From: Junio C Hamano <gitster@pobox.com>
To: Emily Shaffer <emilyshaffer@google.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH v6 2/2] tr2: log parent process name
Date: Thu, 22 Jul 2021 14:02:38 -0700 [thread overview]
Message-ID: <xmqqwnpi83kh.fsf@gitster.g> (raw)
In-Reply-To: <20210722012707.205776-3-emilyshaffer@google.com> (Emily Shaffer's message of "Wed, 21 Jul 2021 18:27:07 -0700")
Emily Shaffer <emilyshaffer@google.com> writes:
> Unfortunately, there's no cross-platform reliable way to gather the name
> of the parent process. If procfs is present, we can use that; otherwise
> we will need to discover the name another way. However, the process ID
> should be sufficient to look up the process name on most platforms, so
> that code may be shareable.
Is the sentence that begin with "However" still relevant? The
latest get_ancestry_names() does not add anything when the result
read from the procfs is unusable, but the sentence gives a false
impression that it may somehow fall back to show the PID.
> Git for Windows also gathers information about more than one generation
> of parent. In Linux further ancestry info can be gathered with procfs,
> but it's unwieldy to do so. In the interest of later moving Git for
> Windows ancestry logging to the 'cmd_ancestry' event, and in the
> interest of later adding more ancestry to the Linux implementation - or
> of adding this functionality to other platforms which have an easier
> time walking the process tree - let's make 'cmd_ancestry' accept an
> array of parentage.
Clearly written. Nice.
> +`"cmd_ancestry"`::
> + This event contains the text command name for the parent (and earlier
> + generations of parents) of the current process, in an array ordered from
> + nearest parent to furthest great-grandparent. It may not be implemented
> + on all platforms.
> ++
> +------------
> +{
> + "event":"cmd_ancestry",
> + ...
> + "ancestry":["bash","tmux: server","systemd"]
> +}
> +------------
OK.
> diff --git a/compat/linux/procinfo.c b/compat/linux/procinfo.c
> new file mode 100644
> index 0000000000..578fed4cd3
> --- /dev/null
> +++ b/compat/linux/procinfo.c
> @@ -0,0 +1,55 @@
> +#include "cache.h"
> +
> +#include "strbuf.h"
> +#include "strvec.h"
> +#include "trace2.h"
> +
> +static void get_ancestry_names(struct strvec *names)
> +{
> + /*
> + * NEEDSWORK: We could gather the entire pstree into an array to match
> + * functionality with compat/win32/trace2_win32_process_info.c.
> + * To do so, we may want to examine /proc/<pid>/stat. For now, just
> + * gather the immediate parent name which is readily accessible from
> + * /proc/$(getppid())/comm.
> + */
> + struct strbuf procfs_path = STRBUF_INIT;
> + struct strbuf name = STRBUF_INIT;
> +
> + /* try to use procfs if it's present. */
> + strbuf_addf(&procfs_path, "/proc/%d/comm", getppid());
> + if (strbuf_read_file(&name, procfs_path.buf, 0)) {
> + strbuf_release(&procfs_path);
> + strbuf_trim_trailing_newline(&name);
> + strvec_push(names, strbuf_detach(&name, NULL));
At this point, we successfully read from /proc/$(ppid)/comm
and pushed the result into names strvec. I think you would want to
have an explicit "return;" here.
Alternatively, you could put the rest of the function in the
corresponding "else" clause, but I think an early return after each
method successfully collects the result would make a lot more sense.
> + }
> +
> + return;
> + /* NEEDSWORK: add non-procfs-linux implementations here */
This looks the other way around. A future non-procfs-linux
implementation written here will be unreachable code ;-)
Just lose "return;" from here, have one in the if(){} body, and keep
the "here is where you add more/other implementations" comment and
we'd be OK, I think.
> +void trace2_collect_process_info(enum trace2_process_info_reason reason)
> +{
> + if (!trace2_is_enabled())
> + return;
> +
> + /* someday we may want to write something extra here, but not today */
> + if (reason == TRACE2_PROCESS_INFO_EXIT)
> + return;
> +
> + if (reason == TRACE2_PROCESS_INFO_STARTUP) {
> + /*
> + * NEEDSWORK: we could do the entire ptree in an array instead,
> + * see compat/win32/trace2_win32_process_info.c.
