def get_last_block_hash():
"""
Gets the highest block's hash.
Returns:
string -- hash of the highest block
"""
block_dal = BlockServiceDal()
max_height = block_dal.get_max_block_height()
latest_blocks = block_dal.find_by_height(max_height)
if len(latest_blocks) != 0:
return latest_blocks[0]._hash
else:
return ''
def remove_stale_blocks():
"""
Removes stale, unused blocks.
Blocks are removed if starting from the newest block, they do not appear when following the chain of previous blocks.
ie.
[]<-[]<-[]<-[]<-[]<-[]<-[]<-[]<-[]<-[]
^---[]<-[]<-[]<-[]<-[]
In the above scenario, the bottom chain would be removed, moving all of those transactions back to the mempool.
"""
block_dal = BlockServiceDal()
current_height = block_dal.get_max_block_height()
highest_blocks = block_dal.find_by_height(current_height)
# if there is only 1 block at the greatest height, we can prune old blocks
if len(highest_blocks) == 1:
# get all block hashes
all_block_hashes = block_dal.get_all_block_hashes()
correct_block_hashes = set()
block = highest_blocks[0]
# add current highest block to the set of correct blocks
correct_block_hashes.add(block._hash)
# TODO while there is still a previous block
while block.prev_block != 'GENESIS_BLOCK':
block = block_dal.find_by_hash(block.prev_block)
# add to list of correct blocks
correct_block_hashes.add(block._hash)
print("correct_block_hashes len: " +
str(len(correct_block_hashes)))
print("\t" + str(correct_block_hashes))
# get the difference between the two sets of blocks
to_remove = set(all_block_hashes) - correct_block_hashes
print("to_remove: " + str(to_remove))
# remove each of the blocks
for block_hash in to_remove:
print("Removing block: " + block_hash)
BlockService._remove_block_by_hash(block_hash)
def get_max_height():
"""
Method Comment
"""
block_service_dal = BlockServiceDal()
return block_service_dal.get_max_block_height()