62 lines
2.1 KiB
Python
62 lines
2.1 KiB
Python
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"""Assorted utilities shared between parts of apitools."""
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import random
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def calculate_wait_for_retry(retry_attempt, max_wait=60):
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"""Calculate the amount of time to wait before a retry attempt.
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Wait time grows exponentially with the number of attempts. A
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random amount of jitter is added to spread out retry attempts from
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different clients.
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:type retry_attempt: integer
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:param retry_attempt: Retry attempt counter.
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:type max_wait: integer
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:param max_wait: Upper bound for wait time [seconds].
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:rtype: integer
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:returns: Number of seconds to wait before retrying request.
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"""
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wait_time = 2 ** retry_attempt
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max_jitter = wait_time / 4.0
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wait_time += random.uniform(-max_jitter, max_jitter)
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return max(1, min(wait_time, max_wait))
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def acceptable_mime_type(accept_patterns, mime_type):
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"""Check that ``mime_type`` matches one of ``accept_patterns``.
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Note that this function assumes that all patterns in accept_patterns
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will be simple types of the form "type/subtype", where one or both
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of these can be "*". We do not support parameters (i.e. "; q=") in
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patterns.
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:type accept_patterns: list of string
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:param accept_patterns: acceptable MIME types.
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:type mime_type: string
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:param mime_type: the MIME being checked
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:rtype: boolean
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:returns: True if the supplied MIME type matches at least one of the
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patterns, else False.
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"""
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if '/' not in mime_type:
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raise ValueError(
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'Invalid MIME type: "%s"' % mime_type)
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unsupported_patterns = [p for p in accept_patterns if ';' in p]
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if unsupported_patterns:
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raise ValueError(
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'MIME patterns with parameter unsupported: "%s"' % ', '.join(
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unsupported_patterns))
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def _match(pattern, mime_type):
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"""Return True iff mime_type is acceptable for pattern."""
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return all(accept in ('*', provided) for accept, provided
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in zip(pattern.split('/'), mime_type.split('/')))
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return any(_match(pattern, mime_type) for pattern in accept_patterns)
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