WIP send await time in response header - dreyfusdreyfus-await-time

3 files changed, 35 insertions, 12 deletions

diff --git a/src/dreyfus/src/dreyfus_fabric_search.erl b/src/dreyfus/src/dreyfus_fabric_search.erl
index 7e78e5fc3..77a19d44a 100644
--- a/src/dreyfus/src/dreyfus_fabric_search.erl
+++ b/src/dreyfus/src/dreyfus_fabric_search.erl
@@ -27,7 +27,8 @@
     counters,
     start_args,
     replacements,
-    ring_opts
+    ring_opts,
+    await_time = 0
 }).
 
 go(DbName, GroupId, IndexName, QueryArgs) when is_binary(GroupId) ->
@@ -125,7 +126,7 @@ go(DbName, DDoc, IndexName, QueryArgs, Counters, Bookmark, RingOpts) ->
         )
     of
         {ok, Result} ->
-            #state{top_docs = TopDocs} = Result,
+            #state{top_docs = TopDocs, await_time = AwaitTime} = Result,
             #top_docs{
                 total_hits = TotalHits,
                 hits = Hits,
@@ -134,11 +135,11 @@ go(DbName, DDoc, IndexName, QueryArgs, Counters, Bookmark, RingOpts) ->
             } = TopDocs,
             case RawBookmark of
                 true ->
-                    {ok, Bookmark, TotalHits, Hits, Counts, Ranges};
+                    {ok, Bookmark, TotalHits, Hits, Counts, Ranges, AwaitTime};
                 false ->
                     Bookmark1 = dreyfus_bookmark:update(Sort, Bookmark, Hits),
                     Hits1 = remove_sortable(Hits),
-                    {ok, Bookmark1, TotalHits, Hits1, Counts, Ranges}
+                    {ok, Bookmark1, TotalHits, Hits1, Counts, Ranges, AwaitTime}
             end;
         {error, Reason} ->
             {error, Reason}
@@ -178,6 +179,17 @@ handle_message({ok, {top_docs, UpdateSeq, TotalHits, Hits}}, Shard, State) ->
         hits = Hits
     },
     handle_message({ok, TopDocs}, Shard, State);
+handle_message({await_time, Time}, Shard, State) ->
+    case fabric_dict:lookup_element(Shard, State#state.counters) of
+        undefined ->
+            %% already heard from someone else in this range
+            {ok, State};
+        nil ->
+            State1 = State#state{
+                await_time = max(Time, State#state.await_time)
+            },
+            {ok, State1}
+    end;
 handle_message(Error, Worker, State0) ->
     State = upgrade_state(State0),
     case
diff --git a/src/dreyfus/src/dreyfus_httpd.erl b/src/dreyfus/src/dreyfus_httpd.erl
index f6607d644..ae7826ce3 100644
--- a/src/dreyfus/src/dreyfus_httpd.erl
+++ b/src/dreyfus/src/dreyfus_httpd.erl
@@ -26,7 +26,7 @@
 -include_lib("couch/include/couch_db.hrl").
 -import(chttpd, [
     send_method_not_allowed/2,
-    send_json/2, send_json/3,
+    send_json/2, send_json/3, send_json/4,
     send_error/2
 ]).
 
@@ -68,7 +68,7 @@ handle_search_req(
                                 {rows, Hits}
                             ]}
                         );
-                    {ok, Bookmark0, TotalHits, Hits0, Counts0, Ranges0} ->
+                    {ok, Bookmark0, TotalHits, Hits0, Counts0, Ranges0, AwaitTime} ->
                         Hits = hits_to_json(DbName, IncludeDocs, Hits0),
                         Bookmark = dreyfus_bookmark:pack(Bookmark0),
                         Counts =
@@ -85,13 +85,21 @@ handle_search_req(
                                 _ ->
                                     [{ranges, facets_to_json(Ranges0)}]
                             end,
-                        send_json(Req, 200, {
+                        AwaitTimeMs = erlang:convert_time_unit(AwaitTime, native, millisecond),
+                        send_json(
+                            Req,
+                            200,
                             [
-                                {total_rows, TotalHits},
-                                {bookmark, Bookmark},
-                                {rows, Hits}
-                            ] ++ Counts ++ Ranges
-                        });
+                                {"x-cloudant-await-time", integer_to_list(AwaitTimeMs)}
+                            ],
+                            {
+                                [
+                                    {total_rows, TotalHits},
+                                    {bookmark, Bookmark},
+                                    {rows, Hits}
+                                ] ++ Counts ++ Ranges
+                            }
+                        );
                     {error, Reason} ->
                         handle_error(Req, Db, DDoc, RetryCount, RetryPause, Reason)
                 end;
diff --git a/src/dreyfus/src/dreyfus_rpc.erl b/src/dreyfus/src/dreyfus_rpc.erl
index 2ebc5ffe5..4c2e64a8b 100644
--- a/src/dreyfus/src/dreyfus_rpc.erl
+++ b/src/dreyfus/src/dreyfus_rpc.erl
@@ -48,9 +48,12 @@ call(Fun, DbName, DDoc, IndexName, QueryArgs0) ->
         {ok, Index} ->
             case dreyfus_index_manager:get_index(DbName, Index) of
                 {ok, Pid} ->
+                    T0 = erlang:monotonic_time(),
                     case dreyfus_index:await(Pid, MinSeq) of
                         {ok, IndexPid, _Seq} ->
+                            T1 = erlang:monotonic_time(),
                             Result = dreyfus_index:Fun(IndexPid, QueryArgs),
+                            rexi:reply({await_time, T1 - T0}),
                             rexi:reply(Result);
                         % obsolete clauses, remove after upgrade
                         ok ->