view tests/test-verify.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.

prepare repo

  $ hg init a
  $ cd a
  $ echo "some text" > FOO.txt
  $ echo "another text" > bar.txt
  $ echo "more text" > QUICK.txt
  $ hg add
  adding FOO.txt
  adding QUICK.txt
  adding bar.txt
  $ hg ci -mtest1

verify

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  3 files, 1 changesets, 3 total revisions

verify with journal

  $ touch .hg/store/journal
  $ hg verify
  abandoned transaction found - run hg recover
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  3 files, 1 changesets, 3 total revisions
  $ rm .hg/store/journal

introduce some bugs in repo

  $ cd .hg/store/data
  $ mv _f_o_o.txt.i X_f_o_o.txt.i
  $ mv bar.txt.i xbar.txt.i
  $ rm _q_u_i_c_k.txt.i

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
   data/FOO.txt.i@0: missing revlog!
   0: empty or missing FOO.txt
   FOO.txt@0: f62022d3d590 in manifests not found
   data/QUICK.txt.i@0: missing revlog!
   0: empty or missing QUICK.txt
   QUICK.txt@0: 88b857db8eba in manifests not found
   data/bar.txt.i@0: missing revlog!
   0: empty or missing bar.txt
   bar.txt@0: 256559129457 in manifests not found
  3 files, 1 changesets, 0 total revisions
  9 integrity errors encountered!
  (first damaged changeset appears to be 0)
  [1]

  $ cd ../../..
  $ cd ..

test changelog without a manifest

  $ hg init b
  $ cd b
  $ hg branch foo
  marked working directory as branch foo
  (branches are permanent and global, did you want a bookmark?)
  $ hg ci -m branchfoo
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  0 files, 1 changesets, 0 total revisions

test revlog corruption

  $ touch a
  $ hg add a
  $ hg ci -m a

  $ echo 'corrupted' > b
  $ dd if=.hg/store/data/a.i of=start bs=1 count=20 2>/dev/null
  $ cat start b > .hg/store/data/a.i

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
   a@1: broken revlog! (index data/a.i is corrupted)
  warning: orphan revlog 'data/a.i'
  1 files, 2 changesets, 0 total revisions
  1 warnings encountered!
  1 integrity errors encountered!
  (first damaged changeset appears to be 1)
  [1]

  $ cd ..

test revlog format 0

  $ "$TESTDIR/revlog-formatv0.py"
  $ cd formatv0
  $ hg verify
  repository uses revlog format 0
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions
  $ cd ..