Subject: Re: [PATCH v2 4/7] trace2: rename the thread_name argument to trace2_thread_start

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Wed, 12 Oct 2022 23:06:46 +0200

On Wed, Oct 12 2022, Jeff Hostetler via GitGitGadget wrote:

> From: Jeff Hostetler <[email-masked]>
>
> Rename the `thread_name` argument in `tr2tls_create_self()` and
> `trace2_thread_start()` to be `thread_base_name` to make it clearer
> that the passed argument is a component used in the construction of
> the actual `struct tr2tls_thread_ctx.thread_name` variable.
>
> The base name will be used along with the thread id to create a
> unique thread name.

Makes sense.

> This commit does not change how the `thread_name` field is
> allocated or stored within the `tr2tls_thread_ctx` structure.

What this commit does change though, which isn't mentioned here, is...

> diff --git a/trace2/tr2_tls.h b/trace2/tr2_tls.h
> index 1297509fd23..7d1f03a2ea6 100644
> --- a/trace2/tr2_tls.h
> +++ b/trace2/tr2_tls.h
> @@ -25,17 +25,20 @@ struct tr2tls_thread_ctx {
>  /*
>   * Create thread-local storage for the current thread.
>   *
> - * We assume the first thread is "main".  Other threads are given
> - * non-zero thread-ids to help distinguish messages from concurrent
> - * threads.
> - *
> - * Truncate the thread name if necessary to help with column alignment
> - * in printf-style messages.
> + * The first thread in the process will have:
> + *     { .thread_id=0, .thread_name="main" }
> + * Subsequent threads are given a non-zero thread_id and a thread_name
> + * constructed from the id and a thread base name (which is usually just
> + * the name of the thread-proc function).  For example:
> + *     { .thread_id=10, .thread_name="th10fsm-listen" }
> + * This helps to identify and distinguish messages from concurrent threads.
> + * The ctx.thread_name field is truncated if necessary to help with column
> + * alignment in printf-style messages.

...this documentation, which I'd argue should be a separate change, as
nothing's changed about the state of the world with this rename of the
field, this was all true before this rename.