onionr/src/onionrproofs/subprocesspow.py

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#!/usr/bin/env python3
"""Onionr - Private P2P Communication.
Multiprocess proof of work
"""
import os
from multiprocessing import Pipe, Process
import threading
import time
import onionrproofs
import ujson as json
import logger
import onionrcrypto as crypto
from onionrutils import bytesconverter
"""
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
"""
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class SubprocessPOW:
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def __init__(self, data, metadata, subproc_count=None):
"""
Onionr proof of work using multiple processes
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Accepts block data, block metadata
if subproc_count is not set,
os.cpu_count() is used to determine the number of processes
Due to Python GIL multiprocessing/use of external libraries
is necessary to accelerate CPU bound tasks
"""
# No known benefit to using more processes than there are cores.
# Note: os.cpu_count perhaps not always accurate
if subproc_count is None:
subproc_count = os.cpu_count()
self.subproc_count = subproc_count
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self.result = ''
self.shutdown = False
self.data = data
self.metadata = metadata
"""dump dict to measure bytes of json metadata
Cannot reuse later bc the pow token must be added
"""
json_metadata = json.dumps(metadata).encode()
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self.data = bytesconverter.str_to_bytes(data)
compiled_data = bytes(json_metadata + b'\n' + self.data)
# Calculate difficulty. May use better algorithm in the future.
self.difficulty = onionrproofs.getDifficultyForNewBlock(compiled_data)
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logger.info('Computing POW (difficulty: %s)...' % (self.difficulty,))
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self.main_hash = '0' * 64
self.puzzle = self.main_hash[0:min(self.difficulty,
len(self.main_hash))]
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self.shutdown = False
self.payload = None
def start(self):
"""spawn the multiproc handler threads"""
# Create a new thread for each subprocess
for _ in range(self.subproc_count): # noqa
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threading.Thread(target=self._spawn_proc, daemon=True).start()
# Monitor the processes for a payload, shut them down when its found
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while True:
if self.payload is None:
time.sleep(0.1)
else:
self.shutdown = True
return self.payload
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def _spawn_proc(self):
"""Create a child proof of work process
wait for data and send shutdown signal when its found"""
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parent_conn, child_conn = Pipe()
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p = Process(target=self.do_pow, args=(child_conn,), daemon=True)
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p.start()
p.join()
payload = None
try:
while True:
data = parent_conn.recv()
if len(data) >= 1:
payload = data
break
except KeyboardInterrupt:
pass
finally:
parent_conn.send('shutdown')
self.payload = payload
def do_pow(self, pipe):
"""find partial hash colision generating nonce for a block"""
nonce = 0
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data = self.data
metadata = self.metadata
puzzle = self.puzzle
difficulty = self.difficulty
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while True:
# Break if shutdown received
if pipe.poll() and pipe.recv() == 'shutdown':
break
# Load nonce into block metadata
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metadata['pow'] = nonce
# Serialize metadata, combine with block data
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payload = json.dumps(metadata).encode() + b'\n' + data
# Check sha3_256 hash of block, compare to puzzle
# Send payload if puzzle finished
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token = crypto.hashers.sha3_hash(payload)
# ensure token is string
token = bytesconverter.bytes_to_str(token)
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if puzzle == token[0:difficulty]:
pipe.send(payload)
break
nonce += 1