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
# Minimal support for git commands on an hg repository
#
# Copyright 2005, 2006 Chris Mason <mason@suse.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
'''browse the repository in a graphical way
The hgk extension allows browsing the history of a repository in a
graphical way. It requires Tcl/Tk version 8.4 or later. (Tcl/Tk is not
distributed with Mercurial.)
hgk consists of two parts: a Tcl script that does the displaying and
querying of information, and an extension to Mercurial named hgk.py,
which provides hooks for hgk to get information. hgk can be found in
the contrib directory, and the extension is shipped in the hgext
repository, and needs to be enabled.
The :hg:`view` command will launch the hgk Tcl script. For this command
to work, hgk must be in your search path. Alternately, you can specify
the path to hgk in your configuration file::
[hgk]
path = /location/of/hgk
hgk can make use of the extdiff extension to visualize revisions.
Assuming you had already configured extdiff vdiff command, just add::
[hgk]
vdiff=vdiff
Revisions context menu will now display additional entries to fire
vdiff on hovered and selected revisions.
'''
from __future__ import absolute_import
import os
from mercurial.i18n import _
from mercurial.node import (
nullid,
nullrev,
short,
)
from mercurial import (
commands,
obsolete,
patch,
pycompat,
registrar,
scmutil,
)
cmdtable = {}
command = registrar.command(cmdtable)
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = b'ships-with-hg-core'
configtable = {}
configitem = registrar.configitem(configtable)
configitem(
b'hgk', b'path', default=b'hgk',
)
@command(
b'debug-diff-tree',
[
(b'p', b'patch', None, _(b'generate patch')),
(b'r', b'recursive', None, _(b'recursive')),
(b'P', b'pretty', None, _(b'pretty')),
(b's', b'stdin', None, _(b'stdin')),
(b'C', b'copy', None, _(b'detect copies')),
(b'S', b'search', b"", _(b'search')),
],
b'[OPTION]... NODE1 NODE2 [FILE]...',
inferrepo=True,
)
def difftree(ui, repo, node1=None, node2=None, *files, **opts):
"""diff trees from two commits"""
def __difftree(repo, node1, node2, files=None):
assert node2 is not None
if files is None:
files = []
mmap = repo[node1].manifest()
mmap2 = repo[node2].manifest()
m = scmutil.match(repo[node1], files)
st = repo.status(node1, node2, m)
empty = short(nullid)
for f in st.modified:
# TODO get file permissions
ui.writenoi18n(
b":100664 100664 %s %s M\t%s\t%s\n"
% (short(mmap[f]), short(mmap2[f]), f, f)
)
for f in st.added:
ui.writenoi18n(
b":000000 100664 %s %s N\t%s\t%s\n"
% (empty, short(mmap2[f]), f, f)
)
for f in st.removed:
ui.writenoi18n(
b":100664 000000 %s %s D\t%s\t%s\n"
% (short(mmap[f]), empty, f, f)
)
##
while True:
if opts['stdin']:
line = ui.fin.readline()
if not line:
break
line = line.rstrip(pycompat.oslinesep).split(b' ')
node1 = line[0]
if len(line) > 1:
node2 = line[1]
else:
node2 = None
node1 = repo.lookup(node1)
if node2:
node2 = repo.lookup(node2)
else:
node2 = node1
node1 = repo.changelog.parents(node1)[0]
if opts['patch']:
if opts['pretty']:
catcommit(ui, repo, node2, b"")
m = scmutil.match(repo[node1], files)
diffopts = patch.difffeatureopts(ui)
diffopts.git = True
chunks = patch.diff(repo, node1, node2, match=m, opts=diffopts)
for chunk in chunks:
ui.write(chunk)
else:
__difftree(repo, node1, node2, files=files)
if not opts['stdin']:
break
def catcommit(ui, repo, n, prefix, ctx=None):
nlprefix = b'\n' + prefix
if ctx is None:
ctx = repo[n]
# use ctx.node() instead ??
ui.write((b"tree %s\n" % short(ctx.changeset()[0])))
for p in ctx.parents():
ui.write((b"parent %s\n" % p))
date = ctx.date()
description = ctx.description().replace(b"\0", b"")
ui.write((b"author %s %d %d\n" % (ctx.user(), int(date[0]), date[1])))
if b'committer' in ctx.extra():
ui.write((b"committer %s\n" % ctx.extra()[b'committer']))
ui.write((b"revision %d\n" % ctx.rev()))
ui.write((b"branch %s\n" % ctx.branch()))
if obsolete.isenabled(repo, obsolete.createmarkersopt):
if ctx.obsolete():
ui.writenoi18n(b"obsolete\n")
ui.write((b"phase %s\n\n" % ctx.phasestr()))
if prefix != b"":
ui.write(
b"%s%s\n" % (prefix, description.replace(b'\n', nlprefix).strip())
)
else:
ui.write(description + b"\n")
if prefix:
ui.write(b'\0')
@command(b'debug-merge-base', [], _(b'REV REV'))
def base(ui, repo, node1, node2):
"""output common ancestor information"""
node1 = repo.lookup(node1)
node2 = repo.lookup(node2)
n = repo.changelog.ancestor(node1, node2)
ui.write(short(n) + b"\n")
@command(
b'debug-cat-file',
[(b's', b'stdin', None, _(b'stdin'))],
_(b'[OPTION]... TYPE FILE'),
inferrepo=True,
)
def catfile(ui, repo, type=None, r=None, **opts):
"""cat a specific revision"""
# in stdin mode, every line except the commit is prefixed with two
# spaces. This way the our caller can find the commit without magic
# strings
#
prefix = b""
if opts['stdin']:
line = ui.fin.readline()
if not line:
return
(type, r) = line.rstrip(pycompat.oslinesep).split(b' ')
prefix = b" "
else:
if not type or not r:
ui.warn(_(b"cat-file: type or revision not supplied\n"))
commands.help_(ui, b'cat-file')
while r:
if type != b"commit":
ui.warn(_(b"aborting hg cat-file only understands commits\n"))
return 1
n = repo.lookup(r)
catcommit(ui, repo, n, prefix)
if opts['stdin']:
line = ui.fin.readline()
if not line:
break
(type, r) = line.rstrip(pycompat.oslinesep).split(b' ')
else:
