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remotefunction.py
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"""Remote Functions and decorators for the client."""
#-----------------------------------------------------------------------------
# Copyright (C) 2010 The IPython Development Team
#
# Distributed under the terms of the BSD License. The full license is in
# the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
import warnings
from IPython.testing import decorators as testdec
from . import map as Map
from .asyncresult import AsyncMapResult
#-----------------------------------------------------------------------------
# Decorators
#-----------------------------------------------------------------------------
@testdec.skip_doctest
def remote(client, bound=True, block=None, targets=None, balanced=None):
"""Turn a function into a remote function.
This method can be used for map:
In [1]: @remote(client,block=True)
...: def func(a):
...: pass
"""
def remote_function(f):
return RemoteFunction(client, f, bound, block, targets, balanced)
return remote_function
@testdec.skip_doctest
def parallel(client, dist='b', bound=True, block=None, targets='all', balanced=None):
"""Turn a function into a parallel remote function.
This method can be used for map:
In [1]: @parallel(client,block=True)
...: def func(a):
...: pass
"""
def parallel_function(f):
return ParallelFunction(client, f, dist, bound, block, targets, balanced)
return parallel_function
#--------------------------------------------------------------------------
# Classes
#--------------------------------------------------------------------------
class RemoteFunction(object):
"""Turn an existing function into a remote function.
Parameters
----------
client : Client instance
The client to be used to connect to engines
f : callable
The function to be wrapped into a remote function
bound : bool [default: False]
Whether the affect the remote namespace when called
block : bool [default: None]
Whether to wait for results or not. The default behavior is
to use the current `block` attribute of `client`
targets : valid target list [default: all]
The targets on which to execute.
balanced : bool
Whether to load-balance with the Task scheduler or not
"""
client = None # the remote connection
func = None # the wrapped function
block = None # whether to block
bound = None # whether to affect the namespace
targets = None # where to execute
balanced = None # whether to load-balance
def __init__(self, client, f, bound=False, block=None, targets=None, balanced=None):
self.client = client
self.func = f
self.block=block
self.bound=bound
self.targets=targets
if balanced is None:
if targets is None:
balanced = True
else:
balanced = False
self.balanced = balanced
def __call__(self, *args, **kwargs):
return self.client.apply(self.func, args=args, kwargs=kwargs,
block=self.block, targets=self.targets, bound=self.bound, balanced=self.balanced)
class ParallelFunction(RemoteFunction):
"""Class for mapping a function to sequences.
This will distribute the sequences according the a mapper, and call
the function on each sub-sequence. If called via map, then the function
will be called once on each element, rather that each sub-sequence.
Parameters
----------
client : Client instance
The client to be used to connect to engines
f : callable
The function to be wrapped into a remote function
bound : bool [default: False]
Whether the affect the remote namespace when called
block : bool [default: None]
Whether to wait for results or not. The default behavior is
to use the current `block` attribute of `client`
targets : valid target list [default: all]
The targets on which to execute.
balanced : bool
Whether to load-balance with the Task scheduler or not
chunk_size : int or None
The size of chunk to use when breaking up sequences in a load-balanced manner
"""
def __init__(self, client, f, dist='b', bound=False, block=None, targets='all', balanced=None, chunk_size=None):
super(ParallelFunction, self).__init__(client,f,bound,block,targets,balanced)
self.chunk_size = chunk_size
mapClass = Map.dists[dist]
self.mapObject = mapClass()
def __call__(self, *sequences):
len_0 = len(sequences[0])
for s in sequences:
if len(s)!=len_0:
msg = 'all sequences must have equal length, but %i!=%i'%(len_0,len(s))
raise ValueError(msg)
if self.balanced:
if self.chunk_size:
nparts = len_0/self.chunk_size + int(len_0%self.chunk_size > 0)
else:
nparts = len_0
targets = [self.targets]*nparts
else:
if self.chunk_size:
warnings.warn("`chunk_size` is ignored when `balanced=False", UserWarning)
# multiplexed:
targets = self.client._build_targets(self.targets)[-1]
nparts = len(targets)
msg_ids = []
# my_f = lambda *a: map(self.func, *a)
for index, t in enumerate(targets):
args = []
for seq in sequences:
part = self.mapObject.getPartition(seq, index, nparts)
if len(part) == 0:
continue
else:
args.append(part)
if not args:
continue
# print (args)
if hasattr(self, '_map'):
f = map
args = [self.func]+args
else:
f=self.func
ar = self.client.apply(f, args=args, block=False, bound=self.bound,
targets=t, balanced=self.balanced)
msg_ids.append(ar.msg_ids[0])
r = AsyncMapResult(self.client, msg_ids, self.mapObject, fname=self.func.__name__)
if self.block:
try:
return r.get()
except KeyboardInterrupt:
return r
else:
return r
def map(self, *sequences):
"""call a function on each element of a sequence remotely.
This should behave very much like the builtin map, but return an AsyncMapResult
if self.block is False.
"""
# set _map as a flag for use inside self.__call__
self._map = True
try:
ret = self.__call__(*sequences)
finally:
del self._map
return ret
__all__ = ['remote', 'parallel', 'RemoteFunction', 'ParallelFunction']