From a613317745c9b88e2c0d01e9a24f8b5d7b5b242e Mon Sep 17 00:00:00 2001
From: Jan Lehnardt <jan@apache.org>
Date: Sat, 1 Aug 2009 13:50:38 +0000
Subject: implement longpolling for _changes, unify _changes-mode parameters,
 patch by Benoit Chesneau, closes COUCHDB-241

git-svn-id: https://svn.apache.org/repos/asf/couchdb/trunk@799862 13f79535-47bb-0310-9956-ffa450edef68
---
 src/couchdb/couch_httpd_db.erl | 36 ++++++++++++++++++++++--------------
 1 file changed, 22 insertions(+), 14 deletions(-)

(limited to 'src')

diff --git a/src/couchdb/couch_httpd_db.erl b/src/couchdb/couch_httpd_db.erl
index 7498a521..63ae5563 100644
--- a/src/couchdb/couch_httpd_db.erl
+++ b/src/couchdb/couch_httpd_db.erl
@@ -64,12 +64,13 @@ get_changes_timeout(Req, Resp) ->
             fun() -> send_chunk(Resp, "\n"), ok end}
     end.
 
+
 handle_changes_req(#httpd{method='GET',path_parts=[DbName|_]}=Req, Db) ->
     StartSeq = list_to_integer(couch_httpd:qs_value(Req, "since", "0")),
     {ok, Resp} = start_json_response(Req, 200),
     send_chunk(Resp, "{\"results\":[\n"),
-    case couch_httpd:qs_value(Req, "continuous", "false") of
-    "true" ->
+    case couch_httpd:qs_value(Req, "feed", "normal") of
+    ResponseType when ResponseType == "continuous" orelse ResponseType == "longpoll"->
         Self = self(),
         {ok, Notify} = couch_db_update_notifier:start_link(
             fun({_, DbName0}) when DbName0 == DbName ->
@@ -81,16 +82,15 @@ handle_changes_req(#httpd{method='GET',path_parts=[DbName|_]}=Req, Db) ->
         couch_stats_collector:track_process_count(Self,
                             {httpd, clients_requesting_changes}),
         try
-            keep_sending_changes(Req, Resp, Db, StartSeq, <<"">>, Timeout, TimeoutFun)
+            keep_sending_changes(Req, Resp, Db, StartSeq, <<"">>, Timeout, TimeoutFun, ResponseType)
         after
             couch_db_update_notifier:stop(Notify),
             get_rest_db_updated() % clean out any remaining update messages
         end;
-    "false" ->
+    "normal" ->
         {ok, {LastSeq, _Prepend}} =
                 send_changes(Req, Resp, Db, StartSeq, <<"">>),
-        send_chunk(Resp, io_lib:format("\n],\n\"last_seq\":~w}\n", [LastSeq])),
-        end_json_response(Resp)
+        end_sending_changes(Resp, LastSeq)
     end;
 
 handle_changes_req(#httpd{path_parts=[_,<<"_changes">>]}=Req, _Db) ->
@@ -110,17 +110,25 @@ get_rest_db_updated() ->
     receive db_updated -> get_rest_db_updated()
     after 0 -> updated
     end.
+    
+end_sending_changes(Resp, EndSeq) ->
+    send_chunk(Resp, io_lib:format("\n],\n\"last_seq\":~w}\n", [EndSeq])),
+    end_json_response(Resp).
 
-keep_sending_changes(#httpd{user_ctx=UserCtx,path_parts=[DbName|_]}=Req, Resp, Db, StartSeq, Prepend, Timeout, TimeoutFun) ->
+keep_sending_changes(#httpd{user_ctx=UserCtx,path_parts=[DbName|_]}=Req, Resp, Db, StartSeq, Prepend, Timeout, TimeoutFun, ResponseType) ->
     {ok, {EndSeq, Prepend2}} = send_changes(Req, Resp, Db, StartSeq, Prepend),
     couch_db:close(Db),
-    case wait_db_updated(Timeout, TimeoutFun) of
-    updated ->
-        {ok, Db2} = couch_db:open(DbName, [{user_ctx, UserCtx}]),
-        keep_sending_changes(Req, Resp, Db2, EndSeq, Prepend2, Timeout, TimeoutFun);
-    stop ->
-        send_chunk(Resp, io_lib:format("\n],\n\"last_seq\":~w}\n", [EndSeq])),
-        end_json_response(Resp)
+    if
+    EndSeq > StartSeq, ResponseType == "longpoll" ->
+        end_sending_changes(Resp, EndSeq);
+    true ->
+        case wait_db_updated(Timeout, TimeoutFun) of
+        updated ->
+            {ok, Db2} = couch_db:open(DbName, [{user_ctx, UserCtx}]),
+            keep_sending_changes(Req, Resp, Db2, EndSeq, Prepend2, Timeout, TimeoutFun, ResponseType);
+        stop ->
+            end_sending_changes(Resp, EndSeq)
+        end
     end.
 
 send_changes(Req, Resp, Db, StartSeq, Prepend0) ->
-- 
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