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lythonic.periodic

Time and scheduling utilities.

Time and scheduling utilities.

This module provides tools for working with time intervals, frequencies, and periodic tasks:

Time Simulation

SimulatedTime allows testing time-dependent code by offsetting the clock:

from lythonic.periodic import stime
from datetime import timedelta

stime.set_offset(timedelta(days=1))  # Pretend it's tomorrow
print(stime.get_datetime())
stime.reset()  # Back to real time

Frequencies and Intervals

  • Frequency: Human-friendly periods (weekly, monthly, quarterly, annually)
  • FrequencyOffset: Frequency with day offset (e.g., "20th of each month")
  • Interval: Precise duration with multiplier (e.g., "3M" for 3 months, "2W" for 2 weeks)
from lythonic.periodic import Frequency, Interval
from datetime import date

freq = Frequency("monthly")
print(freq.first_day(date(2025, 11, 15)))  # 2025-11-01
print(freq.last_day(date(2025, 11, 15)))   # 2025-11-30

interval = Interval.from_string("2W")
print(interval.timedelta())  # 14 days

Periodic Tasks

Run async tasks at specified intervals:

from lythonic.periodic import PeriodicTask, run_all

task = PeriodicTask(freq=60, logic=my_function)  # Run every 60 seconds
await run_all(task)

Timing with Moment

Track elapsed time between checkpoints:

from lythonic.periodic import Moment

m = Moment.start()
# ... do work ...
m = m.capture("step1")
# ... more work ...
m = m.capture("done")
print(m.chain())  # [start] 0.5s-> [step1] 1.2s-> [done]

stime = SimulatedTime() module-attribute

SimulatedTime 

>>> st = SimulatedTime()
>>> st.get_datetime().tzinfo
datetime.timezone.utc
>>> cmp = lambda ss: abs((st.get_datetime()-utc_now()).total_seconds()-ss) < 1e-3
>>> cmp(0)
True
>>> st.set_offset(timedelta(days=1))
>>> cmp(86400)
True
>>> st.set_offset(timedelta(days=1).total_seconds())
>>> cmp(86400)
True
>>> st.set_now(utc_now() + timedelta(days=1))
>>> cmp(86400)
True
>>> st.set_now( (utc_now() - timedelta(days=1)).timestamp() )
>>> cmp(-86400)
True
>>> st.is_real_time()
False
>>> st.reset()
>>> st.is_real_time()
True
Source code in src/lythonic/periodic.py 
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class SimulatedTime:
    """
    >>> st = SimulatedTime()
    >>> st.get_datetime().tzinfo
    datetime.timezone.utc
    >>> cmp = lambda ss: abs((st.get_datetime()-utc_now()).total_seconds()-ss) < 1e-3
    >>> cmp(0)
    True
    >>> st.set_offset(timedelta(days=1))
    >>> cmp(86400)
    True
    >>> st.set_offset(timedelta(days=1).total_seconds())
    >>> cmp(86400)
    True
    >>> st.set_now(utc_now() + timedelta(days=1))
    >>> cmp(86400)
    True
    >>> st.set_now( (utc_now() - timedelta(days=1)).timestamp() )
    >>> cmp(-86400)
    True
    >>> st.is_real_time()
    False
    >>> st.reset()
    >>> st.is_real_time()
    True
    """

    offset: float

    def __init__(self, offset: float = 0.0) -> None:
        self.offset = offset

    def time(self):
        return tt.time() + self.offset

    def set_offset(self, offset: timedelta | float):
        if isinstance(offset, timedelta):
            self.offset = offset.total_seconds()
        else:
            self.offset = offset

    def set_now(self, dt: datetime | float):
        if isinstance(dt, datetime):
            epoch = dt.timestamp()
        else:
            epoch = dt
        self.offset = epoch - tt.time()

    def reset(self):
        self.offset = 0.0

    def is_real_time(self):
        return self.offset == 0.0

    def get_datetime(self) -> datetime:
        return datetime.fromtimestamp(self.time(), tz=UTC)

