annotate tests/test-lfconvert.t @ 44118:f81c17ec303c

hgdemandimport: apply lazy module loading to sys.meta_path finders

Python's `sys.meta_path` finders are the primary objects whose job it
is to find a module at import time. When `import` is called, Python
iterates objects in this list and calls `o.find_spec(...)` to find
a `ModuleSpec` (or None if the module couldn't be found by that
finder). If no meta path finder can find a module, import fails.

One of the default meta path finders is `PathFinder`. Its job is to
import modules from the filesystem and is probably the most important
importer. This finder looks at `sys.path` and `sys.path_hooks` to do
its job.

The `ModuleSpec` returned by `MetaPathImporter.find_spec()` has a
`loader` attribute, which defines the concrete module loader to use.
`sys.path_hooks` is a hook point for teaching `PathFinder` to
instantiate custom loader types.

Previously, we injected a custom `sys.path_hook` that told `PathFinder`
to wrap the default loaders with a loader that creates a module object
that is lazy.

This approach worked. But its main limitation was that it only applied
to the `PathFinder` meta path importer. There are other meta path
importers that are registered. And in the case of PyOxidizer loading
modules from memory, `PathFinder` doesn't come into play since
PyOxidizer's own meta path importer was handling all imports.

This commit changes our approach to lazy module loading by proxying
all meta path importers. Specifically, we overload the `find_spec()`
method to swap in a wrapped loader on the `ModuleSpec` before it
is returned. The end result of this is all meta path importers should
be lazy.

As much as I would have loved to utilize .__class__ manipulation to
achieve this, some meta path importers are implemented in C/Rust
in such a way that they cannot be monkeypatched. This is why we
use __getattribute__ to define a proxy.

Also, this change could theoretically open us up to regressions in
meta path importers whose loader is creating module objects which
can't be monkeypatched. But I'm not aware of any of these in the
wild. So I think we'll be safe.

According to hyperfine, this change yields a decent startup time win of
5-6ms:

```
Benchmark #1: ~/.pyenv/versions/3.6.10/bin/python ./hg version
  Time (mean ± σ):      86.8 ms ±   0.5 ms    [User: 78.0 ms, System: 8.7 ms]
  Range (min … max):    86.0 ms …  89.1 ms    50 runs

  Time (mean ± σ):      81.1 ms ±   2.7 ms    [User: 74.5 ms, System: 6.5 ms]
  Range (min … max):    77.8 ms …  90.5 ms    50 runs

Benchmark #2: ~/.pyenv/versions/3.7.6/bin/python ./hg version
  Time (mean ± σ):      78.9 ms ±   0.6 ms    [User: 70.2 ms, System: 8.7 ms]
  Range (min … max):    78.1 ms …  81.2 ms    50 runs

  Time (mean ± σ):      73.4 ms ±   0.6 ms    [User: 65.3 ms, System: 8.0 ms]
  Range (min … max):    72.4 ms …  75.7 ms    50 runs

Benchmark #3: ~/.pyenv/versions/3.8.1/bin/python ./hg version
  Time (mean ± σ):      78.1 ms ±   0.6 ms    [User: 70.2 ms, System: 7.9 ms]
  Range (min … max):    77.4 ms …  80.9 ms    50 runs

  Time (mean ± σ):      72.1 ms ±   0.4 ms    [User: 64.4 ms, System: 7.6 ms]
  Range (min … max):    71.4 ms …  74.1 ms    50 runs
```

Differential Revision: https://phab.mercurial-scm.org/D7954

  $ USERCACHE="$TESTTMP/cache"; export USERCACHE
  $ mkdir "${USERCACHE}"
  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > largefiles =
  > share =
  > strip =
  > convert =
  > [largefiles]
  > minsize = 0.5
  > patterns = **.other
  >     **.dat
  > usercache=${USERCACHE}
  > EOF

