89 lines
2.6 KiB
Python
89 lines
2.6 KiB
Python
import functools
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import time
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import warnings
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from . import exceptions
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def _get_relevant_photodb(instance):
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from . import objects
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if isinstance(instance, objects.ObjectBase):
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photodb = instance.photodb
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else:
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photodb = instance
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return photodb
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def required_feature(features):
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'''
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Declare that the photodb or object method requires certain 'enable_*'
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fields in the config.
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'''
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if isinstance(features, str):
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features = [features]
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def wrapper(method):
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@functools.wraps(method)
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def wrapped_required_feature(self, *args, **kwargs):
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photodb = _get_relevant_photodb(self)
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config = photodb.config['enable_feature']
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# Using the received string like "photo.new", try to navigate the
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# config and wind up at a True or False. All other values invalid.
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# Allow KeyErrors to raise themselves.
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for feature in features:
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cfg = config
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pieces = feature.split('.')
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for piece in pieces:
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cfg = cfg[piece]
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if cfg is True:
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pass
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elif cfg is False:
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raise exceptions.FeatureDisabled(method.__qualname__)
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else:
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raise ValueError(f'Bad required_feature: "{feature}" led to {cfg}')
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return method(self, *args, **kwargs)
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return wrapped_required_feature
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return wrapper
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def not_implemented(function):
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'''
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Decorator to remember what needs doing.
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'''
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warnings.warn(f'{function.__name__} is not implemented')
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return function
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def time_me(function):
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'''
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After the function is run, print the elapsed time.
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'''
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@functools.wraps(function)
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def timed_function(*args, **kwargs):
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start = time.time()
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result = function(*args, **kwargs)
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end = time.time()
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duration = end - start
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print(f'{function.__name__}: {duration:0.8f}')
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return result
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return timed_function
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def transaction(method):
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'''
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Open a savepoint before running the method.
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If the method fails, roll back to that savepoint.
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'''
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@functools.wraps(method)
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def wrapped_transaction(self, *args, **kwargs):
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photodb = _get_relevant_photodb(self)
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savepoint_id = photodb.savepoint(message=method.__qualname__)
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try:
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result = method(self, *args, **kwargs)
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except Exception as e:
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photodb.rollback(savepoint=savepoint_id)
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raise
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else:
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return result
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return wrapped_transaction
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