Frequency

People friendly interval

>>> Frequency("weekly").first_day(date(2025, 11, 21))
datetime.date(2025, 11, 17)
>>> Frequency("weekly").last_day(date(2025, 11, 21))
datetime.date(2025, 11, 23)
>>> Frequency("monthly").first_day(date(2025, 11, 21))
datetime.date(2025, 11, 1)
>>> Frequency("monthly").last_day(date(2025, 11, 21))
datetime.date(2025, 11, 30)
>>> Frequency("quarterly").first_day(date(2025, 11, 21))
datetime.date(2025, 10, 1)
>>> Frequency("quarterly").last_day(date(2025, 11, 21))
datetime.date(2025, 12, 31)
>>> Frequency("quarterly").first_day(date(2025, 2, 21))
datetime.date(2025, 1, 1)
>>> Frequency("quarterly").last_day(date(2025, 2, 21))
datetime.date(2025, 3, 31)
>>> Frequency("quarterly").last_day(date(2025, 5, 21))
datetime.date(2025, 6, 30)
>>> Frequency("annually").first_day(date(2025, 11, 21))
datetime.date(2025, 1, 1)
>>> Frequency("annually").last_day(date(2025, 11, 21))
datetime.date(2025, 12, 31)
Source code in src/lythonic/periodic.py 
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class Frequency:
    """People friendly interval

    >>> Frequency("weekly").first_day(date(2025, 11, 21))
    datetime.date(2025, 11, 17)
    >>> Frequency("weekly").last_day(date(2025, 11, 21))
    datetime.date(2025, 11, 23)
    >>> Frequency("monthly").first_day(date(2025, 11, 21))
    datetime.date(2025, 11, 1)
    >>> Frequency("monthly").last_day(date(2025, 11, 21))
    datetime.date(2025, 11, 30)
    >>> Frequency("quarterly").first_day(date(2025, 11, 21))
    datetime.date(2025, 10, 1)
    >>> Frequency("quarterly").last_day(date(2025, 11, 21))
    datetime.date(2025, 12, 31)
    >>> Frequency("quarterly").first_day(date(2025, 2, 21))
    datetime.date(2025, 1, 1)
    >>> Frequency("quarterly").last_day(date(2025, 2, 21))
    datetime.date(2025, 3, 31)
    >>> Frequency("quarterly").last_day(date(2025, 5, 21))
    datetime.date(2025, 6, 30)
    >>> Frequency("annually").first_day(date(2025, 11, 21))
    datetime.date(2025, 1, 1)
    >>> Frequency("annually").last_day(date(2025, 11, 21))
    datetime.date(2025, 12, 31)
    """

    frequency: FrequencyType

    def __init__(self, frequency: FrequencyType) -> None:
        self.frequency = frequency

    @classmethod
    def ensure(cls, frequency: "Frequency|FrequencyType") -> "Frequency":
        if isinstance(frequency, Frequency):
            return frequency
        return cls(frequency)

    def first_day(self, as_of: date) -> date:
        if self.frequency == "weekly":
            return as_of - timedelta(days=as_of.weekday())
        elif self.frequency == "monthly":
            return as_of.replace(day=1)
        elif self.frequency == "quarterly":
            return as_of.replace(day=1, month=((as_of.month - 1) // 3) * 3 + 1)
        elif self.frequency == "annually":
            return as_of.replace(day=1, month=1)
        else:
            raise AssertionError(f"Invalid frequency: {self.frequency}")

    def last_day(self, as_of: date) -> date:
        if self.frequency == "weekly":
            return as_of + timedelta(days=6 - as_of.weekday())
        elif self.frequency == "monthly":
            return as_of.replace(day=calendar.monthrange(as_of.year, as_of.month)[1])
        elif self.frequency == "quarterly":
            month = ((as_of.month - 1) // 3) * 3 + 3
            return as_of.replace(day=calendar.monthrange(as_of.year, month)[1], month=month)
        elif self.frequency == "annually":
            return as_of.replace(day=31, month=12)
        else:
            raise AssertionError(f"Invalid frequency: {self.frequency}")

    def min_max_offset(
        self,
    ) -> tuple[int, int]:
        if self.frequency == "weekly":
            return (-7, 7)
        elif self.frequency == "monthly":
            return (-31, 31)
        elif self.frequency == "quarterly":
            return (-92, 92)
        elif self.frequency == "annually":
            return (-366, 366)
        else:
            raise AssertionError(f"Invalid frequency: {self.frequency}")

    def assert_offset(self, offset: int) -> None:
        min_offset, max_offset = self.min_max_offset()
        assert min_offset <= offset < max_offset, (
            f"Invalid offset: {offset} for frequency: {self.frequency} expected between {min_offset} and {max_offset}"
        )

