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ORPA-pyOpenRPA/WPy32-3720/python-3.7.2/Lib/site-packages/dask/delayed.py

647 lines
20 KiB

6 years ago
from __future__ import absolute_import, division, print_function
import operator
import types
import uuid
import warnings
try:
from cytoolz import curry, concat, unique, merge
except ImportError:
from toolz import curry, concat, unique, merge
from . import config, threaded
from .base import is_dask_collection, dont_optimize, DaskMethodsMixin
from .base import tokenize as _tokenize
from .compatibility import apply, Iterator, is_dataclass, dataclass_fields
from .core import quote
from .context import globalmethod
from .optimization import cull
from .utils import funcname, methodcaller, OperatorMethodMixin, ensure_dict
from .highlevelgraph import HighLevelGraph
__all__ = ['Delayed', 'delayed']
def unzip(ls, nout):
"""Unzip a list of lists into ``nout`` outputs."""
out = list(zip(*ls))
if not out:
out = [()] * nout
return out
def finalize(collection):
assert is_dask_collection(collection)
name = 'finalize-' + tokenize(collection)
keys = collection.__dask_keys__()
finalize, args = collection.__dask_postcompute__()
layer = {name: (finalize, keys) + args}
graph = HighLevelGraph.from_collections(name, layer, dependencies=[collection])
return Delayed(name, graph)
def unpack_collections(expr):
"""Normalize a python object and merge all sub-graphs.
- Replace ``Delayed`` with their keys
- Convert literals to things the schedulers can handle
- Extract dask graphs from all enclosed values
Parameters
----------
expr : object
The object to be normalized. This function knows how to handle
dask collections, as well as most builtin python types.
Returns
-------
task : normalized task to be run
collections : a tuple of collections
Examples
--------
>>> a = delayed(1, 'a')
>>> b = delayed(2, 'b')
>>> task, collections = unpack_collections([a, b, 3])
>>> task # doctest: +SKIP
['a', 'b', 3]
>>> collections # doctest: +SKIP
(a, b)
>>> task, collections = unpack_collections({a: 1, b: 2})
>>> task # doctest: +SKIP
(dict, [['a', 1], ['b', 2]])
>>> collections # doctest: +SKIP
{a, b}
"""
if isinstance(expr, Delayed):
return expr._key, (expr,)
if is_dask_collection(expr):
finalized = finalize(expr)
return finalized._key, (finalized,)
if isinstance(expr, Iterator):
expr = tuple(expr)
typ = type(expr)
if typ in (list, tuple, set):
args, collections = unzip((unpack_collections(e) for e in expr), 2)
args = list(args)
collections = tuple(unique(concat(collections), key=id))
# Ensure output type matches input type
if typ is not list:
args = (typ, args)
return args, collections
if typ is dict:
args, collections = unpack_collections([[k, v] for k, v in expr.items()])
return (dict, args), collections
if typ is slice:
args, collections = unpack_collections([expr.start, expr.stop, expr.step])
return (slice,) + tuple(args), collections
if is_dataclass(expr):
args, collections = unpack_collections([[f.name, getattr(expr, f.name)] for f in
dataclass_fields(expr)])
return (apply, typ, (), (dict, args)), collections
return expr, ()
def to_task_dask(expr):
"""Normalize a python object and merge all sub-graphs.
- Replace ``Delayed`` with their keys
- Convert literals to things the schedulers can handle
- Extract dask graphs from all enclosed values
Parameters
----------
expr : object
The object to be normalized. This function knows how to handle
``Delayed``s, as well as most builtin python types.
Returns
-------
task : normalized task to be run
dask : a merged dask graph that forms the dag for this task
Examples
--------
>>> a = delayed(1, 'a')
>>> b = delayed(2, 'b')
>>> task, dask = to_task_dask([a, b, 3])
>>> task # doctest: +SKIP
['a', 'b', 3]
>>> dict(dask) # doctest: +SKIP
{'a': 1, 'b': 2}
>>> task, dasks = to_task_dask({a: 1, b: 2})
>>> task # doctest: +SKIP
(dict, [['a', 1], ['b', 2]])
>>> dict(dask) # doctest: +SKIP
{'a': 1, 'b': 2}
"""
warnings.warn("The dask.delayed.to_dask_dask function has been "
"Deprecated in favor of unpack_collections", stacklevel=2)
if isinstance(expr, Delayed):
return expr.key, expr.dask
if is_dask_collection(expr):
name = 'finalize-' + tokenize(expr, pure=True)
keys = expr.__dask_keys__()
opt = getattr(expr, '__dask_optimize__', dont_optimize)
finalize, args = expr.__dask_postcompute__()
dsk = {name: (finalize, keys) + args}
dsk.update(opt(expr.__dask_graph__(), keys))
return name, dsk
if isinstance(expr, Iterator):
expr = list(expr)
typ = type(expr)
if typ in (list, tuple, set):
args, dasks = unzip((to_task_dask(e) for e in expr), 2)
args = list(args)
dsk = merge(dasks)
# Ensure output type matches input type
return (args, dsk) if typ is list else ((typ, args), dsk)
if typ is dict:
args, dsk = to_task_dask([[k, v] for k, v in expr.items()])
return (dict, args), dsk
if is_dataclass(expr):
args, dsk = to_task_dask([[f.name, getattr(expr, f.name)] for f in
dataclass_fields(expr)])
return (apply, typ, (), (dict, args)), dsk
if typ is slice:
args, dsk = to_task_dask([expr.start, expr.stop, expr.step])
return (slice,) + tuple(args), dsk
return expr, {}
def tokenize(*args, **kwargs):
"""Mapping function from task -> consistent name.
