params,

diff --git a/src/mam/mod_mam_rdbms_prefs.erl b/src/mam/mod_mam_rdbms_prefs.erl
@@ -21,12 +21,7 @@
 
 -ignore_xref([remove_archive/4, start/2, stop/1, supported_features/0]).
 
--import(mongoose_rdbms,
-        [prepare/4,
-         escape_string/1,
-         escape_integer/1,
-         use_escaped_string/1,
-         use_escaped_integer/1]).
+-import(mongoose_rdbms, [prepare/4]).
 
 -include("mongoose.hrl").
 -include("jlib.hrl").

diff --git a/src/rdbms/mongoose_rdbms.erl b/src/rdbms/mongoose_rdbms.erl
@@ -56,24 +56,6 @@
                sql_query/0,
                sql_query_part/0]).
 
--callback escape_binary(binary()) -> sql_query_part().
--callback escape_string(binary()|list()) -> sql_query_part().
-
--callback unescape_binary(binary()) -> binary().
--callback connect(Args :: any(), QueryTimeout :: non_neg_integer()) ->
-    {ok, Connection :: term()} | {error, Reason :: any()}.
--callback disconnect(Connection :: term()) -> any().
--callback query(Connection :: term(), Query :: any(), Timeout :: infinity | non_neg_integer()) ->
-    query_result().
--callback prepare(Connection :: term(), Name :: atom(),
-                  Table :: binary(), Fields :: [binary()], Statement :: iodata()) ->
-    {ok, Ref :: term()} | {error, Reason :: any()}.
--callback execute(Connection :: term(), Ref :: term(), Parameters :: [term()],
-                  Timeout :: infinity | non_neg_integer()) -> query_result().
-
-%% If not defined, generic escaping is used
--optional_callbacks([escape_string/1]).
-
 %% External exports
 -export([prepare/4,
          prepared/1,
@@ -136,20 +118,6 @@
               use_escaped/1, use_escaped_binary/1, use_escaped_boolean/1,
               use_escaped_like/1, use_escaped_null/1]).
 
--define(MONGOOSE_RDBMS_BACKEND, mongoose_rdbms_backend).
--ignore_xref([
-    {?MONGOOSE_RDBMS_BACKEND, unescape_binary, 1},
-    {?MONGOOSE_RDBMS_BACKEND, disconnect, 1},
-    {?MONGOOSE_RDBMS_BACKEND, query, 3},
-    {?MONGOOSE_RDBMS_BACKEND, execute, 4},
-    {?MONGOOSE_RDBMS_BACKEND, prepare, 5},
-    {?MONGOOSE_RDBMS_BACKEND, escape_string, 1},
-    {?MONGOOSE_RDBMS_BACKEND, backend, 0},
-    {?MONGOOSE_RDBMS_BACKEND, escape_binary, 1},
-    {?MONGOOSE_RDBMS_BACKEND, backend_name, 0},
-    {?MONGOOSE_RDBMS_BACKEND, connect, 2}
-]).
-
 %% internal usage
 -export([get_db_info/1]).
 
@@ -226,7 +194,7 @@ execute_successfully(HostType, Name, Parameters) ->
         {updated, _} = Result ->
             Result;
         Other ->
-            Log = #{what => sql_execute_failed, host => HostType,statement_name => Name,
+            Log = #{what => sql_execute_failed, host => HostType, statement_name => Name,
                     statement_query => query_name_to_string(Name),
                     statement_params => Parameters, reason => Other},
             ?LOG_ERROR(Log),
@@ -468,7 +436,7 @@ escape_like_internal(S) when is_list(S) ->
     [escape_like_character(C) || C <- S].
 
 escape_string_internal(S) ->
-    case erlang:function_exported(mongoose_rdbms_backend:backend(), escape_string, 1) of
+    case mongoose_backend:is_exported(global, ?MODULE, escape_string, 1) of
         true ->
             mongoose_rdbms_backend:escape_string(S);
         false ->
@@ -763,9 +731,8 @@ abort_on_driver_error({Reply, State}) ->
 
 -spec db_engine(HostType :: server()) -> odbc | mysql | pgsql | undefined.
 db_engine(_HostType) ->
-    try mongoose_rdbms_backend:backend_name()
-    catch error:undef -> undefined end.
-
+    try mongoose_backend:get_backend_name(global, ?MODULE)
+    catch error:badarg -> undefined end.
 
