Mercurial > hg
view tests/test-ctxmanager.py @ 31467:08ecec297521
bdiff: use Python memory allocator in fixws
Python has its own memory allocation APIs. For allocations
<= 512 bytes, it allocates memory from arenas. This means that
average small allocations don't call the system allocator, which
makes them faster. Also, arena allocations cut down on memory
fragmentation, which can matter for performance in long-running
processes.
Another advantage of using the Python memory allocator is that
allocations are tracked by Python. This is a bigger deal in
Python 3, as modern versions of Python have some decent built-in
tools for examining memory usage, leaks, etc.
This patch converts a trivial malloc() + free() in the bdiff code
to use the Python allocator APIs. Since the object being
operated on is a line, chances are it will use an arena. So,
this could have a net positive impact on performance (although
I didn't measure it).
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Thu, 09 Mar 2017 11:54:25 -0800 |
parents | 441491aba8c3 |
children | 68c43a416585 |
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from __future__ import absolute_import import silenttestrunner import unittest from mercurial import util class contextmanager(object): def __init__(self, name, trace): self.name = name self.entered = False self.exited = False self.trace = trace def __enter__(self): self.entered = True self.trace(('enter', self.name)) return self def __exit__(self, exc_type, exc_val, exc_tb): self.exited = exc_type, exc_val, exc_tb self.trace(('exit', self.name)) def __repr__(self): return '<ctx %r>' % self.name class ctxerror(Exception): pass class raise_on_enter(contextmanager): def __enter__(self): self.trace(('raise', self.name)) raise ctxerror(self.name) class raise_on_exit(contextmanager): def __exit__(self, exc_type, exc_val, exc_tb): self.trace(('raise', self.name)) raise ctxerror(self.name) def ctxmgr(name, trace): return lambda: contextmanager(name, trace) class test_ctxmanager(unittest.TestCase): def test_basics(self): trace = [] addtrace = trace.append with util.ctxmanager(ctxmgr('a', addtrace), ctxmgr('b', addtrace)) as c: a, b = c.enter() c.atexit(addtrace, ('atexit', 'x')) c.atexit(addtrace, ('atexit', 'y')) self.assertEqual(trace, [('enter', 'a'), ('enter', 'b'), ('atexit', 'y'), ('atexit', 'x'), ('exit', 'b'), ('exit', 'a')]) def test_raise_on_enter(self): trace = [] addtrace = trace.append def go(): with util.ctxmanager(ctxmgr('a', addtrace), lambda: raise_on_enter('b', addtrace)) as c: c.enter() addtrace('unreachable') self.assertRaises(ctxerror, go) self.assertEqual(trace, [('enter', 'a'), ('raise', 'b'), ('exit', 'a')]) def test_raise_on_exit(self): trace = [] addtrace = trace.append def go(): with util.ctxmanager(ctxmgr('a', addtrace), lambda: raise_on_exit('b', addtrace)) as c: c.enter() addtrace('running') self.assertRaises(ctxerror, go) self.assertEqual(trace, [('enter', 'a'), ('enter', 'b'), 'running', ('raise', 'b'), ('exit', 'a')]) if __name__ == '__main__': silenttestrunner.main(__name__)