def get_utxoset_merkle_root(self):
"""Returns the merkle root of the utxoset. This implies that
the utxoset is first put into a merkle tree.
For now, the merkle tree and its root will be computed each
time. This obviously is not efficient and a better approach
that limits the repetition of the same computation when
unnecesary should be sought. For instance, future optimizations
could simply re-compute the branches of the tree that were
affected by a change.
The transaction hash (id) and output index should be sufficient
to uniquely identify a utxo, and consequently only that
information from a utxo record is needed to compute the merkle
root. Hence, each node of the merkle tree should contain the
tuple (txid, output_index).
.. important:: The leaves of the tree will need to be sorted in
some kind of lexicographical order.
Returns:
str: Merkle root in hexadecimal form.
"""
utxoset = backend.query.get_unspent_outputs(self.connection)
# TODO Once ready, use the already pre-computed utxo_hash field.
# See common/transactions.py for details.
hashes = [
sha3_256('{}{}'.format(utxo['transaction_id'],
utxo['output_index']).encode()).digest()
for utxo in utxoset
]
# TODO Notice the sorted call!
return merkleroot(sorted(hashes))
def test_merkleroot():
from bigchaindb.tendermint.utils import merkleroot
hashes = [sha3_256(i.encode()).digest() for i in 'abc']
assert merkleroot(hashes) == (
'78c7c394d3158c218916b7ae0ebdea502e0f4e85c08e3b371e3dfd824d389fa3')