119 lines
3.4 KiB
Python
119 lines
3.4 KiB
Python
# -*- coding: utf-8 -*-
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#
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# Copyright 2012-2014 Romain Dorgueil
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from abc import ABCMeta, abstractmethod
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from queue import Queue
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from bonobo.constants import BEGIN, END
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from bonobo.errors import AbstractError, InactiveReadableError, InactiveWritableError
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from bonobo.nodes import noop
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BUFFER_SIZE = 8192
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class Readable(metaclass=ABCMeta):
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"""Interface for things you can read from."""
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@abstractmethod
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def get(self, block=True, timeout=None):
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"""Read. Block/timeout are there for Queue compat."""
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raise AbstractError(self.get)
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class Writable(metaclass=ABCMeta):
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"""Interface for things you can write to."""
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@abstractmethod
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def put(self, data, block=True, timeout=None):
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"""Write. Block/timeout are there for Queue compat."""
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raise AbstractError(self.put)
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class Input(Queue, Readable, Writable):
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def __init__(self, maxsize=BUFFER_SIZE):
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Queue.__init__(self, maxsize)
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self._runlevel = 0
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self._writable_runlevel = 0
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self.on_initialize = noop
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self.on_begin = noop
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self.on_end = noop
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self.on_finalize = noop
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def put(self, data, block=True, timeout=None):
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# Begin token is a metadata to raise the input runlevel.
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if data == BEGIN:
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if not self._runlevel:
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self.on_initialize()
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self._runlevel += 1
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self._writable_runlevel += 1
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# callback
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self.on_begin()
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return
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# Check we are actually able to receive data.
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if self._writable_runlevel < 1:
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raise InactiveWritableError('Cannot put() on an inactive {}.'.format(Writable.__name__))
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if data == END:
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self._writable_runlevel -= 1
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return Queue.put(self, data, block, timeout)
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def _decrement_runlevel(self):
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if self._runlevel == 1:
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self.on_finalize()
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self._runlevel -= 1
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self.on_end()
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def get(self, block=True, timeout=None):
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if not self.alive:
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raise InactiveReadableError('Cannot get() on an inactive {}.'.format(Readable.__name__))
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data = Queue.get(self, block, timeout)
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if data == END:
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self._decrement_runlevel()
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if not self.alive:
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raise InactiveReadableError(
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'Cannot get() on an inactive {} (runlevel just reached 0).'.format(Readable.__name__)
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)
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return self.get(block, timeout)
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return data
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def shutdown(self):
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while self._runlevel >= 1:
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self._decrement_runlevel()
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def empty(self):
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self.mutex.acquire()
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while self._qsize() and self.queue[0] == END:
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self._runlevel -= 1
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Queue._get(self)
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self.mutex.release()
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return Queue.empty(self)
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@property
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def alive(self):
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return self._runlevel > 0
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