summaryrefslogtreecommitdiff
path: root/io
diff options
context:
space:
mode:
authorDaniel P. Berrange <berrange@redhat.com>2017-10-09 15:34:06 +0100
committerDaniel P. Berrange <berrange@redhat.com>2017-10-16 16:57:08 +0100
commit57b0cdf152b7266e68bfa3e84635d4bdb64ef2cd (patch)
treea8159682a8e0665cfa813eb2d176724727cc49af /io
parenta7b20a8efa28e5f22c26c06cd06c2f12bc863493 (diff)
io: simplify websocket ping reply handling
We must ensure we don't get flooded with ping replies if the outbound channel is slow. Currently we do this by keeping the ping reply in a separate temporary buffer and only writing it if the encoutput buffer is completely empty. This is overly pessimistic, as it is reasonable to add a ping reply to the encoutput buffer even if it has previous data in it, as long as that previous data doesn't include a ping reply. To track this better, put the ping reply directly into the encoutput buffer, and then record the size of encoutput at this time in pong_remain. As we write encoutput to the underlying channel, we can decrement the pong_remain counter. Once it hits zero, we can accept further ping replies for transmission. Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Diffstat (limited to 'io')
-rw-r--r--io/channel-websock.c28
1 files changed, 15 insertions, 13 deletions
diff --git a/io/channel-websock.c b/io/channel-websock.c
index 04bcc059cd..6083f74c9b 100644
--- a/io/channel-websock.c
+++ b/io/channel-websock.c
@@ -825,11 +825,14 @@ static int qio_channel_websock_decode_payload(QIOChannelWebsock *ioc,
}
return -1;
} else if (ioc->opcode == QIO_CHANNEL_WEBSOCK_OPCODE_PING) {
- /* ping frames produce an immediate reply */
- buffer_reset(&ioc->ping_reply);
- qio_channel_websock_encode_buffer(
- ioc, &ioc->ping_reply, QIO_CHANNEL_WEBSOCK_OPCODE_PONG,
- &ioc->encinput);
+ /* ping frames produce an immediate reply, as long as we've not still
+ * got a previous pong queued, in which case we drop the new pong */
+ if (ioc->pong_remain == 0) {
+ qio_channel_websock_encode_buffer(
+ ioc, &ioc->encoutput, QIO_CHANNEL_WEBSOCK_OPCODE_PONG,
+ &ioc->encinput);
+ ioc->pong_remain = ioc->encoutput.offset;
+ }
} /* pong frames are ignored */
if (payload_len) {
@@ -888,7 +891,6 @@ static void qio_channel_websock_finalize(Object *obj)
buffer_free(&ioc->encoutput);
buffer_free(&ioc->rawinput);
buffer_free(&ioc->rawoutput);
- buffer_free(&ioc->ping_reply);
object_unref(OBJECT(ioc->master));
if (ioc->io_tag) {
g_source_remove(ioc->io_tag);
@@ -946,12 +948,7 @@ static ssize_t qio_channel_websock_write_wire(QIOChannelWebsock *ioc,
ssize_t ret;
ssize_t done = 0;
- /* ping replies take priority over binary data */
- if (!ioc->ping_reply.offset) {
- qio_channel_websock_encode(ioc);
- } else if (!ioc->encoutput.offset) {
- buffer_move_empty(&ioc->encoutput, &ioc->ping_reply);
- }
+ qio_channel_websock_encode(ioc);
while (ioc->encoutput.offset > 0) {
ret = qio_channel_write(ioc->master,
@@ -968,6 +965,11 @@ static ssize_t qio_channel_websock_write_wire(QIOChannelWebsock *ioc,
}
buffer_advance(&ioc->encoutput, ret);
done += ret;
+ if (ioc->pong_remain < ret) {
+ ioc->pong_remain = 0;
+ } else {
+ ioc->pong_remain -= ret;
+ }
}
return done;
}
@@ -1026,7 +1028,7 @@ static void qio_channel_websock_set_watch(QIOChannelWebsock *ioc)
return;
}
- if (ioc->encoutput.offset || ioc->ping_reply.offset) {
+ if (ioc->encoutput.offset) {
cond |= G_IO_OUT;
}
if (ioc->encinput.offset < QIO_CHANNEL_WEBSOCK_MAX_BUFFER &&