Support for reduce views in _list. closes COUCHDB-260. Thanks Jason Davies.

git-svn-id: https://svn.apache.org/repos/asf/couchdb/trunk@747679 13f79535-47bb-0310-9956-ffa450edef68

5 files changed, 239 insertions, 66 deletions

diff --git a/share/www/script/test/list_views.js b/share/www/script/test/list_views.js
index de593035..a25eed30 100644
--- a/share/www/script/test/list_views.js
+++ b/share/www/script/test/list_views.js
@@ -59,8 +59,8 @@ couchTests.list_views = function(debug) {
         } else {
           // tail
           return {body : '</ul>'+
-              '<p>FirstKey: '+row_info.first_key+ 
-              ' LastKey: '+row_info.prev_key+'</p>'};
+              '<p>FirstKey: '+(row_info ? row_info.first_key : '')+ 
+              ' LastKey: '+(row_info ? row_info.prev_key : '')+'</p>'};
         }
       }),
       acceptSwitch: stringFun(function(head, row, req, row_info) {
@@ -127,6 +127,9 @@ couchTests.list_views = function(debug) {
             }
           }
         });
+      }),
+      emptyList: stringFun(function(head, row, req, row_info) {
+        return { body: "" };
       })
     }
   };
@@ -175,6 +178,13 @@ couchTests.list_views = function(debug) {
   T(xhr.status == 200);
   T(/Total Rows/.test(xhr.responseText));
   T(/Offset: null/.test(xhr.responseText));
+
+  // reduce with 0 rows
+  var xhr = CouchDB.request("GET", "/test_suite_db/_list/lists/simpleForm/withReduce?startkey=30");
+  T(xhr.status == 200);
+  T(/Total Rows/.test(xhr.responseText));
+  T(/Offset: undefined/.test(xhr.responseText));
+
   
   // when there is a reduce present, but not used
   var xhr = CouchDB.request("GET", "/test_suite_db/_list/lists/simpleForm/withReduce?reduce=false");
@@ -182,6 +192,11 @@ couchTests.list_views = function(debug) {
   T(/Total Rows/.test(xhr.responseText));
   T(/Key: 1/.test(xhr.responseText));
   
+  // when there is a reduce present, and used
+  var xhr = CouchDB.request("GET", "/test_suite_db/_list/lists/simpleForm/withReduce?group=true");
+  T(xhr.status == 200);
+  T(/Key: 1/.test(xhr.responseText));
+  
   // with accept headers for HTML
   xhr = CouchDB.request("GET", "/test_suite_db/_list/lists/acceptSwitch/basicView", {
     headers: {
@@ -203,14 +218,25 @@ couchTests.list_views = function(debug) {
   T(xhr.responseText.match(/entry/));
 
   // now with extra qs params
-  xhr = CouchDB.request("GET", "/test_suite_db/_list/lists/qsParams/basicView?foo=blam");
+  var xhr = CouchDB.request("GET", "/test_suite_db/_list/lists/qsParams/basicView?foo=blam");
   T(xhr.responseText.match(/blam/));
   
-
   // aborting iteration
-  xhr = CouchDB.request("GET", "/test_suite_db/_list/lists/stopIter/basicView");
+  var xhr = CouchDB.request("GET", "/test_suite_db/_list/lists/stopIter/basicView");
   T(xhr.responseText.match(/^head 0 1 2 tail$/));
   xhr = CouchDB.request("GET", "/test_suite_db/_list/lists/stopIter2/basicView");
   T(xhr.responseText.match(/^head 0 1 2 tail$/));
 
+  // aborting iteration with reduce
+  var xhr = CouchDB.request("GET", "/test_suite_db/_list/lists/stopIter/withReduce?group=true");
+  T(xhr.responseText.match(/^head 0 1 2 tail$/));
+  xhr = CouchDB.request("GET", "/test_suite_db/_list/lists/stopIter2/withReduce?group=true");
+  T(xhr.responseText.match(/^head 0 1 2 tail$/));
+
+  // empty list
+  var xhr = CouchDB.request("GET", "/test_suite_db/_list/lists/emptyList/basicView");
+  T(xhr.responseText.match(/^$/));
+  xhr = CouchDB.request("GET", "/test_suite_db/_list/lists/emptyList/withReduce?group=true");
+  T(xhr.responseText.match(/^$/));
+
 };
diff --git a/src/couchdb/couch_db.hrl b/src/couchdb/couch_db.hrl
index 443ac73f..89d8965e 100644
--- a/src/couchdb/couch_db.hrl
+++ b/src/couchdb/couch_db.hrl
@@ -161,6 +161,11 @@
     send_row
 }).
 