Parameters
----------
args : object
Python objects that summarize the task.
pure : boolean, optional
If True, a consistent hash function is tried on the input. If this
fails, then a unique identifier is used. If False (default), then a
unique identifier is always used.
"""
pure = kwargs.pop('pure', None)
if pure is None:
pure = config.get('delayed_pure', False)
if pure:
return _tokenize(*args, **kwargs)
else:
return str(uuid.uuid4())
@curry
def delayed(obj, name=None, pure=None, nout=None, traverse=True):
"""Wraps a function or object to produce a ``Delayed``.
``Delayed`` objects act as proxies for the object they wrap, but all
operations on them are done lazily by building up a dask graph internally.
Parameters
----------
obj : object
The function or object to wrap
name : string or hashable, optional
The key to use in the underlying graph for the wrapped object. Defaults
to hashing content. Note that this only affects the name of the object
wrapped by this call to delayed, and *not* the output of delayed
function calls - for that use ``dask_key_name=`` as described below.
pure : bool, optional
Indicates whether calling the resulting ``Delayed`` object is a pure
operation. If True, arguments to the call are hashed to produce
deterministic keys. If not provided, the default is to check the global
``delayed_pure`` setting, and fallback to ``False`` if unset.
nout : int, optional
The number of outputs returned from calling the resulting ``Delayed``
object. If provided, the ``Delayed`` output of the call can be iterated
into ``nout`` objects, allowing for unpacking of results. By default
iteration over ``Delayed`` objects will error. Note, that ``nout=1``
expects ``obj``, to return a tuple of length 1, and consequently for
``nout=0``, ``obj`` should return an empty tuple.
traverse : bool, optional
By default dask traverses builtin python collections looking for dask
objects passed to ``delayed``. For large collections this can be
expensive. If ``obj`` doesn't contain any dask objects, set
``traverse=False`` to avoid doing this traversal.
Examples
--------
Apply to functions to delay execution:
>>> def inc(x):
... return x + 1
>>> inc(10)
11
>>> x = delayed(inc, pure=True)(10)
>>> type(x) == Delayed
True
>>> x.compute()
11
Can be used as a decorator:
>>> @delayed(pure=True)
... def add(a, b):
... return a + b
>>> add(1, 2).compute()
3
``delayed`` also accepts an optional keyword ``pure``. If False, then
subsequent calls will always produce a different ``Delayed``. This is
useful for non-pure functions (such as ``time`` or ``random``).
>>> from random import random
>>> out1 = delayed(random, pure=False)()
>>> out2 = delayed(random, pure=False)()
>>> out1.key == out2.key
False
If you know a function is pure (output only depends on the input, with no
global state), then you can set ``pure=True``. This will attempt to apply a
consistent name to the output, but will fallback on the same behavior of
``pure=False`` if this fails.
>>> @delayed(pure=True)
... def add(a, b):
... return a + b
>>> out1 = add(1, 2)
>>> out2 = add(1, 2)
>>> out1.key == out2.key
True
Instead of setting ``pure`` as a property of the callable, you can also set
it contextually using the ``delayed_pure`` setting. Note that this
influences the *call* and not the *creation* of the callable:
>>> import dask
>>> @delayed
... def mul(a, b):
... return a * b
>>> with dask.config.set(delayed_pure=True):
... print(mul(1, 2).key == mul(1, 2).key)
True
>>> with dask.config.set(delayed_pure=False):
... print(mul(1, 2).key == mul(1, 2).key)
False
The key name of the result of calling a delayed object is determined by
hashing the arguments by default. To explicitly set the name, you can use
the ``dask_key_name`` keyword when calling the function:
>>> add(1, 2) # doctest: +SKIP
Delayed('add-3dce7c56edd1ac2614add714086e950f')
>>> add(1, 2, dask_key_name='three')
Delayed('three')
Note that objects with the same key name are assumed to have the same
result. If you set the names explicitly you should make sure your key names
are different for different results.
