Fixes COUCHDB-799 - More granular ETags for views.

ETags for views now only change when their underlying view index
changes due to indexing or purges. ETags are also specific to each
view.

Thanks to Klaus Trainer for the patch.



git-svn-id: https://svn.apache.org/repos/asf/couchdb/trunk@1006339 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 13 insertions, 14 deletions

diff --git a/src/couchdb/couch_httpd_view.erl b/src/couchdb/couch_httpd_view.erl
index 65598a68..8829de02 100644
--- a/src/couchdb/couch_httpd_view.erl
+++ b/src/couchdb/couch_httpd_view.erl
@@ -17,7 +17,7 @@
 
 -export([parse_view_params/3]).
 -export([make_view_fold_fun/7, finish_view_fold/4, finish_view_fold/5, view_row_obj/3]).
--export([view_group_etag/2, view_group_etag/3, make_reduce_fold_funs/6]).
+-export([view_etag/3, view_etag/4, make_reduce_fold_funs/6]).
 -export([design_doc_view/5, parse_bool_param/1, doc_member/2]).
 -export([make_key_options/1, load_view/4]).
 
@@ -113,7 +113,7 @@ output_map_view(Req, View, Group, Db, QueryArgs, nil) ->
         limit = Limit,
         skip = SkipCount
     } = QueryArgs,
-    CurrentEtag = view_group_etag(Group, Db),
+    CurrentEtag = view_etag(Db, Group, View),
     couch_httpd:etag_respond(Req, CurrentEtag, fun() ->
         {ok, RowCount} = couch_view:get_row_count(View),
         FoldlFun = make_view_fold_fun(Req, QueryArgs, CurrentEtag, Db, Group#group.current_seq, RowCount, #view_fold_helper_funs{reduce_count=fun couch_view:reduce_to_count/1}),
@@ -129,7 +129,7 @@ output_map_view(Req, View, Group, Db, QueryArgs, Keys) ->
         limit = Limit,
         skip = SkipCount
     } = QueryArgs,
-    CurrentEtag = view_group_etag(Group, Db, Keys),
+    CurrentEtag = view_etag(Db, Group, View, Keys),
     couch_httpd:etag_respond(Req, CurrentEtag, fun() ->
         {ok, RowCount} = couch_view:get_row_count(View),
         FoldAccInit = {Limit, SkipCount, undefined, []},
@@ -154,7 +154,7 @@ output_reduce_view(Req, Db, View, Group, QueryArgs, nil) ->
         skip = Skip,
         group_level = GroupLevel
     } = QueryArgs,
-    CurrentEtag = view_group_etag(Group, Db),
+    CurrentEtag = view_etag(Db, Group, View),
     couch_httpd:etag_respond(Req, CurrentEtag, fun() ->
         {ok, GroupRowsFun, RespFun} = make_reduce_fold_funs(Req, GroupLevel,
                 QueryArgs, CurrentEtag, Group#group.current_seq,
@@ -172,7 +172,7 @@ output_reduce_view(Req, Db, View, Group, QueryArgs, Keys) ->
         skip = Skip,
         group_level = GroupLevel
     } = QueryArgs,
-    CurrentEtag = view_group_etag(Group, Db, Keys),
+    CurrentEtag = view_etag(Db, Group, View, Keys),
     couch_httpd:etag_respond(Req, CurrentEtag, fun() ->
         {ok, GroupRowsFun, RespFun} = make_reduce_fold_funs(Req, GroupLevel,
                 QueryArgs, CurrentEtag, Group#group.current_seq,
@@ -607,16 +607,15 @@ send_json_reduce_row(Resp, {Key, Value}, RowFront) ->
     send_chunk(Resp, RowFront ++ ?JSON_ENCODE({[{key, Key}, {value, Value}]})),
     {ok, ",\r\n"}.
 
-view_group_etag(Group, Db) ->
-    view_group_etag(Group, Db, nil).
+view_etag(Db, Group, View) ->
+    view_etag(Db, Group, View, nil).
 
-view_group_etag(#group{sig=Sig,current_seq=CurrentSeq}, _Db, Extra) ->
-    % ?LOG_ERROR("Group ~p",[Group]),
-    % This is not as granular as it could be.
-    % If there are updates to the db that do not effect the view index,
-    % they will change the Etag. For more granular Etags we'd need to keep
-    % track of the last Db seq that caused an index change.
-    couch_httpd:make_etag({Sig, CurrentSeq, Extra}).
+view_etag(Db, Group, {reduce, _, _, View}, Extra) ->
+    view_etag(Db, Group, View, Extra);
+view_etag(Db, Group, {temp_reduce, View}, Extra) ->
+    view_etag(Db, Group, View, Extra);
+view_etag(_Db, #group{sig=Sig}, #view{update_seq=UpdateSeq, purge_seq=PurgeSeq}, Extra) ->
+    couch_httpd:make_etag({Sig, UpdateSeq, PurgeSeq, Extra}).
 
 % the view row has an error
 view_row_obj(_Db, {{Key, error}, Value}, _IncludeDocs) ->