Mercurial > hg
view tests/test-import-context.t @ 27475:a2e2a8fa5fd1
revlog: avoid string slice when decompressing u* chunks
Revlog chunks can be stored uncompressed. If the first byte of the
raw data is \0, we store the data as is. Else we prefix it with 'u'.
Before, we performed a string slice to strip out the 'u' prefix.
With this patch, we use a buffer to avoid an extra memory copy and
associated garbage collection overhead.
I was unable to verify any performance impact of this patch. For both
mozilla-central and the hg repos, the number of manifest revisions
with 'u' prefixes is very small - under 1%. So this change likely
isn't called enough to have an impact on manifest reading. However,
the reasoning behind this change is solid, so it should be safe.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sun, 20 Dec 2015 16:00:27 -0800 |
parents | f2719b387380 |
children | 75be14993fda |
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Test applying context diffs $ cat > writepatterns.py <<EOF > import sys > > path = sys.argv[1] > lasteol = sys.argv[2] == '1' > patterns = sys.argv[3:] > > fp = file(path, 'wb') > for i, pattern in enumerate(patterns): > count = int(pattern[0:-1]) > char = pattern[-1] + '\n' > if not lasteol and i == len(patterns) - 1: > fp.write((char*count)[:-1]) > else: > fp.write(char*count) > fp.close() > EOF $ cat > cat.py <<EOF > import sys > sys.stdout.write(repr(file(sys.argv[1], 'rb').read()) + '\n') > EOF Initialize the test repository $ hg init repo $ cd repo $ python ../writepatterns.py a 0 5A 1B 5C 1D $ python ../writepatterns.py b 1 1A 1B $ python ../writepatterns.py c 1 5A $ python ../writepatterns.py d 1 5A 1B $ hg add adding a adding b adding c adding d $ hg ci -m addfiles Add file, missing a last end of line $ hg import --no-commit - <<EOF > *** /dev/null 2010-10-16 18:05:49.000000000 +0200 > --- b/newnoeol 2010-10-16 18:23:26.000000000 +0200 > *************** > *** 0 **** > --- 1,2 ---- > + a > + b > \ No newline at end of file > *** a/a Sat Oct 16 16:35:51 2010 > --- b/a Sat Oct 16 16:35:51 2010 > *************** > *** 3,12 **** > A > A > A > ! B > C > C > C > C > C > ! D > \ No newline at end of file > --- 3,13 ---- > A > A > A > ! E > C > C > C > C > C > ! F > ! F > > *** a/b 2010-10-16 18:40:38.000000000 +0200 > --- /dev/null 2010-10-16 18:05:49.000000000 +0200 > *************** > *** 1,2 **** > - A > - B > --- 0 ---- > *** a/c Sat Oct 16 21:34:26 2010 > --- b/c Sat Oct 16 21:34:27 2010 > *************** > *** 3,5 **** > --- 3,7 ---- > A > A > A > + B > + B > *** a/d Sat Oct 16 21:47:20 2010 > --- b/d Sat Oct 16 21:47:22 2010 > *************** > *** 2,6 **** > A > A > A > - A > - B > --- 2,4 ---- > EOF applying patch from stdin $ hg st M a M c M d A newnoeol R b What's in a $ python ../cat.py a 'A\nA\nA\nA\nA\nE\nC\nC\nC\nC\nC\nF\nF\n' $ python ../cat.py newnoeol 'a\nb' $ python ../cat.py c 'A\nA\nA\nA\nA\nB\nB\n' $ python ../cat.py d 'A\nA\nA\nA\n' $ cd ..