Pass asynchronous websocket.send() to stdout/stderr wrapper class - python-3.x

Question

I have a class function which unbuffers stdout and stderr, like so:
class Unbuffered:
def __init__(self, stream):
self.stream = stream
def write(self, data):
data = data.strip()
if data.startswith("INFO: "):
data = data[6:]
if '[' in data:
progress = re.compile(r"\[(\d+)/(\d+)\]")
data = progress.match(data)
total = data.group(2)
current = data.group(1)
data = '{0}/{1}'.format(current, total)
if data.startswith("ERROR: "):
data = data[7:]
self.stream.write(data + '\n')
self.stream.flush()
def __getattr__(self, attr):
return getattr(self.stream, attr)
The output is from a function run in ProcessPoolExecutor when inbound from websocket arrives.
I want the output printed in console as well as sent to my websocket client. I tried asyncing Unbuffered and passing websocket instance to it but no luck.
UPDATE: The essentials of run() and my websocket handler() look something like this:
def run(url, path):
logging.addLevelName(25, "INFO")
fmt = logging.Formatter('%(levelname)s: %(message)s')
#----
output.progress_stream = Unbuffered(sys.stderr)
stream = Unbuffered(sys.stdout)
#----
level = logging.INFO
hdlr = logging.StreamHandler(stream)
hdlr.setFormatter(fmt)
log.addHandler(hdlr)
log.setLevel(level)
get_media(url, opt)
async def handler(websocket, path):
while True:
inbound = json.loads(await websocket.recv())
if inbound is None:
break
url = inbound['url']
if 'path' in inbound:
path = inbound['path'].rstrip(os.path.sep) + os.path.sep
else:
path = os.path.expanduser("~") + os.path.sep
# blah more code
while inbound != None:
await asyncio.sleep(.001)
await loop.run_in_executor(None, run, url, path)
run(), handler() and Unbuffered are separate from each other.

Answer 1

Rewriting get_media() to use asyncio instead of running it in a different thread would be the best. Otherwise, there are some options to communicate between a regular thread and coroutines, for example, using a socketpair:
import asyncio
import socket
import threading
import time
import random
# threads stuff
def producer(n, writer):
for i in range(10):
# print("sending", i)
writer.send("message #{}.{}\n".format(n, i).encode())
time.sleep(random.uniform(0.1, 1))
def go(writer):
threads = [threading.Thread(target=producer, args=(i + 1, writer,))
for i in range(5)]
for t in threads:
t.start()
for t in threads:
t.join()
writer.send("bye\n".encode())
# asyncio coroutines
async def clock():
for i in range(11):
print("The time is", i)
await asyncio.sleep(1)
async def main(reader):
buffer = ""
while True:
buffer += (await loop.sock_recv(reader, 10000)).decode()
# print(len(buffer))
while "\n" in buffer:
msg, _nl, buffer = buffer.partition("\n")
print("Got", msg)
if msg == "bye":
return
reader, writer = socket.socketpair()
reader.setblocking(False)
threading.Thread(target=go, args=(writer,)).start()
# time.sleep(1.5) # socket is buffering
loop = asyncio.get_event_loop()
loop.run_until_complete(asyncio.wait([clock(), main(reader)]))
loop.close()
You can also try this 3rd-party thread+asyncio compatible queue: janus