FrequencyOffset 

>>> FrequencyOffset(Frequency("weekly"), 0).boundaries(date(2025, 11, 21))
(datetime.date(2025, 11, 17), datetime.date(2025, 11, 23))
>>> FrequencyOffset("weekly", 1).boundaries(date(2025, 11, 21))
(datetime.date(2025, 11, 18), datetime.date(2025, 11, 24))
>>> FrequencyOffset(Frequency("weekly"), -1).boundaries(date(2025, 11, 21))
(datetime.date(2025, 11, 16), datetime.date(2025, 11, 22))
>>> on20thOfMonth = FrequencyOffset(Frequency("monthly"), 19)
>>> on20thOfMonth.boundaries(date(2025, 11, 21))
(datetime.date(2025, 11, 20), datetime.date(2025, 12, 19))
>>> on20thOfMonth.boundaries(on20thOfMonth.boundaries(date(2025, 11, 21))[1]+timedelta(days=1))
(datetime.date(2025, 12, 20), datetime.date(2026, 1, 19))
>>> on3rdBeforeEndOfMonth = FrequencyOffset("monthly", -3)
>>> b1 = on3rdBeforeEndOfMonth.boundaries(date(2025, 11, 21)); b1
(datetime.date(2025, 10, 29), datetime.date(2025, 11, 27))
>>> b2 = on3rdBeforeEndOfMonth.boundaries(b1[1]+timedelta(days=1)); b2
(datetime.date(2025, 11, 28), datetime.date(2025, 12, 28))
>>> b3 = on3rdBeforeEndOfMonth.boundaries(b2[1]+timedelta(days=1)); b3
(datetime.date(2025, 12, 29), datetime.date(2026, 1, 28))
>>> b4 = on3rdBeforeEndOfMonth.boundaries(b3[1]+timedelta(days=1)); b4
(datetime.date(2026, 1, 29), datetime.date(2026, 2, 25))
Source code in src/lythonic/periodic.py 
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class FrequencyOffset:
    """
    >>> FrequencyOffset(Frequency("weekly"), 0).boundaries(date(2025, 11, 21))
    (datetime.date(2025, 11, 17), datetime.date(2025, 11, 23))
    >>> FrequencyOffset("weekly", 1).boundaries(date(2025, 11, 21))
    (datetime.date(2025, 11, 18), datetime.date(2025, 11, 24))
    >>> FrequencyOffset(Frequency("weekly"), -1).boundaries(date(2025, 11, 21))
    (datetime.date(2025, 11, 16), datetime.date(2025, 11, 22))
    >>> on20thOfMonth = FrequencyOffset(Frequency("monthly"), 19)
    >>> on20thOfMonth.boundaries(date(2025, 11, 21))
    (datetime.date(2025, 11, 20), datetime.date(2025, 12, 19))
    >>> on20thOfMonth.boundaries(on20thOfMonth.boundaries(date(2025, 11, 21))[1]+timedelta(days=1))
    (datetime.date(2025, 12, 20), datetime.date(2026, 1, 19))
    >>> on3rdBeforeEndOfMonth = FrequencyOffset("monthly", -3)
    >>> b1 = on3rdBeforeEndOfMonth.boundaries(date(2025, 11, 21)); b1
    (datetime.date(2025, 10, 29), datetime.date(2025, 11, 27))
    >>> b2 = on3rdBeforeEndOfMonth.boundaries(b1[1]+timedelta(days=1)); b2
    (datetime.date(2025, 11, 28), datetime.date(2025, 12, 28))
    >>> b3 = on3rdBeforeEndOfMonth.boundaries(b2[1]+timedelta(days=1)); b3
    (datetime.date(2025, 12, 29), datetime.date(2026, 1, 28))
    >>> b4 = on3rdBeforeEndOfMonth.boundaries(b3[1]+timedelta(days=1)); b4
    (datetime.date(2026, 1, 29), datetime.date(2026, 2, 25))
    """

    frequency: Frequency
    offset: int

    def __init__(self, frequency: Frequency | FrequencyType, offset: int) -> None:
        self.frequency = Frequency.ensure(frequency)
        self.frequency.assert_offset(offset)
        self.offset = offset

