Safer incremental sync (erlang-ls#1222)

* didOpen: Handle indexing through els_index_buffer to avoid race
* didSave: Read and index file through els_index_buffer, this should introduce a
synchronization point if the index data has become out of sync.

apps/els_lsp/src/els_index_buffer.erl

@@ -11,6 +11,7 @@
  , stop/0
  , apply_edits_async/2
  , flush/1
+ , load/2
  ]).
 
 -include_lib("kernel/include/logger.hrl").
@@ -42,6 +43,15 @@ apply_edits_async(Uri, Edits) ->
  ?SERVER ! {apply_edits, Uri, Edits},
  ok.
 
+-spec load(uri(), binary()) -> ok.
+load(Uri, Text) ->
+ Ref = make_ref(),
+ ?SERVER ! {load, self(), Ref, Uri, Text},
+ receive
+ {Ref, done} ->
+ ok
+ end.
+
 -spec flush(uri()) -> ok.
 flush(Uri) ->
  Ref = make_ref(),
@@ -71,6 +81,15 @@ loop() ->
  [?SERVER, Uri, {E, R, St}])
  end,
  Pid ! {Ref, done},
+ loop();
+ {load, Pid, Ref, Uri, Text} ->
+ try
+ do_load(Uri, Text)
+ catch E:R:St ->
+ ?LOG_ERROR("[~p] Crashed while loading ~p: ~p",
+ [?SERVER, Uri, {E, R, St}])
+ end,
+ Pid ! {Ref, done},
  loop()
  end.
 
@@ -97,6 +116,17 @@ do_flush(Uri) ->
  [?SERVER, Uri, Duration div 1000]),
  ok.
 
+-spec do_load(uri(), binary()) -> ok.
+do_load(Uri, Text) ->
+ ?LOG_DEBUG("[~p] Loading ~p", [?SERVER, Uri]),
+ {Duration, ok} =
+ timer:tc(fun() ->
+ els_indexing:index(Uri, Text, 'deep')
+ end),
+ ?LOG_DEBUG("[~p] Done load ~p [duration: ~pms]",
+ [?SERVER, Uri, Duration div 1000]),
+ ok.
+
 -spec receive_all(uri(), binary()) -> binary().
 receive_all(Uri, Text0) ->
  receive

apps/els_lsp/src/els_text_synchronization.erl

@@ -46,18 +46,19 @@ did_change(Params) ->
 
 -spec did_open(map()) -> ok.
 did_open(Params) ->
- TextDocument = maps:get(<<"textDocument">>, Params),
- Uri = maps:get(<<"uri">> , TextDocument),
- Text = maps:get(<<"text">> , TextDocument),
- ok  = els_indexing:index(Uri, Text, 'deep'),
+ #{<<"textDocument">> := #{ <<"uri">> := Uri
+    , <<"text">> := Text}} = Params,
+ ok = els_index_buffer:load(Uri, Text),
+ ok = els_index_buffer:flush(Uri),
  Provider = els_diagnostics_provider,
  els_provider:handle_request(Provider, {run_diagnostics, Params}),
  ok.
 
 -spec did_save(map()) -> ok.
 did_save(Params) ->
- TextDocument = maps:get(<<"textDocument">>, Params),
- Uri = maps:get(<<"uri">> , TextDocument),
+ #{<<"textDocument">> := #{<<"uri">> := Uri}} = Params,
+ {ok, Text} = file:read_file(els_uri:path(Uri)),
+ ok = els_index_buffer:load(Uri, Text),
  ok = els_index_buffer:flush(Uri),
  Provider = els_diagnostics_provider,
  els_provider:handle_request(Provider, {run_diagnostics, Params}),