view tests/test-convert-tla.t @ 17616:9535a0dc41f2

store: implement fncache basic path encoding in C

(This is not yet enabled; it will be turned on in a followup patch.)

The path encoding performed by fncache is complex and (perhaps
surprisingly) slow enough to negatively affect the overall performance
of Mercurial.

For a short path (< 120 bytes), the Python code can be reduced to a fairly
tractable state machine that either determines that nothing needs to be
done in a single pass, or performs the encoding in a second pass.

For longer paths, we avoid the more complicated hashed encoding scheme
for now, and fall back to Python.

Raw performance: I measured in a repo containing 150,000 files in its tip
manifest, with a median path name length of 57 bytes, and 95th percentile
of 96 bytes.

In this repo, the Python code takes 3.1 seconds to encode all path
names, while the hybrid C-and-Python code (called from Python) takes
0.21 seconds, for a speedup of about 14.

Across several other large repositories, I've measured the speedup from
the C code at between 26x and 40x.

For path names above 120 bytes where we must fall back to Python for
hashed encoding, the speedup is about 1.7x.  Thus absolute performance
will depend strongly on the characteristics of a particular repository.

  $ "$TESTDIR/hghave" tla symlink || exit 80
  $ tla my-id "mercurial <[e-mail]>"
  $ echo "[extensions]" >> $HGRCPATH
  $ echo "convert=" >> $HGRCPATH
  $ echo 'graphlog =' >> $HGRCPATH

create tla archive

  $ tla make-archive tla@mercurial--convert `pwd`/hg-test-convert-tla

initialize tla repo

  $ mkdir tla-repo
  $ cd tla-repo/
  $ tla init-tree tla@mercurial--convert/tla--test--0
  $ tla import
  * creating version tla@mercurial--convert/tla--test--0
  * imported tla@mercurial--convert/tla--test--0

create initial files

  $ echo 'this is a file' > a
  $ tla add a
  $ mkdir src
  $ tla add src
  $ cd src
  $ dd count=1 if=/dev/zero of=b > /dev/null 2> /dev/null
  $ tla add b
  $ tla commit -s "added a file, src and src/b (binary)"
  A/ .arch-ids
  A/ src
  A/ src/.arch-ids
  A  .arch-ids/a.id
  A  a
  A  src/.arch-ids/=id
  A  src/.arch-ids/b.id
  A  src/b
  * update pristine tree (tla@mercurial--convert/tla--test--0--base-0 => tla--test--0--patch-1)
  * committed tla@mercurial--convert/tla--test--0--patch-1

create link file and modify a

  $ ln -s ../a a-link
  $ tla add a-link
  $ echo 'this a modification to a' >> ../a
  $ tla commit -s "added link to a and modify a"
  A  src/.arch-ids/a-link.id
  A  src/a-link
  M  a
  * update pristine tree (tla@mercurial--convert/tla--test--0--patch-1 => tla--test--0--patch-2)
  * committed tla@mercurial--convert/tla--test--0--patch-2

create second link and modify b

  $ ln -s ../a a-link-2
  $ tla add a-link-2
  $ dd count=1 seek=1 if=/dev/zero of=b > /dev/null 2> /dev/null
  $ tla commit -s "added second link and modify b"
  A  src/.arch-ids/a-link-2.id
  A  src/a-link-2
  Mb src/b
  * update pristine tree (tla@mercurial--convert/tla--test--0--patch-2 => tla--test--0--patch-3)
  * committed tla@mercurial--convert/tla--test--0--patch-3

b file to link and a-link-2 to regular file

  $ rm -f a-link-2
  $ echo 'this is now a regular file' > a-link-2
  $ ln -sf ../a b
  $ tla commit -s "file to link and link to file test"
  fl src/b
  lf src/a-link-2
  * update pristine tree (tla@mercurial--convert/tla--test--0--patch-3 => tla--test--0--patch-4)
  * committed tla@mercurial--convert/tla--test--0--patch-4

move a-link-2 file and src directory

  $ cd ..
  $ tla mv src/a-link-2 c
  $ tla mv src test
  $ tla commit -s "move and rename a-link-2 file and src directory"
  D/ src/.arch-ids
  A/ test/.arch-ids
  /> src	test
  => src/.arch-ids/a-link-2.id	.arch-ids/c.id
  => src/a-link-2	c
  => src/.arch-ids/=id	test/.arch-ids/=id
  => src/.arch-ids/a-link.id	test/.arch-ids/a-link.id
  => src/.arch-ids/b.id	test/.arch-ids/b.id
  * update pristine tree (tla@mercurial--convert/tla--test--0--patch-4 => tla--test--0--patch-5)
  * committed tla@mercurial--convert/tla--test--0--patch-5
  $ cd ..

converting tla repo to Mercurial

  $ hg convert tla-repo tla-repo-hg
  initializing destination tla-repo-hg repository
  analyzing tree version tla@mercurial--convert/tla--test--0...
  scanning source...
  sorting...
  converting...
  5 initial import
  4 added a file, src and src/b (binary)
  3 added link to a and modify a
  2 added second link and modify b
  1 file to link and link to file test
  0 move and rename a-link-2 file and src directory
  $ tla register-archive -d tla@mercurial--convert
  $ glog()
  > {
  >     hg glog --template '{rev} "{desc|firstline}" files: {files}\n' "$@"
  > }

show graph log

  $ glog -R tla-repo-hg
  o  5 "move and rename a-link-2 file and src directory" files: c src/a-link src/a-link-2 src/b test/a-link test/b
  |
  o  4 "file to link and link to file test" files: src/a-link-2 src/b
  |
  o  3 "added second link and modify b" files: src/a-link-2 src/b
  |
  o  2 "added link to a and modify a" files: a src/a-link
  |
  o  1 "added a file, src and src/b (binary)" files: a src/b
  |
  o  0 "initial import" files:
  
  $ hg up -q -R tla-repo-hg
  $ hg -R tla-repo-hg manifest --debug
  c4072c4b72e1cabace081888efa148ee80ca3cbb 644   a
  0201ac32a3a8e86e303dff60366382a54b48a72e 644   c
  c0067ba5ff0b7c9a3eb17270839d04614c435623 644 @ test/a-link
  375f4263d86feacdea7e3c27100abd1560f2a973 644 @ test/b