PERF: leverage tzlocal package to provide 2000x speedup for dateutil.tz.tzlocal operations

LICENSES/TZLOCAL_LICENSE

@@ -0,0 +1,19 @@
+Copyright 2011-2017 Lennart Regebro
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

asv_bench/benchmarks/timeseries.py

@@ -62,7 +62,8 @@ def time_to_pydatetime(self, index_type):
 
 class TzLocalize(object):
 
-    params = [None, 'US/Eastern', 'UTC', dateutil.tz.tzutc()]
+    params = [None, 'US/Eastern', 'UTC', dateutil.tz.tzutc(),
+              dateutil.tz.tzlocal()]
     param_names = 'tz'
 
     def setup(self, tz):
@@ -394,7 +395,8 @@ def time_dup_string_tzoffset_dates(self, cache):
 
 class DatetimeAccessor(object):
 
-    params = [None, 'US/Eastern', 'UTC', dateutil.tz.tzutc()]
+    params = [None, 'US/Eastern', 'UTC', dateutil.tz.tzutc(),
+              dateutil.tz.tzlocal()]
     param_names = 'tz'
 
     def setup(self, tz):

pandas/_libs/src/tzlocal/__init__.py

@@ -0,0 +1,5 @@
+import sys
+if sys.platform == 'win32':
+    from pandas._libs.src.tzlocal.win32 import get_localzone, reload_localzone
+else:
+    from pandas._libs.src.tzlocal.unix import get_localzone, reload_localzone

