Re: [PATCH] trace2: log progress time and throughput

> Junio C Hamano <gitster@pobox.com> writes:
> 
>> Derrick Stolee <stolee@gmail.com> writes:
>> ...
>>> This trace2_region_leave() needs to be conditional on the progress
>>> being non-null. The pattern used by consumers of the progress API is:
>>>
>>> 	if (my_progress_condition)
>>> 		start_progress(&progress);
>>>
>>> 	do {
>>> 		display_progress(&progress, count);
>>> 	} while (condition);
>>>
>>> 	stop_progress(&progress);
>>>
>>> The condition to show progress or not is conditional on an option that
>>> is external to the progress API.
>>>
>>> The fix for this patch is simple: make the trace2_region_leave() be
>>> conditional on "p_progress && *p_progress".
> 
> Oops.  That means that we need to apply the fix before -rc1 to
> 'master' X-<.

> -- >8 --
> Subject: progress: call trace2_region_leave() only after calling _enter()
> From: Derrick Stolee <dstolee@microsoft.com>
> 
> A user of progress API calls start_progress() conditionally and
> depends on the display_progress() and stop_progress() functions to
> become no-op when start_progress() hasn't been called.
> 
> As we added a call to trace2_region_enter() to start_progress(), the
> calls to other trace2 API calls from the progress API functions must
> make sure that these trace2 calls are skipped when start_progress()
> hasn't been called on the progress struct.  Specifically, do not
> call trace2_region_leave() from stop_progress() when we haven't
> called start_progress(), which would have called the matching
> trace2_region_enter().
> 
> Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  progress.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/progress.c b/progress.c
> index 6d2dcff0b6..3eda914518 100644
> --- a/progress.c
> +++ b/progress.c
> @@ -329,13 +329,9 @@ void stop_progress(struct progress **p_progress)
>  			trace2_data_intmax("progress", the_repository,
>  					   "total_bytes",
>  					   (*p_progress)->throughput->curr_total);
> -	}
>  
> -	trace2_region_leave("progress",
> -			    p_progress && *p_progress
> -				? (*p_progress)->title
> -				: NULL,
> -			    the_repository);
> +		trace2_region_leave("progress", (*p_progress)->title, the_repository);
> +	}
>  
>  	stop_progress_msg(p_progress, _("done"));
>  }