[PATCH v2 2/2] [GSOC] ref-filter: reuse output buffer
From: ZheNing Hu <adlternative@gmail.com>
When we use `git for-each-ref`, every ref will allocate its own output strbuf and error strbuf. But we can reuse the final strbuf for each step ref's output. The error buffer will also be reused, despite the fact that the git will exit when `format_ref_array_item()` return a non-zero value and output the contents of the error buffer.
The performance for `git for-each-ref` on the Git repository itself with performance testing tool `hyperfine` changes from 23.7 ms ± 0.9 ms to 22.2 ms ± 1.0 ms. Optimization is relatively minor.
At the same time, we apply this optimization to `git tag -l` and `git branch -l`.
This approach is similar to the one used by 79ed0a5 (cat-file: use a single strbuf for all output, 2018-08-14) to speed up the cat-file builtin.
Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Jeff King <peff@peff.net>
Helped-by: René Scharfe <l.s.r@web.de>
Signed-off-by: ZheNing Hu <adlternative@gmail.com>
---
builtin/branch.c | 10 ++++++----
builtin/for-each-ref.c | 13 +++++++------
builtin/tag.c | 13 +++++++------
3 files changed, 20 insertions(+), 16 deletions(-)
Show changes to 3 files +20 −16
builtin/branch.c, builtin/for-each-ref.c, builtin/tag.c
diff --git a/builtin/branch.c b/builtin/branch.c
index bcc00bcf182d..b23b1d1752af 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -411,6 +411,8 @@ static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sortin
{
int i;
struct ref_array array;
+ struct strbuf out = STRBUF_INIT;
+ struct strbuf err = STRBUF_INIT;
int maxwidth = 0;
const char *remote_prefix = "";
char *to_free = NULL;
@@ -440,8 +442,8 @@ static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sortin
ref_array_sort(sorting, &array);
for (i = 0; i < array.nr; i++) {
- struct strbuf out = STRBUF_INIT;
- struct strbuf err = STRBUF_INIT;
+ strbuf_reset(&err);
+ strbuf_reset(&out);
if (format_ref_array_item(array.items[i], format, &out, &err))
die("%s", err.buf);
if (column_active(colopts)) {
@@ -452,10 +454,10 @@ static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sortin
fwrite(out.buf, 1, out.len, stdout);
putchar('\n');
}
- strbuf_release(&err);
- strbuf_release(&out);
}
+ strbuf_release(&err);
+ strbuf_release(&out);
ref_array_clear(&array);
free(to_free);
}
diff --git a/builtin/for-each-ref.c b/builtin/for-each-ref.c
index 8520008604e3..b529228c6239 100644
--- a/builtin/for-each-ref.c
+++ b/builtin/for-each-ref.c
@@ -22,6 +22,8 @@ int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
struct ref_array array;
struct ref_filter filter;
struct ref_format format = REF_FORMAT_INIT;
+ struct strbuf output = STRBUF_INIT;
+ struct strbuf err = STRBUF_INIT;
struct option opts[] = {
OPT_BIT('s', "shell", &format.quote_style,
@@ -81,17 +83,16 @@ int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
if (!maxcount || array.nr < maxcount)
maxcount = array.nr;
for (i = 0; i < maxcount; i++) {
- struct strbuf output = STRBUF_INIT;
- struct strbuf err = STRBUF_INIT;
-
+ strbuf_reset(&err);
+ strbuf_reset(&output);
if (format_ref_array_item(array.items[i], &format, &output, &err))
die("%s", err.buf);
fwrite(output.buf, 1, output.len, stdout);
putchar('\n');
-
- strbuf_release(&err);
- strbuf_release(&output);
}
+
+ strbuf_release(&err);
+ strbuf_release(&output);
ref_array_clear(&array);
return 0;
}
diff --git a/builtin/tag.c b/builtin/tag.c
index d92d8e110b4d..82fcfc098242 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -39,6 +39,8 @@ static int list_tags(struct ref_filter *filter, struct ref_sorting *sorting,
struct ref_format *format)
{
struct ref_array array;
+ struct strbuf output = STRBUF_INIT;
+ struct strbuf err = STRBUF_INIT;
char *to_free = NULL;
int i;
@@ -64,17 +66,16 @@ static int list_tags(struct ref_filter *filter, struct ref_sorting *sorting,
ref_array_sort(sorting, &array);
for (i = 0; i < array.nr; i++) {
- struct strbuf output = STRBUF_INIT;
- struct strbuf err = STRBUF_INIT;
-
+ strbuf_reset(&output);
+ strbuf_reset(&err);
if (format_ref_array_item(array.items[i], format, &output, &err))
die("%s", err.buf);
fwrite(output.buf, 1, output.len, stdout);
putchar('\n');
-
- strbuf_release(&err);
- strbuf_release(&output);
}
+
+ strbuf_release(&err);
+ strbuf_release(&output);
ref_array_clear(&array);
free(to_free);
--
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