[couchdb] 02/02: support Websocket protocol for continuous response

[rn...@apache.org]

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rnewson pushed a commit to branch changes-websocket
in repository https://gitbox.apache.org/repos/asf/couchdb.git

commit 63df98f8386db02137aed5a3e07394b6500fa971
Author: Robert Newson <rn...@apache.org>
AuthorDate: Mon Jun 26 21:29:08 2023 +0100

    support Websocket protocol for continuous response
    
    I currently send a data frame as the heartbeat but we should
    tweak mochiweb_websocket so we can send pong messages which looks
    like this;
    
    diff --git a/src/mochiweb_websocket.erl b/src/mochiweb_websocket.erl
    index 22ef924..396db82 100644
    --- a/src/mochiweb_websocket.erl
    +++ b/src/mochiweb_websocket.erl
    @@ -74,6 +74,9 @@ call_body({M, F}, Payload, State, ReplyChannel) ->
     call_body(Body, Payload, State, ReplyChannel) ->
         Body(Payload, State, ReplyChannel).
    
    +send(Socket, pong, hybi) ->
    +    Payload = <<1:1, 0:3, 10:4, 1:4, 0:8>>,
    +    mochiweb_socket:send(Socket, Payload);
     send(Socket, Payload, hybi) ->
         Prefix = <<1:1, 0:3, 1:4,
                   (payload_length(iolist_size(Payload)))/binary>>,
    
    and then change;
    
    ReplyChannel("\n"),
    
    to
    
    ReplyChannel(pong),
---
 src/chttpd/src/chttpd_db.erl | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/chttpd/src/chttpd_db.erl b/src/chttpd/src/chttpd_db.erl
index 791ee86f3..05ca6d95a 100644
--- a/src/chttpd/src/chttpd_db.erl
+++ b/src/chttpd/src/chttpd_db.erl
@@ -166,7 +166,7 @@ handle_changes_req1(#httpd{} = Req, Db) ->
 % websocket goop
 changes_callback(start, #cacc{feed = continuous, websocket = true} = Acc) ->
     {ReentryWs, ReplyChannel} = mochiweb_websocket:upgrade_connection(
-        Acc#cacc.mochi, fun client_ws_loop/3),
+        Acc#cacc.mochi#httpd.mochi_req, fun client_ws_loop/3),
     {ok, Acc#cacc{mochi = undefined, websocket = {ws, ReentryWs, ReplyChannel}}};
 changes_callback({change, Change}, #cacc{websocket = {ws, _ReentryWs, ReplyChannel}} = Acc) ->
     chttpd_stats:incr_rows(),
@@ -175,6 +175,8 @@ changes_callback({change, Change}, #cacc{websocket = {ws, _ReentryWs, ReplyChann
 changes_callback(timeout, #cacc{websocket = {ws, _ReentryWs, ReplyChannel}} = Acc) ->
     ReplyChannel("\n"),
     {ok, Acc};
+changes_callback(waiting_for_updates, #cacc{websocket = {ws, _ReentryWs, ReplyChannel}} = Acc) ->
+    {ok, Acc};
 changes_callback({stop, EndSeq, Pending}, #cacc{websocket = {ws, _ReentryWs, ReplyChannel}} = Acc) ->
     Row =
         {[
@@ -182,7 +184,7 @@ changes_callback({stop, EndSeq, Pending}, #cacc{websocket = {ws, _ReentryWs, Rep
             {<<"pending">>, Pending}
         ]},
     ReplyChannel(?JSON_ENCODE(Row)),
-    {stop, Acc};
+    {ok, Acc};
 
 % callbacks for continuous feed (newline-delimited JSON Objects)
 changes_callback(start, #cacc{feed = continuous} = Acc) ->