 -spec connect(Settings :: term(), Retry :: non_neg_integer(), RetryAfter :: non_neg_integer(),
               MaxRetryDelay :: non_neg_integer()) -> {ok, term()} | {error, any()}.
@@ -777,7 +744,7 @@ connect(Settings, Retry, RetryAfter, MaxRetryDelay) ->
             Error;
         Error ->
             SleepFor = rand:uniform(RetryAfter),
-            Backend = mongoose_rdbms_backend:backend_name(),
+            Backend = mongoose_backend:get_backend_name(global, ?MODULE),
             ?LOG_ERROR(#{what => rdbms_connection_attempt_error, backend => Backend,
                 error => Error, sleep_for => SleepFor}),
             timer:sleep(timer:seconds(SleepFor)),

diff --git a/src/rdbms/mongoose_rdbms_backend.erl b/src/rdbms/mongoose_rdbms_backend.erl
@@ -0,0 +1,82 @@
+%%%-------------------------------------------------------------------
+%%% @copyright 2021, Erlang Solutions Ltd.
+%%% @doc Proxy module for rdbms backends.
+%%%
+%%% @end
+%%%-------------------------------------------------------------------
+-module(mongoose_rdbms_backend).
+-export([escape_binary/1,
+         escape_string/1,
+         unescape_binary/1,
+         connect/2,
+         disconnect/1,
+         query/3,
+         prepare/5,
+         execute/4]).
+
+-define(MAIN_MODULE, mongoose_rdbms).
+
+
+-callback escape_binary(binary()) -> mongoose_rdbms:sql_query_part().
+-callback escape_string(binary()|list()) -> mongoose_rdbms:sql_query_part().
+
+-callback unescape_binary(binary()) -> binary().
+-callback connect(Args :: any(), QueryTimeout :: non_neg_integer()) ->
+    {ok, Connection :: term()} | {error, Reason :: any()}.
+-callback disconnect(Connection :: term()) -> any().
+-callback query(Connection :: term(), Query :: any(), Timeout :: infinity | non_neg_integer()) ->
+    mongoose_rdbms:query_result().
+-callback prepare(Connection :: term(), Name :: atom(),
+                  Table :: binary(), Fields :: [binary()], Statement :: iodata()) ->
+                     {ok, Ref :: term()} | {error, Reason :: any()}.
+-callback execute(Connection :: term(), Ref :: term(), Parameters :: [term()],
+                  Timeout :: infinity | non_neg_integer()) -> mongoose_rdbms:query_result().
+
+%% If not defined, generic escaping is used
+-optional_callbacks([escape_string/1]).
+
+
+-spec escape_binary(binary()) -> mongoose_rdbms:sql_query_part().
+escape_binary(Binary) ->
+    Args = [Binary],
+    mongoose_backend:call(global, ?MAIN_MODULE, ?FUNCTION_NAME, Args).
+
+-spec escape_string(binary() | list()) -> mongoose_rdbms:sql_query_part().
+escape_string(String) ->
+    Args = [String],
+    mongoose_backend:call(global, ?MAIN_MODULE, ?FUNCTION_NAME, Args).
+
+-spec unescape_binary(binary()) -> binary().
+unescape_binary(Binary) ->
+    Args = [Binary],
+    mongoose_backend:call(global, ?MAIN_MODULE, ?FUNCTION_NAME, Args).
+
+-spec connect(Settings :: any(), QueryTimeout :: non_neg_integer()) ->
+    {ok, Connection :: term()} | {error, Reason :: any()}.
+connect(Settings, QueryTimeout) ->
+    Args = [Settings, QueryTimeout],
+    mongoose_backend:call(global, ?MAIN_MODULE, ?FUNCTION_NAME, Args).
+
+-spec disconnect(Connection :: term()) -> any().
+disconnect(Connection) ->
+    Args = [Connection],
+    mongoose_backend:call(global, ?MAIN_MODULE, ?FUNCTION_NAME, Args).
+
+-spec query(Connection :: term(), Query :: any(), Timeout :: infinity | non_neg_integer()) ->
+    mongoose_rdbms:query_result().
+query(Connection, Query, Timeout) ->
+    Args = [Connection, Query, Timeout],
+    mongoose_backend:call_tracked(global, ?MAIN_MODULE, ?FUNCTION_NAME, Args).
+
+-spec prepare(Connection :: term(), Name :: atom(),
+              Table :: binary(), Fields :: [binary()], Statement :: iodata()) ->
+                 {ok, Ref :: term()} | {error, Reason :: any()}.
+prepare(Connection, Name, Table, Fields, Statement) ->
+    Args = [Connection, Name, Table, Fields, Statement],
+    mongoose_backend:call(global, ?MAIN_MODULE, ?FUNCTION_NAME, Args).
+
+-spec execute(Connection :: term(), Ref :: term(), Parameters :: [term()],
+              Timeout :: infinity | non_neg_integer()) -> mongoose_rdbms:query_result().
+execute(Connection, Ref, Parameters, Timeout) ->
+    Args = [Connection, Ref, Parameters, Timeout],
+    mongoose_backend:call_tracked(global, ?MAIN_MODULE, ?FUNCTION_NAME, Args).
diff --git a/src/rdbms/mongoose_rdbms_mysql.erl b/src/rdbms/mongoose_rdbms_mysql.erl
@@ -16,7 +16,7 @@
 
 -module(mongoose_rdbms_mysql).
 -author('konrad.zemek@erlang-solutions.com').
--behaviour(mongoose_rdbms).
+-behaviour(mongoose_rdbms_backend).
 
