mercurial/utils/dateutil.py

util: allow lrucachedict to track cost of entries

Currently, lrucachedict allows tracking of arbitrary items with the
only limit being the total number of items in the cache.

Caches can be a lot more useful when they are bound by the size
of the items in them rather than the number of elements in the
cache.

In preparation for teaching lrucachedict to enforce a max size of
cached items, we teach lrucachedict to optionally associate a numeric
cost value with each node.

We purposefully let the caller define their own cost for nodes.

This does introduce some overhead. Most of it comes from __setitem__,
since that function now calls into insert(), thus introducing Python
function call overhead.

$ hg perflrucachedict --size 4 --gets 1000000 --sets 1000000 --mixed 1000000
! gets
! wall 0.599552 comb 0.600000 user 0.600000 sys 0.000000 (best of 17)
! wall 0.614643 comb 0.610000 user 0.610000 sys 0.000000 (best of 17)
! inserts
! <not available>
! wall 0.655817 comb 0.650000 user 0.650000 sys 0.000000 (best of 16)
! sets
! wall 0.540448 comb 0.540000 user 0.540000 sys 0.000000 (best of 18)
! wall 0.805644 comb 0.810000 user 0.810000 sys 0.000000 (best of 13)
! mixed
! wall 0.651556 comb 0.660000 user 0.660000 sys 0.000000 (best of 15)
! wall 0.781357 comb 0.780000 user 0.780000 sys 0.000000 (best of 13)

$ hg perflrucachedict --size 1000 --gets 1000000 --sets 1000000 --mixed 1000000
! gets
! wall 0.621014 comb 0.620000 user 0.620000 sys 0.000000 (best of 16)
! wall 0.615146 comb 0.620000 user 0.620000 sys 0.000000 (best of 17)
! inserts
! <not available>
! wall 0.698115 comb 0.700000 user 0.700000 sys 0.000000 (best of 15)
! sets
! wall 0.560247 comb 0.560000 user 0.560000 sys 0.000000 (best of 18)
! wall 0.832495 comb 0.830000 user 0.830000 sys 0.000000 (best of 12)
! mixed
! wall 0.686172 comb 0.680000 user 0.680000 sys 0.000000 (best of 15)
! wall 0.841359 comb 0.840000 user 0.840000 sys 0.000000 (best of 12)

We're still under 1us per insert, which seems like reasonable
performance for a cache.

If we comment out updating of self.totalcost during insert(),
performance of insert() is identical to __setitem__ before. However,
I don't want to make total cost evaluation lazy because it has
significant performance implications for when we need to evaluate the
total cost at mutation time (it requires a cache traversal, which could
be expensive for large caches).

Differential Revision: https://phab.mercurial-scm.org/D4502

# util.py - Mercurial utility functions relative to dates
#
#  Copyright 2018 Boris Feld <[e-mail]>
#
# 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, print_function

import calendar
import datetime
import time

from ..i18n import _
from .. import (
    encoding,
    error,
    pycompat,
)

# used by parsedate
defaultdateformats = (
    '%Y-%m-%dT%H:%M:%S', # the 'real' ISO8601
    '%Y-%m-%dT%H:%M',    #   without seconds
    '%Y-%m-%dT%H%M%S',   # another awful but legal variant without :
    '%Y-%m-%dT%H%M',     #   without seconds
    '%Y-%m-%d %H:%M:%S', # our common legal variant
    '%Y-%m-%d %H:%M',    #   without seconds
    '%Y-%m-%d %H%M%S',   # without :
    '%Y-%m-%d %H%M',     #   without seconds
    '%Y-%m-%d %I:%M:%S%p',
    '%Y-%m-%d %H:%M',
    '%Y-%m-%d %I:%M%p',
    '%Y-%m-%d',
    '%m-%d',
    '%m/%d',
    '%m/%d/%y',
    '%m/%d/%Y',
    '%a %b %d %H:%M:%S %Y',
    '%a %b %d %I:%M:%S%p %Y',
    '%a, %d %b %Y %H:%M:%S',        #  GNU coreutils "/bin/date --rfc-2822"
    '%b %d %H:%M:%S %Y',
    '%b %d %I:%M:%S%p %Y',
    '%b %d %H:%M:%S',
    '%b %d %I:%M:%S%p',
    '%b %d %H:%M',
    '%b %d %I:%M%p',
    '%b %d %Y',
    '%b %d',
    '%H:%M:%S',
    '%I:%M:%S%p',
    '%H:%M',
    '%I:%M%p',
)

extendeddateformats = defaultdateformats + (
    "%Y",
    "%Y-%m",
    "%b",
    "%b %Y",
)

