Mercurial > hg
view mercurial/py3kcompat.py @ 27895:2d6a89e79b48
scmutil: support background file closing
Closing files that have been appended to is relatively slow on
Windows/NTFS. This makes several Mercurial operations slower on
Windows.
The workaround to this issue is conceptually simple: use multiple
threads for I/O. Unfortunately, Python doesn't scale well to multiple
threads because of the GIL. And, refactoring our code to use threads
everywhere would be a huge undertaking. So, we decide to tackle this
problem by starting small: establishing a thread pool for closing
files.
This patch establishes a mechanism for closing file handles on separate
threads. The coordinator object is basically a queue of file handles to
operate on and a thread pool consuming from the queue.
When files are opened through the VFS layer, the caller can specify
that delay closing is allowed.
A proxy class for file handles has been added. We must use a proxy
because it isn't possible to modify __class__ on built-in types. This
adds some overhead. But as future patches will show, this overhead
is cancelled out by the benefit of closing file handles on background
threads.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Thu, 14 Jan 2016 13:34:59 -0800 |
parents | 5bfd01a3c2a9 |
children |
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# py3kcompat.py - compatibility definitions for running hg in py3k # # Copyright 2010 Renato Cunha <renatoc@gmail.com> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import import builtins import numbers Number = numbers.Number def bytesformatter(format, args): '''Custom implementation of a formatter for bytestrings. This function currently relies on the string formatter to do the formatting and always returns bytes objects. >>> bytesformatter(20, 10) 0 >>> bytesformatter('unicode %s, %s!', ('string', 'foo')) b'unicode string, foo!' >>> bytesformatter(b'test %s', 'me') b'test me' >>> bytesformatter('test %s', 'me') b'test me' >>> bytesformatter(b'test %s', b'me') b'test me' >>> bytesformatter('test %s', b'me') b'test me' >>> bytesformatter('test %d: %s', (1, b'result')) b'test 1: result' ''' # The current implementation just converts from bytes to unicode, do # what's needed and then convert the results back to bytes. # Another alternative is to use the Python C API implementation. if isinstance(format, Number): # If the fixer erroneously passes a number remainder operation to # bytesformatter, we just return the correct operation return format % args if isinstance(format, bytes): format = format.decode('utf-8', 'surrogateescape') if isinstance(args, bytes): args = args.decode('utf-8', 'surrogateescape') if isinstance(args, tuple): newargs = [] for arg in args: if isinstance(arg, bytes): arg = arg.decode('utf-8', 'surrogateescape') newargs.append(arg) args = tuple(newargs) ret = format % args return ret.encode('utf-8', 'surrogateescape') builtins.bytesformatter = bytesformatter origord = builtins.ord def fakeord(char): if isinstance(char, int): return char return origord(char) builtins.ord = fakeord if __name__ == '__main__': import doctest doctest.testmod()