def _get_checkpoints(cls, db: DatabaseAPI) -> Tuple[Hash32, ...]:
concatenated_checkpoints = db.get(
SchemaV1.make_checkpoint_headers_key())
if concatenated_checkpoints is None:
return ()
else:
return tuple(
Hash32(concatenated_checkpoints[index:index + 32])
for index in range(0, len(concatenated_checkpoints), 32))
def _persist_checkpoint_header(
cls,
db: DatabaseAPI,
header: BlockHeaderAPI,
score: int
) -> None:
db.set(
header.hash,
rlp.encode(header),
)
# Add new checkpoint header
previous_checkpoints = cls._get_checkpoints(db)
new_checkpoints = previous_checkpoints + (header.hash,)
db.set(
SchemaV1.make_checkpoint_headers_key(),
b''.join(new_checkpoints),
)
previous_score = score - header.difficulty
cls._set_hash_scores_to_db(db, header, previous_score)
cls._set_as_canonical_chain_head(db, header, GENESIS_PARENT_HASH)
_, gaps = cls._update_header_chain_gaps(db, header)
# check if the parent block number exists, and is not a match for checkpoint.parent_hash
parent_block_num = BlockNumber(header.block_number - 1)
try:
parent_hash = cls._get_canonical_block_hash(db, parent_block_num)
except HeaderNotFound:
# no parent to check
pass
else:
# User is asserting that the checkpoint must be canonical, so if the parent doesn't
# match, then the parent must not be canonical, and should be de-canonicalized.
if parent_hash != header.parent_hash:
# does the correct header exist in the database?
try:
true_parent = cls._get_block_header_by_hash(db, header.parent_hash)
except HeaderNotFound:
# True parent unavailable, just delete the now non-canonical one
cls._decanonicalize_single(db, parent_block_num, gaps)
else:
# True parent should have already been canonicalized during
# _set_as_canonical_chain_head()
raise ValidationError(
f"Why was a non-matching parent header {parent_hash!r} left as canonical "
f"after _set_as_canonical_chain_head() and {true_parent} is available?"
)
cls._decanonicalize_descendant_orphans(db, header, new_checkpoints)