pandas/_libs/src/tzlocal/unix.py

@@ -0,0 +1,164 @@
+import os
+import pytz
+import re
+
+from pandas._libs.src.tzlocal import utils
+
+_cache_tz = None
+
+
+def _tz_from_env(tzenv):
+    if tzenv[0] == ':':
+        tzenv = tzenv[1:]
+
+    # TZ specifies a file
+    if os.path.exists(tzenv):
+        with open(tzenv, 'rb') as tzfile:
+            return pytz.tzfile.build_tzinfo('local', tzfile)
+
+    # TZ specifies a zoneinfo zone.
+    try:
+        tz = pytz.timezone(tzenv)
+        # That worked, so we return this:
+        return tz
+    except pytz.UnknownTimeZoneError:
+        raise pytz.UnknownTimeZoneError(
+            "tzlocal() does not support non-zoneinfo timezones like %s. \n"
+            "Please use a timezone in the form of Continent/City")
+
+
+def _try_tz_from_env():
+    tzenv = os.environ.get('TZ')
+    if tzenv:
+        try:
+            return _tz_from_env(tzenv)
+        except pytz.UnknownTimeZoneError:
+            pass
+
+
+def _get_localzone(_root='/'):
+    """Tries to find the local timezone configuration.
+
+    This method prefers finding the timezone name and passing that to pytz,
+    over passing in the localtime file, as in the later case the zoneinfo
+    name is unknown.
+
+    The parameter _root makes the function look for files like /etc/localtime
+    beneath the _root directory. This is primarily used by the tests.
+    In normal usage you call the function without parameters."""
+
+    tzenv = _try_tz_from_env()
+    if tzenv:
+        return tzenv
+
+    # Now look for distribution specific configuration files
+    # that contain the timezone name.
+    for configfile in ('etc/timezone', 'var/db/zoneinfo'):
+        tzpath = os.path.join(_root, configfile)
+        try:
+            with open(tzpath, 'rb') as tzfile:
+                data = tzfile.read()
+
+                # Issue #3 was that /etc/timezone was a zoneinfo file.
+                # That's a misconfiguration, but we need to handle it gracefully:
+                if data[:5] == b'TZif2':
+                    continue
+
+                etctz = data.strip().decode()
+                if not etctz:
+                    # Empty file, skip
+                    continue
+                for etctz in data.decode().splitlines():
+                    # Get rid of host definitions and comments:
+                    if ' ' in etctz:
+                        etctz, dummy = etctz.split(' ', 1)
+                    if '#' in etctz:
+                        etctz, dummy = etctz.split('#', 1)
+                    if not etctz:
+                        continue
+                    return pytz.timezone(etctz.replace(' ', '_'))
+        except IOError:
+            # File doesn't exist or is a directory
+            continue
+
+    # CentOS has a ZONE setting in /etc/sysconfig/clock,
+    # OpenSUSE has a TIMEZONE setting in /etc/sysconfig/clock and
+    # Gentoo has a TIMEZONE setting in /etc/conf.d/clock
+    # We look through these files for a timezone:
+
+    zone_re = re.compile(r'\s*ZONE\s*=\s*\"')
+    timezone_re = re.compile(r'\s*TIMEZONE\s*=\s*\"')
+    end_re = re.compile('\"')
+
+    for filename in ('etc/sysconfig/clock', 'etc/conf.d/clock'):
+        tzpath = os.path.join(_root, filename)
+        try:
+            with open(tzpath, 'rt') as tzfile:
+                data = tzfile.readlines()
+
+            for line in data:
+                # Look for the ZONE= setting.
+                match = zone_re.match(line)
+                if match is None:
+                    # No ZONE= setting. Look for the TIMEZONE= setting.
+                    match = timezone_re.match(line)
+                if match is not None:
+                    # Some setting existed
+                    line = line[match.end():]
+                    etctz = line[:end_re.search(line).start()]
+
+                    # We found a timezone
+                    return pytz.timezone(etctz.replace(' ', '_'))
+        except IOError:
+            # File doesn't exist or is a directory
+            continue
+
+    # systemd distributions use symlinks that include the zone name,
+    # see manpage of localtime(5) and timedatectl(1)
+    tzpath = os.path.join(_root, 'etc/localtime')
+    if os.path.exists(tzpath) and os.path.islink(tzpath):
+        tzpath = os.path.realpath(tzpath)
+        start = tzpath.find("/")+1
+        while start is not 0:
+            tzpath = tzpath[start:]
+            try:
+                return pytz.timezone(tzpath)
+            except pytz.UnknownTimeZoneError:
+                pass
+            start = tzpath.find("/")+1
+
+    # Are we under Termux on Android? It's not officially supported, because
+    # there is no reasonable way to run tests for this, but let's make an effort.
+    if os.path.exists('/system/bin/getprop'):
+        import subprocess
+        androidtz = subprocess.check_output(['getprop', 'persist.sys.timezone'])
+        return pytz.timezone(androidtz.strip().decode())
+
+    # No explicit setting existed. Use localtime
+    for filename in ('etc/localtime', 'usr/local/etc/localtime'):
+        tzpath = os.path.join(_root, filename)
+
+        if not os.path.exists(tzpath):
+            continue
+        with open(tzpath, 'rb') as tzfile:
+            return pytz.tzfile.build_tzinfo('local', tzfile)
+
+    raise pytz.UnknownTimeZoneError('Can not find any timezone configuration')
+
+
+def get_localzone():
+    """Get the computers configured local timezone, if any."""
+    global _cache_tz
+    if _cache_tz is None:
+        _cache_tz = _get_localzone()
+
+    utils.assert_tz_offset(_cache_tz)
+    return _cache_tz
+
+
+def reload_localzone():
+    """Reload the cached localzone. You need to call this if the timezone has changed."""
+    global _cache_tz
+    _cache_tz = _get_localzone()
+    utils.assert_tz_offset(_cache_tz)
+    return _cache_tz

pandas/_libs/src/tzlocal/utils.py

@@ -0,0 +1,38 @@
+# -*- coding: utf-8 -*-
+import datetime
+
+
+def get_system_offset():
+    """Get system's timezone offset using built-in library time.
+
+    For the Timezone constants (altzone, daylight, timezone, and tzname), the
+    value is determined by the timezone rules in effect at module load time or
+    the last time tzset() is called and may be incorrect for times in the past.
+
+    To keep compatibility with Windows, we're always importing time module here.
+    """
+    import time
+    if time.daylight and time.localtime().tm_isdst > 0:
+        return -time.altzone
+    else:
+        return -time.timezone
+
+
+def get_tz_offset(tz):
+    """Get timezone's offset using built-in function datetime.utcoffset()."""
+    return int(datetime.datetime.now(tz).utcoffset().total_seconds())
+
+
+def assert_tz_offset(tz):
+    """Assert that system's timezone offset equals to the timezone offset found.
+
+    If they don't match, we probably have a misconfiguration, for example, an
+    incorrect timezone set in /etc/timezone file in systemd distributions."""
+    tz_offset = get_tz_offset(tz)
+    system_offset = get_system_offset()
+    if tz_offset != system_offset:
+        msg = ('Timezone offset does not match system offset: {0} != {1}. '
+               'Please, check your config files.').format(
+                   tz_offset, system_offset
+               )
+        raise ValueError(msg)