>>> add(1, 2, dask_key_name='three') # doctest: +SKIP
>>> add(2, 1, dask_key_name='three') # doctest: +SKIP
>>> add(2, 2, dask_key_name='four') # doctest: +SKIP
``delayed`` can also be applied to objects to make operations on them lazy:
>>> a = delayed([1, 2, 3])
>>> isinstance(a, Delayed)
True
>>> a.compute()
[1, 2, 3]
The key name of a delayed object is hashed by default if ``pure=True`` or
is generated randomly if ``pure=False`` (default). To explicitly set the
name, you can use the ``name`` keyword:
>>> a = delayed([1, 2, 3], name='mylist')
>>> a
Delayed('mylist')
Delayed results act as a proxy to the underlying object. Many operators
are supported:
>>> (a + [1, 2]).compute()
[1, 2, 3, 1, 2]
>>> a[1].compute()
2
Method and attribute access also works:
>>> a.count(2).compute()
1
Note that if a method doesn't exist, no error will be thrown until runtime:
>>> res = a.not_a_real_method()
>>> res.compute() # doctest: +SKIP
AttributeError("'list' object has no attribute 'not_a_real_method'")
"Magic" methods (e.g. operators and attribute access) are assumed to be
pure, meaning that subsequent calls must return the same results. This
behavior is not overrideable through the ``delayed`` call, but can be
modified using other ways as described below.
To invoke an impure attribute or operator, you'd need to use it in a
delayed function with ``pure=False``:
>>> class Incrementer(object):
... def __init__(self):
... self._n = 0
... @property
... def n(self):
... self._n += 1
... return self._n
...
>>> x = delayed(Incrementer())
>>> x.n.key == x.n.key
True
>>> get_n = delayed(lambda x: x.n, pure=False)
>>> get_n(x).key == get_n(x).key
False
In contrast, methods are assumed to be impure by default, meaning that
subsequent calls may return different results. To assume purity, set
`pure=True`. This allows sharing of any intermediate values.
>>> a.count(2, pure=True).key == a.count(2, pure=True).key
True
As with function calls, method calls also respect the global
``delayed_pure`` setting and support the ``dask_key_name`` keyword:
>>> a.count(2, dask_key_name="count_2")
Delayed('count_2')
>>> with dask.config.set(delayed_pure=True):
... print(a.count(2).key == a.count(2).key)
True
"""
if isinstance(obj, Delayed):
return obj
if is_dask_collection(obj) or traverse:
task, collections = unpack_collections(obj)
else:
task = quote(obj)
collections = set()
if task is obj:
if not (nout is None or (type(nout) is int and nout >= 0)):
raise ValueError("nout must be None or a non-negative integer,"
" got %s" % nout)
if not name:
try:
prefix = obj.__name__
except AttributeError:
prefix = type(obj).__name__
token = tokenize(obj, nout, pure=pure)
name = '%s-%s' % (prefix, token)
return DelayedLeaf(obj, name, pure=pure, nout=nout)
else:
if not name:
name = '%s-%s' % (type(obj).__name__, tokenize(task, pure=pure))
layer = {name: task}
graph = HighLevelGraph.from_collections(name, layer, dependencies=collections)
return Delayed(name, graph)
def right(method):
"""Wrapper to create 'right' version of operator given left version"""
def _inner(self, other):
return method(other, self)
return _inner
def optimize(dsk, keys, **kwargs):
dsk = ensure_dict(dsk)
dsk2, _ = cull(dsk, keys)
return dsk2
def rebuild(dsk, key, length):
return Delayed(key, dsk, length)
class Delayed(DaskMethodsMixin, OperatorMethodMixin):
"""Represents a value to be computed by dask.
Equivalent to the output from a single key in a dask graph.
