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0596c4a810
Sort of a hacky hammer, but * The original design of the analytics system mistakenly attempted to play nicely with non-UTC datetimes. * Timezone errors are really hard to find and debug, and don't jump out that easily when reading code. I don't know of any outstanding errors, but putting a few "assert this timezone is in UTC" around will hopefully reduce the chance that there are any current or future timezone errors. Note that none of these functions are called outside of the analytics code (and tests). This commit also doesn't change any current behavior, assuming a database where all datetimes have been being stored in UTC.
33 lines
1.2 KiB
Python
33 lines
1.2 KiB
Python
from zerver.lib.timestamp import floor_to_hour, floor_to_day, \
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timestamp_to_datetime, verify_UTC
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from analytics.lib.counts import CountStat
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from datetime import datetime, timedelta
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from typing import List, Optional
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# If min_length is None, returns end_times from ceiling(start) to floor(end), inclusive.
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# If min_length is greater than 0, pads the list to the left.
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# So informally, time_range(Sep 20, Sep 22, day, None) returns [Sep 20, Sep 21, Sep 22],
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# and time_range(Sep 20, Sep 22, day, 5) returns [Sep 18, Sep 19, Sep 20, Sep 21, Sep 22]
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def time_range(start, end, frequency, min_length):
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# type: (datetime, datetime, str, Optional[int]) -> List[datetime]
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verify_UTC(start)
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verify_UTC(end)
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if frequency == CountStat.HOUR:
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end = floor_to_hour(end)
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step = timedelta(hours=1)
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elif frequency == CountStat.DAY:
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end = floor_to_day(end)
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step = timedelta(days=1)
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else:
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raise AssertionError("Unknown frequency: %s" % (frequency,))
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times = []
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if min_length is not None:
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start = min(start, end - (min_length-1)*step)
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current = end
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while current >= start:
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times.append(current)
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current -= step
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return list(reversed(times))
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