"lfconvert" works
  $ hg init bigfile-repo
  $ cd bigfile-repo
  $ cat >> .hg/hgrc <<EOF
  > [extensions]
  > largefiles = !
  > EOF
  $ mkdir sub
  $ dd if=/dev/zero bs=1k count=256 > large 2> /dev/null
  $ dd if=/dev/zero bs=1k count=256 > large2 2> /dev/null
  $ echo normal > normal1
  $ echo alsonormal > sub/normal2
  $ dd if=/dev/zero bs=1k count=10 > sub/maybelarge.dat 2> /dev/null
  $ hg addremove
  adding large
  adding large2
  adding normal1
  adding sub/maybelarge.dat
  adding sub/normal2
  $ hg commit -m"add large, normal1" large normal1
  $ hg commit -m"add sub/*" sub

Test tag parsing
  $ cat >> .hgtags <<EOF
  > IncorrectlyFormattedTag!
  > invalidhash sometag
  > 0123456789abcdef anothertag
  > EOF
  $ hg add .hgtags
  $ hg commit -m"add large2" large2 .hgtags

Test link+rename largefile codepath
  $ [ -d .hg/largefiles ] && echo fail || echo pass
  pass
  $ cd ..
  $ hg lfconvert --size 0.2 bigfile-repo largefiles-repo
  initializing destination largefiles-repo
  skipping incorrectly formatted tag IncorrectlyFormattedTag!
  skipping incorrectly formatted id invalidhash
  no mapping for id 0123456789abcdef
#if symlink
  $ hg --cwd bigfile-repo rename large2 large3
  $ ln -sf large bigfile-repo/large3
  $ hg --cwd bigfile-repo commit -m"make large2 a symlink" large2 large3
  $ hg lfconvert --size 0.2 bigfile-repo largefiles-repo-symlink
  initializing destination largefiles-repo-symlink
  skipping incorrectly formatted tag IncorrectlyFormattedTag!
  skipping incorrectly formatted id invalidhash
  no mapping for id 0123456789abcdef
  abort: renamed/copied largefile large3 becomes symlink
  [255]
#endif
  $ cd bigfile-repo
  $ hg strip --no-backup 2
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ cd ..
  $ rm -rf largefiles-repo largefiles-repo-symlink

  $ hg lfconvert --size 0.2 bigfile-repo largefiles-repo
  initializing destination largefiles-repo

"lfconvert" converts content correctly
  $ cd largefiles-repo
  $ hg up
  getting changed largefiles
  2 largefiles updated, 0 removed
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg locate
  .hglf/large
  .hglf/sub/maybelarge.dat
  normal1
  sub/normal2
  $ cat normal1
  normal
  $ cat sub/normal2
  alsonormal
  $ md5sum.py large sub/maybelarge.dat
  ec87a838931d4d5d2e94a04644788a55  large
  1276481102f218c981e0324180bafd9f  sub/maybelarge.dat

"lfconvert" adds 'largefiles' to .hg/requires.
  $ cat .hg/requires
  dotencode
  fncache
  generaldelta
  largefiles
  revlogv1
  sparserevlog
  store
  testonly-simplestore (reposimplestore !)

"lfconvert" includes a newline at the end of the standin files.
  $ cat .hglf/large .hglf/sub/maybelarge.dat
  2e000fa7e85759c7f4c254d4d9c33ef481e459a7
  34e163be8e43c5631d8b92e9c43ab0bf0fa62b9c
  $ cd ..

