[GitHub] [couchdb] nickva commented on a diff in pull request #4059: Reduce complexity of "possible_ancestors" from quadratic to linear.

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

nickva commented on code in PR #4059:
URL: https://github.com/apache/couchdb/pull/4059#discussion_r895047297


##########
src/couch/src/couch_db.erl:
##########
@@ -2102,28 +2102,12 @@ possible_ancestors(_FullInfo, []) ->
 possible_ancestors(FullInfo, MissingRevs) ->
     #doc_info{revs = RevsInfo} = couch_doc:to_doc_info(FullInfo),
     LeafRevs = [Rev || #rev_info{rev = Rev} <- RevsInfo],
-    % Find the revs that are possible parents of this rev
-    lists:foldl(
-        fun({LeafPos, LeafRevId}, Acc) ->
-            % this leaf is a "possible ancenstor" of the missing
-            % revs if this LeafPos lessthan any of the missing revs
-            case
-                lists:any(
-                    fun({MissingPos, _}) ->
-                        LeafPos < MissingPos
-                    end,
-                    MissingRevs
-                )
-            of
-                true ->
-                    [{LeafPos, LeafRevId} | Acc];
-                false ->
-                    Acc
-            end
-        end,
-        [],
-        LeafRevs
-    ).
+    % Find the revs that are possible parents of this rev. A leaf is a possible
+    % ancestor if the leaf position is less than any of the missing revs, and
+    % if it's less than the any, it means it's also less than the maximum

Review Comment:
   Definitely a typo. Will fix it.



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