+-record(reduce_fold_helper_funs, {
+    start_response,
+    send_row
+}).
+
 -record(extern_resp_args, {
     code = 200,
     stop = false,
diff --git a/src/couchdb/couch_httpd_show.erl b/src/couchdb/couch_httpd_show.erl
index cc7d4d08..a6c795c6 100644
--- a/src/couchdb/couch_httpd_show.erl
+++ b/src/couchdb/couch_httpd_show.erl
@@ -19,7 +19,7 @@
 
 -import(couch_httpd,
     [send_json/2,send_json/3,send_json/4,send_method_not_allowed/2,
-    start_json_response/2,send_chunk/2,end_json_response/1,
+    start_json_response/2,send_chunk/2,
     start_chunked_response/3, send_error/4]).
     
 handle_doc_show_req(#httpd{
@@ -87,13 +87,13 @@ send_view_list_response(Lang, ListSrc, ViewName, DesignId, Req, Db) ->
                 MapView = couch_view:extract_map_view(ReduceView),
                 output_map_list(Req, Lang, ListSrc, MapView, Group, Db, QueryArgs);
             _ ->
-                throw({not_implemented, reduce_view_lists})
+                output_reduce_list(Req, Lang, ListSrc, ReduceView, Group, Db, QueryArgs)
             end;
         {not_found, Reason} ->
             throw({not_found, Reason})
         end
     end.
-    
+
 output_map_list(#httpd{mochi_req=MReq}=Req, Lang, ListSrc, View, Group, Db, QueryArgs) ->
     #view_query_args{
         limit = Limit,
@@ -137,13 +137,18 @@ output_map_list(#httpd{mochi_req=MReq}=Req, Lang, ListSrc, View, Group, Db, Quer
                 stop = StopIter,
                 data = RowBody
             } = couch_httpd_external:parse_external_response(JsonResp),
-            RowFront2 = case RowFront of
-            nil -> [];
-            _ -> RowFront
-            end,
             case StopIter of
             true -> stop;
-            _ -> send_chunk(Resp, RowFront2 ++ binary_to_list(RowBody))
+            _ ->
+                RowFront2 = case RowFront of
+                nil -> [];
+                _ -> RowFront
+                end,
+                Chunk = RowFront2 ++ binary_to_list(RowBody),
+                case Chunk of
+                    [] -> {ok, Resp};
+                    _ -> send_chunk(Resp, Chunk)
+                end
             end
         end,
     
@@ -155,26 +160,94 @@ output_map_list(#httpd{mochi_req=MReq}=Req, Lang, ListSrc, View, Group, Db, Quer
             }),
         FoldAccInit = {Limit, SkipCount, undefined, []},
         FoldResult = couch_view:fold(View, Start, Dir, FoldlFun, FoldAccInit),
-        finish_view_list(Req, Db, QueryServer, RowCount, FoldResult, StartListRespFun)
+        finish_list(Req, Db, QueryServer, CurrentEtag, FoldResult, StartListRespFun, RowCount)
     end).
 
