Avoid use of state variables in event emissions to save gas

[code423n4]

Handle

0xRajeev

Vulnerability details

Impact

Where possible, use equivalent function parameters or local variables in event emits instead of state variables to prevent expensive SLOADs. Post-Berlin, SLOADs on state variables accessed first-time in a transaction increased from 800 gas to 2100, which is a 2.5x increase.

Proof of Concept

In setDependencies(), writing the addresses to local variables first and then using them both in writing to state variables and in emit will save will save 4 SLOADS worth 21004 = 8400 gas. https://github.com/code-423n4/2021-06-gro/blob/091660467fc8d13741f8aafcec80f1e8cf129a33/contracts/DepositHandler.sol#L65 Doing the same thing in WithdrawHandler.sol will save 5 SLOADS worth 21005 = 10500 gas. https://github.com/code-423n4/2021-06-gro/blob/091660467fc8d13741f8aafcec80f1e8cf129a33/contracts/WithdrawHandler.sol#L74-L88

Tools Used

Manual Analysis

Recommended Mitigation Steps

Use equivalent function parameters or local variables in event emits instead of state variables.

[kitty-the-kat]

Functions not used a lot, gas saving overtime would be low, not a priority.