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#!/usr/bin/env python
#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
#
"""
Support for amqp 'reference' content (as opposed to inline content)
"""
import threading
from queue import Queue, Closed
class NotOpened(Exception): pass
class AlreadyOpened(Exception): pass
"""
A representation of a reference id; can be passed wherever amqp
content is required in place of inline data
"""
class ReferenceId:
def __init__(self, id):
self.id = id
"""
Holds content received through 'reference api'. Instances of this
class will be placed in the consumers queue on receiving a transfer
(assuming the reference has been opened). Data can be retrieved in
chunks (as append calls are received) or in full (after reference has
been closed signalling data s complete).
"""
class Reference:
def __init__(self, id):
self.id = id
self.chunks = Queue(0)
def close(self):
self.chunks.close()
def append(self, bytes):
self.chunks.put(bytes)
def get_chunk(self):
return self.chunks.get()
def get_complete(self):
data = ""
for chunk in self:
data += chunk
return data
def next(self):
try:
return self.get_chunk()
except Closed, e:
raise StopIteration
def __iter__(self):
return self
"""
Manages a set of opened references. New references can be opened and
existing references can be retrieved or closed.
"""
class References:
def __init__(self):
self.map = {}
self.lock = threading.Lock()
def get(self, id):
self.lock.acquire()
try:
try:
ref = self.map[id]
except KeyError:
raise NotOpened()
finally:
self.lock.release()
return ref
def open(self, id):
self.lock.acquire()
try:
if id in self.map: raise AlreadyOpened()
self.map[id] = Reference(id)
finally:
self.lock.release()
def close(self, id):
self.get(id).close()
self.lock.acquire()
try:
self.map.pop(id)
finally:
self.lock.release()
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