Class _VirtualClock

tests/virtual_time.py:210–236

The loop's virtual clock. `time()` only moves when `advance()` is called (by the selector), and is what asyncio reads for scheduling -- it must stay raw so the sub-nanosecond timer tie-break (see _VirtualTimeLoop) is not swamped. `read()` is the wall-clock view: the same virtual time, b

class _VirtualClock:
    """The loop's virtual clock.

    `time()` only moves when `advance()` is called (by the selector), and is what asyncio reads for
    scheduling -- it must stay raw so the sub-nanosecond timer tie-break (see _VirtualTimeLoop) is
    not swamped. `read()` is the wall-clock view: the same virtual time, but nudged to stay
    strictly increasing within a tick so synchronously-created items get distinct, ordered
    `created_at`. The high-water mark lives here (per loop), so it resets naturally with each test's
    fresh loop -- no global state.
    """

    __slots__ = ("_time", "_read")

    def __init__(self) -> None:
        self._time = 0.0
        self._read = 0.0

    def time(self) -> float:
        return self._time

    def advance(self, seconds: float) -> None:
        if seconds > 0:
            self._time += seconds

    def read(self) -> float:
        self._read = self._time if self._time > self._read else self._read + _TICK_EPSILON
        return self._read


class _AutojumpSelector(selectors.BaseSelector):