130 lines
4.5 KiB
Python
130 lines
4.5 KiB
Python
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from __future__ import annotations
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import bisect
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from math import ceil
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from time import monotonic
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import rich.repr
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@rich.repr.auto(angular=True)
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class ETA:
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"""Calculate speed and estimate time to arrival."""
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def __init__(
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self, estimation_period: float = 60, extrapolate_period: float = 30
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) -> None:
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"""Create an ETA.
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Args:
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estimation_period: Period in seconds, used to calculate speed.
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extrapolate_period: Maximum number of seconds used to estimate progress after last sample.
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"""
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self.estimation_period = estimation_period
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self.max_extrapolate = extrapolate_period
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self._samples: list[tuple[float, float]] = [(0.0, 0.0)]
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self._add_count = 0
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def __rich_repr__(self) -> rich.repr.Result:
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yield "speed", self.speed
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yield "eta", self.get_eta(monotonic())
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@property
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def first_sample(self) -> tuple[float, float]:
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"""First sample."""
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assert self._samples, "Assumes samples not empty"
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return self._samples[0]
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@property
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def last_sample(self) -> tuple[float, float]:
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"""Last sample."""
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assert self._samples, "Assumes samples not empty"
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return self._samples[-1]
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def reset(self) -> None:
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"""Start ETA calculations from current time."""
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del self._samples[:]
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def add_sample(self, time: float, progress: float) -> None:
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"""Add a new sample.
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Args:
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time: Time when sample occurred.
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progress: Progress ratio (0 is start, 1 is complete).
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"""
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if self._samples and self.last_sample[1] > progress:
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# If progress goes backwards, we need to reset calculations
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self.reset()
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self._samples.append((time, progress))
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self._add_count += 1
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if self._add_count % 100 == 0:
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# Prune periodically so we don't accumulate vast amounts of samples
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self._prune()
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def _prune(self) -> None:
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"""Prune old samples."""
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if len(self._samples) <= 10:
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# Keep at least 10 samples
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return
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prune_time = self._samples[-1][0] - self.estimation_period
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index = bisect.bisect_left(self._samples, (prune_time, 0))
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del self._samples[:index]
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def _get_progress_at(self, time: float) -> tuple[float, float]:
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"""Get the progress at a specific time."""
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index = bisect.bisect_left(self._samples, (time, 0))
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if index >= len(self._samples):
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return self.last_sample
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if index == 0:
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return self.first_sample
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# Linearly interpolate progress between two samples
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time1, progress1 = self._samples[index - 1]
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time2, progress2 = self._samples[index]
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factor = (time - time1) / (time2 - time1)
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intermediate_progress = progress1 + (progress2 - progress1) * factor
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return time, intermediate_progress
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@property
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def speed(self) -> float | None:
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"""The current speed, or `None` if it couldn't be calculated."""
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if len(self._samples) < 2:
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# Need at least 2 samples to calculate speed
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return None
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recent_sample_time, progress2 = self.last_sample
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progress_start_time, progress1 = self._get_progress_at(
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recent_sample_time - self.estimation_period
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)
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if recent_sample_time - progress_start_time < 1:
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# Require at least a second span to calculate speed.
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return None
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time_delta = recent_sample_time - progress_start_time
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distance = progress2 - progress1
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speed = distance / time_delta if time_delta else 0
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return speed
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def get_eta(self, time: float) -> int | None:
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"""Estimated seconds until completion, or `None` if no estimate can be made.
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Args:
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time: Current time.
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"""
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speed = self.speed
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if not speed:
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# Not enough samples to guess
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return None
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recent_time, recent_progress = self.last_sample
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remaining = 1.0 - recent_progress
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if remaining <= 0:
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# Complete
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return 0
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# The bar is not complete, so we will extrapolate progress
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# This will give us a countdown, even with no samples
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time_since_sample = min(self.max_extrapolate, time - recent_time)
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extrapolate_progress = speed * time_since_sample
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# We don't want to extrapolate all the way to 0, as that would erroneously suggest it is finished
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eta = max(1.0, (remaining - extrapolate_progress) / speed)
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return ceil(eta)
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