add some changesets to rename/remove/merge
  $ cd bigfile-repo
  $ hg mv -q sub stuff
  $ hg commit -m"rename sub/ to stuff/"
  $ hg update -q 1
  $ echo blah >> normal3
  $ echo blah >> sub/normal2
  $ echo blah >> sub/maybelarge.dat
  $ md5sum.py sub/maybelarge.dat
  1dd0b99ff80e19cff409702a1d3f5e15  sub/maybelarge.dat
  $ hg commit -A -m"add normal3, modify sub/*"
  adding normal3
  created new head
  $ hg rm large normal3
  $ hg commit -q -m"remove large, normal3"
  $ hg merge
  tool internal:merge (for pattern stuff/maybelarge.dat) can't handle binary
  no tool found to merge stuff/maybelarge.dat
  file 'stuff/maybelarge.dat' needs to be resolved.
  You can keep (l)ocal [working copy], take (o)ther [merge rev], or leave (u)nresolved.
  What do you want to do? u
  merging sub/normal2 and stuff/normal2 to stuff/normal2
  0 files updated, 1 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
  [1]
  $ hg cat -r . sub/maybelarge.dat > stuff/maybelarge.dat
  $ hg resolve -m stuff/maybelarge.dat
  (no more unresolved files)
  $ hg commit -m"merge"
  $ hg log -G --template "{rev}:{node|short}  {desc|firstline}\n"
  @    5:4884f215abda  merge
  |\
  | o  4:7285f817b77e  remove large, normal3
  | |
  | o  3:67e3892e3534  add normal3, modify sub/*
  | |
  o |  2:c96c8beb5d56  rename sub/ to stuff/
  |/
  o  1:020c65d24e11  add sub/*
  |
  o  0:117b8328f97a  add large, normal1
  
  $ cd ..

lfconvert with rename, merge, and remove
  $ rm -rf largefiles-repo
  $ hg lfconvert --size 0.2 bigfile-repo largefiles-repo
  initializing destination largefiles-repo
  $ cd largefiles-repo
  $ hg log -G --template "{rev}:{node|short}  {desc|firstline}\n"
  o    5:9cc5aa7204f0  merge
  |\
  | o  4:a5a02de7a8e4  remove large, normal3
  | |
  | o  3:55759520c76f  add normal3, modify sub/*
  | |
  o |  2:261ad3f3f037  rename sub/ to stuff/
  |/
  o  1:334e5237836d  add sub/*
  |
  o  0:d4892ec57ce2  add large, normal1
  
  $ hg locate -r 2
  .hglf/large
  .hglf/stuff/maybelarge.dat
  normal1
  stuff/normal2
  $ hg locate -r 3
  .hglf/large
  .hglf/sub/maybelarge.dat
  normal1
  normal3
  sub/normal2
  $ hg locate -r 4
  .hglf/sub/maybelarge.dat
  normal1
  sub/normal2
  $ hg locate -r 5
  .hglf/stuff/maybelarge.dat
  normal1
  stuff/normal2
  $ hg update
  getting changed largefiles
  1 largefiles updated, 0 removed
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat stuff/normal2
  alsonormal
  blah
  $ md5sum.py stuff/maybelarge.dat
  1dd0b99ff80e19cff409702a1d3f5e15  stuff/maybelarge.dat
  $ cat .hglf/stuff/maybelarge.dat
  76236b6a2c6102826c61af4297dd738fb3b1de38
  $ cd ..

"lfconvert" error cases
  $ hg lfconvert http://localhost/foo foo
  abort: http://localhost/foo is not a local Mercurial repo
  [255]
  $ hg lfconvert foo ssh://localhost/foo
  abort: ssh://localhost/foo is not a local Mercurial repo
  [255]
  $ hg lfconvert nosuchrepo foo
  abort: repository nosuchrepo not found!
  [255]
  $ hg share -q -U bigfile-repo shared
  $ printf 'bogus' > shared/.hg/sharedpath
  $ hg lfconvert shared foo
  abort: .hg/sharedpath points to nonexistent directory $TESTTMP/bogus!
  [255]
  $ hg lfconvert bigfile-repo largefiles-repo
  initializing destination largefiles-repo
  abort: repository largefiles-repo already exists!
  [255]

add another largefile to the new largefiles repo
  $ cd largefiles-repo
  $ dd if=/dev/zero bs=1k count=1k > anotherlarge 2> /dev/null
  $ hg add --lfsize=1 anotherlarge
  $ hg commit -m "add anotherlarge (should be a largefile)"
  $ cat .hglf/anotherlarge
  3b71f43ff30f4b15b5cd85dd9e95ebc7e84eb5a3
  $ hg tag mytag
  $ cd ..

