Configuring Pre-hooks

Pre-hooks are very powerful feature of the Fusion Vaults. They allow an execution of an additional functions before invoking a primary action.

Because the pre-hooks are very powerful functionality their management should always be done by user with a long timelock. IPOR web app will be alerting liquidity providers about the use of unverified pre-hooks.

What is a pre-hook

Fusion vault allows for an execution of a code when invoking restricted methods on the core vault. Pre-hooks are not available to methods on managers.

Pre-hooks are smart contracts with an access to the memory of the contract and authority to execute functions. They can be used for various applications such as:

• updating balance cache on markets

• raising exceptions (effectively pausing functions)

• triggering auto-withdrawals from complex strategies

• etc.

Due to that power and flexibility it is important that the user allowed to modify the prehooks has timelock configured

To add pre-hook to the vault use setPreHookImplementaions

PlasmaVaultGovernance(PLASMA_VAULT)
    .setPreHookImplementations(selectors, preHooks, substrates);

where selectors are the signatures of restricted methods on the vault, pre-hooks are addresses of implementations and substrates are the params required by the pre-hooks.

Example implementation can be found in below test case: https://github.com/IPOR-Labs/ipor-fusion/blob/main/test/pre_hooks/UpdateBalancesIgnoreDustPreHookTest.t.sol . It demonstrates the use of the pre-hook that rebalances the cache of the vault before deposit and withdrawal while ignoring balances with dust.

List of the deployed prehooks: https://github.com/IPOR-Labs/ipor-abi?tab=readme-ov-file#prehooks-list