git/strbuf.c, branch v2.5.2

Merge branch 'jh/strbuf-read-use-read-in-full' into maint

2015-09-04T02:17:50Z

strbuf_read() used to have one extra iteration (and an unnecessary strbuf_grow() of 8kB), which was eliminated. * jh/strbuf-read-use-read-in-full: strbuf_read(): skip unnecessary strbuf_grow() at eof

strbuf_read(): skip unnecessary strbuf_grow() at eof

2015-08-10T19:51:13Z

The loop in strbuf_read() uses xread() repeatedly while extending the strbuf until the call returns zero. If the buffer is sufficiently large to begin with, this results in xread() returning the remainder of the file to the end (returning non-zero), the loop extending the strbuf, and then making another call to xread() to have it return zero. By using read_in_full(), we can tell when the read reached the end of file: when it returns less than was requested, it's eof. This way we can avoid an extra iteration that allocates an extra 8kB that is never used. Signed-off-by: Jim Hill Reviewed-by: Jeff King Signed-off-by: Junio C Hamano

Merge branch 'mh/strbuf-read-file-returns-ssize-t'

2015-07-13T21:00:27Z

Avoid possible ssize_t to int truncation. * mh/strbuf-read-file-returns-ssize-t: strbuf: strbuf_read_file() should return ssize_t

strbuf: strbuf_read_file() should return ssize_t

2015-07-04T01:25:02Z

It is currently declared to return int, which could overflow for large files. Signed-off-by: Michael Haggerty Signed-off-by: Junio C Hamano

strbuf_getwholeline: use getdelim if it is available

2015-04-16T15:15:05Z

We spend a lot of time in strbuf_getwholeline in a tight loop reading characters from a stdio handle into a buffer. The libc getdelim() function can do this for us with less overhead. It's in POSIX.1-2008, and was a GNU extension before that. Therefore we can't rely on it, but can fall back to the existing getc loop when it is not available. The HAVE_GETDELIM knob is turned on automatically for Linux, where we have glibc. We don't need to set any new feature-test macros, because we already define _GNU_SOURCE. Other systems that implement getdelim may need to other macros (probably _POSIX_C_SOURCE >= 200809L), but we can address that along with setting the Makefile knob after testing the feature on those systems. Running "git rev-parse refs/heads/does-not-exist" on a repo with an extremely large (1.6GB) packed-refs file went from (best-of-5): real 0m8.601s user 0m8.084s sys 0m0.524s to: real 0m6.768s user 0m6.340s sys 0m0.432s for a wall-clock speedup of 21%. Based on a patch from Rasmus Villemoes . Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

strbuf_getwholeline: avoid calling strbuf_grow

2015-04-16T15:15:05Z

As with the recent speedup to strbuf_addch, we can avoid calling strbuf_grow() in a tight loop of single-character adds by instead checking strbuf_avail. Note that we would instead call strbuf_addch directly here, but it does more work than necessary: it will NUL-terminate the result for each character read. Instead, in this loop we read the characters one by one and then add the terminator manually at the end. Running "git rev-parse refs/heads/does-not-exist" on a repo with an extremely large (1.6GB) packed-refs file went from (best-of-5): real 0m10.948s user 0m10.548s sys 0m0.412s to: real 0m8.601s user 0m8.084s sys 0m0.524s for a wall-clock speedup of 21%. Helped-by: Eric Sunshine Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

strbuf_getwholeline: use getc_unlocked

2015-04-16T15:15:04Z

strbuf_getwholeline calls getc in a tight loop. On modern libc implementations, the stdio code locks the handle for every operation, which means we are paying a significant overhead. We can get around this by locking the handle for the whole loop and using the unlocked variant. Running "git rev-parse refs/heads/does-not-exist" on a repo with an extremely large (1.6GB) packed-refs file went from: real 0m18.900s user 0m18.472s sys 0m0.448s to: real 0m10.953s user 0m10.384s sys 0m0.580s for a wall-clock speedup of 42%. All times are best-of-3, and done on a glibc 2.19 system. Note that we call into strbuf_grow while holding the lock. It's possible for that function to call other stdio functions (e.g., printing to stderr when dying due to malloc error); however, the POSIX.1-2001 definition of flockfile makes it clear that the locks are per-handle, so we are fine unless somebody else tries to read from our same handle. This doesn't ever happen in the current code, and is unlikely to be added in the future (we would have to do something exotic like add a die_routine that tried to read from stdin). Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

strbuf_getwholeline: use getc macro

2015-04-16T15:15:04Z

strbuf_getwholeline calls fgetc in a tight loop. Using the getc form, which can be implemented as a macro, should be faster (and we do not care about it evaluating our argument twice, as we just have a plain variable). On my glibc system, running "git rev-parse refs/heads/does-not-exist" on a file with an extremely large (1.6GB) packed-refs file went from (best of 3 runs): real 0m19.383s user 0m18.876s sys 0m0.528s to: real 0m18.900s user 0m18.472s sys 0m0.448s for a wall-clock speedup of 2.5%. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

Merge branch 'jc/strbuf-add-lines-avoid-sp-ht-sequence'

2015-01-07T20:49:19Z

The commented output used to blindly add a SP before the payload line, resulting in "# \t\n" when the payload began with a HT. Instead, produce "#\t\n". * jc/strbuf-add-lines-avoid-sp-ht-sequence: strbuf_add_commented_lines(): avoid SP-HT sequence in commented lines

strbuf_add_commented_lines(): avoid SP-HT sequence in commented lines

2014-10-27T21:13:59Z

The strbuf_add_commented_lines() function passes a pair of prefixes, one to be used for a non-empty line, and the other for an empty line, to underlying add_lines(). The former is set to a comment char followed by a SP, while the latter is set to just the comment char. This is designed to give a SP after the comment character, e.g. "# \n", on a line with some text, and to avoid emitting an unsightly "# \n" for an empty line. Teach this machinery to also use the latter space-less prefix when the payload line begins with a tab, to show e.g. "#\t\n"; otherwise we will end up showing "# \t\n" which is similarly unsightly. Signed-off-by: Junio C Hamano