Balance Update Log

The BalanceUpdate log is used to track changes in user pool balances. It is emitted each time a deposit or withdraw action is called to reflect a user's portfolio update.

Data Structure

The BalanceUpdate log contains the following data:

• strategyId (uint16): Identifier for the strategy

• poolId (bytes4): Identifier for the pool

• balanceBefore (uint256): User's balance before the update

• balanceAfter (uint256): User's balance after the update

• feeInTokens (uint256): Amount of fee taken in tokens

Notes

• If the pool issues share tokens, balances are expressed using these tokens

• If the pool doesn't issue share tokens, balances are expressed using the deposited currency

• Both balanceBefore and balanceAfter are logged to account for tokens that accrue over time

Importance of Logging Both Balances

We log both balanceBefore and balanceAfter for several important reasons:

Accrual Tokens

Some tokens accrue value over time. By logging both balances, we can accurately capture this accrual between actions.

Complete Accounting

To fully account for a balance update, we need to consider:

• The balance before the action

• The balance after the action

• Fees taken (logged separately as feeInTokens)

• Any deposit or withdrawal amount (derived from the other values)

Accurate Historical Data

If we only logged the balanceAfter and relied on the previous action's balanceAfter as the current balanceBefore, we would miss any token accrual between actions.

Simplified Calculations

Having both balances makes it easier to calculate the exact change in balance due to the action, separate from any accrual or other factors.

Summary

By logging both balances, we ensure that our system can accurately track and account for all changes in user balances, regardless of the token type or any value accrual mechanisms.