| Submitter | via Mercurial-devel |
|---|---|
| Date | March 14, 2017, 9:55 p.m. |
| Message ID | <375345ceabc9f14e780d.1489528539@martinvonz.mtv.corp.google.com> |
| Download | mbox | patch |
| Permalink | /patch/19342/ |
| State | Changes Requested |
| Headers | show |
Comments
On Tue, Mar 14, 2017 at 2:55 PM, Martin von Zweigbergk via Mercurial-devel < mercurial-devel@mercurial-scm.org> wrote: > # HG changeset patch > # User Martin von Zweigbergk <martinvonz@google.com> > # Date 1489528461 25200 > # Tue Mar 14 14:54:21 2017 -0700 > # Node ID 375345ceabc9f14e780d8a8efd00ed32ffc6396c > # Parent 3d3109339b57341b333c1112beb41dd281fa944a > py3: make py3 compat.iterbytestr simpler and faster > > I don't have a py3.5 installed, so I have not run tests on this, but > maybe it works? > > $ python3 -m timeit -s 's=b"a"*100' 'for x in iter(s[i:i + 1] for i in > range(len(s))): pass' > 100000 loops, best of 3: 10.3 usec per loop > > $ python3 -m timeit -s 's=b"a"*100' 'for x in map(chr, s): pass' > 100000 loops, best of 3: 6.16 usec per loop > > (I picked the best "before" time and worst "after" time out of a few runs.) > > diff -r 3d3109339b57 -r 375345ceabc9 mercurial/pycompat.py > --- a/mercurial/pycompat.py Mon Mar 13 11:19:24 2017 -0700 > +++ b/mercurial/pycompat.py Tue Mar 14 14:54:21 2017 -0700 > @@ -78,7 +78,7 @@ > > def iterbytestr(s): > """Iterate bytes as if it were a str object of Python 2""" > - return iter(s[i:i + 1] for i in range(len(s))) > + return map(chr, s) > > The change to map() makes sense to me and I can understand how it would be faster. However, chr returns a Python 3 str instead of bytes, which is wrong. Try the following: return map(struct.Struct('>B').pack, s) > def sysstr(s): > """Return a keyword str to be passed to Python functions such as >
On Tue, Mar 14, 2017 at 3:19 PM, Gregory Szorc <gregory.szorc@gmail.com> wrote: > On Tue, Mar 14, 2017 at 2:55 PM, Martin von Zweigbergk via Mercurial-devel > <mercurial-devel@mercurial-scm.org> wrote: >> >> # HG changeset patch >> # User Martin von Zweigbergk <martinvonz@google.com> >> # Date 1489528461 25200 >> # Tue Mar 14 14:54:21 2017 -0700 >> # Node ID 375345ceabc9f14e780d8a8efd00ed32ffc6396c >> # Parent 3d3109339b57341b333c1112beb41dd281fa944a >> py3: make py3 compat.iterbytestr simpler and faster >> >> I don't have a py3.5 installed, so I have not run tests on this, but >> maybe it works? >> >> $ python3 -m timeit -s 's=b"a"*100' 'for x in iter(s[i:i + 1] for i in >> range(len(s))): pass' >> 100000 loops, best of 3: 10.3 usec per loop >> >> $ python3 -m timeit -s 's=b"a"*100' 'for x in map(chr, s): pass' >> 100000 loops, best of 3: 6.16 usec per loop >> >> (I picked the best "before" time and worst "after" time out of a few >> runs.) >> >> diff -r 3d3109339b57 -r 375345ceabc9 mercurial/pycompat.py >> --- a/mercurial/pycompat.py Mon Mar 13 11:19:24 2017 -0700 >> +++ b/mercurial/pycompat.py Tue Mar 14 14:54:21 2017 -0700 >> @@ -78,7 +78,7 @@ >> >> def iterbytestr(s): >> """Iterate bytes as if it were a str object of Python 2""" >> - return iter(s[i:i + 1] for i in range(len(s))) >> + return map(chr, s) >> > > The change to map() makes sense to me and I can understand how it would be > faster. However, chr returns a Python 3 str instead of bytes, which is > wrong. Try the following: > > return map(struct.Struct('>B').pack, s) Ah. That's still noticeably faster: ~7us. I'll send a v2. Thanks. > >> >> def sysstr(s): >> """Return a keyword str to be passed to Python functions such as > >
Patch
diff -r 3d3109339b57 -r 375345ceabc9 mercurial/pycompat.py --- a/mercurial/pycompat.py Mon Mar 13 11:19:24 2017 -0700 +++ b/mercurial/pycompat.py Tue Mar 14 14:54:21 2017 -0700 @@ -78,7 +78,7 @@ def iterbytestr(s): """Iterate bytes as if it were a str object of Python 2""" - return iter(s[i:i + 1] for i in range(len(s))) + return map(chr, s) def sysstr(s): """Return a keyword str to be passed to Python functions such as