buffer: allow a buffer to shrink gracefully

the idea behind this patch is to allow the buffer to shrink, but
make this a seldom operation. The buffers average size is measured
exponentionally smoothed with am alpha of 1/128.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 1446203414-4013-20-git-send-email-kraxel@redhat.com

1 files changed, 1 insertions, 0 deletions

diff --git a/include/qemu/buffer.h b/include/qemu/buffer.h
index 0a69b3a..dead9b7 100644
--- a/include/qemu/buffer.h
+++ b/include/qemu/buffer.h
@@ -37,6 +37,7 @@ struct Buffer {
     char *name;
     size_t capacity;
     size_t offset;
+    uint64_t avg_size;
     uint8_t *buffer;
 };