round-trip: converting back to a normal (non-largefiles) repo with
"lfconvert --to-normal" should give the same as ../bigfile-repo.  The
convert extension is disabled to show config items can be loaded without it.
  $ cd largefiles-repo
  $ hg --config extensions.convert=! lfconvert --to-normal . ../normal-repo
  initializing destination ../normal-repo
  0 additional largefiles cached
  scanning source...
  sorting...
  converting...
  7 add large, normal1
  6 add sub/*
  5 rename sub/ to stuff/
  4 add normal3, modify sub/*
  3 remove large, normal3
  2 merge
  1 add anotherlarge (should be a largefile)
  0 Added tag mytag for changeset 17126745edfd
  $ cd ../normal-repo
  $ cat >> .hg/hgrc <<EOF
  > [extensions]
  > largefiles = !
  > EOF

  $ hg log -G --template "{rev}:{node|short}  {desc|firstline}\n"
  o  7:b5fedc110b9d  Added tag mytag for changeset 867ab992ecf4
  |
  o  6:867ab992ecf4  add anotherlarge (should be a largefile)
  |
  o    5:4884f215abda  merge
  |\
  | o  4:7285f817b77e  remove large, normal3
  | |
  | o  3:67e3892e3534  add normal3, modify sub/*
  | |
  o |  2:c96c8beb5d56  rename sub/ to stuff/
  |/
  o  1:020c65d24e11  add sub/*
  |
  o  0:117b8328f97a  add large, normal1
  
  $ hg update
  5 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg locate
  .hgtags
  anotherlarge
  normal1
  stuff/maybelarge.dat
  stuff/normal2
  $ [ -d .hg/largefiles ] && echo fail || echo pass
  pass

  $ cd ..

Clearing the usercache ensures that commitctx doesn't try to cache largefiles
from the working dir on a convert.
  $ rm "${USERCACHE}"/*
  $ hg convert largefiles-repo
  assuming destination largefiles-repo-hg
  initializing destination largefiles-repo-hg repository
  scanning source...
  sorting...
  converting...
  7 add large, normal1
  6 add sub/*
  5 rename sub/ to stuff/
  4 add normal3, modify sub/*
  3 remove large, normal3
  2 merge
  1 add anotherlarge (should be a largefile)
  0 Added tag mytag for changeset 17126745edfd

  $ hg -R largefiles-repo-hg log -G --template "{rev}:{node|short}  {desc|firstline}\n"
  o  7:2f08f66459b7  Added tag mytag for changeset 17126745edfd
  |
  o  6:17126745edfd  add anotherlarge (should be a largefile)
  |
  o    5:9cc5aa7204f0  merge
  |\
  | o  4:a5a02de7a8e4  remove large, normal3
  | |
  | o  3:55759520c76f  add normal3, modify sub/*
  | |
  o |  2:261ad3f3f037  rename sub/ to stuff/
  |/
  o  1:334e5237836d  add sub/*
  |
  o  0:d4892ec57ce2  add large, normal1
  
Verify will fail (for now) if the usercache is purged before converting, since
largefiles are not cached in the converted repo's local store by the conversion
process.
  $ cd largefiles-repo-hg
  $ cat >> .hg/hgrc <<EOF
  > [experimental]
  > evolution.createmarkers=True
  > EOF
  $ hg debugobsolete `hg log -r tip -T "{node}"`
  1 new obsolescence markers
  obsoleted 1 changesets
  $ cd ..

  $ hg -R largefiles-repo-hg verify --large --lfa
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 8 changesets with 13 changes to 9 files
  searching 7 changesets for largefiles
  changeset 0:d4892ec57ce2: large references missing $TESTTMP/largefiles-repo-hg/.hg/largefiles/2e000fa7e85759c7f4c254d4d9c33ef481e459a7
  changeset 1:334e5237836d: sub/maybelarge.dat references missing $TESTTMP/largefiles-repo-hg/.hg/largefiles/34e163be8e43c5631d8b92e9c43ab0bf0fa62b9c
  changeset 2:261ad3f3f037: stuff/maybelarge.dat references missing $TESTTMP/largefiles-repo-hg/.hg/largefiles/34e163be8e43c5631d8b92e9c43ab0bf0fa62b9c
  changeset 3:55759520c76f: sub/maybelarge.dat references missing $TESTTMP/largefiles-repo-hg/.hg/largefiles/76236b6a2c6102826c61af4297dd738fb3b1de38
  changeset 5:9cc5aa7204f0: stuff/maybelarge.dat references missing $TESTTMP/largefiles-repo-hg/.hg/largefiles/76236b6a2c6102826c61af4297dd738fb3b1de38
  changeset 6:17126745edfd: anotherlarge references missing $TESTTMP/largefiles-repo-hg/.hg/largefiles/3b71f43ff30f4b15b5cd85dd9e95ebc7e84eb5a3
  verified existence of 6 revisions of 4 largefiles
  [1]
  $ hg -R largefiles-repo-hg showconfig paths
  [1]


