Add error propagation to couch_eval and couch_views_indexer (#3553)

When ApiMod:acquire_map_context returns with {error, any()}, the caller(s) fail with badmatch. This commit changes the caller hierarchy so that those {error, _} are propagated back and a failing update gets retried (up to retry_limit times).

4 files changed, 92 insertions, 8 deletions

diff --git a/src/couch_eval/src/couch_eval.erl b/src/couch_eval/src/couch_eval.erl
index f87ba97b9..059507d4e 100644
--- a/src/couch_eval/src/couch_eval.erl
+++ b/src/couch_eval/src/couch_eval.erl
@@ -86,8 +86,12 @@ acquire_map_context(DbName, DDocId, Language, Sig, Lib, MapFuns) ->
         lib => Lib,
         map_funs => MapFuns
     },
-    {ok, Ctx} = ApiMod:acquire_map_context(CtxOpts),
-    {ok, {ApiMod, Ctx}}.
+    case ApiMod:acquire_map_context(CtxOpts) of
+        {ok, Ctx} ->
+            {ok, {ApiMod, Ctx}};
+        {error, Error} ->
+            {error, Error}
+    end.
 
 
 -spec release_map_context(context()) -> ok | {error, any()}.
diff --git a/src/couch_eval/test/couch_eval_error_tests.erl b/src/couch_eval/test/couch_eval_error_tests.erl
new file mode 100644
index 000000000..6713c8afe
--- /dev/null
+++ b/src/couch_eval/test/couch_eval_error_tests.erl
@@ -0,0 +1,54 @@
+% 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_eval_error_tests).
+
+-include_lib("couch/include/couch_eunit.hrl").
+-include_lib("couch/include/couch_db.hrl").
+
+-define(LANG_BINARY, <<"foo_lang">>).
+-define(LANG_STRING, binary_to_list(?LANG_BINARY)).
+
+
+setup() ->
+    meck:new(mock_language_server, [non_strict]),
+    Ctx = test_util:start_couch(),
+    config:set("couch_eval.languages", ?LANG_STRING,
+        atom_to_list(mock_language_server)),
+    Ctx.
+
+
+teardown(Ctx) ->
+    test_util:stop_couch(Ctx),
+    meck:unload().
+
+
+error_test_() ->
+    {
+        "Error tests",
+        {
+            setup,
+            fun setup/0, fun teardown/1,
+            [
+                fun acquire_map_context_error_handled/0
+            ]
+        }
+    }.
+
+
+acquire_map_context_error_handled() ->
+    meck:expect(mock_language_server, acquire_map_context, fun(_) ->
+        {error, foo_error}
+    end),
+    Result = couch_eval:acquire_map_context(<<"foo">>, <<"bar">>, ?LANG_BINARY,
+        <<"baz">>, <<"quux">>, [<<"quuz">>]),
+    ?assertEqual({error, foo_error}, Result).
diff --git a/src/couch_views/src/couch_views_indexer.erl b/src/couch_views/src/couch_views_indexer.erl
index 7f0e2d5f2..9a1295ee7 100644
--- a/src/couch_views/src/couch_views_indexer.erl
+++ b/src/couch_views/src/couch_views_indexer.erl
@@ -561,15 +561,19 @@ start_query_server(#mrst{qserver = nil} = Mrst) ->
         lib = Lib,
         views = Views
     } = Mrst,
-    {ok, QServer} = couch_eval:acquire_map_context(
+    case couch_eval:acquire_map_context(
             DbName,
             DDocId,
             Language,
             Sig,
             Lib,
             [View#mrview.def || View <- Views]
-        ),
-    Mrst#mrst{qserver = QServer};
+        ) of
+        {ok, QServer} ->
+            Mrst#mrst{qserver = QServer};
+        {error, Error} ->
+            error(Error)
+    end;
 
 start_query_server(#mrst{} = Mrst) ->
     Mrst.
diff --git a/src/couch_views/test/couch_views_indexer_test.erl b/src/couch_views/test/couch_views_indexer_test.erl
index c41db3b4f..9613ba327 100644
--- a/src/couch_views/test/couch_views_indexer_test.erl
+++ b/src/couch_views/test/couch_views_indexer_test.erl
@@ -21,6 +21,8 @@
 
 -define(MAP_FUN1, <<"map_fun1">>).
 -define(MAP_FUN2, <<"map_fun2">>).
+-define(QUERY_SERVER_LANG_BINARY, <<"foo_lang">>).
+-define(QUERY_SERVER_LANG_STRING, binary_to_list(?QUERY_SERVER_LANG_BINARY)).
 
 
 indexer_test_() ->
@@ -53,7 +55,8 @@ indexer_test_() ->
                     ?TDEF_FE(handle_db_recreated_when_running),
                     ?TDEF_FE(handle_db_recreated_after_finished),
                     ?TDEF_FE(handle_doc_updated_when_running),
-                    ?TDEF_FE(index_can_recover_from_crash, 60)
+                    ?TDEF_FE(index_can_recover_from_crash, 60),
+                    ?TDEF_FE(handle_acquire_map_context_error)
                 ]
             }
         }
@@ -448,7 +451,8 @@ multiple_doc_update_with_existing_rows(Db) ->
     ?assertEqual([
         row(<<"0">>, 0, 0),
         row(<<"1">>, 2, 2)
-    ], Out2).    
+    ], Out2).
+
 
 handle_db_recreated_when_running(Db) ->
     DbName = fabric2_db:name(Db),
@@ -569,7 +573,8 @@ handle_doc_updated_when_running(Db) ->
     }, couch_jobs:wait(SubId, finished, infinity)),
 
     Args = #mrargs{update = false},
-    {ok, Out2} = couch_views:query(Db, DDoc, ?MAP_FUN1, fun fold_fun/2, [], Args),
+    {ok, Out2} = couch_views:query(Db, DDoc, ?MAP_FUN1, fun fold_fun/2, [],
+        Args),
     ?assertEqual([
         row(<<"0">>, 0, 0)
     ], Out2).
@@ -610,6 +615,23 @@ index_can_recover_from_crash(Db) ->
     ], Out).
 
 
+handle_acquire_map_context_error(_) ->
+    meck:new(mock_language_server, [non_strict]),
+    config:set("couch_eval.languages", ?QUERY_SERVER_LANG_STRING,
+        atom_to_list(mock_language_server)),
+    meck:expect(mock_language_server, acquire_map_context, fun(_) ->
+        {error, foo_error}
+    end),
+    ?assertError(foo_error, couch_views_indexer:start_query_server(#mrst{
+        db_name = "DbName",
+        idx_name = "DDocId",
+        language = ?QUERY_SERVER_LANG_BINARY,
+        sig = "Sig",
+        lib = "Lib",
+        views = []
+    })).
+
+
 row(Id, Key, Value) ->
     {row, [
         {id, Id},