Re: [Qemu-devel] [PATCH v2 15/21] char-udp: flush as much buffer as possible

[Philippe Mathieu-Daudé]

On 02/27/2017 10:41 AM, Marc-André Lureau wrote:

Instead of flushing the buffer byte by byte, call qemu_chr_be_write()
with as much byte possible accepted by the front-end.

Factor out buffer flushing in a common function udp_chr_flush_buffer().

Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>

Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>

---
 chardev/char-udp.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/chardev/char-udp.c b/chardev/char-udp.c
index 2c6c7ddd73..5364b5fc59 100644
--- a/chardev/char-udp.c
+++ b/chardev/char-udp.c
@@ -51,6 +51,18 @@ static int udp_chr_write(Chardev *chr, const uint8_t *buf, 
int len)
         s->ioc, (const char *)buf, len, NULL);
 }

+static void udp_chr_flush_buffer(UdpChardev *s)
+{
+    Chardev *chr = CHARDEV(s);
+
+    while (s->max_size > 0 && s->bufptr < s->bufcnt) {
+        int n = MIN(s->max_size, s->bufcnt - s->bufptr);
+        qemu_chr_be_write(chr, &s->buf[s->bufptr], n);
+        s->bufptr += n;
+        s->max_size = qemu_chr_be_can_write(chr);
+    }
+}
+
 static int udp_chr_read_poll(void *opaque)
 {
     Chardev *chr = CHARDEV(opaque);
@@ -61,11 +73,8 @@ static int udp_chr_read_poll(void *opaque)
     /* If there were any stray characters in the queue process them
      * first
      */
-    while (s->max_size > 0 && s->bufptr < s->bufcnt) {
-        qemu_chr_be_write(chr, &s->buf[s->bufptr], 1);
-        s->bufptr++;
-        s->max_size = qemu_chr_be_can_write(chr);
-    }
+    udp_chr_flush_buffer(s);
+
     return s->max_size;
 }

@@ -85,13 +94,8 @@ static gboolean udp_chr_read(QIOChannel *chan, GIOCondition 
cond, void *opaque)
         return FALSE;
     }
     s->bufcnt = ret;
-
     s->bufptr = 0;
-    while (s->max_size > 0 && s->bufptr < s->bufcnt) {
-        qemu_chr_be_write(chr, &s->buf[s->bufptr], 1);
-        s->bufptr++;
-        s->max_size = qemu_chr_be_can_write(chr);
-    }
+    udp_chr_flush_buffer(s);

     return TRUE;
 }