AccQueue Smart Contract

The AccQueue contract represents a Merkle Tree where each leaf insertion only updates a subtree. To obtain the main tree root, the subtrees must be merged together by the contract owner. This requires at least two operations, a mergeSubRoots and a merge.

The contract can be initialized to work as a traditional Merkle Tree (2 leaves per node) or a Quinary Tree (5 leaves per node). This can be achieved by passing either two or five as parameter to the constructor (_hashLength). Any other values should not be accepted.

Below are presented the most important functions of the smart contract:

• enqueue - Allows to add a leaf to the queue for the current subtree. Only one parameter is accepted and that is the leaf to insert.
• insertSubTree - Admin only function which allows to insert a full subtree (batch enqueue)
• mergeSubRoots - Allows the contract owner to merge all of the subtrees to form the shortest possible tree. The argument _numSrQueueOps can be used to perform the operation in multiple transactions (as this might trigger the block gas limit).
• merge - Allows the contract admin to form a main tree with the desired depth. The depth must fit all of the leaves.