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From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Jeff Hostetler via GitGitGadget <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, Jeff Hostetler <git@jeffhostetler.com>,
	Derrick Stolee <stolee@gmail.com>,
	Matheus Tavares <matheus.bernardino@usp.br>,
	Johannes Sixt <j6t@kdbg.org>,
	Jeff Hostetler <jeffhost@microsoft.com>
Subject: Re: [PATCH v2 5/9] trace2: add thread-name override to perf target
Date: Wed, 29 Dec 2021 02:48:33 +0100	[thread overview]
Message-ID: <211229.86ilv8gos7.gmgdl@evledraar.gmail.com> (raw)
In-Reply-To: <82c445b75f1002bcfa0a770bd47038a747d98970.1640720202.git.gitgitgadget@gmail.com>


On Tue, Dec 28 2021, Jeff Hostetler via GitGitGadget wrote:

> From: Jeff Hostetler <jeffhost@microsoft.com>
>
> Teach the message formatter in the Trace2 perf target to accept an
> optional thread name argument.  This will override the thread name
> inherited from the thread local storage data block.
>
> This will be used in a future commit for global events that should
> not be tied to a particular thread, such as a global stopwatch timer.

We already have a "ctx", and that "ctx" has a "thread_name", but here
and in the preceding commit we're adding a "thread_name" to every caller
of these functions in case we'd like to override it.

Wouldn't it make more sense to just pass a "ctx" to these functions? One
of them already takes it, here's an (obviously incomplete) fixup on top
of your series to make the one that doesn't take a "ctx", and for the
only non-NULL users of "thread_name" to just use a trivial helper to
pass in a "ctx" with a new "thread_name", then to swap it back.

It would make for a smaller diffstat for this already large series, or
we could do exactly what we're doing now, but avoid the churn of
adjusting every caller by introducing a new sister function for those
who want this parameter to be non-NULL.

(The below patch is "broken" in that __FILE__ and __LINE__ need to be
passed in as parameters, but this is just a trivial change for
show/commentary)

diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
index b9eb2cdb77a..7aaec83dff7 100644
--- a/trace2/tr2_tgt_event.c
+++ b/trace2/tr2_tgt_event.c
@@ -82,16 +82,15 @@ static void fn_term(void)
 static void event_fmt_prepare(const char *event_name, const char *file,
 			      int line, const struct repository *repo,
 			      struct json_writer *jw,
-			      const char *thread_name_override)
+			      struct tr2tls_thread_ctx *ctx)
 {
 	struct tr2_tbuf tb_now;
+	if (!ctx)
+		ctx = tr2tls_get_self();
 
 	jw_object_string(jw, "event", event_name);
 	jw_object_string(jw, "sid", tr2_sid_get());
-	jw_object_string(jw, "thread",
-			 ((thread_name_override && *thread_name_override)
-			  ? thread_name_override
-			  : tr2tls_get_self()->thread_name));
+	jw_object_string(jw, "thread", ctx->thread_name);
 
 	/*
 	 * In brief mode, only emit <time> on these 2 event types.
@@ -111,6 +110,20 @@ static void event_fmt_prepare(const char *event_name, const char *file,
 		jw_object_intmax(jw, "repo", repo->trace2_repo_id);
 }
 
+static void event_fmt_prepare_tn(const char *event_name, const char *file,
+				 int line, const struct repository *repo,
+				 struct json_writer *jw,
+				 const char *thread_name)
+{
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	const char *tmp;
+
+	tmp = ctx->thread_name;
+	ctx->thread_name = thread_name;
+	event_fmt_prepare(event_name, __FILE__, __LINE__, NULL, jw, ctx);
+	ctx->thread_name = tmp;
+}
+
 static void fn_too_many_files_fl(const char *file, int line)
 {
 	const char *event_name = "too_many_files";
@@ -629,7 +642,7 @@ static void fn_timer(uint64_t us_elapsed_absolute,
 	double t_abs = (double)us_elapsed_absolute / 1000000.0;
 
 	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, __FILE__, __LINE__, NULL, &jw, thread_name);
+	event_fmt_prepare_tn(event_name, __FILE__, __LINE__, NULL, &jw, thread_name);
 	jw_object_double(&jw, "t_abs", 6, t_abs);
 	jw_object_string(&jw, "name", timer_name);
 	jw_object_intmax(&jw, "count", interval_count);
@@ -654,7 +667,7 @@ static void fn_counter(uint64_t us_elapsed_absolute,
 	double t_abs = (double)us_elapsed_absolute / 1000000.0;
 
