view tests/test-convert-svn-source.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

#require svn svn-bindings

  $ filter_svn_output () {
  >     egrep -v 'Committing|Updating|(^$)' | sed -e 's/done$//' || true
  > }

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > convert =
  > [convert]
  > svn.trunk = mytrunk
  > EOF

  $ svnadmin create svn-repo
  $ SVNREPOPATH=`pwd`/svn-repo
  $ SVNREPOURL="`"$PYTHON" $TESTDIR/svnurlof.py \"$SVNREPOPATH\"`"
  $ INVALIDREVISIONID=svn:x2147622-4a9f-4db4-a8d3-13562ff547b2/proj%20B/mytrunk@1
  $ VALIDREVISIONID=svn:a2147622-4a9f-4db4-a8d3-13562ff547b2/proj%20B/mytrunk/mytrunk@1

Now test that it works with trunk/tags layout, but no branches yet.

Initial svn import

  $ mkdir projB
  $ cd projB
  $ mkdir mytrunk
  $ mkdir tags
  $ cd ..

  $ svn import -m "init projB" projB "$SVNREPOURL/proj%20B" | filter_svn_output | sort
  Adding         projB/mytrunk
  Adding         projB/tags
  Committed revision 1.

Update svn repository

  $ svn co "$SVNREPOURL/proj%20B/mytrunk" B | filter_svn_output
  Checked out revision 1.
  $ cd B
  $ echo hello > 'letter .txt'
  $ svn add 'letter .txt' | filter_svn_output
  A         letter .txt
  $ svn ci -m hello | filter_svn_output
  Adding         letter .txt
  Transmitting file data .
  Committed revision 2.

  $ svn-safe-append.py world 'letter .txt'
  $ svn ci -m world | filter_svn_output
  Sending        letter .txt
  Transmitting file data .
  Committed revision 3.

  $ svn copy -m "tag v0.1" "$SVNREPOURL/proj%20B/mytrunk" "$SVNREPOURL/proj%20B/tags/v0.1" | filter_svn_output
  Committed revision 4.

  $ svn-safe-append.py 'nice day today!' 'letter .txt'
  $ svn ci -m "nice day" | filter_svn_output
  Sending        letter .txt
  Transmitting file data .
  Committed revision 5.
  $ cd ..

Convert to hg once and also test localtimezone option

NOTE: This doesn't check all time zones -- it merely determines that
the configuration option is taking effect.

An arbitrary (U.S.) time zone is used here.  TZ=US/Hawaii is selected
since it does not use DST (unlike other U.S. time zones) and is always
a fixed difference from UTC.

  $ TZ=US/Hawaii hg convert --config convert.localtimezone=True "$SVNREPOURL/proj%20B" B-hg
  initializing destination B-hg repository
  scanning source...
  sorting...
  converting...
  3 init projB
  2 hello
  1 world
  0 nice day
  updating tags

Update svn repository again

  $ cd B
  $ svn-safe-append.py "see second letter" 'letter .txt'
  $ echo "nice to meet you" > letter2.txt
  $ svn add letter2.txt | filter_svn_output
  A         letter2.txt
  $ svn ci -m "second letter" | filter_svn_output
  Sending        letter .txt
  Adding         letter2.txt
  Transmitting file data ..
  Committed revision 6.

  $ svn copy -m "tag v0.2" "$SVNREPOURL/proj%20B/mytrunk" "$SVNREPOURL/proj%20B/tags/v0.2" | filter_svn_output
  Committed revision 7.

  $ svn-safe-append.py "blah-blah-blah" letter2.txt
  $ svn ci -m "work in progress" | filter_svn_output
  Sending        letter2.txt
  Transmitting file data .
  Committed revision 8.
  $ cd ..

  $ hg convert -s svn "$SVNREPOURL/proj%20B/non-existent-path" dest
  initializing destination dest repository
  abort: no revision found in module /proj B/non-existent-path
  [255]

########################################

Test incremental conversion

  $ TZ=US/Hawaii hg convert --config convert.localtimezone=True "$SVNREPOURL/proj%20B" B-hg
  scanning source...
  sorting...
  converting...
  1 second letter
  0 work in progress
  updating tags

  $ cd B-hg
  $ hg log -G --template '{rev} {desc|firstline} date: {date|date} files: {files}\n'
  o  7 update tags date: * +0000 files: .hgtags (glob)
  |
  o  6 work in progress date: * -1000 files: letter2.txt (glob)
  |
  o  5 second letter date: * -1000 files: letter .txt letter2.txt (glob)
  |
  o  4 update tags date: * +0000 files: .hgtags (glob)
  |
  o  3 nice day date: * -1000 files: letter .txt (glob)
  |
  o  2 world date: * -1000 files: letter .txt (glob)
  |
  o  1 hello date: * -1000 files: letter .txt (glob)
  |
  o  0 init projB date: * -1000 files: (glob)
  
  $ hg tags -q
  tip
  v0.2
  v0.1
  $ cd ..

Test filemap
  $ echo 'include letter2.txt' > filemap
  $ hg convert --filemap filemap "$SVNREPOURL/proj%20B/mytrunk" fmap
  initializing destination fmap repository
  scanning source...
  sorting...
  converting...
  5 init projB
  4 hello
  3 world
  2 nice day
  1 second letter
  0 work in progress
  $ hg -R fmap branch -q
  default
  $ hg log -G -R fmap --template '{rev} {desc|firstline} files: {files}\n'
  o  1 work in progress files: letter2.txt
  |
  o  0 second letter files: letter2.txt
  
Convert with --full adds and removes files that didn't change

  $ cd B
  $ echo >> "letter .txt"
  $ svn ci -m 'nothing' | filter_svn_output
  Sending        letter .txt
  Transmitting file data .
  Committed revision 9.
  $ cd ..

