dirstate-tree: optimize HashMap lookups with raw_entry_mut
This switches to using `HashMap` from the hashbrown crate,
in order to use its `raw_entry_mut` method.
The standard library’s `HashMap` is also based on this same crate,
but `raw_entry_mut` is not yet stable there:
https://github.com/rust-lang/rust/issues/56167
Using version 0.9 because 0.10 is yanked and 0.11 requires Rust 1.49
This replaces in `DirstateMap::get_or_insert_node` a call to
`HashMap<K, V>::entry` with `K = WithBasename<Cow<'on_disk, HgPath>>`.
`entry` takes and consumes an "owned" `key: K` parameter, in case a new entry
ends up inserted. This key is converted by `to_cow` from a value that borrows
the `'path` lifetime.
When this function is called by `Dirstate::new_v1`, `'path` is in fact
the same as `'on_disk` so `to_cow` can return an owned key that contains
`Cow::Borrowed`.
For other callers, `to_cow` needs to create a `Cow::Owned` and thus make
a costly heap memory allocation. This is wasteful if this key was already
present in the map. Even when inserting a new node this is typically the case
for its ancestor nodes (assuming most directories have numerous descendants).
Differential Revision: https://phab.mercurial-scm.org/D12317
#!/usr/bin/env python3
#
# mercurial - scalable distributed SCM
#
# Copyright 2005-2007 Olivia Mackall <olivia@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
import os
import sys
libdir = '@LIBDIR@'
if libdir != '@' 'LIBDIR' '@':
if not os.path.isabs(libdir):
libdir = os.path.join(
os.path.dirname(os.path.realpath(__file__)), libdir
)
libdir = os.path.abspath(libdir)
sys.path.insert(0, libdir)
# Make `pip install --user ...` packages available to the official Windows
# build. Most py2 packaging installs directly into the system python
# environment, so no changes are necessary for other platforms. The Windows
# py2 package uses py2exe, which lacks a `site` module. Hardcode it according
# to the documentation.
if getattr(sys, 'frozen', None) == 'console_exe':
vi = sys.version_info
appdata = os.environ.get('APPDATA')
if appdata:
sys.path.append(
os.path.join(
appdata,
'Python',
'Python%d%d' % (vi[0], vi[1]),
'site-packages',
)
)
from hgdemandimport import tracing
with tracing.log('hg script'):
# enable importing on demand to reduce startup time
try:
if sys.version_info[0] < 3 or sys.version_info >= (3, 6):
import hgdemandimport
hgdemandimport.enable()
except ImportError:
sys.stderr.write(
"abort: couldn't find mercurial libraries in [%s]\n"
% ' '.join(sys.path)
)
sys.stderr.write("(check your install and PYTHONPATH)\n")
sys.exit(-1)
from mercurial import dispatch
dispatch.run()