 	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, __FILE__, __LINE__, NULL, &jw, thread_name);
+	event_fmt_prepare_tn(event_name, __FILE__, __LINE__, NULL, &jw, thread_name);
 	jw_object_double(&jw, "t_abs", 6, t_abs);
 	jw_object_string(&jw, "name", counter_name);
 	jw_object_intmax(&jw, "value", value);

  reply	other threads:[~2021-12-29  1:53 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-20 15:01 [PATCH 0/9] Trace2 stopwatch timers and global counters Jeff Hostetler via GitGitGadget
2021-12-20 15:01 ` [PATCH 1/9] trace2: use size_t alloc,nr_open_regions in tr2tls_thread_ctx Jeff Hostetler via GitGitGadget
2021-12-20 15:01 ` [PATCH 2/9] trace2: convert tr2tls_thread_ctx.thread_name from strbuf to char* Jeff Hostetler via GitGitGadget
2021-12-20 16:31   ` Ævar Arnfjörð Bjarmason
2021-12-20 19:07     ` Jeff Hostetler
2021-12-20 19:35       ` Ævar Arnfjörð Bjarmason
2021-12-22 16:32         ` Jeff Hostetler
2021-12-21  7:33     ` Junio C Hamano
2021-12-21  7:22   ` Junio C Hamano
2021-12-22 16:28     ` Jeff Hostetler
2021-12-22 19:57       ` Junio C Hamano
2021-12-20 15:01 ` [PATCH 3/9] trace2: defer free of TLS CTX until program exit Jeff Hostetler via GitGitGadget
2021-12-21  7:30   ` Junio C Hamano
2021-12-22 21:59     ` Jeff Hostetler
2021-12-22 22:56       ` Junio C Hamano
2021-12-22 23:04         ` Jeff Hostetler
2021-12-23  7:38         ` Johannes Sixt
2021-12-23 18:18           ` Junio C Hamano
2021-12-27 18:51             ` Jeff Hostetler
2021-12-20 15:01 ` [PATCH 4/9] trace2: add thread-name override to event target Jeff Hostetler via GitGitGadget
2021-12-20 15:01 ` [PATCH 5/9] trace2: add thread-name override to perf target Jeff Hostetler via GitGitGadget
2021-12-20 15:01 ` [PATCH 6/9] trace2: add timer events to perf and event target formats Jeff Hostetler via GitGitGadget
2021-12-20 16:39   ` Ævar Arnfjörð Bjarmason
2021-12-20 19:44     ` Jeff Hostetler
2021-12-21 14:20   ` Derrick Stolee
2021-12-20 15:01 ` [PATCH 7/9] trace2: add stopwatch timers Jeff Hostetler via GitGitGadget
2021-12-20 16:42   ` Ævar Arnfjörð Bjarmason
2021-12-22 21:38     ` Jeff Hostetler
2021-12-21 14:45   ` Derrick Stolee
2021-12-22 21:57     ` Jeff Hostetler
2021-12-20 15:01 ` [PATCH 8/9] trace2: add counter events to perf and event target formats Jeff Hostetler via GitGitGadget
2021-12-20 16:51   ` Ævar Arnfjörð Bjarmason
2021-12-22 22:56     ` Jeff Hostetler
2021-12-20 15:01 ` [PATCH 9/9] trace2: add global counters Jeff Hostetler via GitGitGadget
2021-12-20 17:14   ` Ævar Arnfjörð Bjarmason
2021-12-22 22:18     ` Jeff Hostetler
2021-12-21 14:51 ` [PATCH 0/9] Trace2 stopwatch timers and " Derrick Stolee
2021-12-21 23:27   ` Matheus Tavares
2021-12-28 19:36 ` [PATCH v2 " Jeff Hostetler via GitGitGadget
2021-12-28 19:36   ` [PATCH v2 1/9] trace2: use size_t alloc,nr_open_regions in tr2tls_thread_ctx Jeff Hostetler via GitGitGadget
2021-12-29  0:48     ` Ævar Arnfjörð Bjarmason
2021-12-28 19:36   ` [PATCH v2 2/9] trace2: convert tr2tls_thread_ctx.thread_name from strbuf to flex array Jeff Hostetler via GitGitGadget
2021-12-29  1:11     ` Ævar Arnfjörð Bjarmason
2021-12-29 16:46       ` Jeff Hostetler
2021-12-28 19:36   ` [PATCH v2 3/9] trace2: defer free of thread local storage until program exit Jeff Hostetler via GitGitGadget
2021-12-28 19:36   ` [PATCH v2 4/9] trace2: add thread-name override to event target Jeff Hostetler via GitGitGadget
2021-12-28 19:36   ` [PATCH v2 5/9] trace2: add thread-name override to perf target Jeff Hostetler via GitGitGadget
2021-12-29  1:48     ` Ævar Arnfjörð Bjarmason [this message]
2021-12-29 17:15       ` Jeff Hostetler
2021-12-28 19:36   ` [PATCH v2 6/9] trace2: add timer events to perf and event target formats Jeff Hostetler via GitGitGadget
2021-12-28 19:36   ` [PATCH v2 7/9] trace2: add stopwatch timers Jeff Hostetler via GitGitGadget
2021-12-28 19:36   ` [PATCH v2 8/9] trace2: add counter events to perf and event target formats Jeff Hostetler via GitGitGadget
2021-12-28 19:36   ` [PATCH v2 9/9] trace2: add global counters Jeff Hostetler via GitGitGadget
2021-12-29  1:54   ` [PATCH v2 0/9] Trace2 stopwatch timers and " Ævar Arnfjörð Bjarmason
2021-12-30 16:42     ` Jeff Hostetler

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