> + */
> + struct strvec names = STRVEC_INIT;
> +
> + get_ancestry_names(&names);
> +
> + if (names.nr)
> + trace2_cmd_ancestry(names.v);
> + strvec_clear(&names);
> + }
> +
> + return;
> +}
Good.
Thanks.
next prev parent reply other threads:[~2021-07-22 21:02 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-07 0:29 [PATCH] tr2: log parent process name Emily Shaffer
2021-05-07 3:25 ` Bagas Sanjaya
2021-05-07 17:09 ` Emily Shaffer
2021-05-10 12:29 ` Ævar Arnfjörð Bjarmason
2021-05-11 21:31 ` Junio C Hamano
2021-05-14 22:06 ` Emily Shaffer
2021-05-16 3:48 ` Junio C Hamano
2021-05-17 20:17 ` Emily Shaffer
2021-05-11 17:28 ` Jeff Hostetler
2021-05-14 22:07 ` Emily Shaffer
2021-05-20 21:05 ` [PATCH v2] " Emily Shaffer
2021-05-20 21:36 ` Randall S. Becker
2021-05-20 23:23 ` Emily Shaffer
2021-05-21 13:20 ` Randall S. Becker
2021-05-21 16:24 ` Randall S. Becker
2021-05-21 2:09 ` Junio C Hamano
2021-05-21 19:02 ` Emily Shaffer
2021-05-21 23:22 ` Junio C Hamano
2021-05-24 18:37 ` Emily Shaffer
2021-05-21 19:15 ` Jeff Hostetler
2021-05-21 20:05 ` Emily Shaffer
2021-05-21 20:23 ` Randall S. Becker
2021-05-22 11:18 ` Jeff Hostetler
2021-05-24 23:33 ` Ævar Arnfjörð Bjarmason
2021-05-24 20:10 ` [PATCH v3] " Emily Shaffer
2021-05-24 20:49 ` Emily Shaffer
2021-05-25 3:54 ` Junio C Hamano
2021-05-25 13:33 ` Randall S. Becker
2021-06-08 18:58 ` [PATCH v4] " Emily Shaffer
2021-06-08 20:56 ` Emily Shaffer
2021-06-08 22:10 ` [PATCH v5] " Emily Shaffer
2021-06-08 22:16 ` Randall S. Becker
2021-06-08 22:24 ` Emily Shaffer
2021-06-08 22:39 ` Randall S. Becker
2021-06-09 20:17 ` Emily Shaffer
2021-06-16 8:42 ` Junio C Hamano
2021-06-28 16:45 ` Jeff Hostetler
2021-06-29 23:51 ` Emily Shaffer
2021-06-30 6:10 ` Ævar Arnfjörð Bjarmason
2021-07-22 0:21 ` Emily Shaffer
2021-07-22 1:27 ` [PATCH v6 0/2] " Emily Shaffer
2021-07-22 1:27 ` [PATCH v6 1/2] tr2: make process info collection platform-generic Emily Shaffer
2021-08-02 9:34 ` Ævar Arnfjörð Bjarmason
2021-07-22 1:27 ` [PATCH v6 2/2] tr2: log parent process name Emily Shaffer
2021-07-22 21:02 ` Junio C Hamano [this message]
2021-08-02 9:38 ` Ævar Arnfjörð Bjarmason
2021-08-02 12:45 ` Ævar Arnfjörð Bjarmason
2021-08-02 10:22 ` Ævar Arnfjörð Bjarmason
2021-08-02 12:47 ` Ævar Arnfjörð Bjarmason
2021-08-02 15:23 ` Jeff Hostetler
2021-08-02 16:10 ` Randall S. Becker
2021-08-02 18:41 ` Ævar Arnfjörð Bjarmason
2021-08-25 23:19 ` [PATCH 0/6] tr2: plug memory leaks + logic errors + Win32 & Linux feature parity Ævar Arnfjörð Bjarmason
2021-08-25 23:19 ` [PATCH 1/6] tr2: remove NEEDSWORK comment for "non-procfs" implementations Ævar Arnfjörð Bjarmason
2021-08-25 23:19 ` [PATCH 2/6] tr2: clarify TRACE2_PROCESS_INFO_EXIT comment under Linux Ævar Arnfjörð Bjarmason
2021-08-25 23:19 ` [PATCH 3/6] tr2: stop leaking "thread_name" memory Ævar Arnfjörð Bjarmason
