[09/11] couch commit: updated refs/heads/master to 7ab7995

[rn...@apache.org]

Send a real EventSource event for heartbeat

The EventSource connection can get stuck (in TCP half-open state*) and there's no way
for the client to detect that. This commit changes the way heartbeat is sent, instead of
sending a newline character, it sends an empty event of type heartbeat:

    event: heartbeat
    data:

This event doesn't have an id: field, so the client will retain its latest Last-Event-ID state.

This doesn't change the expectations of clients that used EventSource till now, because they
subscribe to the 'message' event type. To get the 'heartbeat' events a client will need to
explicitly subscribe to it:

    source.addEventListener('heartbeat', function () { /* cancel a timer that would otherwise reconnect the source */ });

* this can happen when you suspend your laptop, on flaky internet connection, ADSL reconnect,
bad wifi signals, bad routers etc. Pretty often in a typical internet usage nowadays.


Project: http://git-wip-us.apache.org/repos/asf/couchdb-couch/repo
Commit: http://git-wip-us.apache.org/repos/asf/couchdb-couch/commit/845bf752
Tree: http://git-wip-us.apache.org/repos/asf/couchdb-couch/tree/845bf752
Diff: http://git-wip-us.apache.org/repos/asf/couchdb-couch/diff/845bf752

Branch: refs/heads/master
Commit: 845bf7529a3bc565d6446a7fa6cc5fd1a140653e
Parents: c625e21
Author: Damjan Georgievski <gd...@gmail.com>
Authored: Fri May 2 17:04:41 2014 +0200
Committer: Robert Newson <rn...@apache.org>
Committed: Wed May 21 15:17:18 2014 +0100

----------------------------------------------------------------------
 src/couch_httpd_db.erl | 2 ++
 1 file changed, 2 insertions(+)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/couchdb-couch/blob/845bf752/src/couch_httpd_db.erl
----------------------------------------------------------------------
diff --git a/src/couch_httpd_db.erl b/src/couch_httpd_db.erl
index 8c7ae77..ad8654a 100644
--- a/src/couch_httpd_db.erl
+++ b/src/couch_httpd_db.erl
@@ -105,6 +105,8 @@ handle_changes_req2(Req, Db) ->
                 io_lib:format("\n],\n\"last_seq\":~w}\n", [EndSeq])
             ),
             end_json_response(Resp);
+        (timeout, "eventsource") ->
+            send_chunk(Resp, "event: heartbeat\ndata: \n\n");
         (timeout, _) ->
             send_chunk(Resp, "\n")
         end