[Libguestfs] [PATCH libnbd 2/3] states: Add handle h->wflags field.

[Richard W.M. Jones]

There's an obvious bug in this patch in that it doesn't reset the
h->wflags field in all cases.  Updated patch below.

I rechecked the performance measurements and they are the same after
the updated patch.

Rich.

>From 15a687b50acecebcfd3dc6222d93e6df984b83c6 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones at redhat.com>
Date: Sat, 8 Jun 2019 19:12:22 +0100
Subject: [PATCH] states: Add handle h->wflags field.

This field contains optimization flags (ie. MSG_MORE) which are passed
through to the socket layer if it supports them.  The flags are reset
automatically when we move to another state.
---
 generator/states.c | 10 +++++++---
 lib/internal.h     |  1 +
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/generator/states.c b/generator/states.c
index e879a83..b0dab83 100644
--- a/generator/states.c
+++ b/generator/states.c
@@ -91,8 +91,8 @@ send_from_wbuf (struct nbd_handle *h)
   ssize_t r;
 
   if (h->wlen == 0)
-    return 0;                   /* move to next state */
-  r = h->sock->ops->send (h, h->sock, h->wbuf, h->wlen, 0);
+    goto next_state;
+  r = h->sock->ops->send (h, h->sock, h->wbuf, h->wlen, h->wflags);
   if (r == -1) {
     if (errno == EAGAIN || errno == EWOULDBLOCK)
       return 1;                 /* more data */
@@ -102,9 +102,13 @@ send_from_wbuf (struct nbd_handle *h)
   h->wbuf += r;
   h->wlen -= r;
   if (h->wlen == 0)
-    return 0;                   /* move to next state */
+    goto next_state;
   else
     return 1;                   /* more data */
+
+ next_state:
+  h->wflags = 0;                /* reset this when moving to next state */
+  return 0;                     /* move to next state */
 }
 
 /*----- End of prologue. -----*/
diff --git a/lib/internal.h b/lib/internal.h
index 1ffb5b7..e7be05b 100644
--- a/lib/internal.h
+++ b/lib/internal.h
@@ -110,6 +110,7 @@ struct nbd_handle {
   /* As above, but for writing using send_from_wbuf. */
   const void *wbuf;
   size_t wlen;
+  int wflags;
 
   /* Static buffer used for short amounts of data, such as handshake
    * and commands.
-- 
2.21.0



-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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