py-libp2p/demos/bee_movie/ordered_queue.py

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2019-04-05 05:05:53 +08:00
import asyncio
"""
NOTE: ISSUE IS THAT THERE task IS BLOCKING SINCE IT IS WAITING ON SAME COROUTINE THAT
WE ARE RUNNING ON
"""
class OrderedQueue():
def __init__(self):
self.last_gotten_seqno = 0
self.queue = asyncio.PriorityQueue()
self.task = None
async def put(self, item):
print("Put " + str(item))
seqno = item[0]
await self.queue.put(item)
print("Added to queue " + str(item))
if self.last_gotten_seqno + 1 == seqno and self.task is not None:
# Allow get future to return the most recent item that is put
print("Set called")
self.task.set()
async def get(self):
print("get")
print(str(self.last_gotten_seqno))
if self.queue.qsize() > 0:
front_item = await self.queue.get()
if front_item[0] == self.last_gotten_seqno + 1:
print("Trivial get " + str(front_item))
self.last_gotten_seqno += 1
return front_item
else:
# Put element back as it should not be delivered yet
print("Front item put back 1")
print(str(self.last_gotten_seqno))
print(front_item[1])
await self.queue.put(front_item)
print("Front item put back 2")
print("get 2")
# Wait until
self.task = asyncio.Event()
print("get 3")
await self.task.wait()
print("get 4")
item = await self.queue.get()
print("get 5")
# print(str(item) + " got from queue")
# Remove task
self.task = None
self.last_gotten_seqno += 1
return item