-finish_view_list(Req, Db, QueryServer, TotalRows, 
-    FoldResult, StartListRespFun) ->
-    case FoldResult of
-    {ok, {_, _, undefined, _}} ->
-        {ok, Resp, BeginBody} = StartListRespFun(Req, 200, TotalRows, null),
-        JsonTail = couch_query_servers:render_list_tail(QueryServer, Req, Db),
+output_reduce_list(#httpd{mochi_req=MReq}=Req, Lang, ListSrc, View, Group, Db, QueryArgs) ->
+    #view_query_args{
+        limit = Limit,
+        direction = Dir,
+        skip = SkipCount,
+        start_key = StartKey,
+        start_docid = StartDocId,
+        end_key = EndKey,
+        end_docid = EndDocId,
+        group_level = GroupLevel
+    } = QueryArgs,
+    % get the os process here
+    % pass it into the view fold with closures
+    {ok, QueryServer} = couch_query_servers:start_view_list(Lang, ListSrc),
+    Headers = MReq:get(headers),
+    Hlist = mochiweb_headers:to_list(Headers),
+    Accept = proplists:get_value('Accept', Hlist),
+    CurrentEtag = couch_httpd_view:view_group_etag(Group, {Lang, ListSrc, Accept}),
+
+    StartListRespFun = fun(Req2, _Etag, _, _) ->
+        JsonResp = couch_query_servers:render_reduce_head(QueryServer, 
+            Req2, Db),
         #extern_resp_args{
-            data = Tail
-        } = couch_httpd_external:parse_external_response(JsonTail),
-        send_chunk(Resp, BeginBody ++ Tail),
-        send_chunk(Resp, []);
-    {ok, {_, _, Resp, _AccRevRows}} ->
+            code = Code,
+            data = BeginBody,
+            ctype = CType,
+            headers = ExtHeaders
+        } = couch_httpd_external:parse_external_response(JsonResp),
+        JsonHeaders = couch_httpd_external:default_or_content_type(CType, ExtHeaders),
+        {ok, Resp} = start_chunked_response(Req, Code, JsonHeaders),
+        {ok, Resp, binary_to_list(BeginBody)}
+    end,
+    
+    SendListRowFun = fun(Resp, {Key, Value}, RowFront) ->
+        JsonResp = couch_query_servers:render_reduce_row(QueryServer, 
+            Req, Db, {Key, Value}),
+        #extern_resp_args{
+            stop = StopIter,
+            data = RowBody
+        } = couch_httpd_external:parse_external_response(JsonResp),
+        RowFront2 = case RowFront of
+        nil -> [];
+        _ -> RowFront
+        end,
+        case StopIter of
+        true -> stop;
+        _ ->
+            Chunk = RowFront2 ++ binary_to_list(RowBody),
+            case Chunk of
+                [] -> {ok, Resp};
+                _ -> send_chunk(Resp, Chunk)
+            end
+        end
+    end,
+    
+    {ok, GroupRowsFun, RespFun} = couch_httpd_view:make_reduce_fold_funs(Req, GroupLevel, QueryArgs, CurrentEtag, 
+    #reduce_fold_helper_funs{
+        start_response = StartListRespFun,
+        send_row = SendListRowFun
+    }),
+    FoldAccInit = {Limit, SkipCount, undefined, []},
+    FoldResult = couch_view:fold_reduce(View, Dir, {StartKey, StartDocId},
+        {EndKey, EndDocId}, GroupRowsFun, RespFun,
+        FoldAccInit),
+    finish_list(Req, Db, QueryServer, CurrentEtag, FoldResult, StartListRespFun, null).
+
+finish_list(Req, Db, QueryServer, Etag, FoldResult, StartListRespFun, TotalRows) ->
+    case FoldResult of
+    {ok, Acc} ->
         JsonTail = couch_query_servers:render_list_tail(QueryServer, Req, Db),
         #extern_resp_args{
             data = Tail
         } = couch_httpd_external:parse_external_response(JsonTail),
-        send_chunk(Resp, Tail),
+        {Resp, BeginBody} = case Acc of
+        {_, _, undefined, _} ->
+            {ok, Resp2, BeginBody2} = StartListRespFun(Req, Etag, TotalRows, null),
+            {Resp2, BeginBody2};
+        {_, _, Resp2, _} ->
+            {Resp2, ""}
+        end,
+        Chunk = BeginBody ++ binary_to_list(Tail),
+        case Chunk of
+            [] -> ok;
+            _ -> send_chunk(Resp, Chunk)
+        end,
         send_chunk(Resp, []);
     Error ->
         throw(Error)
diff --git a/src/couchdb/couch_httpd_view.erl b/src/couchdb/couch_httpd_view.erl
index c4e2174e..6b9befe1 100644
--- a/src/couchdb/couch_httpd_view.erl
+++ b/src/couchdb/couch_httpd_view.erl
@@ -16,7 +16,7 @@
 -export([handle_view_req/2,handle_temp_view_req/2]).
 