    def boundaries(self, as_of: date) -> tuple[date, date]:
        """
        Return the boundaries around the given date (inclusive).
        """
        if self.offset >= 0:
            d = self.frequency.first_day(as_of)
            dd = (
                self.frequency.first_day(d - timedelta(days=1)),
                d,
                self.frequency.last_day(as_of) + timedelta(days=1),
            )
            with_delta = [t + timedelta(days=self.offset) for t in dd]
        else:
            d = self.frequency.last_day(as_of)
            dd = (
                self.frequency.first_day(as_of) - timedelta(days=1),
                d,
                self.frequency.last_day(d + timedelta(days=1)),
            )
            with_delta = [t + timedelta(days=1 + self.offset) for t in dd]

        assert with_delta[0] <= as_of
        if as_of < with_delta[1]:
            return with_delta[0], with_delta[1] - timedelta(days=1)
        else:
            assert with_delta[1] <= as_of < with_delta[2]
            return with_delta[1], with_delta[2] - timedelta(days=1)

boundaries(as_of)

Return the boundaries around the given date (inclusive).

Source code in src/lythonic/periodic.py 
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def boundaries(self, as_of: date) -> tuple[date, date]:
    """
    Return the boundaries around the given date (inclusive).
    """
    if self.offset >= 0:
        d = self.frequency.first_day(as_of)
        dd = (
            self.frequency.first_day(d - timedelta(days=1)),
            d,
            self.frequency.last_day(as_of) + timedelta(days=1),
        )
        with_delta = [t + timedelta(days=self.offset) for t in dd]
    else:
        d = self.frequency.last_day(as_of)
        dd = (
            self.frequency.first_day(as_of) - timedelta(days=1),
            d,
            self.frequency.last_day(d + timedelta(days=1)),
        )
        with_delta = [t + timedelta(days=1 + self.offset) for t in dd]

    assert with_delta[0] <= as_of
    if as_of < with_delta[1]:
        return with_delta[0], with_delta[1] - timedelta(days=1)
    else:
        assert with_delta[1] <= as_of < with_delta[2]
        return with_delta[1], with_delta[2] - timedelta(days=1)

IntervalUnit

Bases: Enum

Approximate time interval units expressed in days.

>>> for n in "usmhDWMQY": print(f"{n} = {IntervalUnit.from_string(n).timedelta()}")
u = 0:00:00.000001
s = 0:00:01
m = 0:01:00
h = 1:00:00
D = 1 day, 0:00:00
W = 7 days, 0:00:00
M = 30 days, 10:30:43.200000
Q = 91 days, 7:32:09.600000
Y = 365 days, 6:08:38.400000
>>> [i.name for i in IntervalUnit]
['u', 's', 'm', 'h', 'D', 'W', 'M', 'Q', 'Y']
>>> IntervalUnit.minutes
IntervalUnit.m
>>> list(IntervalUnit.aliases())
['microseconds', 'seconds', 'minutes', 'hours', 'days', 'weeks', 'months', 'quarters', 'years']
Source code in src/lythonic/periodic.py 
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class IntervalUnit(Enum):
    """
    Approximate time interval units expressed in days.

    >>> for n in "usmhDWMQY": print(f"{n} = {IntervalUnit.from_string(n).timedelta()}")
    u = 0:00:00.000001
    s = 0:00:01
    m = 0:01:00
    h = 1:00:00
    D = 1 day, 0:00:00
    W = 7 days, 0:00:00
    M = 30 days, 10:30:43.200000
    Q = 91 days, 7:32:09.600000
    Y = 365 days, 6:08:38.400000
    >>> [i.name for i in IntervalUnit]
    ['u', 's', 'm', 'h', 'D', 'W', 'M', 'Q', 'Y']
    >>> IntervalUnit.minutes
    IntervalUnit.m
    >>> list(IntervalUnit.aliases())
    ['microseconds', 'seconds', 'minutes', 'hours', 'days', 'weeks', 'months', 'quarters', 'years']

    """

    u = microseconds = 1 / (1_000_000 * SECONDS_IN_DAY)
    s = seconds = 1 / SECONDS_IN_DAY
    m = minutes = 1 / (60 * 24)
    h = hours = 1 / 24
    D = days = 1
    W = weeks = 7
    M = months = YEAR_IN_DAYS / 12
    Q = quarters = YEAR_IN_DAYS / 4
    Y = years = YEAR_IN_DAYS

