Libguestfs - Apr 2023 - [libnbd PATCH 11/23] generator/C: print_trace_enter: break "enter" to a common new line

Going forward, we'd like to wrap long string literals. The recently
introduced "pr_wrap_cstr" function may only be called right after the
opening quote of the string literal has been produced. In the
"print_trace_enter" function, we start a long string literal with
"enter:"; however, because we either pass the literal to debug() or
debug_direct(), this "enter:" is spelled out twice. Factor
"enter:" out to
a common line, also ensuring that we'll have as much room for wrapping as
possible.

Example effect [lib/api.c]:
> @@ -6220,7 +6360,8 @@ nbd_supports_uri (struct nbd_handle *h)
>
>    /* This function must not call set_error. */
>    if_debug (h) {
> -    debug_direct (h, "nbd_supports_uri", "enter:");
> +    debug_direct (h, "nbd_supports_uri",
> +                  "enter:");
>    }
>
>    ret = nbd_unlocked_supports_uri (h);
> @@ -6260,7 +6401,8 @@ nbd_get_uri (struct nbd_handle *h)
>
>    pthread_mutex_lock (&h->lock);
>    if_debug (h) {
> -    debug (h, "enter:");
> +    debug (h,
> +           "enter:");
>    }
>
>    if (unlikely (!get_uri_in_permitted_state (h))) {
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2172516
Signed-off-by: Laszlo Ersek <lersek at redhat.com>
---
 generator/C.ml | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/generator/C.ml b/generator/C.ml
index b65d3de2e82d..0ccf6970d43c 100644
--- a/generator/C.ml
+++ b/generator/C.ml
@@ -734,11 +734,17 @@ let
       | Int64 _ | SizeT _
       | SockAddrAndLen _ | UInt _ | UInt32 _ | UInt64 _ | UIntPtr _ -> ()
     ) args;
-    if may_set_error then
-      pr "    debug (h, \"enter:"
-    else (
-      pr "    debug_direct (h, \"nbd_%s\", \"enter:"
name
-    );
+    let indent +      if may_set_error then (
+        pr "    debug (h,\n";
+        spaces 11
+      )
+      else (
+        pr "    debug_direct (h, \"nbd_%s\",\n" name;
+        spaces 18
+      ) in
+    pr "%s\"" indent;
+    pr "enter:";
     List.iter (
       function
       | Bool n -> pr " %s=%%s" n

On Tue, Apr 25, 2023 at 09:10:55AM +0200, Laszlo Ersek
wrote:
> Going forward, we'd like to wrap long string literals. The recently
> introduced "pr_wrap_cstr" function may only be called right after
the
> opening quote of the string literal has been produced. In the
> "print_trace_enter" function, we start a long string literal with
> "enter:"; however, because we either pass the literal to debug()
or
> debug_direct(), this "enter:" is spelled out twice. Factor
"enter:" out to
> a common line, also ensuring that we'll have as much room for wrapping
as
> possible.
> 
> Example effect [lib/api.c]:
> 
> > @@ -6220,7 +6360,8 @@ nbd_supports_uri (struct nbd_handle *h)
> >
> >    /* This function must not call set_error. */
> >    if_debug (h) {
> > -    debug_direct (h, "nbd_supports_uri",
"enter:");
> > +    debug_direct (h, "nbd_supports_uri",
> > +                  "enter:");
> >    }
> >
> >    ret = nbd_unlocked_supports_uri (h);
> > @@ -6260,7 +6401,8 @@ nbd_get_uri (struct nbd_handle *h)
> >
> >    pthread_mutex_lock (&h->lock);
> >    if_debug (h) {
> > -    debug (h, "enter:");
> > +    debug (h,
> > +           "enter:");
Looks a little funny to not wrap here; but it's generated code, and
the context above makes it obvious why it is easier to wrap in both
places (when the debug_direct call above has an obvious reason for
wrapping).  So far, I have no objections to this series, but I've hit
the end of my reviewing day.

For 1-11:

Reviewed-by: Eric Blake <eblake at redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org