break
# git rev-tree is a confusing thing. You can supply a number of
# commit sha1s on the command line, and it walks the commit history
# telling you which commits are reachable from the supplied ones via
# a bitmask based on arg position.
# you can specify a commit to stop at by starting the sha1 with ^
def revtree(ui, args, repo, full=b"tree", maxnr=0, parents=False):
def chlogwalk():
count = len(repo)
i = count
l = [0] * 100
chunk = 100
while True:
if chunk > i:
chunk = i
i = 0
else:
i -= chunk
for x in pycompat.xrange(chunk):
if i + x >= count:
l[chunk - x :] = [0] * (chunk - x)
break
if full is not None:
if (i + x) in repo:
l[x] = repo[i + x]
l[x].changeset() # force reading
else:
if (i + x) in repo:
l[x] = 1
for x in pycompat.xrange(chunk - 1, -1, -1):
if l[x] != 0:
yield (i + x, full is not None and l[x] or None)
if i == 0:
break
# calculate and return the reachability bitmask for sha
def is_reachable(ar, reachable, sha):
if len(ar) == 0:
return 1
mask = 0
for i in pycompat.xrange(len(ar)):
if sha in reachable[i]:
mask |= 1 << i
return mask
reachable = []
stop_sha1 = []
want_sha1 = []
count = 0
# figure out which commits they are asking for and which ones they
# want us to stop on
for i, arg in enumerate(args):
if arg.startswith(b'^'):
s = repo.lookup(arg[1:])
stop_sha1.append(s)
want_sha1.append(s)
elif arg != b'HEAD':
want_sha1.append(repo.lookup(arg))
# calculate the graph for the supplied commits
for i, n in enumerate(want_sha1):
reachable.append(set())
visit = [n]
reachable[i].add(n)
while visit:
n = visit.pop(0)
if n in stop_sha1:
continue
for p in repo.changelog.parents(n):
if p not in reachable[i]:
reachable[i].add(p)
visit.append(p)
if p in stop_sha1:
continue
# walk the repository looking for commits that are in our
# reachability graph
for i, ctx in chlogwalk():
if i not in repo:
continue
n = repo.changelog.node(i)
mask = is_reachable(want_sha1, reachable, n)
if mask:
parentstr = b""
if parents:
pp = repo.changelog.parents(n)
if pp[0] != nullid:
parentstr += b" " + short(pp[0])
if pp[1] != nullid:
parentstr += b" " + short(pp[1])
if not full:
ui.write(b"%s%s\n" % (short(n), parentstr))
elif full == b"commit":
ui.write(b"%s%s\n" % (short(n), parentstr))
catcommit(ui, repo, n, b' ', ctx)
else:
(p1, p2) = repo.changelog.parents(n)
(h, h1, h2) = map(short, (n, p1, p2))
(i1, i2) = map(repo.changelog.rev, (p1, p2))
date = ctx.date()[0]
ui.write(b"%s %s:%s" % (date, h, mask))
mask = is_reachable(want_sha1, reachable, p1)
if i1 != nullrev and mask > 0:
ui.write(b"%s:%s " % (h1, mask)),
mask = is_reachable(want_sha1, reachable, p2)
if i2 != nullrev and mask > 0:
ui.write(b"%s:%s " % (h2, mask))
ui.write(b"\n")
if maxnr and count >= maxnr:
break
count += 1
# git rev-list tries to order things by date, and has the ability to stop
# at a given commit without walking the whole repo. TODO add the stop
# parameter
@command(
b'debug-rev-list',
[
(b'H', b'header', None, _(b'header')),
(b't', b'topo-order', None, _(b'topo-order')),
(b'p', b'parents', None, _(b'parents')),
(b'n', b'max-count', 0, _(b'max-count')),
],
b'[OPTION]... REV...',
)
def revlist(ui, repo, *revs, **opts):
"""print revisions"""
if opts[b'header']:
full = b"commit"
else:
full = None
copy = [x for x in revs]
revtree(ui, copy, repo, full, opts['max_count'], opts[r'parents'])
@command(
b'view',
[(b'l', b'limit', b'', _(b'limit number of changes displayed'), _(b'NUM'))],
_(b'[-l LIMIT] [REVRANGE]'),
helpcategory=command.CATEGORY_CHANGE_NAVIGATION,
)
def view(ui, repo, *etc, **opts):
"""start interactive history viewer"""
opts = pycompat.byteskwargs(opts)
os.chdir(repo.root)
optstr = b' '.join(
[b'--%s %s' % (k, v) for k, v in pycompat.iteritems(opts) if v]
)
if repo.filtername is None:
optstr += b'--hidden'
cmd = ui.config(b"hgk", b"path") + b" %s %s" % (optstr, b" ".join(etc))
ui.debug(b"running %s\n" % cmd)
ui.system(cmd, blockedtag=b'hgk_view')