def makedate(timestamp=None):
    '''Return a unix timestamp (or the current time) as a (unixtime,
    offset) tuple based off the local timezone.'''
    if timestamp is None:
        timestamp = time.time()
    if timestamp < 0:
        hint = _("check your clock")
        raise error.Abort(_("negative timestamp: %d") % timestamp, hint=hint)
    delta = (datetime.datetime.utcfromtimestamp(timestamp) -
             datetime.datetime.fromtimestamp(timestamp))
    tz = delta.days * 86400 + delta.seconds
    return timestamp, tz

def datestr(date=None, format='%a %b %d %H:%M:%S %Y %1%2'):
    """represent a (unixtime, offset) tuple as a localized time.
    unixtime is seconds since the epoch, and offset is the time zone's
    number of seconds away from UTC.

    >>> datestr((0, 0))
    'Thu Jan 01 00:00:00 1970 +0000'
    >>> datestr((42, 0))
    'Thu Jan 01 00:00:42 1970 +0000'
    >>> datestr((-42, 0))
    'Wed Dec 31 23:59:18 1969 +0000'
    >>> datestr((0x7fffffff, 0))
    'Tue Jan 19 03:14:07 2038 +0000'
    >>> datestr((-0x80000000, 0))
    'Fri Dec 13 20:45:52 1901 +0000'
    """
    t, tz = date or makedate()
    if "%1" in format or "%2" in format or "%z" in format:
        sign = (tz > 0) and "-" or "+"
        minutes = abs(tz) // 60
        q, r = divmod(minutes, 60)
        format = format.replace("%z", "%1%2")
        format = format.replace("%1", "%c%02d" % (sign, q))
        format = format.replace("%2", "%02d" % r)
    d = t - tz
    if d > 0x7fffffff:
        d = 0x7fffffff
    elif d < -0x80000000:
        d = -0x80000000
    # Never use time.gmtime() and datetime.datetime.fromtimestamp()
    # because they use the gmtime() system call which is buggy on Windows
    # for negative values.
    t = datetime.datetime(1970, 1, 1) + datetime.timedelta(seconds=d)
    s = encoding.strtolocal(t.strftime(encoding.strfromlocal(format)))
    return s

def shortdate(date=None):
    """turn (timestamp, tzoff) tuple into iso 8631 date."""
    return datestr(date, format='%Y-%m-%d')

def parsetimezone(s):
    """find a trailing timezone, if any, in string, and return a
       (offset, remainder) pair"""
    s = pycompat.bytestr(s)

    if s.endswith("GMT") or s.endswith("UTC"):
        return 0, s[:-3].rstrip()

    # Unix-style timezones [+-]hhmm
    if len(s) >= 5 and s[-5] in "+-" and s[-4:].isdigit():
        sign = (s[-5] == "+") and 1 or -1
        hours = int(s[-4:-2])
        minutes = int(s[-2:])
        return -sign * (hours * 60 + minutes) * 60, s[:-5].rstrip()

    # ISO8601 trailing Z
    if s.endswith("Z") and s[-2:-1].isdigit():
        return 0, s[:-1]

    # ISO8601-style [+-]hh:mm
    if (len(s) >= 6 and s[-6] in "+-" and s[-3] == ":" and
        s[-5:-3].isdigit() and s[-2:].isdigit()):
        sign = (s[-6] == "+") and 1 or -1
        hours = int(s[-5:-3])
        minutes = int(s[-2:])
        return -sign * (hours * 60 + minutes) * 60, s[:-6]

    return None, s

def strdate(string, format, defaults=None):
    """parse a localized time string and return a (unixtime, offset) tuple.
    if the string cannot be parsed, ValueError is raised."""
    if defaults is None:
        defaults = {}

    # NOTE: unixtime = localunixtime + offset
    offset, date = parsetimezone(string)

    # add missing elements from defaults
    usenow = False # default to using biased defaults
    for part in ("S", "M", "HI", "d", "mb", "yY"): # decreasing specificity
        part = pycompat.bytestr(part)
        found = [True for p in part if ("%"+p) in format]
        if not found:
            date += "@" + defaults[part][usenow]
            format += "@%" + part[0]
        else:
            # We've found a specific time element, less specific time
            # elements are relative to today
            usenow = True

    timetuple = time.strptime(encoding.strfromlocal(date),
                              encoding.strfromlocal(format))
    localunixtime = int(calendar.timegm(timetuple))
    if offset is None:
        # local timezone
        unixtime = int(time.mktime(timetuple))
        offset = unixtime - localunixtime
    else:
        unixtime = localunixtime + offset
    return unixtime, offset

def parsedate(date, formats=None, bias=None):
    """parse a localized date/time and return a (unixtime, offset) tuple.

    The date may be a "unixtime offset" string or in one of the specified
    formats. If the date already is a (unixtime, offset) tuple, it is returned.