2021-08-26 3:09 ` Taylor Blau
2021-08-25 23:19 ` [PATCH 4/6] tr2: fix memory leak & logic error in 2f732bf15e6 Ævar Arnfjörð Bjarmason
2021-08-26 3:21 ` Taylor Blau
2021-08-25 23:19 ` [PATCH 5/6] tr2: do compiler enum check in trace2_collect_process_info() Ævar Arnfjörð Bjarmason
2021-08-26 3:23 ` Taylor Blau
2021-08-25 23:19 ` [PATCH 6/6] tr2: log N parent process names on Linux Ævar Arnfjörð Bjarmason
2021-08-25 23:49 ` Eric Sunshine
2021-08-26 4:07 ` Taylor Blau
2021-08-26 12:24 ` "I don't know what the author meant by that..." (was "Re: [PATCH 6/6] tr2: log N parent process names on Linux") Ævar Arnfjörð Bjarmason
2021-08-26 12:22 ` [PATCH v2 0/6] tr2: plug memory leaks + logic errors + Win32 & Linux feature parity Ævar Arnfjörð Bjarmason
2021-08-26 12:22 ` [PATCH v2 1/6] tr2: remove NEEDSWORK comment for "non-procfs" implementations Ævar Arnfjörð Bjarmason
2021-08-26 12:22 ` [PATCH v2 2/6] tr2: clarify TRACE2_PROCESS_INFO_EXIT comment under Linux Ævar Arnfjörð Bjarmason
2021-08-26 12:22 ` [PATCH v2 3/6] tr2: stop leaking "thread_name" memory Ævar Arnfjörð Bjarmason
2021-08-26 12:22 ` [PATCH v2 4/6] tr2: fix memory leak & logic error in 2f732bf15e6 Ævar Arnfjörð Bjarmason
2021-08-26 15:58 ` Eric Sunshine
2021-08-26 16:42 ` Junio C Hamano
2021-08-26 12:22 ` [PATCH v2 5/6] tr2: do compiler enum check in trace2_collect_process_info() Ævar Arnfjörð Bjarmason
2021-08-26 12:22 ` [PATCH v2 6/6] tr2: log N parent process names on Linux Ævar Arnfjörð Bjarmason
2021-08-26 22:38 ` [PATCH v2 0/6] tr2: plug memory leaks + logic errors + Win32 & Linux feature parity Taylor Blau
2021-08-27 8:02 ` [PATCH v3 " Ævar Arnfjörð Bjarmason
2021-08-27 8:02 ` [PATCH v3 1/6] tr2: remove NEEDSWORK comment for "non-procfs" implementations Ævar Arnfjörð Bjarmason
2021-08-27 8:02 ` [PATCH v3 2/6] tr2: clarify TRACE2_PROCESS_INFO_EXIT comment under Linux Ævar Arnfjörð Bjarmason
2021-08-27 8:02 ` [PATCH v3 3/6] tr2: stop leaking "thread_name" memory Ævar Arnfjörð Bjarmason
2021-08-27 8:02 ` [PATCH v3 4/6] tr2: leave the parent list empty upon failure & don't leak memory Ævar Arnfjörð Bjarmason
2021-08-27 8:02 ` [PATCH v3 5/6] tr2: do compiler enum check in trace2_collect_process_info() Ævar Arnfjörð Bjarmason
2021-08-27 8:02 ` [PATCH v3 6/6] tr2: log N parent process names on Linux Ævar Arnfjörð Bjarmason
2021-08-31 0:17 ` [PATCH v3 0/6] tr2: plug memory leaks + logic errors + Win32 & Linux feature parity Taylor Blau
2021-08-02 10:30 ` [PATCH v6 2/2] tr2: log parent process name Ævar Arnfjörð Bjarmason
2021-08-02 16:24 ` Junio C Hamano
2021-08-02 18:42 ` Ævar Arnfjörð Bjarmason
2021-07-22 16:59 ` [PATCH v6 0/2] " Jeff Hostetler
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=xmqqwnpi83kh.fsf@gitster.g \
--to=gitster@pobox.com \
--cc=emilyshaffer@google.com \
--cc=git@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).