ui: extend VNC trottling tracing to SASL codepaths

In previous commit:

  commit 6aa22a29187e1908f5db738d27c64a9efc8d0bfa
  Author: Daniel P. Berrange <berrange@redhat.com>
  Date:   Mon Dec 18 19:12:27 2017 +0000

    ui: add trace events related to VNC client throttling

trace points related to unthrottling client I/O were missed from the
SASL codepaths.

Reported-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-id: 20180205114938.15784-5-berrange@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/vnc-auth-sasl.c

@@ -79,12 +79,23 @@ size_t vnc_client_write_sasl(VncState *vs)
 
     vs->sasl.encodedOffset += ret;
     if (vs->sasl.encodedOffset == vs->sasl.encodedLength) {
+        bool throttled = vs->force_update_offset != 0;
+        size_t offset;
         if (vs->sasl.encodedRawLength >= vs->force_update_offset) {
             vs->force_update_offset = 0;
         } else {
             vs->force_update_offset -= vs->sasl.encodedRawLength;
         }
+        if (throttled && vs->force_update_offset == 0) {
+            trace_vnc_client_unthrottle_forced(vs, vs->ioc);
+        }
+        offset = vs->output.offset;
         buffer_advance(&vs->output, vs->sasl.encodedRawLength);
+        if (offset >= vs->throttle_output_offset &&
+            vs->output.offset < vs->throttle_output_offset) {
+            trace_vnc_client_unthrottle_incremental(vs, vs->ioc,
+                                                    vs->output.offset);
+        }
         vs->sasl.encoded = NULL;
         vs->sasl.encodedOffset = vs->sasl.encodedLength = 0;
     }