In-depth study of Sui Lutris to understand the secret of Sui Network's high performance

Source of this article: MystenLabs

Compilation: Sui World

Blockchain technology has come a long way since the creation of Bitcoin a decade ago. With the emergence of new use cases such as games and NFTs, the blockchain community is constantly exploring ways to improve the efficiency of the technology, especially in terms of handling high loads and providing real-time latency. The L1 blockchain faces two major challenges, one is to achieve high throughput while maintaining low latency, and the other is to ensure the long-term stability of the consensus protocol. While addressing these challenges, decentralization should be maintained through dynamic participation of validators and reconfiguration of validators.

One way to achieve high throughput is to use a DAG-based consensus protocol, such as narwhale/Bullshark used by Sui. These consensus protocols enable blockchains to process large numbers of transactions simultaneously, making them ideal for use cases such as gaming and NFTs. However, the DAG-based protocol will cause a delay of several seconds, which is a high time cost for ordinary transfers or game operations.

On the other hand, no-consensus protocols, such as FastPay, show great promise in reducing latency and scaling. These protocols remove the need for consensus, allowing transactions to be processed quickly without total ordering of independent transactions processed in parallel. However, they are limited to a restricted class of simple blockchain operations, which limits the smart contracts they can perform, and reconfiguring dynamically changing validator sets can be challenging.

Despite their potential, none of these methods are currently used in production-grade blockchains, they are currently only published at academic conferences, and are not widely used by the blockchain community. Sui Lutris is a Sui-enabled protocol that combines DAG-based consensus and consensus-less approaches to achieve the best of both worlds: sub-second latency and sustained throughput of thousands of transactions per second. Sui accomplishes both tasks while maintaining the ability to express complex contracts on shared objects, generate checkpoints, and reconfigure validator sets across epochs.

Combining consensus-based and non-consensus-based methods

Sui Lutris takes a unique approach that combines the two aforementioned approaches. To ensure the security of operations on assets (owned objects) owned by a single owner, the system employs a consensus broadcast protocol among validators, which results in lower latency than consensus. Sui Lutris relies solely on consensus to handle complex smart contracts running on shared objects, i.e. objects that can be changed by any user. Sui Lutris also supports network maintenance operations such as defining checkpoints and reconfiguring validators. This novel strategy provides the best of both worlds when processing transactions in a replicated Byzantine environment.

High-level description and transaction lifecycle in Sui Lutris.

Users with private keys create and sign user transactions to change objects they own, or a mixture of objects they own and shared objects, transactions are sent to each Sui Lutris validator node (usually through a full node), and validator nodes execute A series of validity and security checks, sign it, and return the signed transaction to the client, and the client collects responses from the vast majority of verification nodes to form a transaction certificate. At this point, the transaction can be considered is irreversible (reaches finality).

Once the certificate is assembled, it will be sent back to all validators, who check their validity and acknowledge receipt to the client. If the transaction involves an exclusive object, the transaction certificate can be processed and executed immediately without waiting for the consensus engine (direct fast path). All certificates are forwarded to our DAG-based consensus protocol (also operated by Sui validators). The total sequence of consensus final output certificates; validator checks and executes those transactions that include shared objects, clients can collect the responses of the vast majority of validators, assemble them into an effect certificate, and use it as proof of transaction settlement, then , forming checkpoints for each consensus commit, which is also used to drive the reconfiguration protocol.

In addition to the main transaction flow shown in the diagram above, Sui Lutris also provides a number of facilities to support production-grade blockchains:

1. Implement a checkpoint protocol after reaching finality, which produces a causal history of all transactions in the system. This is used for full auditing, and to keep full nodes and lagging validators in sync in an efficient manner.

2. Sui Lutris supports reconfiguration at the end of each epoch. At this time, the set of validators and their voting rights may change. To ensure that all final transactions are included in an epoch, each epoch needs to be carefully closed and finalized is safe.

3. In the previous consensus-free protocol, when a vulnerable client double-spends assets, the assets will be locked forever, Sui Lutris safely "unlocks" the wrongly locked assets at the end of the epoch, minimizing the damage of bugs .

Sui Lutris supports Sui, a blockchain that manages large amounts of value for users, and the full technical report provides more details on how the safety and liveness protocols operate, and how they synchronize with partials in standard distributed systems models. Proof of Security for Byzantine Participants.

About Sui Lutris, the complete technical report can be clicked to understand: