contrib/zmq/zmq_sub.py

   1 #!/usr/bin/env python3
   2 # Copyright (c) 2014-2016 The Bitcoin Core developers
   3 # Distributed under the MIT software license, see the accompanying
   4 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
   5
   6 """
   7     ZMQ example using python3's asyncio
   8
   9     Bitcoin should be started with the command line arguments:
  10         bitcoind -testnet -daemon \
  11                 -zmqpubhashblock=tcp://127.0.0.1:28332 \
  12                 -zmqpubrawtx=tcp://127.0.0.1:28332 \
  13                 -zmqpubhashtx=tcp://127.0.0.1:28332 \
  14                 -zmqpubhashblock=tcp://127.0.0.1:28332
  15
  16     We use the asyncio library here.  `self.handle()` installs itself as a
  17     future at the end of the function.  Since it never returns with the event
  18     loop having an empty stack of futures, this creates an infinite loop.  An
  19     alternative is to wrap the contents of `handle` inside `while True`.
  20
  21     A blocking example using python 2.7 can be obtained from the git history:
  22     https://github.com/bitcoin/bitcoin/blob/37a7fe9e440b83e2364d5498931253937abe9294/contrib/zmq/zmq_sub.py
  23 """
  24
  25 import binascii
  26 import asyncio
  27 import zmq
  28 import zmq.asyncio
  29 import signal
  30 import struct
  31 import sys
  32
  33 if not (sys.version_info.major >= 3 and sys.version_info.minor >= 5):
  34     print("This example only works with Python 3.5 and greater")
  35     sys.exit(1)
  36
  37 port = 28332
  38
  39 class ZMQHandler():
  40     def __init__(self):
  41         self.loop = zmq.asyncio.install()
  42         self.zmqContext = zmq.asyncio.Context()
  43
  44         self.zmqSubSocket = self.zmqContext.socket(zmq.SUB)
  45         self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "hashblock")
  46         self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "hashtx")
  47         self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "rawblock")
  48         self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "rawtx")
  49         self.zmqSubSocket.connect("tcp://127.0.0.1:%i" % port)
  50
  51     async def handle(self) :
  52         msg = await self.zmqSubSocket.recv_multipart()
  53         topic = msg[0]
  54         body = msg[1]
  55         sequence = "Unknown"
  56         if len(msg[-1]) == 4:
  57           msgSequence = struct.unpack('<I', msg[-1])[-1]
  58           sequence = str(msgSequence)
  59         if topic == b"hashblock":
  60             print('- HASH BLOCK ('+sequence+') -')
  61             print(binascii.hexlify(body))
  62         elif topic == b"hashtx":
  63             print('- HASH TX  ('+sequence+') -')
  64             print(binascii.hexlify(body))
  65         elif topic == b"rawblock":
  66             print('- RAW BLOCK HEADER ('+sequence+') -')
  67             print(binascii.hexlify(body[:80]))
  68         elif topic == b"rawtx":
  69             print('- RAW TX ('+sequence+') -')
  70             print(binascii.hexlify(body))
  71         # schedule ourselves to receive the next message
  72         asyncio.ensure_future(self.handle())
  73
  74     def start(self):
  75         self.loop.add_signal_handler(signal.SIGINT, self.stop)
  76         self.loop.create_task(self.handle())
  77         self.loop.run_forever()
  78
  79     def stop(self):
  80         self.loop.stop()
  81         self.zmqContext.destroy()
  82
  83 daemon = ZMQHandler()
  84 daemon.start()