  $ echo 'rename letter2.txt letter3.txt' > filemap
  $ hg convert --filemap filemap --full "$SVNREPOURL/proj%20B/mytrunk" fmap
  scanning source...
  sorting...
  converting...
  0 nothing
  $ hg -R fmap st --change tip
  A letter .txt
  A letter3.txt
  R letter2.txt

test invalid splicemap1

  $ cat > splicemap <<EOF
  > $INVALIDREVISIONID $VALIDREVISIONID
  > EOF
  $ hg convert --splicemap splicemap "$SVNREPOURL/proj%20B/mytrunk" smap
  initializing destination smap repository
  abort: splicemap entry svn:x2147622-4a9f-4db4-a8d3-13562ff547b2/proj%20B/mytrunk@1 is not a valid revision identifier
  [255]

Test stop revision
  $ hg convert --rev 1 "$SVNREPOURL/proj%20B/mytrunk" stoprev
  initializing destination stoprev repository
  scanning source...
  sorting...
  converting...
  0 init projB
  $ hg -R stoprev branch -q
  default

Check convert_revision extra-records.
This is also the only place testing more than one extra field in a revision.

  $ cd stoprev
  $ hg tip --debug | grep extra
  extra:       branch=default
  extra:       convert_revision=svn:........-....-....-....-............/proj B/mytrunk@1 (re)
  $ cd ..

Test converting empty heads (issue3347).
Also tests getting logs directly without debugsvnlog.

  $ svnadmin create svn-empty
  $ svnadmin load -q svn-empty < "$TESTDIR/svn/empty.svndump"
  $ hg --config convert.svn.trunk= --config convert.svn.debugsvnlog=0 convert svn-empty
  assuming destination svn-empty-hg
  initializing destination svn-empty-hg repository
  scanning source...
  sorting...
  converting...
  1 init projA
  0 adddir
  $ hg --config convert.svn.trunk= convert "$SVNREPOURL/../svn-empty/trunk"
  assuming destination trunk-hg
  initializing destination trunk-hg repository
  scanning source...
  sorting...
  converting...
  1 init projA
  0 adddir

Test that a too-new repository format is properly rejected:
  $ mv svn-empty/format format
  $ echo 999 > svn-empty/format
It's important that this command explicitly specify svn, otherwise it
can have surprising side effects (like falling back to a perforce
depot that can be seen from the test environment and slurping from that.)
  $ hg convert --source-type svn svn-empty this-will-fail
  initializing destination this-will-fail repository
  file:/*/$TESTTMP/svn-empty does not look like a Subversion repository to libsvn version 1.*.* (glob)
  abort: svn-empty: missing or unsupported repository
  [255]
  $ mv format svn-empty/format

enable svn subrepos

  $ cat >> $HGRCPATH <<EOF
  > [subrepos]
  > svn:allowed = true
  > EOF

try converting when we have an svn subrepo and a merge in hg superrepo (issue5657)

  $ cd "$TESTTMP"
  $ hg init withmerge
  $ cd withmerge
  $ echo "subrepo = [svn]$SVNREPOURL" >.hgsub
  $ hg add .hgsub
  $ svn checkout "$SVNREPOURL" subrepo | sort
  A    subrepo/proj B
  A    subrepo/proj B/mytrunk
  A    subrepo/proj B/mytrunk/letter .txt
  A    subrepo/proj B/mytrunk/letter2.txt
  A    subrepo/proj B/tags
  A    subrepo/proj B/tags/v0.1
  A    subrepo/proj B/tags/v0.1/letter .txt
  A    subrepo/proj B/tags/v0.2
  A    subrepo/proj B/tags/v0.2/letter .txt
  A    subrepo/proj B/tags/v0.2/letter2.txt
  Checked out revision 9.
  $ hg ci -m "Adding svn subrepo"
  $ touch file1.txt
  $ hg add file1.txt
  $ hg ci -m "Adding file1"
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ touch file2.txt
  $ hg add file2.txt
  $ hg ci -m "Adding file2"
  created new head
  $ hg merge 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -m "merged"
  $ cd ..
  $ hg --config extensions.convert= convert withmerge withmerge-converted
  initializing destination withmerge-converted repository
  scanning source...
  sorting...
  converting...
  3 Adding svn subrepo
  2 Adding file1
  1 Adding file2
  0 merged
  $ cd withmerge-converted
  $ hg up | sort
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved
  A    subrepo/proj B
  A    subrepo/proj B/mytrunk
  A    subrepo/proj B/mytrunk/letter .txt
  A    subrepo/proj B/mytrunk/letter2.txt
  A    subrepo/proj B/tags
  A    subrepo/proj B/tags/v0.1
  A    subrepo/proj B/tags/v0.1/letter .txt
  A    subrepo/proj B/tags/v0.2
  A    subrepo/proj B/tags/v0.2/letter .txt
  A    subrepo/proj B/tags/v0.2/letter2.txt
  Checked out revision 9.
  $ ls
  file1.txt
  file2.txt
  subrepo