    @classmethod
    def from_string(cls, n: str) -> "IntervalUnit":
        return cls[n]

    @classmethod
    def aliases(cls) -> dict[str, "IntervalUnit"]:
        return {n: e for n, e in cls.__members__.items() if len(n) != 1}

    def timedelta(self) -> timedelta:
        return timedelta(days=self.value)

    @override
    def __str__(self) -> str:
        return self.name

    @override
    def __repr__(self) -> str:
        return f"IntervalUnit.{str(self)}"

Interval

Mapping years, month, and quarter to real numbers of approximate days. Weeks and days mapped to integer. "

>>> p = lambda i: f"{i} {i.timedelta()}"
>>> p(Interval(2, IntervalUnit.s))
'2s 0:00:02'
>>> p(Interval.from_string("2s"))
'2s 0:00:02'
>>> p(Interval.from_string("2seconds"))
'2s 0:00:02'
>>> p(Interval.from_string("2 seconds"))
'2s 0:00:02'
>>> p(Interval.from_string("2 second"))
Traceback (most recent call last):
...
ValueError: ('Invalid interval string', '2 second')
>>> p(Interval(1, IntervalUnit.D))
'1D 1 day, 0:00:00'
>>> float(Interval.from_string("1D"))
1.0
>>> float(Interval.from_string("3h"))
0.125
>>> Interval.from_string("1D") == Interval(1, IntervalUnit.D)
True
>>> Interval("1D") >= Interval.from_string("23 hours")
True
>>> Interval(Interval("1D")) >= Interval.from_string("24 hours")
True
>>> Interval.from_string("1D") >= Interval.from_string("25 hours")
False
Source code in src/lythonic/periodic.py 
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@final
@total_ordering
class Interval:
    """Mapping years, month, and quarter to real numbers of approximate days. Weeks and days mapped to integer. "

    >>> p = lambda i: f"{i} {i.timedelta()}"
    >>> p(Interval(2, IntervalUnit.s))
    '2s 0:00:02'
    >>> p(Interval.from_string("2s"))
    '2s 0:00:02'
    >>> p(Interval.from_string("2seconds"))
    '2s 0:00:02'
    >>> p(Interval.from_string("2 seconds"))
    '2s 0:00:02'
    >>> p(Interval.from_string("2 second"))
    Traceback (most recent call last):
    ...
    ValueError: ('Invalid interval string', '2 second')
    >>> p(Interval(1, IntervalUnit.D))
    '1D 1 day, 0:00:00'
    >>> float(Interval.from_string("1D"))
    1.0
    >>> float(Interval.from_string("3h"))
    0.125
    >>> Interval.from_string("1D") == Interval(1, IntervalUnit.D)
    True
    >>> Interval("1D") >= Interval.from_string("23 hours")
    True
    >>> Interval(Interval("1D")) >= Interval.from_string("24 hours")
    True
    >>> Interval.from_string("1D") >= Interval.from_string("25 hours")
    False
    """

    FREQ_RE = re.compile(f"(\\d+)([{''.join(p.name for p in IntervalUnit)}])")
    ALIAS_FREQ_RE = re.compile(f"(\\d+) ?({'|'.join(IntervalUnit.aliases())})")

    multiplier: int
    period: IntervalUnit

    def __init__(
        self, multiplier_or_value: "int|str|Interval", period: IntervalUnit | None = None
    ) -> None:
        if isinstance(multiplier_or_value, int):
            assert period is not None
            self.multiplier = multiplier_or_value
            self.period = period
        else:
            if isinstance(multiplier_or_value, str):
                multiplier_or_value = Interval.from_string(multiplier_or_value)
            self.multiplier = multiplier_or_value.multiplier
            self.period = multiplier_or_value.period

    @classmethod
    def from_string_safe(cls, s: "Interval|str|None") -> "Interval | None":
        if s is None:
            return None
        if isinstance(s, Interval):
            return s
        return cls.from_string(s)

    @classmethod
    def from_string(cls, s: str) -> "Interval":
        m = cls.matcher(s)
        if m:
            n, p = m.groups()
            return cls(int(n), IntervalUnit.from_string(p))
        else:
            raise ValueError("Invalid interval string", s)

    @classmethod
    def matcher(cls, s: str) -> re.Match[str] | None:
        return re.match(cls.FREQ_RE, s) or re.match(cls.ALIAS_FREQ_RE, s)

    def timedelta(self) -> timedelta:
        return self.multiplier * self.period.timedelta()

    def __float__(self) -> float:
        """Interval duration in days"""
        return float(self.multiplier * self.period.value)