 -export([parse_view_query/1,parse_view_query/2,parse_view_query/4,make_view_fold_fun/6,
-    finish_view_fold/3, view_row_obj/3, view_group_etag/1, view_group_etag/2]).
+    finish_view_fold/3, view_row_obj/3, view_group_etag/1, view_group_etag/2, make_reduce_fold_funs/5]).
 
 -import(couch_httpd,
     [send_json/2,send_json/3,send_json/4,send_method_not_allowed/2,send_chunk/2,
@@ -145,13 +145,11 @@ output_reduce_view(Req, View, Group, QueryArgs, nil) ->
     } = QueryArgs,
     CurrentEtag = view_group_etag(Group),
     couch_httpd:etag_respond(Req, CurrentEtag, fun() ->
-        {ok, Resp} = start_json_response(Req, 200, [{"Etag",CurrentEtag}]),
-        {ok, GroupRowsFun, RespFun} = make_reduce_fold_funs(Resp, GroupLevel),
-        send_chunk(Resp, "{\"rows\":["),
-        {ok, _} = couch_view:fold_reduce(View, Dir, {StartKey, StartDocId}, 
-            {EndKey, EndDocId}, GroupRowsFun, RespFun, {"", Skip, Limit}),
-        send_chunk(Resp, "]}"),
-        end_json_response(Resp)
+        {ok, GroupRowsFun, RespFun} = make_reduce_fold_funs(Req, GroupLevel, QueryArgs, CurrentEtag, #reduce_fold_helper_funs{}),
+        FoldAccInit = {Limit, Skip, undefined, []},
+        {ok, {_, _, Resp, _}} = couch_view:fold_reduce(View, Dir, {StartKey, StartDocId}, 
+            {EndKey, EndDocId}, GroupRowsFun, RespFun, FoldAccInit),
+        finish_reduce_fold(Req, Resp)
     end);
     
 output_reduce_view(Req, View, Group, QueryArgs, Keys) ->
@@ -165,22 +163,25 @@ output_reduce_view(Req, View, Group, QueryArgs, Keys) ->
     } = QueryArgs,
     CurrentEtag = view_group_etag(Group),
     couch_httpd:etag_respond(Req, CurrentEtag, fun() ->
-        {ok, Resp} = start_json_response(Req, 200, [{"Etag",CurrentEtag}]),
-        {ok, GroupRowsFun, RespFun} = make_reduce_fold_funs(Resp, GroupLevel),
-        send_chunk(Resp, "{\"rows\":["),
-        lists:foldl(
-            fun(Key, AccSeparator) ->
-                {ok, {NewAcc, _, _}} = couch_view:fold_reduce(View, Dir, {Key, StartDocId}, 
-                    {Key, EndDocId}, GroupRowsFun, RespFun, 
-                    {AccSeparator, Skip, Limit}),
-                NewAcc % Switch to comma
+        {ok, GroupRowsFun, RespFun} = make_reduce_fold_funs(Req, GroupLevel, QueryArgs, CurrentEtag, #reduce_fold_helper_funs{}),
+        {Resp, _} = lists:foldl(
+            fun(Key, {Resp, AccSeparator}) ->
+                FoldAccInit = {Limit, Skip, Resp, AccSeparator},
+                {_, {_, _, Resp2, NewAcc}} = couch_view:fold_reduce(View, Dir, {Key, StartDocId}, 
+                    {Key, EndDocId}, GroupRowsFun, RespFun, FoldAccInit),
+                % Switch to comma
+                {Resp2, NewAcc}
             end,
-        "", Keys), % Start with no comma
-        send_chunk(Resp, "]}"),
-        end_json_response(Resp)
+        {undefined, []}, Keys), % Start with no comma
+        finish_reduce_fold(Req, Resp)
     end).
     
