"""Cross-interpreter Channels High Level Module."""
import time
import _interpchannels as _channels
from . import _crossinterp
# aliases:
from _interpchannels import (
ChannelError, ChannelNotFoundError, ChannelClosedError,
ChannelEmptyError, ChannelNotEmptyError,
)
from ._crossinterp import (
UNBOUND_ERROR, UNBOUND_REMOVE,
)
__all__ = [
'UNBOUND', 'UNBOUND_ERROR', 'UNBOUND_REMOVE',
'create', 'list_all',
'SendChannel', 'RecvChannel',
'ChannelError', 'ChannelNotFoundError', 'ChannelEmptyError',
'ItemInterpreterDestroyed',
]
class ItemInterpreterDestroyed(ChannelError,
_crossinterp.ItemInterpreterDestroyed):
"""Raised from get() and get_nowait()."""
UNBOUND = _crossinterp.UnboundItem.singleton('queue', __name__)
def _serialize_unbound(unbound):
if unbound is UNBOUND:
unbound = _crossinterp.UNBOUND
return _crossinterp.serialize_unbound(unbound)
def _resolve_unbound(flag):
resolved = _crossinterp.resolve_unbound(flag, ItemInterpreterDestroyed)
if resolved is _crossinterp.UNBOUND:
resolved = UNBOUND
return resolved
def create(*, unbounditems=UNBOUND):
"""Return (recv, send) for a new cross-interpreter channel.
The channel may be used to pass data safely between interpreters.
"unbounditems" sets the default for the send end of the channel.
See SendChannel.send() for supported values. The default value
is UNBOUND, which replaces the unbound item when received.
"""
unbound = _serialize_unbound(unbounditems)
unboundop, = unbound
cid = _channels.create(unboundop)
recv, send = RecvChannel(cid), SendChannel(cid, _unbound=unbound)
return recv, send
def list_all():
"""Return a list of (recv, send) for all open channels."""
return [(RecvChannel(cid), SendChannel(cid, _unbound=unbound))
for cid, unbound in _channels.list_all()]
class _ChannelEnd:
"""The base class for RecvChannel and SendChannel."""
_end = None
def __new__(cls, cid):
self = super().__new__(cls)
if self._end == 'send':
cid = _channels._channel_id(cid, send=True, force=True)
elif self._end == 'recv':
cid = _channels._channel_id(cid, recv=True, force=True)
else:
raise NotImplementedError(self._end)
self._id = cid
return self
def __repr__(self):
return f'{type(self).__name__}(id={int(self._id)})'
def __hash__(self):
return hash(self._id)
def __eq__(self, other):
if isinstance(self, RecvChannel):
if not isinstance(other, RecvChannel):
return NotImplemented
elif not isinstance(other, SendChannel):
return NotImplemented
return other._id == self._id
# for pickling:
def __getnewargs__(self):
return (int(self._id),)
# for pickling:
def __getstate__(self):
return None
@property
def id(self):
return self._id
@property
def _info(self):
return _channels.get_info(self._id)
@property
def is_closed(self):
return self._info.closed
_NOT_SET = object()
class RecvChannel(_ChannelEnd):
"""The receiving end of a cross-interpreter channel."""
_end = 'recv'
def recv(self, timeout=None, *,
_sentinel=object(),
_delay=10 / 1000, # 10 milliseconds
):
"""Return the next object from the channel.
This blocks until an object has been sent, if none have been
sent already.
"""
if timeout is not None:
timeout = int(timeout)
if timeout < 0:
raise ValueError(f'timeout value must be non-negative')
end = time.time() + timeout
obj, unboundop = _channels.recv(self._id, _sentinel)
while obj is _sentinel:
time.sleep(_delay)
if timeout is not None and time.time() >= end:
raise TimeoutError
obj, unboundop = _channels.recv(self._id, _sentinel)
if unboundop is not None:
assert obj is None, repr(obj)
return _resolve_unbound(unboundop)
return obj
def recv_nowait(self, default=_NOT_SET):
"""Return the next object from the channel.
If none have been sent then return the default if one
is provided or fail with ChannelEmptyError. Otherwise this
is the same as recv().
"""
if default is _NOT_SET:
obj, unboundop = _channels.recv(self._id)
else:
obj, unboundop = _channels.recv(self._id, default)
if unboundop is not None:
assert obj is None, repr(obj)
return _resolve_unbound(unboundop)
return obj
def close(self):
_channels.close(self._id, recv=True)
class SendChannel(_ChannelEnd):
"""The sending end of a cross-interpreter channel."""
_end = 'send'
def __new__(cls, cid, *, _unbound=None):
if _unbound is None:
try:
op = _channels.get_channel_defaults(cid)
_unbound = (op,)
except ChannelNotFoundError:
_unbound = _serialize_unbound(UNBOUND)
self = super().__new__(cls, cid)
self._unbound = _unbound
return self
@property
def is_closed(self):
info = self._info
return info.closed or info.closing
def send(self, obj, timeout=None, *,
unbound=None,
):
"""Send the object (i.e. its data) to the channel's receiving end.
This blocks until the object is received.
"""
if unbound is None:
unboundop, = self._unbound
else:
unboundop, = _serialize_unbound(unbound)
_channels.send(self._id, obj, unboundop, timeout=timeout, blocking=True)
def send_nowait(self, obj, *,
unbound=None,
):
"""Send the object to the channel's receiving end.
If the object is immediately received then return True
(else False). Otherwise this is the same as send().
"""
if unbound is None:
unboundop, = self._unbound
else:
unboundop, = _serialize_unbound(unbound)
# XXX Note that at the moment channel_send() only ever returns
# None. This should be fixed when channel_send_wait() is added.
# See bpo-32604 and gh-19829.
return _channels.send(self._id, obj, unboundop, blocking=False)
def send_buffer(self, obj, timeout=None, *,
unbound=None,
):
"""Send the object's buffer to the channel's receiving end.
This blocks until the object is received.
"""
if unbound is None:
unboundop, = self._unbound
else:
unboundop, = _serialize_unbound(unbound)
_channels.send_buffer(self._id, obj, unboundop,
timeout=timeout, blocking=True)
def send_buffer_nowait(self, obj, *,
unbound=None,
):
"""Send the object's buffer to the channel's receiving end.
If the object is immediately received then return True
(else False). Otherwise this is the same as send().
"""
if unbound is None:
unboundop, = self._unbound
else:
unboundop, = _serialize_unbound(unbound)
return _channels.send_buffer(self._id, obj, unboundop, blocking=False)
def close(self):
_channels.close(self._id, send=True)
# XXX This is causing leaks (gh-110318):
_channels._register_end_types(SendChannel, RecvChannel)
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