[PATCH] trace2: add dots directly to strbuf in perf_fmt_prepare()

René Scharfe· Nov 4, 2019, 19:27 UTC · lore

The initialization function of the Trace2 performance format target sets aside a stash of dots for indenting output. Get rid of it and use strbuf_addchars() to provide dots on demand instead. This shortens the code, gets rid of a small heap allocation and is a bit more efficient.

Signed-off-by: René Scharfe <l.s.r@web.de>
---
 trace2/tr2_tgt_perf.c | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

Show changes to trace2/tr2_tgt_perf.c +2 −16

diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
index ffac8029ad..a8018f18cc 100644
--- a/trace2/tr2_tgt_perf.c
+++ b/trace2/tr2_tgt_perf.c
@@ -26,12 +26,9 @@ static int tr2env_perf_be_brief;
 #define TR2FMT_PERF_REPO_WIDTH (3)
 #define TR2FMT_PERF_CATEGORY_WIDTH (12)

-#define TR2_DOTS_BUFFER_SIZE (100)
 #define TR2_INDENT (2)
 #define TR2_INDENT_LENGTH(ctx) (((ctx)->nr_open_regions - 1) * TR2_INDENT)

-static struct strbuf dots = STRBUF_INIT;
-
 static int fn_init(void)
 {
 	int want = tr2_dst_trace_want(&tr2dst_perf);
@@ -41,8 +38,6 @@ static int fn_init(void)
 	if (!want)
 		return want;

-	strbuf_addchars(&dots, '.', TR2_DOTS_BUFFER_SIZE);
-
 	brief = tr2_sysenv_get(TR2_SYSENV_PERF_BRIEF);
 	if (brief && *brief &&
 	    ((want_brief = git_parse_maybe_bool(brief)) != -1))
@@ -54,8 +49,6 @@ static int fn_init(void)
 static void fn_term(void)
 {
 	tr2_dst_trace_disable(&tr2dst_perf);
-
-	strbuf_release(&dots);
 }

 /*
@@ -138,14 +131,8 @@ static void perf_fmt_prepare(const char *event_name,
 	strbuf_addf(buf, "%-*.*s | ", TR2FMT_PERF_CATEGORY_WIDTH,
 		    TR2FMT_PERF_CATEGORY_WIDTH, (category ? category : ""));

-	if (ctx->nr_open_regions > 0) {
-		int len_indent = TR2_INDENT_LENGTH(ctx);
-		while (len_indent > dots.len) {
-			strbuf_addbuf(buf, &dots);
-			len_indent -= dots.len;
-		}
-		strbuf_addf(buf, "%.*s", len_indent, dots.buf);
-	}
+	if (ctx->nr_open_regions > 0)
+		strbuf_addchars(buf, '.', TR2_INDENT_LENGTH(ctx));
 }

 static void perf_io_write_fl(const char *file, int line, const char *event_name,
--
2.24.0

Jeff King· Nov 4, 2019, 19:55 UTC · re: René Scharfe · lore

Re: [PATCH] trace2: add dots directly to strbuf in perf_fmt_prepare()

On Mon, Nov 04, 2019 at 08:27:54PM +0100, René Scharfe wrote:

> The initialization function of the Trace2 performance format target sets
> aside a stash of dots for indenting output.  Get rid of it and use
> strbuf_addchars() to provide dots on demand instead.  This shortens the
> code, gets rid of a small heap allocation and is a bit more efficient.

Yeah, the end result is much easier on the eyes. I am scratching my head at whether there is any advantage to copying the separate buffer, but I don't see one. The likelihood of having to allocate in the final "buf" strbuf is the same either way.

-Peff

Jeff Hostetler· Nov 5, 2019, 15:00 UTC · re: René Scharfe · lore

Re: [PATCH] trace2: add dots directly to strbuf in perf_fmt_prepare()

On 11/4/2019 2:27 PM, René Scharfe wrote:

Show 6 quoted lines

> The initialization function of the Trace2 performance format target sets
> aside a stash of dots for indenting output.  Get rid of it and use
> strbuf_addchars() to provide dots on demand instead.  This shortens the
> code, gets rid of a small heap allocation and is a bit more efficient.
> 
> Signed-off-by: René Scharfe <l.s.r@web.de>

Looks good! Thanks for simplifying my otherwise convoluted code. Jeff

patchtrace2: add dots directly to strbuf in perf_fmt_prepare()