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"""Dependency utilities
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Authors:
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* Min RK
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"""
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#-----------------------------------------------------------------------------
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# Copyright (C) 2010-2011 The IPython Development Team
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#
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# Distributed under the terms of the BSD License. The full license is in
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# the file COPYING, distributed as part of this software.
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#-----------------------------------------------------------------------------
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from types import ModuleType
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from IPython.parallel.client.asyncresult import AsyncResult
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from IPython.parallel.error import UnmetDependency
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from IPython.parallel.util import interactive
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from IPython.utils import py3compat
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class depend(object):
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"""Dependency decorator, for use with tasks.
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`@depend` lets you define a function for engine dependencies
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just like you use `apply` for tasks.
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Examples
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--------
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::
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@depend(df, a,b, c=5)
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def f(m,n,p)
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view.apply(f, 1,2,3)
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will call df(a,b,c=5) on the engine, and if it returns False or
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raises an UnmetDependency error, then the task will not be run
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and another engine will be tried.
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"""
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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 hasattr(self.f, 'func_globals') and hasattr(self.df, 'func_globals'):
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# self.df.func_globals = self.f.func_globals
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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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if not py3compat.PY3:
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@property
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def __name__(self):
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return self.func_name
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@interactive
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def _require(*names):
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"""Helper for @require decorator."""
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from IPython.parallel.error import UnmetDependency
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user_ns = globals()
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for name in names:
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if name in user_ns:
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continue
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try:
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exec 'import %s'%name in user_ns
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except ImportError:
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raise UnmetDependency(name)
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return True
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def require(*mods):
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"""Simple decorator for requiring names to be importable.
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Examples
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--------
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In [1]: @require('numpy')
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...: def norm(a):
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...: import numpy
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...: return numpy.linalg.norm(a,2)
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"""
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names = []
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for mod in mods:
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if isinstance(mod, ModuleType):
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mod = mod.__name__
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if isinstance(mod, basestring):
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names.append(mod)
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else:
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raise TypeError("names must be modules or module names, not %s"%type(mod))
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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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Parameters
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----------
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dependencies: list/set of msg_ids or AsyncResult objects or output of Dependency.as_dict()
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The msg_ids to depend on
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all : bool [default True]
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Whether the dependency should be considered met when *all* depending tasks have completed
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or only when *any* have been completed.
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success : bool [default True]
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Whether to consider successes as fulfilling dependencies.
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failure : bool [default False]
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Whether to consider failures as fulfilling dependencies.
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If `all=success=True` and `failure=False`, then the task will fail with an ImpossibleDependency
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as soon as the first depended-upon task fails.
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"""
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all=True
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success=True
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failure=True
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def __init__(self, dependencies=[], all=True, success=True, failure=False):
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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 = dependencies.get('success', success)
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failure = dependencies.get('failure', failure)
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dependencies = dependencies.get('dependencies', [])
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ids = []
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# extract ids from various sources:
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if isinstance(dependencies, (basestring, AsyncResult)):
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dependencies = [dependencies]
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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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if not (success or failure):
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raise ValueError("Must depend on at least one of successes or failures!")
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self.success=success
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self.failure = failure
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def check(self, completed, failed=None):
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"""check whether our dependencies have been met."""
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if len(self) == 0:
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return True
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against = set()
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if self.success:
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against = completed
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if failed is not None and self.failure:
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against = against.union(failed)
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if self.all:
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return self.issubset(against)
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else:
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return not self.isdisjoint(against)
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def unreachable(self, completed, failed=None):
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"""return whether this dependency has become impossible."""
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if len(self) == 0:
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return False
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against = set()
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if not self.success:
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against = completed
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if failed is not None and not self.failure:
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against = against.union(failed)
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if self.all:
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return not self.isdisjoint(against)
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else:
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return self.issubset(against)
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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=self.success,
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failure=self.failure
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)
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__all__ = ['depend', 'require', 'dependent', 'Dependency']
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