Mercurial > hg
view mercurial/py3kcompat.py @ 27430:e240e914d226 stable
revlog: seek to end of file before writing (issue4943)
Revlogs were recently refactored to open file handles in "a+" and use a
persistent file handle for reading and writing. This drastically
reduced the number of file handles being opened.
Unfortunately, it appears that some versions of Solaris lose the file
offset when performing a write after the handle has been seeked.
The simplest workaround is to seek to EOF on files opened in a+ mode
before writing to them, which is what this patch does.
Ideally, this code would exist in the vfs layer. However, this would
require creating a proxy class for file objects in order to provide a
custom implementation of write(). This would add overhead. Since
revlogs are the only files we open in a+ mode, the one-off workaround
in revlog.py should be sufficient.
This patch appears to have little to no impact on performance on my
Linux machine.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Thu, 17 Dec 2015 17:16:02 -0800 |
parents | a7a9d84f5e4a |
children | 5bfd01a3c2a9 |
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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. import builtins from numbers import 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()