    >>> parsedate(b' today ') == parsedate(
    ...     datetime.date.today().strftime('%b %d').encode('ascii'))
    True
    >>> parsedate(b'yesterday ') == parsedate(
    ...     (datetime.date.today() - datetime.timedelta(days=1)
    ...      ).strftime('%b %d').encode('ascii'))
    True
    >>> now, tz = makedate()
    >>> strnow, strtz = parsedate(b'now')
    >>> (strnow - now) < 1
    True
    >>> tz == strtz
    True
    """
    if bias is None:
        bias = {}
    if not date:
        return 0, 0
    if isinstance(date, tuple) and len(date) == 2:
        return date
    if not formats:
        formats = defaultdateformats
    date = date.strip()

    if date == 'now' or date == _('now'):
        return makedate()
    if date == 'today' or date == _('today'):
        date = datetime.date.today().strftime(r'%b %d')
        date = encoding.strtolocal(date)
    elif date == 'yesterday' or date == _('yesterday'):
        date = (datetime.date.today() -
                datetime.timedelta(days=1)).strftime(r'%b %d')
        date = encoding.strtolocal(date)

    try:
        when, offset = map(int, date.split(' '))
    except ValueError:
        # fill out defaults
        now = makedate()
        defaults = {}
        for part in ("d", "mb", "yY", "HI", "M", "S"):
            # this piece is for rounding the specific end of unknowns
            b = bias.get(part)
            if b is None:
                if part[0:1] in "HMS":
                    b = "00"
                else:
                    b = "0"

            # this piece is for matching the generic end to today's date
            n = datestr(now, "%" + part[0:1])

            defaults[part] = (b, n)

        for format in formats:
            try:
                when, offset = strdate(date, format, defaults)
            except (ValueError, OverflowError):
                pass
            else:
                break
        else:
            raise error.ParseError(
                _('invalid date: %r') % pycompat.bytestr(date))
    # validate explicit (probably user-specified) date and
    # time zone offset. values must fit in signed 32 bits for
    # current 32-bit linux runtimes. timezones go from UTC-12
    # to UTC+14
    if when < -0x80000000 or when > 0x7fffffff:
        raise error.ParseError(_('date exceeds 32 bits: %d') % when)
    if offset < -50400 or offset > 43200:
        raise error.ParseError(_('impossible time zone offset: %d') % offset)
    return when, offset

def matchdate(date):
    """Return a function that matches a given date match specifier

    Formats include:

    '{date}' match a given date to the accuracy provided

    '<{date}' on or before a given date

    '>{date}' on or after a given date

    >>> p1 = parsedate(b"10:29:59")
    >>> p2 = parsedate(b"10:30:00")
    >>> p3 = parsedate(b"10:30:59")
    >>> p4 = parsedate(b"10:31:00")
    >>> p5 = parsedate(b"Sep 15 10:30:00 1999")
    >>> f = matchdate(b"10:30")
    >>> f(p1[0])
    False
    >>> f(p2[0])
    True
    >>> f(p3[0])
    True
    >>> f(p4[0])
    False
    >>> f(p5[0])
    False
    """

    def lower(date):
        d = {'mb': "1", 'd': "1"}
        return parsedate(date, extendeddateformats, d)[0]

    def upper(date):
        d = {'mb': "12", 'HI': "23", 'M': "59", 'S': "59"}
        for days in ("31", "30", "29"):
            try:
                d["d"] = days
                return parsedate(date, extendeddateformats, d)[0]
            except error.ParseError:
                pass
        d["d"] = "28"
        return parsedate(date, extendeddateformats, d)[0]

    date = date.strip()

    if not date:
        raise error.Abort(_("dates cannot consist entirely of whitespace"))
    elif date[0] == "<":
        if not date[1:]:
            raise error.Abort(_("invalid day spec, use '<DATE'"))
        when = upper(date[1:])
        return lambda x: x <= when
    elif date[0] == ">":
        if not date[1:]:
            raise error.Abort(_("invalid day spec, use '>DATE'"))
        when = lower(date[1:])
        return lambda x: x >= when
    elif date[0] == "-":
        try:
            days = int(date[1:])
        except ValueError:
            raise error.Abort(_("invalid day spec: %s") % date[1:])
        if days < 0:
            raise error.Abort(_("%s must be nonnegative (see 'hg help dates')")
                % date[1:])
        when = makedate()[0] - days * 3600 * 24
        return lambda x: x >= when
    elif " to " in date:
        a, b = date.split(" to ")
        start, stop = lower(a), upper(b)
        return lambda x: x >= start and x <= stop
    else:
        start, stop = lower(date), upper(date)
        return lambda x: x >= start and x <= stop