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9200a2e543
* from __future__ import annotations
* fixup! from __future__ import annotations
* fixup! from __future__ import annotations
* fixup! Format Python code with psf/black push
Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
59 lines
1.8 KiB
Python
59 lines
1.8 KiB
Python
from __future__ import annotations
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def allocation_num(number_of_bytes: int, partitions: int) -> list[str]:
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"""
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Divide a number of bytes into x partitions.
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In a multi-threaded download, this algorithm could be used to provide
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each worker thread with a block of non-overlapping bytes to download.
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For example:
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for i in allocation_list:
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requests.get(url,headers={'Range':f'bytes={i}'})
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parameter
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------------
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: param number_of_bytes
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: param partitions
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return
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------------
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: return: list of bytes to be assigned to each worker thread
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Examples:
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------------
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>>> allocation_num(16647, 4)
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['0-4161', '4162-8322', '8323-12483', '12484-16647']
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>>> allocation_num(888, 888)
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Traceback (most recent call last):
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...
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ValueError: partitions can not >= number_of_bytes!
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>>> allocation_num(888, 999)
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Traceback (most recent call last):
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...
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ValueError: partitions can not >= number_of_bytes!
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>>> allocation_num(888, -4)
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Traceback (most recent call last):
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...
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ValueError: partitions must be a positive number!
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"""
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if partitions <= 0:
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raise ValueError("partitions must be a positive number!")
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if partitions >= number_of_bytes:
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raise ValueError("partitions can not >= number_of_bytes!")
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bytes_per_partition = number_of_bytes // partitions
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allocation_list = [f"0-{bytes_per_partition}"]
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for i in range(1, partitions - 1):
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length = f"{bytes_per_partition * i + 1}-{bytes_per_partition * (i + 1)}"
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allocation_list.append(length)
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allocation_list.append(
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f"{(bytes_per_partition * (partitions - 1)) + 1}-" f"{number_of_bytes}"
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)
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return allocation_list
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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