pandas/_libs/src/tzlocal/win32.py

@@ -0,0 +1,104 @@
+try:
+    import _winreg as winreg
+except ImportError:
+    import winreg
+
+import pytz
+
+from pandas._libs.src.tzlocal.windows_tz import win_tz
+from pandas._libs.src.tzlocal import utils
+
+_cache_tz = None
+
+
+def valuestodict(key):
+    """Convert a registry key's values to a dictionary."""
+    dict = {}
+    size = winreg.QueryInfoKey(key)[1]
+    for i in range(size):
+        data = winreg.EnumValue(key, i)
+        dict[data[0]] = data[1]
+    return dict
+
+
+def get_localzone_name():
+    # Windows is special. It has unique time zone names (in several
+    # meanings of the word) available, but unfortunately, they can be
+    # translated to the language of the operating system, so we need to
+    # do a backwards lookup, by going through all time zones and see which
+    # one matches.
+    handle = winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE)
+
+    TZLOCALKEYNAME = r"SYSTEM\CurrentControlSet\Control\TimeZoneInformation"
+    localtz = winreg.OpenKey(handle, TZLOCALKEYNAME)
+    keyvalues = valuestodict(localtz)
+    localtz.Close()
+
+    if 'TimeZoneKeyName' in keyvalues:
+        # Windows 7 (and Vista?)
+
+        # For some reason this returns a string with loads of NUL bytes at
+        # least on some systems. I don't know if this is a bug somewhere, I
+        # just work around it.
+        tzkeyname = keyvalues['TimeZoneKeyName'].split('\x00', 1)[0]
+    else:
+        # Windows 2000 or XP
+
+        # This is the localized name:
+        tzwin = keyvalues['StandardName']
+
+        # Open the list of timezones to look up the real name:
+        TZKEYNAME = r"SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones"
+        tzkey = winreg.OpenKey(handle, TZKEYNAME)
+
+        # Now, match this value to Time Zone information
+        tzkeyname = None
+        for i in range(winreg.QueryInfoKey(tzkey)[0]):
+            subkey = winreg.EnumKey(tzkey, i)
+            sub = winreg.OpenKey(tzkey, subkey)
+            data = valuestodict(sub)
+            sub.Close()
+            try:
+                if data['Std'] == tzwin:
+                    tzkeyname = subkey
+                    break
+            except KeyError:
+                # This timezone didn't have proper configuration.
+                # Ignore it.
+                pass
+
+        tzkey.Close()
+        handle.Close()
+
+    if tzkeyname is None:
+        raise LookupError('Can not find Windows timezone configuration')
+
+    timezone = win_tz.get(tzkeyname)
+    if timezone is None:
+        # Nope, that didn't work. Try adding "Standard Time",
+        # it seems to work a lot of times:
+        timezone = win_tz.get(tzkeyname + " Standard Time")
+
+    # Return what we have.
+    if timezone is None:
+        raise pytz.UnknownTimeZoneError('Can not find timezone ' + tzkeyname)
+
+    return timezone
+
+
+def get_localzone():
+    """Returns the zoneinfo-based tzinfo object that matches the Windows-configured timezone."""
+    global _cache_tz
+    if _cache_tz is None:
+        _cache_tz = pytz.timezone(get_localzone_name())
+
+    utils.assert_tz_offset(_cache_tz)
+    return _cache_tz
+
+
+def reload_localzone():
+    """Reload the cached localzone. You need to call this if the timezone has changed."""
+    global _cache_tz
+    _cache_tz = pytz.timezone(get_localzone_name())
+    utils.assert_tz_offset(_cache_tz)
+    return _cache_tz