 -include("mongoose.hrl").
 

diff --git a/src/rdbms/mongoose_rdbms_odbc.erl b/src/rdbms/mongoose_rdbms_odbc.erl
@@ -16,7 +16,7 @@
 
 -module(mongoose_rdbms_odbc).
 -author('konrad.zemek@erlang-solutions.com').
--behaviour(mongoose_rdbms).
+-behaviour(mongoose_rdbms_backend).
 -include("mongoose_logger.hrl").
 
 -export([escape_binary/1, escape_string/1,

diff --git a/src/rdbms/mongoose_rdbms_pgsql.erl b/src/rdbms/mongoose_rdbms_pgsql.erl
@@ -16,7 +16,7 @@
 
 -module(mongoose_rdbms_pgsql).
 -author('konrad.zemek@erlang-solutions.com').
--behaviour(mongoose_rdbms).
+-behaviour(mongoose_rdbms_backend).
 
 -include_lib("epgsql/include/epgsql.hrl").
 

diff --git a/src/wpool/mongoose_wpool_rdbms.erl b/src/wpool/mongoose_wpool_rdbms.erl
@@ -38,15 +38,9 @@ stop(_, _) ->
 %% Helper functions
 do_start(HostType, Tag, WpoolOpts0, RdbmsOpts) when is_list(WpoolOpts0) and is_list(RdbmsOpts) ->
     BackendName = backend_name(RdbmsOpts),
-    try mongoose_rdbms_backend:backend_name() of
-        BackendName -> ok;
-        OtherBackend ->
-            throw(#{reason => "Cannot start an RDBMS connection pool: only one RDBMS backend can be used",
-                    opts => RdbmsOpts, new_backend => BackendName, existing_backend => OtherBackend})
-    catch
-        error:undef ->
-            backend_module:create(mongoose_rdbms, BackendName, [query, execute])
-    end,
+    BackendOpts = RdbmsOpts ++ [{backend, BackendName}],
+    mongoose_backend:init(global, mongoose_rdbms, [query, execute], BackendOpts),
+
     mongoose_metrics:ensure_db_pool_metric({rdbms, HostType, Tag}),
     WpoolOpts = make_wpool_opts(WpoolOpts0, RdbmsOpts),
     ProcName = mongoose_wpool:make_pool_name(rdbms, HostType, Tag),

diff --git a/test/mongoose_rdbms_SUITE.erl b/test/mongoose_rdbms_SUITE.erl
@@ -39,28 +39,30 @@ tests() ->
 init_per_group(odbc, Config) ->
     case code:ensure_loaded(eodbc) of
         {module, eodbc} ->
+            mongoose_backend:init(global, mongoose_rdbms, [], [{backend, odbc}]),
             [{db_type, odbc} | Config];
         _ ->
             {skip, no_odbc_application}
     end;
 init_per_group(Group, Config) ->
+    mongoose_backend:init(global, mongoose_rdbms, [], [{backend, Group}]),
     [{db_type, Group} | Config].
 
 end_per_group(_, Config) ->
+    % clean up after mongoose_backend:init
+    persistent_term:erase({backend_module, global, mongoose_rdbms}),
     Config.
 
 init_per_testcase(does_backoff_increase_to_a_point, Config) ->
     DbType = ?config(db_type, Config),
-    backend_module:create(mongoose_rdbms, DbType, []),
-    meck_config(DbType),
+    meck_config(),
     meck_db(DbType),
     meck_connection_error(DbType),
     meck_rand(),
     [{db_opts, [{server, server(DbType)}, {keepalive_interval, 2}, {start_interval, 10}]} | Config];
 init_per_testcase(_, Config) ->
     DbType = ?config(db_type, Config),
-    backend_module:create(mongoose_rdbms, DbType, []),
-    meck_config(DbType),
+    meck_config(),
     meck_db(DbType),
     [{db_opts, [{server, server(DbType)}, {keepalive_interval, ?KEEPALIVE_INTERVAL},
                 {start_interval, ?MAX_INTERVAL}]} | Config].
@@ -95,11 +97,11 @@ keepalive_exit(Config) ->
         ct:fail(no_down_message)
     end.
 
-%% 5 retries. Max retry 10. Iniitial retry 2.
+%% 5 retries. Max retry 10. Initial retry 2.
 %% We should get a sequence: 2 -> 4 -> 10 -> 10 -> 10.
 does_backoff_increase_to_a_point(Config) ->
     {error, _} = gen_server:start(mongoose_rdbms, ?config(db_opts, Config), []),
-    % We expect to have 2 at the begininng, then values up to 10 and 10 three times in total
+    % We expect to have 2 at the beginning, then values up to 10 and 10 three times in total
     receive_backoffs(2, 10, 3).
 
 receive_backoffs(InitialValue, MaxValue, MaxCount) ->
@@ -128,7 +130,7 @@ meck_rand() ->
 meck_unload_rand() ->
     meck:unload(rand).
 
-meck_config(Server) ->
+meck_config() ->
     meck:new(ejabberd_config, [no_link]),
     meck:expect(ejabberd_config, get_local_option,
                 fun(max_fsm_queue) -> 1024;