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"""Dependency utilities"""
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from IPython.external.decorator import decorator
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from error import UnmetDependency
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from asyncresult import AsyncResult
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class depend(object):
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"""Dependency decorator, for use with tasks."""
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def __init__(self, f, *args, **kwargs):
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self.f = f
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self.args = args
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self.kwargs = kwargs
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def __call__(self, f):
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return dependent(f, self.f, *self.args, **self.kwargs)
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class dependent(object):
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"""A function that depends on another function.
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This is an object to prevent the closure used
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in traditional decorators, which are not picklable.
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"""
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def __init__(self, f, df, *dargs, **dkwargs):
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self.f = f
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self.func_name = getattr(f, '__name__', 'f')
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self.df = df
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self.dargs = dargs
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self.dkwargs = dkwargs
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def __call__(self, *args, **kwargs):
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if self.df(*self.dargs, **self.dkwargs) is False:
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raise UnmetDependency()
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return self.f(*args, **kwargs)
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@property
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def __name__(self):
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return self.func_name
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def _require(*names):
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for name in names:
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try:
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__import__(name)
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except ImportError:
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return False
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return True
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def require(*names):
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return depend(_require, *names)
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class Dependency(set):
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"""An object for representing a set of msg_id dependencies.
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Subclassed from set()."""
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all=True
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success_only=True
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def __init__(self, dependencies=[], all=True, success_only=True):
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if isinstance(dependencies, dict):
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# load from dict
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all = dependencies.get('all', True)
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success_only = dependencies.get('success_only', success_only)
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dependencies = dependencies.get('dependencies', [])
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ids = []
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if isinstance(dependencies, AsyncResult):
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ids.extend(AsyncResult.msg_ids)
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else:
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for d in dependencies:
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if isinstance(d, basestring):
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ids.append(d)
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elif isinstance(d, AsyncResult):
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ids.extend(d.msg_ids)
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else:
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raise TypeError("invalid dependency type: %r"%type(d))
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set.__init__(self, ids)
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self.all = all
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self.success_only=success_only
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def check(self, completed, failed=None):
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if failed is not None and not self.success_only:
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completed = completed.union(failed)
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if len(self) == 0:
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return True
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if self.all:
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return self.issubset(completed)
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else:
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return not self.isdisjoint(completed)
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def unreachable(self, failed):
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if len(self) == 0 or len(failed) == 0 or not self.success_only:
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return False
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# print self, self.success_only, self.all, failed
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if self.all:
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return not self.isdisjoint(failed)
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else:
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return self.issubset(failed)
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def as_dict(self):
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"""Represent this dependency as a dict. For json compatibility."""
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return dict(
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dependencies=list(self),
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all=self.all,
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success_only=self.success_only,
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)
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__all__ = ['depend', 'require', 'dependent', 'Dependency']
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