-make_reduce_fold_funs(Resp, GroupLevel) ->
+make_reduce_fold_funs(Req, GroupLevel, _QueryArgs, Etag, HelperFuns) ->
+    #reduce_fold_helper_funs{
+        start_response = StartRespFun,
+        send_row = SendRowFun
+    } = apply_default_helper_funs(HelperFuns),
+
     GroupRowsFun =
         fun({_Key1,_}, {_Key2,_}) when GroupLevel == 0 ->
             true;
@@ -190,31 +191,47 @@ make_reduce_fold_funs(Resp, GroupLevel) ->
         ({Key1,_}, {Key2,_}) ->
             Key1 == Key2
         end,
-    RespFun = fun(_Key, _Red, {AccSeparator,AccSkip,AccLimit}) when AccSkip > 0 ->
-        {ok, {AccSeparator,AccSkip-1,AccLimit}};
-    (_Key, _Red, {AccSeparator,0,AccLimit}) when AccLimit == 0 ->
-        {stop, {AccSeparator,0,AccLimit}};
-    (_Key, Red, {AccSeparator,0,AccLimit}) when GroupLevel == 0 ->
-        Json = ?JSON_ENCODE({[{key, null}, {value, Red}]}),
-        send_chunk(Resp, AccSeparator ++ Json),
-        {ok, {",",0,AccLimit-1}};
-    (Key, Red, {AccSeparator,0,AccLimit})
+    RespFun = fun(_Key, _Red, {AccLimit, AccSkip, Resp, AccSeparator}) when AccSkip > 0 ->
+        {ok, {AccLimit, AccSkip - 1, Resp, AccSeparator}};
+    (_Key, _Red, {0, 0, Resp, AccSeparator}) ->
+        {stop, {0, 0, Resp, AccSeparator}};
+    (_Key, Red, {AccLimit, 0, Resp, AccSeparator}) when GroupLevel == 0 ->
+        {ok, Resp2, RowSep} = case Resp of
+        undefined -> StartRespFun(Req, Etag, null, null);
+        _ -> {ok, Resp, nil}
+        end,
+        RowResult = case SendRowFun(Resp2, {null, Red}, RowSep) of
+        stop -> stop;
+        _ -> ok
+        end,
+        {RowResult, {AccLimit - 1, 0, Resp2, AccSeparator}};
+    (Key, Red, {AccLimit, 0, Resp, AccSeparator})
             when is_integer(GroupLevel) 
             andalso is_list(Key) ->
-        Json = ?JSON_ENCODE(
-            {[{key, lists:sublist(Key, GroupLevel)},{value, Red}]}),
-        send_chunk(Resp, AccSeparator ++ Json),
-        {ok, {",",0,AccLimit-1}};
-    (Key, Red, {AccSeparator,0,AccLimit}) ->
-        Json = ?JSON_ENCODE({[{key, Key}, {value, Red}]}),
-        send_chunk(Resp, AccSeparator ++ Json),
-        {ok, {",",0,AccLimit-1}}
+        {ok, Resp2, RowSep} = case Resp of
+        undefined -> StartRespFun(Req, Etag, null, null);
+        _ -> {ok, Resp, nil}
+        end,
+        RowResult = case SendRowFun(Resp2, {lists:sublist(Key, GroupLevel), Red}, RowSep) of
+        stop -> stop;
+        _ -> ok
+        end,
+        {RowResult, {AccLimit - 1, 0, Resp2, AccSeparator}};
+    (Key, Red, {AccLimit, 0, Resp, AccSeparator}) ->
+        {ok, Resp2, RowSep} = case Resp of
+        undefined -> StartRespFun(Req, Etag, null, null);
+        _ -> {ok, Resp, nil}
+        end,
+        RowResult = case SendRowFun(Resp2, {Key, Red}, RowSep) of
+        stop -> stop;
+        _ -> ok
+        end,
+        {RowResult, {AccLimit - 1, 0, Resp2, AccSeparator}}
     end,
     {ok, GroupRowsFun, RespFun}.
     
