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#!/usr/bin/env python3
# Copyright (c) 2014-2017 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""
ZMQ example using python3's asyncio
Bitcoin should be started with the command line arguments:
bitcoind -testnet -daemon \
-zmqpubrawtx=tcp://127.0.0.1:28332 \
-zmqpubrawblock=tcp://127.0.0.1:28332 \
-zmqpubhashtx=tcp://127.0.0.1:28332 \
-zmqpubhashblock=tcp://127.0.0.1:28332
We use the asyncio library here. `self.handle()` installs itself as a
future at the end of the function. Since it never returns with the event
loop having an empty stack of futures, this creates an infinite loop. An
alternative is to wrap the contents of `handle` inside `while True`.
The `@asyncio.coroutine` decorator and the `yield from` syntax found here
was introduced in python 3.4 and has been deprecated in favor of the `async`
and `await` keywords respectively.
A blocking example using python 2.7 can be obtained from the git history:
https://github.com/bitcoin/bitcoin/blob/37a7fe9e440b83e2364d5498931253937abe9294/contrib/zmq/zmq_sub.py
"""
import binascii
import asyncio
import zmq
import zmq.asyncio
import signal
import struct
import sys
if not (sys.version_info.major >= 3 and sys.version_info.minor >= 4):
print("This example only works with Python 3.4 and greater")
sys.exit(1)
port = 28332
class ZMQHandler():
def __init__(self):
self.loop = zmq.asyncio.install()
self.zmqContext = zmq.asyncio.Context()
self.zmqSubSocket = self.zmqContext.socket(zmq.SUB)
self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "hashblock")
self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "hashtx")
self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "rawblock")
self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "rawtx")
self.zmqSubSocket.connect("tcp://127.0.0.1:%i" % port)
@asyncio.coroutine
def handle(self) :
msg = yield from self.zmqSubSocket.recv_multipart()
topic = msg[0]
body = msg[1]
sequence = "Unknown"
if len(msg[-1]) == 4:
msgSequence = struct.unpack('<I', msg[-1])[-1]
sequence = str(msgSequence)
if topic == b"hashblock":
print('- HASH BLOCK ('+sequence+') -')
print(binascii.hexlify(body))
elif topic == b"hashtx":
print('- HASH TX ('+sequence+') -')
print(binascii.hexlify(body))
elif topic == b"rawblock":
print('- RAW BLOCK HEADER ('+sequence+') -')
print(binascii.hexlify(body[:80]))
elif topic == b"rawtx":
print('- RAW TX ('+sequence+') -')
print(binascii.hexlify(body))
# schedule ourselves to receive the next message
asyncio.ensure_future(self.handle())
def start(self):
self.loop.add_signal_handler(signal.SIGINT, self.stop)
self.loop.create_task(self.handle())
self.loop.run_forever()
def stop(self):
self.loop.stop()
self.zmqContext.destroy()
daemon = ZMQHandler()
daemon.start()
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