Libguestfs - Jun 2023 - [PATCH libnbd 2/2] generator: state machine: Be less verbose in debug messages

Logging state transitions in debug mode produces huge amounts of
output which is not especially helpful.  This change removes this
debugging output.  This reduces the debug output by approximately two
thirds.
---
 generator/state_machine_generator.ml | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/generator/state_machine_generator.ml
b/generator/state_machine_generator.ml
index 274e290952..52c497646d 100644
--- a/generator/state_machine_generator.ml
+++ b/generator/state_machine_generator.ml
@@ -380,9 +380,6 @@ let
       pr "        h, &next, blocked\n";
       pr "      );\n";
       pr "  if (get_next_state (h) != next) {\n";
-      pr "    debug (h, \"transition: %%s -> %%s\",\n";
-      pr "           \"%s\",\n" display_name;
-      pr "           nbd_internal_state_short_string (next));\n";
       pr "    set_next_state (h, next);\n";
       pr "  }\n";
       pr "  return r;\n";
@@ -423,15 +420,6 @@ let
             pr "    case %s:\n" (c_string_of_external_event e);
             if state != next_state then (
               pr "      set_next_state (h, %s);\n"
next_state.parsed.state_enum;
-              pr "      debug (";
-              let print_debug_args () -                pr "h, \"event
%%s: %%s -> %%s\", ";
-                pr "\"%s\", \"%s\",
\"%s\");"
-                   (string_of_external_event e)
-                   display_name next_state.parsed.display_name;
-              in
-              pr_wrap ',' print_debug_args;
-              pr "\n"
             );
             pr "      goto ok;\n";
         ) events;
-- 
2.40.1

On Mon, Jun 12, 2023 at 07:27:53PM +0100, Richard W.M. Jones
wrote:
> Logging state transitions in debug mode produces huge amounts of
> output which is not especially helpful.  This change removes this
> debugging output.  This reduces the debug output by approximately two
> thirds.
> ---
>  generator/state_machine_generator.ml | 12 ------------
>  1 file changed, 12 deletions(-)
> 
> diff --git a/generator/state_machine_generator.ml
b/generator/state_machine_generator.ml
> index 274e290952..52c497646d 100644
> --- a/generator/state_machine_generator.ml
> +++ b/generator/state_machine_generator.ml
> @@ -380,9 +380,6 @@ let
>        pr "        h, &next, blocked\n";
>        pr "      );\n";
>        pr "  if (get_next_state (h) != next) {\n";
> -      pr "    debug (h, \"transition: %%s ->
%%s\",\n";
> -      pr "           \"%s\",\n" display_name;
> -      pr "           nbd_internal_state_short_string
(next));\n";
>        pr "    set_next_state (h, next);\n";
>        pr "  }\n";
>        pr "  return r;\n";
> @@ -423,15 +420,6 @@ let
>              pr "    case %s:\n" (c_string_of_external_event e);
>              if state != next_state then (
>                pr "      set_next_state (h, %s);\n"
next_state.parsed.state_enum;
> -              pr "      debug (";
> -              let print_debug_args () > -                pr "h,
\"event %%s: %%s -> %%s\", ";
> -                pr "\"%s\", \"%s\",
\"%s\");"
> -                   (string_of_external_event e)
> -                   display_name next_state.parsed.display_name;
> -              in
> -              pr_wrap ',' print_debug_args;
> -              pr "\n"
All that work Laszlo did to nicely wrap these lines.  If we decide to
go with a multi-level debug (DEBUG=1 being the default for 'make
check', DEBUG=2 for extra-verbose debugging), we'd probably implement
that by either adding an argument to the existing debug() macro, or
adding yet another macro that takes an explicit level (and the
existing debug() macro forwards to the other macro with a level of 1),
so it's not too hard to choose which lines are super-verbose-only.

But I'm fine with this patch as-is, if we don't have a strong reason
to keep the state transitions in the debug logs.

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

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
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