    @override
    def __hash__(self):
        return hash((self.multiplier, self.period))

    @override
    def __eq__(self, other: object) -> bool:
        assert isinstance(other, Interval)
        return self.timedelta() == other.timedelta()

    def __lt__(self, other: object) -> bool:
        assert isinstance(other, Interval)
        return self.timedelta() < other.timedelta()

    def match(self, d: date | datetime, as_of: date | datetime) -> bool:
        return d <= as_of and d + self.timedelta() > as_of

    def find_file(
        self,
        path: Path,
        as_of: date | datetime,
        suffix: str = ".csv",
    ) -> Path | None:
        ff = list(
            reversed(
                sorted(
                    (date_from_name(f.name), f)
                    for f in path.glob(f"*{suffix}")
                    if re.match(r"^\d{8}", f.name[:8])
                )
            )
        )
        for d, f in ff:
            if d <= as_of:
                if self.match(d, as_of):
                    return f
                else:
                    break
        return None

    @override
    def __str__(self) -> str:
        return f"{self.multiplier}{self.period}"

    @override
    def __repr__(self) -> str:
        return f"Interval({self.multiplier}, {self.period!r})"

__float__()

Interval duration in days

Source code in src/lythonic/periodic.py 
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def __float__(self) -> float:
    """Interval duration in days"""
    return float(self.multiplier * self.period.value)

Moment 

>>> m = Moment.start()
>>> m = m.capture("instant")
>>> tt.sleep(1)
>>> m = m.capture("a second")
>>> s = m.chain()
>>> s.startswith('[start] 0.0'), 's-> [instant] 1.' in s , s.endswith('s-> [a second]')
(True, True, True)
Source code in src/lythonic/periodic.py 
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class Moment:
    """
    >>> m = Moment.start()
    >>> m = m.capture("instant")
    >>> tt.sleep(1)
    >>> m = m.capture("a second")
    >>> s = m.chain()
    >>> s.startswith('[start] 0.0'), 's-> [instant] 1.' in s , s.endswith('s-> [a second]')
    (True, True, True)
    """

    time: float
    name: str
    prev: "Moment | None"

    def __init__(self, name: str, prev: "Moment | None" = None) -> None:
        self.time = tt.time()
        self.name = name
        self.prev = prev

    @staticmethod
    def start():
        """capture the starting moment"""
        return Moment("start")

    def capture(self, name: str):
        """capture the named moment relative to this one"""
        return Moment(name, self)

    def elapsed(self):
        """return time in seconds since previous moment"""
        if self.prev is None:
            return 0
        return self.time - self.prev.time

    @override
    def __str__(self):
        return (
            f" {self.elapsed():.3f}s-> [{self.name}]" if self.prev is not None else f"[{self.name}]"
        )

    def chain(self) -> str:
        return str(self) if self.prev is None else self.prev.chain() + str(self)

start() staticmethod

capture the starting moment

Source code in src/lythonic/periodic.py 
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@staticmethod
def start():
    """capture the starting moment"""
    return Moment("start")

capture(name)

capture the named moment relative to this one

Source code in src/lythonic/periodic.py 
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def capture(self, name: str):
    """capture the named moment relative to this one"""
    return Moment(name, self)

elapsed()

return time in seconds since previous moment

Source code in src/lythonic/periodic.py 
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def elapsed(self):
    """return time in seconds since previous moment"""
    if self.prev is None:
        return 0
    return self.time - self.prev.time

PeriodicTask

A task that runs at a specified frequency in seconds.

Use with run_all() to execute multiple tasks in an async event loop.

Source code in src/lythonic/periodic.py 
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class PeriodicTask:
    """
    A task that runs at a specified frequency in seconds.

    Use with `run_all()` to execute multiple tasks in an async event loop.
    """

    freq: int
    logic: Callable[[], Any]
    last_run: float | None = None

    def __init__(self, freq: int, logic: Callable[[], Any]) -> None:
        self.freq = freq
        self.logic = logic

    def is_due(self):
        return self.last_run is None or stime.time() - self.last_run > self.freq

run_all(*tasks, shutdown_event=None, collect_results=_collect_nothing) async

Run multiple periodic tasks in an async loop.

