[couchdb] branch changes-websocket updated (a65ca9265 -> 2ab48cf3f)

[rn...@apache.org]

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in repository https://gitbox.apache.org/repos/asf/couchdb.git


 discard a65ca9265 support Websocket protocol for continuous response
     new 2ab48cf3f support Websocket protocol for continuous response

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Summary of changes:
 src/chttpd/src/chttpd_db.erl | 41 +++++++++++++++++++++++++++++++++++------
 1 file changed, 35 insertions(+), 6 deletions(-)

[couchdb] 01/01: support Websocket protocol for continuous response

[rn...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

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

commit 2ab48cf3f8869be333c03c4119d649082b0bac29
Author: Robert Newson <rn...@apache.org>
AuthorDate: Mon Jun 26 21:29:08 2023 +0100

    support Websocket protocol for continuous response
    
    This isn't full Websocket protocol as mochiweb doesn't have
    the plumbing but it's still useful.
    
    The endpoint will not return a pong if the client sends a ping
    but if the heartbeat parameter is used the server will send pongs
    at that right as a keep-alive.
---
 src/chttpd/src/chttpd_db.erl | 59 ++++++++++++++++++++++++++++++++++++++------
 1 file changed, 51 insertions(+), 8 deletions(-)

diff --git a/src/chttpd/src/chttpd_db.erl b/src/chttpd/src/chttpd_db.erl
index 791ee86f3..8beb94cb6 100644
--- a/src/chttpd/src/chttpd_db.erl
+++ b/src/chttpd/src/chttpd_db.erl
@@ -163,18 +163,29 @@ handle_changes_req1(#httpd{} = Req, Db) ->
             throw({bad_request, Msg})
     end.
 
-% websocket goop
+% websocket callbacks
 changes_callback(start, #cacc{feed = continuous, websocket = true} = Acc) ->
     {ReentryWs, ReplyChannel} = mochiweb_websocket:upgrade_connection(
-        Acc#cacc.mochi, fun client_ws_loop/3),
-    {ok, Acc#cacc{mochi = undefined, websocket = {ws, ReentryWs, ReplyChannel}}};
+        Acc#cacc.mochi#httpd.mochi_req, fun client_ws_loop/3),
+    {ok, Acc#cacc{websocket = {ws, ReentryWs, ReplyChannel}}};
 changes_callback({change, Change}, #cacc{websocket = {ws, _ReentryWs, ReplyChannel}} = Acc) ->
     chttpd_stats:incr_rows(),
     ReplyChannel(?JSON_ENCODE(Change)),
     {ok, Acc};
-changes_callback(timeout, #cacc{websocket = {ws, _ReentryWs, ReplyChannel}} = Acc) ->
-    ReplyChannel("\n"),
+changes_callback(timeout, #cacc{websocket = {ws, _ReentryWs, _ReplyChannel}} = Acc) ->
+    ws_pong(Acc),
     {ok, Acc};
+changes_callback(waiting_for_updates, #cacc{websocket = {ws, _ReentryWs, _ReplyChannel}} = Acc) ->
+    {ok, Acc};
+changes_callback({error, Reason}, #cacc{websocket = {ws, _ReentryWs, ReplyChannel}} = Acc) ->
+    {_Code, ErrorStr, ReasonStr} = chttpd:error_info(Reason),
+    Row =
+        {[
+            {<<"error">>, ErrorStr},
+            {<<"reason">>, ReasonStr}
+         ]},
+    ReplyChannel(?JSON_ENCODE(Row)),
+    ws_close(Acc);
 changes_callback({stop, EndSeq, Pending}, #cacc{websocket = {ws, _ReentryWs, ReplyChannel}} = Acc) ->
     Row =
         {[
@@ -182,7 +193,7 @@ changes_callback({stop, EndSeq, Pending}, #cacc{websocket = {ws, _ReentryWs, Rep
             {<<"pending">>, Pending}
         ]},
     ReplyChannel(?JSON_ENCODE(Row)),
-    {stop, Acc};
+    ws_close(Acc);
 
 % callbacks for continuous feed (newline-delimited JSON Objects)
 changes_callback(start, #cacc{feed = continuous} = Acc) ->
@@ -2584,8 +2595,40 @@ websocket_upgrade_requested(#httpd{} = Req) ->
     Upgrade = chttpd:header_value(Req, "Upgrade"),
     Upgrade =/= undefined andalso string:to_lower(Upgrade) =:= "websocket".
 
-client_ws_loop(_Payload, Broadcaster, _ReplyChannel) ->
-    Broadcaster.
+client_ws_loop(_Payload, State, _ReplyChannel) ->
+    State.
+
+ws_pong(Req) ->
+    Socket = ws_socket(Req),
+    mochiweb_socket:send(Socket, <<1:1, 0:3, 10:4, 0:8>>).
+
+ws_close(Req) ->
+    Socket = ws_socket(Req),
+    mochiweb_socket:send(Socket, <<1:1, 0:3, 10:4, 0:8>>),
+    ws_shutdown(Socket, write),
+    ws_drain(Socket),
+    mochiweb_socket:close(Socket),
+    exit({shutdown, websocket_close}).
+
+ws_drain(Socket) ->
+    Result = gen_tcp:recv(Socket, 8192),
+    case Result of
+        {ok, _Data} ->
+            ws_drain(socket);
+        {error, closed} ->
+            ok
+    end.
+
+ws_socket(#cacc{} = Acc) ->
+    ws_socket(Acc#cacc.mochi#httpd.mochi_req);
+ws_socket({ReqM, _} = Req) ->
+    ReqM:get(socket, Req).
+
+ws_shutdown({ssl, Socket}, How) ->
+    gen_tcp:shutdown(Socket, How);
+ws_shutdown(Socket, How) ->
+    gen_tcp:shutdown(Socket, How).
+
 
 -ifdef(TEST).
 -include_lib("eunit/include/eunit.hrl").