 
 
-
 reverse_key_default(nil) -> {};
 reverse_key_default({}) -> nil;
 reverse_key_default(Key) -> Key.
@@ -470,6 +487,25 @@ apply_default_helper_funs(#view_fold_helper_funs{
         send_row = SendRow2
     }.
 
+apply_default_helper_funs(#reduce_fold_helper_funs{
+    start_response = StartResp,
+    send_row = SendRow
+}=Helpers) ->
+    StartResp2 = case StartResp of
+    undefined -> fun json_reduce_start_resp/4;
+    _ -> StartResp
+    end,
+
+    SendRow2 = case SendRow of
+    undefined -> fun send_json_reduce_row/3;
+    _ -> SendRow
+    end,
+
+    Helpers#reduce_fold_helper_funs{
+        start_response = StartResp2,
+        send_row = SendRow2
+    }.
+
 make_passed_end_fun(Dir, EndKey, EndDocId) ->
     case Dir of
     fwd ->
@@ -496,6 +532,18 @@ send_json_view_row(Resp, Db, {{Key, DocId}, Value}, RowFront, IncludeDocs) ->
     end,
     send_chunk(Resp, RowFront2 ++  ?JSON_ENCODE(JsonObj)).
 
+json_reduce_start_resp(Req, Etag, _, _) ->
+    {ok, Resp} = start_json_response(Req, 200, [{"Etag", Etag}]),
+    BeginBody = "{\"rows\":[\r\n",
+    {ok, Resp, BeginBody}.
+
+send_json_reduce_row(Resp, {Key, Value}, RowFront) ->
+    RowFront2 = case RowFront of
+    nil -> ",\r\n";
+    _ -> RowFront
+    end,
+    send_chunk(Resp, RowFront2 ++ ?JSON_ENCODE({[{key, Key}, {value, Value}]})).
+
 view_group_etag(Group) ->
     view_group_etag(Group, nil).
     
@@ -557,3 +605,14 @@ finish_view_fold(Req, TotalRows, FoldResult) ->
     Error ->
         throw(Error)
     end.
+
+finish_reduce_fold(Req, Resp) ->
+    case Resp of
+    undefined ->
+        send_json(Req, 200, {[
+            {rows, []}
+        ]});
+    Resp ->
+        send_chunk(Resp, "\r\n]}"),
+        end_json_response(Resp)
+    end.
diff --git a/src/couchdb/couch_query_servers.erl b/src/couchdb/couch_query_servers.erl
index 5eca63c2..a33ffada 100644
--- a/src/couchdb/couch_query_servers.erl
+++ b/src/couchdb/couch_query_servers.erl
@@ -18,7 +18,7 @@
 -export([init/1, terminate/2, handle_call/3, handle_cast/2, handle_info/2,code_change/3,stop/0]).
 -export([start_doc_map/2, map_docs/2, stop_doc_map/1]).
 -export([reduce/3, rereduce/3,validate_doc_update/5]).
--export([render_doc_show/5,start_view_list/2,render_list_head/5, render_list_row/4, render_list_tail/3]).
+-export([render_doc_show/5,start_view_list/2,render_list_head/5, render_list_row/4, render_list_tail/3, render_reduce_head/3, render_reduce_row/4]).
 % -export([test/0]).
 
 -include("couch_db.hrl").
@@ -160,6 +160,16 @@ render_list_tail({Lang, Pid}, Req, Db) ->
     JsonResp.
     
     
+render_reduce_head({_Lang, Pid}, Req, Db) ->
+    Head = {[]},
+    JsonReq = couch_httpd_external:json_req_obj(Req, Db),
+    couch_os_process:prompt(Pid, [<<"list_begin">>, Head, JsonReq]).
+
+render_reduce_row({_Lang, Pid}, Req, Db, {Key, Value}) ->
+    JsonRow = {[{key, Key}, {value, Value}]},
+    JsonReq = couch_httpd_external:json_req_obj(Req, Db),
+    couch_os_process:prompt(Pid, [<<"list_row">>, JsonRow, JsonReq]).
+
 
 init([]) ->