"""
__slots__ = ('_key', 'dask', '_length')
def __init__(self, key, dsk, length=None):
self._key = key
self.dask = dsk
self._length = length
def __dask_graph__(self):
return self.dask
def __dask_keys__(self):
return [self.key]
def __dask_layers__(self):
return (self.key,)
def __dask_tokenize__(self):
return self.key
__dask_scheduler__ = staticmethod(threaded.get)
__dask_optimize__ = globalmethod(optimize, key='delayed_optimize')
def __dask_postcompute__(self):
return single_key, ()
def __dask_postpersist__(self):
return rebuild, (self._key, getattr(self, '_length', None))
def __getstate__(self):
return tuple(getattr(self, i) for i in self.__slots__)
def __setstate__(self, state):
for k, v in zip(self.__slots__, state):
setattr(self, k, v)
@property
def key(self):
return self._key
def __repr__(self):
return "Delayed({0})".format(repr(self.key))
def __hash__(self):
return hash(self.key)
def __dir__(self):
return dir(type(self))
def __getattr__(self, attr):
if attr.startswith('_'):
raise AttributeError("Attribute {0} not found".format(attr))
return DelayedAttr(self, attr)
def __setattr__(self, attr, val):
if attr in self.__slots__:
object.__setattr__(self, attr, val)
else:
raise TypeError("Delayed objects are immutable")
def __setitem__(self, index, val):
raise TypeError("Delayed objects are immutable")
def __iter__(self):
if getattr(self, '_length', None) is None:
raise TypeError("Delayed objects of unspecified length are "
"not iterable")
for i in range(self._length):
yield self[i]
def __len__(self):
if getattr(self, '_length', None) is None:
raise TypeError("Delayed objects of unspecified length have "
"no len()")
return self._length
def __call__(self, *args, **kwargs):
pure = kwargs.pop('pure', None)
name = kwargs.pop('dask_key_name', None)
func = delayed(apply, pure=pure)
if name is not None:
return func(self, args, kwargs, dask_key_name=name)
return func(self, args, kwargs)
def __bool__(self):
raise TypeError("Truth of Delayed objects is not supported")
__nonzero__ = __bool__
def __get__(self, instance, cls):
if instance is None:
return self
return types.MethodType(self, instance)
@classmethod
def _get_binary_operator(cls, op, inv=False):
method = delayed(right(op) if inv else op, pure=True)
return lambda *args, **kwargs: method(*args, **kwargs)
_get_unary_operator = _get_binary_operator
def call_function(func, func_token, args, kwargs, pure=None, nout=None):
dask_key_name = kwargs.pop('dask_key_name', None)
pure = kwargs.pop('pure', pure)
if dask_key_name is None:
name = '%s-%s' % (funcname(func),
tokenize(func_token, *args, pure=pure, **kwargs))
else:
name = dask_key_name
args2, collections = unzip(map(unpack_collections, args), 2)
collections = list(concat(collections))
if kwargs:
dask_kwargs, collections2 = unpack_collections(kwargs)
collections.extend(collections2)
task = (apply, func, list(args2), dask_kwargs)
else:
task = (func,) + args2
graph = HighLevelGraph.from_collections(name, {name: task},
dependencies=collections)
nout = nout if nout is not None else None
return Delayed(name, graph, length=nout)
class DelayedLeaf(Delayed):
__slots__ = ('_obj', '_key', '_pure', '_nout')
def __init__(self, obj, key, pure=None, nout=None):
self._obj = obj
self._key = key
self._pure = pure
self._nout = nout
@property
def dask(self):
return HighLevelGraph.from_collections(self._key, {self._key: self._obj},
dependencies=())
def __call__(self, *args, **kwargs):
return call_function(self._obj, self._key, args, kwargs,
pure=self._pure, nout=self._nout)
class DelayedAttr(Delayed):
__slots__ = ('_obj', '_attr', '_key')
def __init__(self, obj, attr):
self._obj = obj
self._attr = attr
self._key = 'getattr-%s' % tokenize(obj, attr, pure=True)
def __getattr__(self, attr):
# Calling np.dtype(dask.delayed(...)) used to result in a segfault, as
# numpy recursively tries to get `dtype` from the object. This is
# likely a bug in numpy. For now, we can do a dumb for if
# `x.dtype().dtype()` is called (which shouldn't ever show up in real
# code). See https://github.com/dask/dask/pull/4374#issuecomment-454381465
if attr == 'dtype' and self._attr == 'dtype':
raise AttributeError("Attribute %s not found" % attr)
return super(DelayedAttr, self).__getattr__(attr)
@property
def dask(self):
layer = {self._key: (getattr, self._obj._key, self._attr)}
return HighLevelGraph.from_collections(self._key, layer,
dependencies=[self._obj])
def __call__(self, *args, **kwargs):
return call_function(methodcaller(self._attr), self._attr, (self._obj,) + args, kwargs)
for op in [operator.abs, operator.neg, operator.pos, operator.invert,
operator.add, operator.sub, operator.mul, operator.floordiv,
operator.truediv, operator.mod, operator.pow, operator.and_,
operator.or_, operator.xor, operator.lshift, operator.rshift,
operator.eq, operator.ge, operator.gt, operator.ne, operator.le,
operator.lt, operator.getitem]:
Delayed._bind_operator(op)
try:
Delayed._bind_operator(operator.matmul)
except AttributeError:
pass
def single_key(seq):
""" Pick out the only element of this list, a list of keys """
return seq[0]