1 files changed, 64 insertions, 0 deletions
diff --git a/apps/fabric/src/fabric_doc_missing_revs.erl b/apps/fabric/src/fabric_doc_missing_revs.erl
new file mode 100644
index 00000000..9a368783
--- /dev/null
+++ b/apps/fabric/src/fabric_doc_missing_revs.erl
@@ -0,0 +1,64 @@
+-module(fabric_doc_missing_revs).
+
+-export([go/2]).
+
+-include("fabric.hrl").
+-include_lib("mem3/include/mem3.hrl").
+
+go(DbName, AllIdsRevs) ->
+    Workers = lists:map(fun({#shard{name=Name, node=Node} = Shard, IdsRevs}) ->
+        Ref = rexi:cast(Node, {fabric_rpc, get_missing_revs, [Name, IdsRevs]}),
+        Shard#shard{ref=Ref}
+    end, group_idrevs_by_shard(DbName, AllIdsRevs)),
+    ResultDict = dict:from_list([{Id, {nil,Revs}} || {Id, Revs} <- AllIdsRevs]),
+    Acc0 = {length(Workers), ResultDict},
+    fabric_util:recv(Workers, #shard.ref, fun handle_message/3, Acc0).
+
+handle_message({rexi_DOWN, _, _, _}, _Worker, Acc0) ->
+    skip_message(Acc0);
+handle_message({rexi_EXIT, _, _, _}, _Worker, Acc0) ->
+    skip_message(Acc0);
+handle_message({ok, Results}, _Worker, {1, D0}) ->
+    D = update_dict(D0, Results),
+    {stop, dict:fold(fun force_reply/3, [], D)};
+handle_message({ok, Results}, _Worker, {WaitingCount, D0}) ->
+    D = update_dict(D0, Results),
+    case dict:fold(fun maybe_reply/3, {stop, []}, D) of
+    continue ->
+        % still haven't heard about some Ids
+        {ok, {WaitingCount - 1, D}};
+    {stop, FinalReply} ->
+        {stop, FinalReply}
+    end.
+
+force_reply(Id, {nil,Revs}, Acc) ->
+    % never heard about this ID, assume it's missing
+    [{Id, Revs} | Acc];
+force_reply(_, [], Acc) ->
+    Acc;
+force_reply(Id, Revs, Acc) ->
+    [{Id, Revs} | Acc].
+
+maybe_reply(_, _, continue) ->
+    continue;
+maybe_reply(_, {nil, _}, _) ->
+    continue;
+maybe_reply(_, [], {stop, Acc}) ->
+    {stop, Acc};
+maybe_reply(Id, Revs, {stop, Acc}) ->
+    {stop, [{Id, Revs} | Acc]}.
+
+group_idrevs_by_shard(DbName, IdsRevs) ->
+    dict:to_list(lists:foldl(fun({Id, Revs}, D0) ->
+        lists:foldl(fun(Shard, D1) ->
+            dict:append(Shard, {Id, Revs}, D1)
+        end, D0, mem3:shards(DbName,Id))
+    end, dict:new(), IdsRevs)).
+
+update_dict(D0, KVs) ->
+    lists:foldl(fun({K,V,_}, D1) -> dict:store(K, V, D1) end, D0, KVs).
+
+skip_message({1, Dict}) ->
+    {stop, dict:fold(fun force_reply/3, [], Dict)};
+skip_message({WaitingCount, Dict}) ->
+    {ok, {WaitingCount-1, Dict}}.