view tests/test-bundle-r.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

  $ hg init test
  $ cd test
  $ hg unbundle "$TESTDIR/bundles/remote.hg"
  adding changesets
  adding manifests
  adding file changes
  added 9 changesets with 7 changes to 4 files (+1 heads)
  new changesets bfaf4b5cbf01:916f1afdef90 (9 drafts)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg up tip
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd ..

  $ for i in 0 1 2 3 4 5 6 7 8; do
  >    mkdir test-"$i"
  >    hg --cwd test-"$i" init
  >    hg -R test bundle -r "$i" test-"$i".hg test-"$i"
  >    cd test-"$i"
  >    hg unbundle ../test-"$i".hg
  >    hg verify
  >    hg tip -q
  >    cd ..
  > done
  searching for changes
  1 changesets found
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets bfaf4b5cbf01 (1 drafts)
  (run 'hg update' to get a working copy)
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 1 changesets with 1 changes to 1 files
  0:bfaf4b5cbf01
  searching for changes
  2 changesets found
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  new changesets bfaf4b5cbf01:21f32785131f (2 drafts)
  (run 'hg update' to get a working copy)
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 2 changesets with 2 changes to 1 files
  1:21f32785131f
  searching for changes
  3 changesets found
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 1 files
  new changesets bfaf4b5cbf01:4ce51a113780 (3 drafts)
  (run 'hg update' to get a working copy)
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 3 changesets with 3 changes to 1 files
  2:4ce51a113780
  searching for changes
  4 changesets found
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 4 changes to 1 files
  new changesets bfaf4b5cbf01:93ee6ab32777 (4 drafts)
  (run 'hg update' to get a working copy)
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 4 changesets with 4 changes to 1 files
  3:93ee6ab32777
  searching for changes
  2 changesets found
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  new changesets bfaf4b5cbf01:c70afb1ee985 (2 drafts)
  (run 'hg update' to get a working copy)
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 2 changesets with 2 changes to 1 files
  1:c70afb1ee985
  searching for changes
  3 changesets found
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 1 files
  new changesets bfaf4b5cbf01:f03ae5a9b979 (3 drafts)
  (run 'hg update' to get a working copy)
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 3 changesets with 3 changes to 1 files
  2:f03ae5a9b979
  searching for changes
  4 changesets found
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 5 changes to 2 files
  new changesets bfaf4b5cbf01:095cb14b1b4d (4 drafts)
  (run 'hg update' to get a working copy)
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 4 changesets with 5 changes to 2 files
  3:095cb14b1b4d
  searching for changes
  5 changesets found
  adding changesets
  adding manifests
  adding file changes
  added 5 changesets with 6 changes to 3 files
  new changesets bfaf4b5cbf01:faa2e4234c7a (5 drafts)
  (run 'hg update' to get a working copy)
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 5 changesets with 6 changes to 3 files
  4:faa2e4234c7a
  searching for changes
  5 changesets found
  adding changesets
  adding manifests
  adding file changes
  added 5 changesets with 5 changes to 2 files
  new changesets bfaf4b5cbf01:916f1afdef90 (5 drafts)
  (run 'hg update' to get a working copy)
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 5 changesets with 5 changes to 2 files
  4:916f1afdef90
  $ cd test-8
  $ hg pull ../test-7
  pulling from ../test-7
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 2 changes to 3 files (+1 heads)
  new changesets c70afb1ee985:faa2e4234c7a
  1 local changesets published
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 9 changesets with 7 changes to 4 files
  $ hg rollback
  repository tip rolled back to revision 4 (undo pull)
  $ cd ..

should fail

  $ hg -R test bundle --base 2 -r tip test-bundle-branch1.hg test-3
  abort: --base is incompatible with specifying a destination
  [255]
  $ hg -R test bundle -a -r tip test-bundle-branch1.hg test-3
  abort: --all is incompatible with specifying a destination
  [255]
  $ hg -R test bundle -r tip test-bundle-branch1.hg
  abort: repository default-push not found!
  [255]

