mining_node.py

import hashlib
from time import time
from node import Node


class MiningNode(Node):
    def __init__(self, hostname: str = 'localhost', port: int = 5555) -> None:
        super().__init__(hostname, port, True)
        # Adds special commands for mining nodes
        self.miner_msg_commands = {
            'new_transaction': self.store_transaction
        }
        self.__recent_transactions = []
        self.__mining_difficulty = 6
        self.msg_commands.update(self.miner_msg_commands)

    def store_transaction(self, args) -> str:
        '''
            Stores the transactions after verification and after 10 transactions it includes them in a mined block
        '''
        transaction = args[0]
        self.verify_transaction(transaction)
        self.__recent_transactions += [transaction]
        if len(self.__recent_transactions) >= 10:
            self.mine_block()
            self.__recent_transactions = []
        return 'ok'

    def add_new_block(self, args) -> str:
        '''
            Adds a new block as a node does and if valid restores its transactions 
        '''
        block = args[0]
        response = super().add_new_block(args)
        if response == 'Ok':
            self.__recent_transactions = [i for i in self.__recent_transactions if not i in block['transactions']]
        return response


    def mine_block(self) -> None:
        '''
			This function mines a block meaning it tries different 'extra stuff' until the block hash has a mining dificullty amount of 0's
		'''
        timestamp = str(time())
        transactions_hash = self.merkle_tree(self.__recent_transactions)
        prev_block_hash = self.get_block_hash(self.blockchain['blocks'][-1])
        header_without_nonce = timestamp + transactions_hash + prev_block_hash
        extra_stuff = 0
        found_hash = False
        while not found_hash and self.__recent_transactions != []:
            if extra_stuff%1000000 == 0:
                print(f'Mining node in port {self.port} tryied till {extra_stuff} with timestamp {timestamp}')
            if hashlib.sha256((header_without_nonce + str(extra_stuff)).encode('utf-8')).hexdigest()[:self.__mining_difficulty] == '0'*self.__mining_difficulty:
                found_hash = True
                new_block = {
                    'timestamp': timestamp,
                    'prev_block_hash': prev_block_hash,
                    'merkle_tree_hash': transactions_hash,
                    'extra_stuff': extra_stuff,
                    'transactions': self.__recent_transactions

                }
                print(f'Miner on port {self.port} succeded to hash block with extra stuff: {extra_stuff}')
                # Sends the mined block to all nodes for blockchain updating
                for i in self.mining_nodes: 
                    self.send({'command': 'new_block', 'data': [new_block]}, tuple(i)) 
                for i in self.peers:
                    self.send({'command': 'new_block', 'data': [new_block]}, tuple(i))
                self.blockchain['blocks'] += [new_block] 
                self.__recent_transactions = []
            else:
                extra_stuff += 1