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75 lines
2.5 KiB
Python
75 lines
2.5 KiB
Python
import time
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import json
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from collections import deque
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from .base import BaseChannelBackend
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queues = {}
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groups = {}
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class InMemoryChannelBackend(BaseChannelBackend):
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"""
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In-memory channel implementation. Intended only for use with threading,
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in low-throughput development environments.
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"""
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local_only = True
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def send(self, channel, message):
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# Try JSON encoding it to make sure it would, but store the native version
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json.dumps(message)
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# Add to the deque, making it if needs be
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queues.setdefault(channel, deque()).append((message, time.time() + self.expiry))
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def receive_many(self, channels):
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if not channels:
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raise ValueError("Cannot receive on empty channel list!")
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# Try to pop a message from each channel
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self._clean_expired()
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for channel in channels:
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try:
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# This doesn't clean up empty channels - OK for testing.
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# For later versions, have cleanup w/lock.
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return channel, queues[channel].popleft()[0]
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except (IndexError, KeyError):
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pass
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return None, None
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def _clean_expired(self):
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# Handle expired messages
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for channel, messages in queues.items():
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while len(messages) and messages[0][1] < time.time():
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messages.popleft()
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# Handle expired groups
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for group, channels in list(groups.items()):
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for channel, expiry in list(channels.items()):
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if expiry < (time.time() - 10):
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try:
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del groups[group][channel]
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except KeyError:
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# Another thread might have got there first
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pass
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def group_add(self, group, channel, expiry=None):
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"""
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Adds the channel to the named group for at least 'expiry'
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seconds (expiry defaults to message expiry if not provided).
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"""
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groups.setdefault(group, {})[channel] = time.time() + (expiry or self.expiry)
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def group_discard(self, group, channel):
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"""
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Removes the channel from the named group if it is in the group;
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does nothing otherwise (does not error)
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"""
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try:
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del groups[group][channel]
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except KeyError:
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pass
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def group_channels(self, group):
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"""
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Returns an iterable of all channels in the group.
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"""
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self._clean_expired()
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return groups.get(group, {}).keys()
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