  $ hg -R test bundle --base 2 -r tip test-bundle-branch1.hg
  2 changesets found
  $ hg -R test bundle --base 2 -r 7 test-bundle-branch2.hg
  4 changesets found
  $ hg -R test bundle --base 2 test-bundle-all.hg
  6 changesets found
  $ hg -R test bundle --base 2 --all test-bundle-all-2.hg
  ignoring --base because --all was specified
  9 changesets found
  $ hg -R test bundle --base 3 -r tip test-bundle-should-fail.hg
  1 changesets found

empty bundle

  $ hg -R test bundle --base 7 --base 8 test-bundle-empty.hg
  no changes found
  [1]

issue76 msg2163

  $ hg -R test bundle --base 3 -r 3 -r 3 test-bundle-cset-3.hg
  no changes found
  [1]

Issue1910: 'hg bundle --base $head' does not exclude $head from
result

  $ hg -R test bundle --base 7 test-bundle-cset-7.hg
  4 changesets found

  $ hg clone test-2 test-9
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd test-9

revision 2

  $ hg tip -q
  2:4ce51a113780
  $ hg unbundle ../test-bundle-should-fail.hg
  adding changesets
  transaction abort!
  rollback completed
  abort: 00changelog.i@93ee6ab32777: unknown parent!
  [255]

revision 2

  $ hg tip -q
  2:4ce51a113780
  $ hg unbundle ../test-bundle-all.hg
  adding changesets
  adding manifests
  adding file changes
  added 6 changesets with 4 changes to 4 files (+1 heads)
  new changesets 93ee6ab32777:916f1afdef90 (6 drafts)
  (run 'hg heads' to see heads, 'hg merge' to merge)

revision 8

  $ hg tip -q
  8:916f1afdef90
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 9 changesets with 7 changes to 4 files
  $ hg rollback
  repository tip rolled back to revision 2 (undo unbundle)

revision 2

  $ hg tip -q
  2:4ce51a113780
  $ hg unbundle ../test-bundle-branch1.hg
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  new changesets 93ee6ab32777:916f1afdef90 (2 drafts)
  (run 'hg update' to get a working copy)

revision 4

  $ hg tip -q
  4:916f1afdef90
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 5 changesets with 5 changes to 2 files
  $ hg rollback
  repository tip rolled back to revision 2 (undo unbundle)
  $ hg unbundle ../test-bundle-branch2.hg
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 3 changes to 3 files (+1 heads)
  new changesets c70afb1ee985:faa2e4234c7a (4 drafts)
  (run 'hg heads' to see heads, 'hg merge' to merge)

revision 6

  $ hg tip -q
  6:faa2e4234c7a
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 7 changesets with 6 changes to 3 files
  $ hg rollback
  repository tip rolled back to revision 2 (undo unbundle)
  $ hg unbundle ../test-bundle-cset-7.hg
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  new changesets 93ee6ab32777:916f1afdef90 (2 drafts)
  (run 'hg update' to get a working copy)

revision 4

  $ hg tip -q
  4:916f1afdef90
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 5 changesets with 5 changes to 2 files

  $ cd ../test
  $ hg merge 7
  note: possible conflict - afile was renamed multiple times to:
   adifferentfile
   anotherfile
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -m merge
  $ cd ..
  $ hg -R test bundle --base 2 test-bundle-head.hg
  7 changesets found
  $ hg clone test-2 test-10
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd test-10
  $ hg unbundle ../test-bundle-head.hg
  adding changesets
  adding manifests
  adding file changes
  added 7 changesets with 4 changes to 4 files
  new changesets 93ee6ab32777:03fc0b0e347c (7 drafts)
  (run 'hg update' to get a working copy)

revision 9

  $ hg tip -q
  9:03fc0b0e347c
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 10 changesets with 7 changes to 4 files

  $ cd ..