demandimport: delay loading for "from a import b" with absolute_import
Before this patch, "from a import b" doesn't delay loading module "b",
if absolute_import is enabled, even though "from . import b" does.
For example:
- it is assumed that extension X has "from P import M" for module M
under package P with absolute_import feature
- if importing module M is already delayed before loading extension
X, loading module M in extension X is delayed until actually
referring
util, cmdutil, scmutil or so of Mercurial itself should be
imported by "from . import M" style before loading extension X
- otherwise, module M is loaded immediately at loading extension X,
even if extension X itself isn't used at that "hg" command invocation
Some minor modules (e.g. filemerge or so) of Mercurial itself
aren't imported by "from . import M" style before loading
extension X. And of course, external libraries aren't, too.
This might cause startup performance problem of hg command, because
many bundled extensions already enable absolute_import feature.
To delay loading module for "from a import b" with absolute_import
feature, this patch does below in "from a (or .a) import b" with
absolute_import case:
1. import root module of "name" by system built-in __import__
(referred as _origimport)
2. recurse down the module chain for hierarchical "name"
This logic can be shared with non absolute_import
case. Therefore, this patch also centralizes it into chainmodules().
3. and fall through to process elements in "fromlist" for the leaf
module of "name"
Processing elements in "fromlist" is executed in the code path
after "if _pypy: .... else: ..." clause. Therefore, this patch
replaces "if _pypy:" with "elif _pypy:" to share it.
At 4f1144c3c72b introducing original "work around" for "from a import
b" case, elements in "fromlist" were imported with "level=level". But
"level" might be grater than 1 (e.g. level=2 in "from .. import b"
case) at demandimport() invocation, and importing direct sub-module in
"fromlist" with level grater than 1 causes unexpected result.
IMHO, this seems main reason of "errors for unknown reason" described
in 4f1144c3c72b, and we don't have to worry about it, because this
issue was already fixed by 78d05778907b.
This is reason why this patch removes "errors for unknown reasons"
comment.
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init a
$ cd a
$ echo 'base' > base
$ hg ci -Ambase -d '1 0'
adding base
$ hg qnew -d '1 0' pa
$ hg qnew -d '1 0' pb
$ hg qnew -d '1 0' pc
$ hg qdel
abort: qdelete requires at least one revision or patch name
[255]
$ hg qdel pc
abort: cannot delete applied patch pc
[255]
$ hg qpop
popping pc
now at: pb
Delete the same patch twice in one command (issue2427)
$ hg qdel pc pc
$ hg qseries
pa
pb
$ ls .hg/patches
pa
pb
series
status
$ hg qpop
popping pb
now at: pa
$ hg qdel -k 1
$ ls .hg/patches
pa
pb
series
status
$ hg qdel -r pa
patch pa finalized without changeset message
$ hg qapplied
$ hg log --template '{rev} {desc}\n'
1 [mq]: pa
0 base
$ hg qnew pd
$ hg qnew pe
$ hg qnew pf
$ hg qdel -r pe
abort: cannot delete revision 3 above applied patches
[255]
$ hg qdel -r qbase:pe
patch pd finalized without changeset message
patch pe finalized without changeset message
$ hg qapplied
pf
$ hg log --template '{rev} {desc}\n'
4 [mq]: pf
3 [mq]: pe
2 [mq]: pd
1 [mq]: pa
0 base
$ cd ..
$ hg init b
$ cd b
$ echo 'base' > base
$ hg ci -Ambase -d '1 0'
adding base
$ hg qfinish
abort: no revisions specified
[255]
$ hg qfinish -a
no patches applied
$ hg qnew -d '1 0' pa
$ hg qnew -d '1 0' pb
$ hg qnew pc # XXX fails to apply by /usr/bin/patch if we put a date
$ hg qfinish 0
abort: revision 0 is not managed
[255]
$ hg qfinish pb
abort: cannot delete revision 2 above applied patches
[255]
$ hg qpop
popping pc
now at: pb
$ hg qfinish -a pc
abort: unknown revision 'pc'!
[255]
$ hg qpush
applying pc
patch pc is empty
now at: pc
$ hg qfinish qbase:pb
patch pa finalized without changeset message
patch pb finalized without changeset message
$ hg qapplied
pc
$ hg log --template '{rev} {desc}\n'
3 imported patch pc
2 [mq]: pb
1 [mq]: pa
0 base
$ hg qfinish -a pc
patch pc finalized without changeset message
$ hg qapplied
$ hg log --template '{rev} {desc}\n'
3 imported patch pc
2 [mq]: pb
1 [mq]: pa
0 base
$ ls .hg/patches
series
status
qdel -k X && hg qimp -e X used to trigger spurious output with versioned queues
$ hg init --mq
$ hg qimport -r 3
$ hg qpop
popping imported_patch_pc
patch queue now empty
$ hg qdel -k imported_patch_pc
$ hg qimp -e imported_patch_pc
adding imported_patch_pc to series file
$ hg qfinish -a
no patches applied
resilience to inconsistency: qfinish -a with applied patches not in series
$ hg qser
imported_patch_pc
$ hg qapplied
$ hg qpush
applying imported_patch_pc
patch imported_patch_pc is empty
now at: imported_patch_pc
$ echo next >> base
$ hg qrefresh -d '1 0'
$ echo > .hg/patches/series # remove 3.diff from series to confuse mq
$ hg qfinish -a
revision 47dfa8501675 refers to unknown patches: imported_patch_pc
more complex state 'both known and unknown patches
$ echo hip >> base
$ hg qnew -f -d '1 0' -m 4 4.diff
$ echo hop >> base
$ hg qnew -f -d '1 0' -m 5 5.diff
$ echo > .hg/patches/series # remove 4.diff and 5.diff from series to confuse mq
$ echo hup >> base
$ hg qnew -f -d '1 0' -m 6 6.diff
$ echo pup > base
$ hg qfinish -a
warning: uncommitted changes in the working directory
revision 2b1c98802260 refers to unknown patches: 5.diff
revision 33a6861311c0 refers to unknown patches: 4.diff
$ cd ..