cat-file: add --buffer option
We use a direct write() to output the results of --batch and
--batch-check. This is good for processes feeding the input
and reading the output interactively, but it introduces
measurable overhead if you do not want this feature. For
example, on linux.git:
$ git rev-list --objects --all | cut -d' ' -f1 >objects
$ time git cat-file --batch-check='%(objectsize)' \
<objects >/dev/null
real 0m5.440s
user 0m5.060s
sys 0m0.384s
This patch adds an option to use regular stdio buffering:
$ time git cat-file --batch-check='%(objectsize)' \
--buffer <objects >/dev/null
real 0m4.975s
user 0m4.888s
sys 0m0.092s
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/git-cat-file.txt b/Documentation/git-cat-file.txt
index 319ab4c..0058bd4 100644
--- a/Documentation/git-cat-file.txt
+++ b/Documentation/git-cat-file.txt
@@ -69,6 +69,13 @@
not be combined with any other options or arguments. See the
section `BATCH OUTPUT` below for details.
+--buffer::
+ Normally batch output is flushed after each object is output, so
+ that a process can interactively read and write from
+ `cat-file`. With this option, the output uses normal stdio
+ buffering; this is much more efficient when invoking
+ `--batch-check` on a large number of objects.
+
--allow-unknown-type::
Allow -s or -t to query broken/corrupt objects of unknown type.
diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index d4101b7..741e100 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -14,6 +14,7 @@
int enabled;
int follow_symlinks;
int print_contents;
+ int buffer_output;
const char *format;
};
@@ -211,14 +212,25 @@
return end - start + 1;
}
-static void print_object_or_die(int fd, struct expand_data *data)
+static void batch_write(struct batch_options *opt, const void *data, int len)
+{
+ if (opt->buffer_output) {
+ if (fwrite(data, 1, len, stdout) != len)
+ die_errno("unable to write to stdout");
+ } else
+ write_or_die(1, data, len);
+}
+
+static void print_object_or_die(struct batch_options *opt, struct expand_data *data)
{
const unsigned char *sha1 = data->sha1;
assert(data->info.typep);
if (data->type == OBJ_BLOB) {
- if (stream_blob_to_fd(fd, sha1, NULL, 0) < 0)
+ if (opt->buffer_output)
+ fflush(stdout);
+ if (stream_blob_to_fd(1, sha1, NULL, 0) < 0)
die("unable to stream %s to stdout", sha1_to_hex(sha1));
}
else {
@@ -234,12 +246,11 @@
if (data->info.sizep && size != data->size)
die("object %s changed size!?", sha1_to_hex(sha1));
- write_or_die(fd, contents, size);
+ batch_write(opt, contents, size);
free(contents);
}
}
-
static int batch_one_object(const char *obj_name, struct batch_options *opt,
struct expand_data *data)
{
@@ -294,12 +305,12 @@
strbuf_expand(&buf, opt->format, expand_format, data);
strbuf_addch(&buf, '\n');
- write_or_die(1, buf.buf, buf.len);
+ batch_write(opt, buf.buf, buf.len);
strbuf_release(&buf);
if (opt->print_contents) {
- print_object_or_die(1, data);
- write_or_die(1, "\n", 1);
+ print_object_or_die(opt, data);
+ batch_write(opt, "\n", 1);
}
return 0;
}
@@ -415,6 +426,7 @@
N_("for blob objects, run textconv on object's content"), 'c'),
OPT_BOOL(0, "allow-unknown-type", &unknown_type,
N_("allow -s and -t to work with broken/corrupt objects")),
+ OPT_BOOL(0, "buffer", &batch.buffer_output, N_("buffer --batch output")),
{ OPTION_CALLBACK, 0, "batch", &batch, "format",
N_("show info and content of objects fed from the standard input"),
PARSE_OPT_OPTARG, batch_option_callback },