Avoid a traceback if a largefile isn't available (issue3519)

Ensure the largefile can be cached in the source if necessary
  $ hg clone -U largefiles-repo issue3519
  $ rm -f "${USERCACHE}"/*
  $ hg -R issue3519 branch -q mybranch
  $ hg -R issue3519 ci -m 'change branch name only'
  $ hg lfconvert --to-normal issue3519 normalized3519
  initializing destination normalized3519
  4 additional largefiles cached
  scanning source...
  sorting...
  converting...
  8 add large, normal1
  7 add sub/*
  6 rename sub/ to stuff/
  5 add normal3, modify sub/*
  4 remove large, normal3
  3 merge
  2 add anotherlarge (should be a largefile)
  1 Added tag mytag for changeset 17126745edfd
  0 change branch name only

Ensure empty commits aren't lost in the conversion
  $ hg -R normalized3519 log -r tip -T '{desc}\n'
  change branch name only

Ensure the abort message is useful if a largefile is entirely unavailable
  $ rm -rf normalized3519
  $ rm "${USERCACHE}"/*
  $ rm issue3519/.hg/largefiles/*
  $ rm largefiles-repo/.hg/largefiles/*
  $ hg lfconvert --to-normal issue3519 normalized3519
  initializing destination normalized3519
  anotherlarge: largefile 3b71f43ff30f4b15b5cd85dd9e95ebc7e84eb5a3 not available from file:/*/$TESTTMP/largefiles-repo (glob)
  stuff/maybelarge.dat: largefile 76236b6a2c6102826c61af4297dd738fb3b1de38 not available from file:/*/$TESTTMP/largefiles-repo (glob)
  stuff/maybelarge.dat: largefile 76236b6a2c6102826c61af4297dd738fb3b1de38 not available from file:/*/$TESTTMP/largefiles-repo (glob)
  sub/maybelarge.dat: largefile 76236b6a2c6102826c61af4297dd738fb3b1de38 not available from file:/*/$TESTTMP/largefiles-repo (glob)
  large: largefile 2e000fa7e85759c7f4c254d4d9c33ef481e459a7 not available from file:/*/$TESTTMP/largefiles-repo (glob)
  sub/maybelarge.dat: largefile 76236b6a2c6102826c61af4297dd738fb3b1de38 not available from file:/*/$TESTTMP/largefiles-repo (glob)
  large: largefile 2e000fa7e85759c7f4c254d4d9c33ef481e459a7 not available from file:/*/$TESTTMP/largefiles-repo (glob)
  stuff/maybelarge.dat: largefile 34e163be8e43c5631d8b92e9c43ab0bf0fa62b9c not available from file:/*/$TESTTMP/largefiles-repo (glob)
  large: largefile 2e000fa7e85759c7f4c254d4d9c33ef481e459a7 not available from file:/*/$TESTTMP/largefiles-repo (glob)
  sub/maybelarge.dat: largefile 34e163be8e43c5631d8b92e9c43ab0bf0fa62b9c not available from file:/*/$TESTTMP/largefiles-repo (glob)
  large: largefile 2e000fa7e85759c7f4c254d4d9c33ef481e459a7 not available from file:/*/$TESTTMP/largefiles-repo (glob)
  0 additional largefiles cached
  11 largefiles failed to download
  abort: all largefiles must be present locally
  [255]