24 lines
553 B
Python
24 lines
553 B
Python
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"""Code for detecting and aborting on cyclic dependency loops."""
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import os
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class CyclicDependencyError(Exception):
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pass
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def _get():
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"""Get the list of held cycle items."""
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return os.environ.get('REDO_CYCLES', '').split(':')
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def add(fid):
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"""Add a lock to the list of held cycle items."""
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items = set(_get())
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items.add(str(fid))
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os.environ['REDO_CYCLES'] = ':'.join(list(items))
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def check(fid):
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if str(fid) in _get():
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# Lock already held by parent: cyclic dependency
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raise CyclicDependencyError()
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