Am 14.08.2018 um 20:20 schrieb Jeff King:
> When we're in batch mode, we end up in batch_object_write()
> for each object, which allocates its own strbuf for each
> call. Instead, we can provide a single "scratch" buffer that
> gets reused for each output. When running:
>
> git cat-file --batch-all-objects --batch-check='%(objectname)'
>
> on git.git, my best-of-five time drops from:
>
> real 0m0.171s
> user 0m0.159s
> sys 0m0.012s
>
> to:
>
> real 0m0.133s
> user 0m0.121s
> sys 0m0.012s
>
> Note that we could do this just by putting the "scratch"
> pointer into "struct expand_data", but I chose instead to
> add an extra parameter to the callstack. That's more
> verbose, but it makes it a bit more obvious what is going
> on, which in turn makes it easy to see where we need to be
> releasing the string in the caller (right after the loop
> which uses it in each case).
>
> Based-on-a-patch-by: René Scharfe <l....@web.de>
> Signed-off-by: Jeff King <p...@peff.net>
> ---
> It also made it easy to see that without the prior patch,
> we'd have been using "buf" for two parameters. :)
Good catch.
>
> builtin/cat-file.c | 28 +++++++++++++++++-----------
> 1 file changed, 17 insertions(+), 11 deletions(-)
>
> diff --git a/builtin/cat-file.c b/builtin/cat-file.c
> index 3ed1d0be80..08dced2614 100644
> --- a/builtin/cat-file.c
> +++ b/builtin/cat-file.c
> @@ -338,11 +338,11 @@ static void print_object_or_die(struct batch_options
> *opt, struct expand_data *d
> }
> }
>
> -static void batch_object_write(const char *obj_name, struct batch_options
> *opt,
> +static void batch_object_write(const char *obj_name,
> + struct strbuf *scratch,
> + struct batch_options *opt,
> struct expand_data *data)
> {
> - struct strbuf buf = STRBUF_INIT;
We could also avoid passing that buffer around by making it static. I
shy away from adding static variables because the resulting code won't
be thread-safe, but that fear might be irrational, especially with
cat-file.
> -
> if (!data->skip_object_info &&
> oid_object_info_extended(the_repository, &data->oid, &data->info,
> OBJECT_INFO_LOOKUP_REPLACE) < 0) {
> @@ -352,10 +352,10 @@ static void batch_object_write(const char *obj_name,
> struct batch_options *opt,
> return;
> }
>
> - strbuf_expand(&buf, opt->format, expand_format, data);
> - strbuf_addch(&buf, '\n');
> - batch_write(opt, buf.buf, buf.len);
> - strbuf_release(&buf);
> + strbuf_reset(scratch);
> + strbuf_expand(scratch, opt->format, expand_format, data);
> + strbuf_addch(scratch, '\n');
> + batch_write(opt, scratch->buf, scratch->len);
>
> if (opt->print_contents) {
> print_object_or_die(opt, data);
> @@ -363,7 +363,9 @@ static void batch_object_write(const char *obj_name,
> struct batch_options *opt,
> }
> }
>
> -static void batch_one_object(const char *obj_name, struct batch_options *opt,
> +static void batch_one_object(const char *obj_name,
> + struct strbuf *scratch,
> + struct batch_options *opt,
> struct expand_data *data)
> {
> struct object_context ctx;
> @@ -405,20 +407,21 @@ static void batch_one_object(const char *obj_name,
> struct batch_options *opt,
> return;
> }
>
> - batch_object_write(obj_name, opt, data);
> + batch_object_write(obj_name, scratch, opt, data);
> }
>
> struct object_cb_data {
> struct batch_options *opt;
> struct expand_data *expand;
> struct oidset *seen;
> + struct strbuf *scratch;
> };
>
> static int batch_object_cb(const struct object_id *oid, void *vdata)
> {
> struct object_cb_data *data = vdata;
> oidcpy(&data->expand->oid, oid);
> - batch_object_write(NULL, data->opt, data->expand);
> + batch_object_write(NULL, data->scratch, data->opt, data->expand);
> return 0;
> }
>
> @@ -509,6 +512,7 @@ static int batch_objects(struct batch_options *opt)
>
> cb.opt = opt;
> cb.expand = &data;
> + cb.scratch = &output;
>
> if (opt->unordered) {
> struct oidset seen = OIDSET_INIT;
> @@ -531,6 +535,7 @@ static int batch_objects(struct batch_options *opt)
> oid_array_clear(&sa);
> }
>
> + strbuf_release(&output);
> return 0;
> }
>
> @@ -559,10 +564,11 @@ static int batch_objects(struct batch_options *opt)
> data.rest = p;
> }
>
> - batch_one_object(input.buf, opt, &data);
> + batch_one_object(input.buf, &output, opt, &data);
> }
>
> strbuf_release(&input);
> + strbuf_release(&output);
> warn_on_object_refname_ambiguity = save_warning;
> return retval;
> }
>
