[PATCH 2/2] cat-file: default to --buffer when --batch-all-objects is used
- From
Jeff King <peff@peff.net>
- Date
- May 18, 2016, 16:56 UTC
- Message-ID
- <20160518165613.GB5607@sigill.intra.peff.net>
- In-Reply-To
- <20160518165411.GA5563@sigill.intra.peff.net>
Traditionally cat-file's batch-mode does not do any output buffering. The reason is that a caller may have pipes connected to its input and output, and would want to use cat-file interactively, getting output immediately for each input it sends.
This may involve a lot of small write() calls, which can be slow. So we introduced --buffer to improve this, but we can't turn it on by default, as it would break the interactive case above.
However, when --batch-all-objects is used, we do not read stdin at all. We generate the output ourselves as quickly as possible, and then exit. In this case buffering is a strict win, and it is simply a hassle for the user to have to remember to specify --buffer.
This patch makes --buffer the default when --batch-all-objects is used. Specifying "--buffer" manually is still OK, and you can even override it with "--no-buffer" if you're a masochist (or debugging).
For some real numbers, running:
git cat-file --batch-all-objects --batch-check='%(objectname)'
on torvalds/linux goes from:
real 0m1.464s user 0m1.208s sys 0m0.252s
to:
real 0m1.230s user 0m1.172s sys 0m0.056s
for a 16% speedup.
Suggested-by: Charles Bailey <charles@hashpling.org> Signed-off-by: Jeff King <peff@peff.net> --- builtin/cat-file.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/builtin/cat-file.c b/builtin/cat-file.c index 5d3180e..618103f 100644 --- a/builtin/cat-file.c +++ b/builtin/cat-file.c @@ -504,6 +504,7 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix) git_config(git_cat_file_config, NULL); + batch.buffer_output = -1; argc = parse_options(argc, argv, prefix, options, cat_file_usage, 0); if (opt) { @@ -527,6 +528,9 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix) usage_with_options(cat_file_usage, options); } + if (batch.buffer_output < 0) + batch.buffer_output = batch.all_objects; + if (batch.enabled) return batch_objects(&batch);
-- 2.8.2.888.gecb1fe3