[Spice-devel] [PATCH spice-server 2/4] red-channel-client: Prevent too tight loop waiting for ACKs

[Frediano Ziglio]

RedChannelClient has a "handle-acks" feature.
If this feature is enabled after the configured number of messages
it waits for an ACK.
If is waiting for an ACK it stops sending messages.
However the write notification was not disabled causing the
loop event to always trigger as the socket in this case is
ready to accept data.
This is noticeable using slow network environments and having
some additional loop instrumentation.

Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
---
 server/red-channel-client.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/server/red-channel-client.c b/server/red-channel-client.c
index 764e6cd7e..98efdfd0b 100644
--- a/server/red-channel-client.c
+++ b/server/red-channel-client.c
@@ -45,6 +45,8 @@
 #define IOV_MAX 1024
 #endif
 
+#define SPICE_WATCH_EVENTS_READ_WRITE (SPICE_WATCH_EVENT_READ|SPICE_WATCH_EVENT_WRITE)
+
 typedef struct SpiceDataHeaderOpaque SpiceDataHeaderOpaque;
 
 typedef uint16_t (*get_msg_type_proc)(SpiceDataHeaderOpaque *header);
@@ -1327,7 +1329,8 @@ void red_channel_client_push(RedChannelClient *rcc)
     while ((pipe_item = red_channel_client_pipe_item_get(rcc))) {
         red_channel_client_send_item(rcc, pipe_item);
     }
-    if (red_channel_client_no_item_being_sent(rcc) && g_queue_is_empty(&rcc->priv->pipe)) {
+    if ((red_channel_client_no_item_being_sent(rcc) && g_queue_is_empty(&rcc->priv->pipe)) ||
+        red_channel_client_waiting_for_ack(rcc)) {
         red_channel_client_watch_update_mask(rcc, SPICE_WATCH_EVENT_READ);
     }
     rcc->priv->during_send = FALSE;
@@ -1452,6 +1455,7 @@ bool red_channel_client_handle_message(RedChannelClient *rcc, uint16_t type,
     case SPICE_MSGC_ACK:
         if (rcc->priv->ack_data.client_generation == rcc->priv->ack_data.generation) {
             rcc->priv->ack_data.messages_window -= rcc->priv->ack_data.client_window;
+            red_channel_client_watch_update_mask(rcc, SPICE_WATCH_EVENTS_READ_WRITE);
             red_channel_client_push(rcc);
         }
         break;
@@ -1542,8 +1546,7 @@ static inline gboolean prepare_pipe_add(RedChannelClient *rcc, RedPipeItem *item
         return FALSE;
     }
     if (g_queue_is_empty(&rcc->priv->pipe)) {
-        red_channel_client_watch_update_mask(rcc,
-                                             SPICE_WATCH_EVENT_READ | SPICE_WATCH_EVENT_WRITE);
+        red_channel_client_watch_update_mask(rcc, SPICE_WATCH_EVENTS_READ_WRITE);
     }
     return TRUE;
 }
-- 
2.13.5