1 files changed, 58 insertions, 19 deletions

diff --git a/src/couchdb/couch_rep.erl b/src/couchdb/couch_rep.erl
index b741f86f..4f6fb673 100644
--- a/src/couchdb/couch_rep.erl
+++ b/src/couchdb/couch_rep.erl
@@ -19,6 +19,8 @@
 
 -include("couch_db.hrl").
 
+-define(REP_ID_VERSION, 2).
+
 -record(state, {
     changes_feed,
     missing_revs,
@@ -59,7 +61,9 @@ replicate(Source, Target) when is_binary(Source), is_binary(Target) ->
 
 %% function handling POST to _replicate
 replicate({Props}=PostBody, UserCtx) ->
-    {BaseId, Extension} = make_replication_id(PostBody, UserCtx),
+    BaseId = make_replication_id({Props}, UserCtx, ?REP_ID_VERSION),
+    Extension = maybe_append_options(
+        [<<"continuous">>, <<"create_target">>], Props),
     Replicator = {BaseId ++ Extension,
         {gen_server, start_link, [?MODULE, [BaseId, PostBody, UserCtx], []]},
         temporary,
@@ -144,8 +148,9 @@ do_init([RepId, {PostProps}, UserCtx] = InitArgs) ->
 
     _ ->
         % Replication using the _changes API (DB sequence update numbers).
-        SourceLog = open_replication_log(Source, RepId),
-        TargetLog = open_replication_log(Target, RepId),
+
+        [SourceLog, TargetLog] = find_replication_logs(
+            [Source, Target], RepId, {PostProps}, UserCtx),
     
         {StartSeq, History} = compare_replication_logs(SourceLog, TargetLog),
 
@@ -451,13 +456,23 @@ maybe_append_options(Options, Props) ->
         end
     end, [], Options).
 
-make_replication_id({Props}, UserCtx) ->
-    %% funky algorithm to preserve backwards compatibility
+% Versioned clauses for generating replication ids
+% If a change is made to how replications are identified
+% add a new clause and increase ?REP_ID_VERSION at the top
+make_replication_id({Props}, UserCtx, 2) ->
+    {ok, HostName} = inet:gethostname(),
+    Port = mochiweb_socket_server:get(couch_httpd, port),
+    Src = get_rep_endpoint(UserCtx, couch_util:get_value(<<"source">>, Props)),
+    Tgt = get_rep_endpoint(UserCtx, couch_util:get_value(<<"target">>, Props)),
+    maybe_append_filters({Props}, [HostName, Port, Src, Tgt]);
+make_replication_id({Props}, UserCtx, 1) ->
     {ok, HostName} = inet:gethostname(),
-    % Port = mochiweb_socket_server:get(couch_httpd, port),
     Src = get_rep_endpoint(UserCtx, couch_util:get_value(<<"source">>, Props)),
     Tgt = get_rep_endpoint(UserCtx, couch_util:get_value(<<"target">>, Props)),
-    Base = [HostName, Src, Tgt] ++
+    maybe_append_filters({Props}, [HostName, Src, Tgt]).
+
+maybe_append_filters({Props}, Base) ->
+    Base2 = Base ++ 
         case couch_util:get_value(<<"filter">>, Props) of
         undefined ->
             case couch_util:get_value(<<"doc_ids">>, Props) of
@@ -469,9 +484,7 @@ make_replication_id({Props}, UserCtx) ->
         Filter ->
             [Filter, couch_util:get_value(<<"query_params">>, Props, {[]})]
         end,
-    Extension = maybe_append_options(
-        [<<"continuous">>, <<"create_target">>], Props),
-    {couch_util:to_hex(couch_util:md5(term_to_binary(Base))), Extension}.
+    couch_util:to_hex(couch_util:md5(term_to_binary(Base2))).
 
 maybe_add_trailing_slash(Url) ->
     re:replace(Url, "[^/]$", "&/", [{return, list}]).
@@ -493,26 +506,52 @@ get_rep_endpoint(_UserCtx, <<"https://",_/binary>>=Url) ->
 get_rep_endpoint(UserCtx, <<DbName/binary>>) ->
     {local, DbName, UserCtx}.
 
-open_replication_log(#http_db{}=Db, RepId) ->
-    DocId = ?LOCAL_DOC_PREFIX ++ RepId,
-    Req = Db#http_db{resource=couch_util:url_encode(DocId)},
+find_replication_logs(Logs, RepId, {Props}, UserCtx) ->
+    LogId = ?l2b(?LOCAL_DOC_PREFIX ++ RepId),
+    fold_replication_logs(Logs, ?REP_ID_VERSION,
+        LogId, LogId, {Props}, UserCtx, []).
+
+% Accumulate the replication logs
+% Falls back to older log document ids and migrates them
+fold_replication_logs([], _Vsn, _LogId, _NewId, {_Props}, _UserCtx, Acc) ->
+    lists:reverse(Acc);
+fold_replication_logs([Db|Rest]=Dbs, Vsn, LogId, NewId,
+        {Props}, UserCtx, Acc) ->
+    case open_replication_log(Db, LogId) of
+    {error, not_found} when Vsn > 1 ->
+        OldRepId = make_replication_id({Props}, UserCtx, Vsn - 1),
+        fold_replication_logs(Dbs, Vsn - 1,
+            ?l2b(?LOCAL_DOC_PREFIX ++ OldRepId), NewId, {Props}, UserCtx, Acc);
+    {error, not_found} ->
+        fold_replication_logs(Rest, ?REP_ID_VERSION, NewId, NewId,
+            {Props}, UserCtx, [#doc{id=NewId}|Acc]);
+    {ok, Doc} when LogId =:= NewId ->
+        fold_replication_logs(Rest, ?REP_ID_VERSION, NewId, NewId,
+            {Props}, UserCtx, [Doc|Acc]);
+    {ok, Doc} ->
+        MigratedLog = #doc{id=NewId,body=Doc#doc.body},
+        fold_replication_logs(Rest, ?REP_ID_VERSION, NewId, NewId,
+            {Props}, UserCtx, [MigratedLog|Acc])
+    end.
+
+open_replication_log(#http_db{}=Db, DocId) ->
+    Req = Db#http_db{resource=couch_util:url_encode(?b2l(DocId))},
     case couch_rep_httpc:request(Req) of
     {[{<<"error">>, _}, {<<"reason">>, _}]} ->
         ?LOG_DEBUG("didn't find a replication log for ~s", [Db#http_db.url]),
-        #doc{id=?l2b(DocId)};
+        {error, not_found};
     Doc ->
         ?LOG_DEBUG("found a replication log for ~s", [Db#http_db.url]),
-        couch_doc:from_json_obj(Doc)
+        {ok, couch_doc:from_json_obj(Doc)}
     end;
-open_replication_log(Db, RepId) ->
-    DocId = ?l2b(?LOCAL_DOC_PREFIX ++ RepId),
+open_replication_log(Db, DocId) ->
     case couch_db:open_doc(Db, DocId, []) of
     {ok, Doc} ->
         ?LOG_DEBUG("found a replication log for ~s", [Db#db.name]),
-        Doc;
+        {ok, Doc};
     _ ->
         ?LOG_DEBUG("didn't find a replication log for ~s", [Db#db.name]),
-        #doc{id=DocId}
+        {error, not_found}
     end.
 
 open_db(Props, UserCtx) ->