view tests/test-check-module-imports.t @ 28487:98d98a645e9d

changelog: add class to represent parsed changelog revisions

Currently, changelog entries are parsed into their respective
components at read time. Many operations are only interested
in a subset of fields of a changelog entry. The parsing and
storing of all the fields adds avoidable overhead.

This patch introduces the "changelogrevision" class. It takes
changelog raw text and exposes the parsed results as attributes.
The code for parsing changelog entries has been moved into its
construction function. changelog.read() has been modified to use
the new class internally while maintaining its existing API.
Future patches will make revision parsing lazy.

We implement the construction function of the new class with
__new__ instead of __init__ so we can use a named tuple to
represent the empty revision. This saves overhead and complexity
of coercing later versions of this class to represent an empty
instance.

While we are here, we add a method on changelog to obtain an
instance of the new type.

The overhead of constructing the new class regresses performance
of revsets accessing this data:

author(mpm)
0.896565
0.929984

desc(bug)
0.887169
0.935642 105%

date(2015)
0.878797
0.908094

extra(rebase_source)
0.865446
0.922624 106%

author(mpm) or author(greg)
1.801832
1.902112 105%

author(mpm) or desc(bug)
1.812438
1.860977

date(2015) or branch(default)
0.968276
1.005824

author(mpm) or desc(bug) or date(2015) or extra(rebase_source)
3.656193
3.743381

Once lazy parsing is implemented, these revsets will all be faster
than before. There is no performance change on revsets that do not
access this data. There /could/ be a performance regression on
operations that perform several changelog reads. However, I can't
think of anything outside of revsets and `hg log` (basically the
same as a revset) that would be impacted.

#require test-repo

  $ import_checker="$TESTDIR"/../contrib/import-checker.py

Run the doctests from the import checker, and make sure
it's working correctly.
  $ TERM=dumb
  $ export TERM
  $ python -m doctest $import_checker

Run additional tests for the import checker

  $ mkdir testpackage

  $ cat > testpackage/multiple.py << EOF
  > from __future__ import absolute_import
  > import os, sys
  > EOF

  $ cat > testpackage/unsorted.py << EOF
  > from __future__ import absolute_import
  > import sys
  > import os
  > EOF

  $ cat > testpackage/stdafterlocal.py << EOF
  > from __future__ import absolute_import
  > from . import unsorted
  > import os
  > EOF

  $ cat > testpackage/requirerelative.py << EOF
  > from __future__ import absolute_import
  > import testpackage.unsorted
  > EOF

  $ cat > testpackage/importalias.py << EOF
  > from __future__ import absolute_import
  > import ui
  > EOF

  $ cat > testpackage/relativestdlib.py << EOF
  > from __future__ import absolute_import
  > from .. import os
  > EOF

  $ cat > testpackage/symbolimport.py << EOF
  > from __future__ import absolute_import
  > from .unsorted import foo
  > EOF

  $ cat > testpackage/latesymbolimport.py << EOF
  > from __future__ import absolute_import
  > from . import unsorted
  > from mercurial.node import hex
  > EOF

  $ cat > testpackage/multiplegroups.py << EOF
  > from __future__ import absolute_import
  > from . import unsorted
  > from . import more
  > EOF

  $ mkdir testpackage/subpackage
  $ cat > testpackage/subpackage/levelpriority.py << EOF
  > from __future__ import absolute_import
  > from . import foo
  > from .. import parent
  > EOF

  $ touch testpackage/subpackage/foo.py
  $ cat > testpackage/subpackage/__init__.py << EOF
  > from __future__ import absolute_import
  > from . import levelpriority  # should not cause cycle
  > EOF

  $ cat > testpackage/subpackage/localimport.py << EOF
  > from __future__ import absolute_import
  > from . import foo
  > def bar():
  >     # should not cause "higher-level import should come first"
  >     from .. import unsorted
  >     # but other errors should be detected
  >     from .. import more
  >     import testpackage.subpackage.levelpriority
  > EOF

  $ cat > testpackage/importmodulefromsub.py << EOF
  > from __future__ import absolute_import
  > from .subpackage import foo  # not a "direct symbol import"
  > EOF

  $ cat > testpackage/importsymbolfromsub.py << EOF
  > from __future__ import absolute_import
  > from .subpackage import foo, nonmodule
  > EOF

  $ cat > testpackage/sortedentries.py << EOF
  > from __future__ import absolute_import
  > from . import (
  >     foo,
  >     bar,
  > )
  > EOF

  $ cat > testpackage/importfromalias.py << EOF
  > from __future__ import absolute_import
  > from . import ui
  > EOF

  $ cat > testpackage/importfromrelative.py << EOF
  > from __future__ import absolute_import
  > from testpackage.unsorted import foo
  > EOF

  $ python "$import_checker" testpackage/*.py testpackage/subpackage/*.py
  testpackage/importalias.py:2: ui module must be "as" aliased to uimod
  testpackage/importfromalias.py:2: ui from testpackage must be "as" aliased to uimod
  testpackage/importfromrelative.py:2: import should be relative: testpackage.unsorted
  testpackage/importfromrelative.py:2: direct symbol import foo from testpackage.unsorted
  testpackage/importsymbolfromsub.py:2: direct symbol import nonmodule from testpackage.subpackage
  testpackage/latesymbolimport.py:3: symbol import follows non-symbol import: mercurial.node
  testpackage/multiple.py:2: multiple imported names: os, sys
  testpackage/multiplegroups.py:3: multiple "from . import" statements
  testpackage/relativestdlib.py:2: relative import of stdlib module
  testpackage/requirerelative.py:2: import should be relative: testpackage.unsorted
  testpackage/sortedentries.py:2: imports from testpackage not lexically sorted: bar < foo
  testpackage/stdafterlocal.py:3: stdlib import "os" follows local import: testpackage
  testpackage/subpackage/levelpriority.py:3: higher-level import should come first: testpackage
  testpackage/subpackage/localimport.py:7: multiple "from .. import" statements
  testpackage/subpackage/localimport.py:8: import should be relative: testpackage.subpackage.levelpriority
  testpackage/symbolimport.py:2: direct symbol import foo from testpackage.unsorted
  testpackage/unsorted.py:3: imports not lexically sorted: os < sys
  [1]

  $ cd "$TESTDIR"/..

There are a handful of cases here that require renaming a module so it
doesn't overlap with a stdlib module name. There are also some cycles
here that we should still endeavor to fix, and some cycles will be
hidden by deduplication algorithm in the cycle detector, so fixing
these may expose other cycles.

  $ hg locate 'mercurial/**.py' 'hgext/**.py' | sed 's-\\-/-g' | python "$import_checker" -
  Import cycle: hgext.largefiles.basestore -> hgext.largefiles.localstore -> hgext.largefiles.basestore
  [1]