Tasks are scheduled based on their freq (in seconds). The loop tick interval is the GCD of all task frequencies for efficiency. Set shutdown_event to signal graceful termination.

Source code in src/lythonic/periodic.py 
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async def run_all(
    *tasks: PeriodicTask,
    shutdown_event: asyncio.Event | None = None,
    collect_results: Callable[[str, Any], None] = _collect_nothing,
):
    """
    Run multiple periodic tasks in an async loop.

    Tasks are scheduled based on their `freq` (in seconds). The loop tick interval
    is the GCD of all task frequencies for efficiency. Set `shutdown_event` to
    signal graceful termination.
    """
    if shutdown_event is None:
        shutdown_event = asyncio.Event()
    if len(tasks) == 0:
        log.warning("No tasks to run")
        return
    tick = gcd(*[t.freq for t in tasks])
    loop = asyncio.get_running_loop()

    while True:
        start = stime.time()
        for t in tasks:
            if t.is_due():
                t.last_run = start

                try:
                    if inspect.iscoroutinefunction(t.logic):
                        r = await t.logic()
                    else:
                        r = await loop.run_in_executor(None, t.logic)
                except (Exception, asyncio.CancelledError) as _:
                    r = sys.exc_info()
                collect_results(t.logic.__name__, r)
            if shutdown_event.is_set():
                return
        elapsed = stime.time() - start
        await asyncio.sleep(tick - elapsed if elapsed < tick else 0)

dt_to_bytes(dt)

Convert datetime to bytes

>>> dt_to_bytes(datetime( 1900,1,1,0,0,0))
b'\xff\xf8&\xef\xb7C`\x00'
>>> dt_to_bytes(datetime( 2000,1,1,0,0,0))
b'\x00\x03]\x01;7\xe0\x00'
Source code in src/lythonic/periodic.py 
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def dt_to_bytes(dt: datetime) -> bytes:
    """
    Convert datetime to bytes

    >>> dt_to_bytes(datetime( 1900,1,1,0,0,0))
    b'\\xff\\xf8&\\xef\\xb7C`\\x00'
    >>> dt_to_bytes(datetime( 2000,1,1,0,0,0))
    b'\\x00\\x03]\\x01;7\\xe0\\x00'
    """
    if dt.tzinfo is None:
        dt = dt.replace(tzinfo=UTC)
    mics = total_microseconds(dt - EPOCH_ZERO)
    return mics.to_bytes(8, "big", signed=True)

dt_from_bytes(b)

Convert bytes to datetime

>>> dt_from_bytes(b'\xff\xf8&\xef\xb7C`\x00')
datetime.datetime(1900, 1, 1, 0, 0, tzinfo=datetime.timezone.utc)
>>> dt_from_bytes(b'\x00\x03]\x01;7\xe0\x00')
datetime.datetime(2000, 1, 1, 0, 0, tzinfo=datetime.timezone.utc)
Source code in src/lythonic/periodic.py 
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def dt_from_bytes(b: bytes) -> datetime:
    """
    Convert  bytes to datetime

    >>> dt_from_bytes(b'\\xff\\xf8&\\xef\\xb7C`\\x00')
    datetime.datetime(1900, 1, 1, 0, 0, tzinfo=datetime.timezone.utc)
    >>> dt_from_bytes(b'\\x00\\x03]\\x01;7\\xe0\\x00')
    datetime.datetime(2000, 1, 1, 0, 0, tzinfo=datetime.timezone.utc)
    """
    mics = int.from_bytes(b, "big", signed=True)
    return EPOCH_ZERO + timedelta(microseconds=mics)

date_from_name(s)

Source code in src/lythonic/periodic.py 
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def date_from_name(s: str) -> date:
    return date(int(s[:4]), int(s[4:6]), int(s[6:8]))

adjust_as_of_date(as_of_date) 

>>> adjust_as_of_date(None) == date.today()
True
>>> adjust_as_of_date(date(2021, 1, 1)) == date(2021, 1, 1)
True
Source code in src/lythonic/periodic.py 
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def adjust_as_of_date(as_of_date: date | None) -> date:
    """
    >>> adjust_as_of_date(None) == date.today()
    True
    >>> adjust_as_of_date(date(2021, 1, 1)) == date(2021, 1, 1)
    True
    """
    return date.today() if as_of_date is None else as_of_date