[GitHub] [couchdb] nickva commented on a diff in pull request #4201: Implement fabric:open_revs/3

[GitBox <gi...@apache.org>]

nickva commented on code in PR #4201:
URL: https://github.com/apache/couchdb/pull/4201#discussion_r998887107


##########
src/fabric/src/fabric_open_revs.erl:
##########
@@ -0,0 +1,455 @@
+% 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(fabric_open_revs).
+
+-export([
+    go/3
+]).
+
+-include_lib("mem3/include/mem3.hrl").
+-include_lib("couch/include/couch_db.hrl").
+
+-record(req, {
+    idrevs,
+    wcnt = 0,
+    rcnt = 0,
+    responses = []
+}).
+
+-record(st, {
+    r,
+    args,
+    reqs,
+    workers
+}).
+
+go(_DbName, [], _Options) ->
+    {ok, []};
+go(DbName, IdsRevsOpts, Options) ->
+    St = init_state(DbName, IdsRevsOpts, Options),
+    WShards = maps:keys(St#st.workers),
+    RexiMon = fabric_util:create_monitors(WShards),
+    try fabric_util:recv(WShards, #shard.ref, fun handle_message/3, St) of
+        {timeout, #st{workers = #{} = Workers1}} ->
+            stop_workers(Workers1),
+            fabric_util:log_timeout(maps:keys(Workers1), "open_revs"),
+            {error, timeout};
+        Else ->
+            Else
+    after
+        rexi_monitor:stop(RexiMon)
+    end.
+
+handle_message([_ | _] = Resps, Worker, #st{} = St) ->
+    #st{workers = Workers, reqs = Reqs, r = R} = St,
+    {ArgsRefs, Workers1} = maps:take(Worker, Workers),
+    ArgsResps = lists:zip(ArgsRefs, Resps),
+    Reqs1 = lists:foldl(fun responses_fold/2, Reqs, ArgsResps),
+    case not r_met(Reqs1, R) andalso have_viable_workers(Workers1) of
+        true ->
+            {ok, St#st{workers = Workers1, reqs = Reqs1}};
+        false ->
+            stop_workers(Workers1),
+            {stop, finalize(St#st.args, Reqs1)}
+    end;
+handle_message({rexi_DOWN, _, {_, NodeRef}, _}, _Worker, #st{} = St) ->
+    #st{workers = Workers, reqs = Reqs} = St,
+    FilterFun = fun(#shard{node = N}) -> N =:= NodeRef end,
+    DeadKeys = lists:filter(FilterFun, maps:keys(Workers)),

Review Comment:
   All the workers sent to that particular node, referenced by `NodeRef` which would be just the node name like `node1@address...`, would be dead. However, there is a chance that there are still other shard copies for the same range which may still return.



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