def create_block(self, moves, commit=True, click=None):
""" Create a block. """
for move in moves:
if not move.valid:
raise InvalidMoveError(move)
block = Block(version=PROTOCOL_VERSION)
block.root_hash = h(''.join(sorted(
(m.id for m in moves))).encode('utf-8')).hexdigest()
block.creator = self.address
block.created_at = datetime.datetime.utcnow()
prev_block = self.session.query(Block).order_by(
Block.id.desc()).first()
if prev_block:
block.id = prev_block.id + 1
block.prev_hash = prev_block.hash
block.difficulty = prev_block.difficulty
difficulty_check_block = self.session.query(Block).get(
max(1, block.id - 10))
avg_timedelta = (
(block.created_at - difficulty_check_block.created_at) /
(block.id - difficulty_check_block.id))
if click:
click.echo(
f'avg: {avg_timedelta}, difficulty: {block.difficulty}')
if avg_timedelta <= datetime.timedelta(0, 5):
block.difficulty = max(0, block.difficulty + 1)
elif avg_timedelta > datetime.timedelta(0, 15):
block.difficulty = max(0, block.difficulty - 1)
else:
#: Genesis block
block.id = 1
block.prev_hash = None
block.difficulty = 0
block.suffix = hashcash._mint(block.serialize(), bits=block.difficulty)
if self.session.query(Block).get(block.id):
return None
block.hash = h(block.serialize() + block.suffix).hexdigest()
for move in moves:
move.block = block
if not block.valid:
raise InvalidBlockError
if commit:
try:
self.session.add(block)
self.session.commit()
except IntegrityError:
return None
return block
def test_mint(challenge, bits):
answer = _mint(challenge, bits)
stamp = challenge + answer
digest = hashlib.sha256(stamp)
assert has_leading_zero_bits(digest.digest(), bits)
assert check(stamp)