From 6aa04d06ade041744bc0fefafb464dde075d4ee8 Mon Sep 17 00:00:00 2001
From: Nick Vatamaniuc <vatamane@gmail.com>
Date: Sat, 16 Mar 2024 03:03:33 -0400
Subject: [PATCH] Fix case clause error in replicator _scheduler/docs response

When a job is completing, there is a period of time when the document isn't
updated yet with the state, and it's also not present in the scheduler ets
table. In that case we return `nil`, but we don't account for that case in the
_scheduler/docs fabric calls.

To fix it, account for `nil` whenever we get the doc state.
---
 src/couch_replicator/src/couch_replicator_fabric.erl         | 4 +++-
 src/couch_replicator/src/couch_replicator_fabric_rpc.erl     | 5 ++++-
 .../test/eunit/couch_replicator_scheduler_docs_tests.erl     | 5 +----
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/couch_replicator/src/couch_replicator_fabric.erl b/src/couch_replicator/src/couch_replicator_fabric.erl
index 9a069fac99c..d570d6f7728 100644
--- a/src/couch_replicator/src/couch_replicator_fabric.erl
+++ b/src/couch_replicator/src/couch_replicator_fabric.erl
@@ -18,7 +18,6 @@
 
 -include_lib("fabric/include/fabric.hrl").
 -include_lib("mem3/include/mem3.hrl").
--include_lib("couch/include/couch_db.hrl").
 -include_lib("couch_mrview/include/couch_mrview.hrl").
 
 docs(DbName, Options, QueryArgs, Callback, Acc) ->
@@ -167,6 +166,9 @@ maybe_fetch_and_filter_doc(Id, undecided, State) ->
         {ok, {Props} = DocInfo} ->
             DocState = couch_util:get_value(state, Props),
             couch_replicator_utils:filter_state(DocState, FilterStates, DocInfo);
+        {ok, nil} ->
+            % could have just completed
+            skip;
         {error, not_found} ->
             % could have been deleted
             skip
diff --git a/src/couch_replicator/src/couch_replicator_fabric_rpc.erl b/src/couch_replicator/src/couch_replicator_fabric_rpc.erl
index f6b9b408099..1a3582928ee 100644
--- a/src/couch_replicator/src/couch_replicator_fabric_rpc.erl
+++ b/src/couch_replicator/src/couch_replicator_fabric_rpc.erl
@@ -17,7 +17,6 @@
 ]).
 
 -include_lib("fabric/include/fabric.hrl").
--include_lib("couch/include/couch_db.hrl").
 -include_lib("couch_mrview/include/couch_mrview.hrl").
 
 docs(DbName, Options, Args0) ->
@@ -80,6 +79,10 @@ rep_doc_state(Shard, Id, {[_ | _]} = Doc, States, HealthThreshold) ->
                     HealthThreshold
                 )
             of
+                {ok, nil} ->
+                    % Could have been just completed. Let the coordinator
+                    % try to refetch it.
+                    undecided;
                 {ok, EtsInfo} ->
                     State = get_doc_state(EtsInfo),
                     couch_replicator_utils:filter_state(State, States, EtsInfo);
diff --git a/src/couch_replicator/test/eunit/couch_replicator_scheduler_docs_tests.erl b/src/couch_replicator/test/eunit/couch_replicator_scheduler_docs_tests.erl
index e04518b6722..15789da692f 100644
--- a/src/couch_replicator/test/eunit/couch_replicator_scheduler_docs_tests.erl
+++ b/src/couch_replicator/test/eunit/couch_replicator_scheduler_docs_tests.erl
@@ -133,10 +133,7 @@ t_scheduler_docs_total_rows({_Ctx, {RepDb, Source, Target}}) ->
             case req(get, SchedulerDocsUrl) of
                 {200, #{<<"docs">> := [_ | _]} = Decoded} ->
                     Decoded;
-                {_, #{<<"error">> := Error, <<"reason">> := Reason}} ->
-                    ?debugVal(Error, 100),
-                    ?debugVal(binary_to_list(Reason), 100);
-                {_, #{}} ->
+                {200, #{<<"docs">> := []}} ->
                     wait
             end
         end,