Calculate and log the consumed compute units for a block of code in a Solana program

solana_compute_usage_cost.rs

/// Calculate and log the consumed compute units for a block of code
///
/// Note: Syscalls cost [100 CU](https://github.com/anza-xyz/agave/blob/d88050cda335f87e872eddbdf8506bc063f039d3/program-runtime/src/compute_budget.rs#L150)
/// It is also not accessible via a program: https://solana.stackexchange.com/questions/19024/how-can-a-rust-program-get-access-to-the-syscall-base-cost-value
#[macro_export]
macro_rules! compute_usage_cost {
    // Log with a custom message
    (
        $msg:expr => $($tt:tt)*
    ) => {
        {
            let initial = sol_remaining_compute_units();
            { $($tt)* };
            let diff = initial-sol_remaining_compute_units();
            msg!("Consumed CUs: {} --> {}", $msg, diff);
            diff
        }
    };

    // Log without a custom message
    ($($tt:tt)*) => {
        {
            let initial = sol_remaining_compute_units();
            { $($tt)* };
            let diff = initial-sol_remaining_compute_units();
            msg!("Consumed CUs: {}", diff);
            diff
        }
    };
}

usage.rs

compute_usage_cost!("with a message" => {
    require!(new_count <= u64::MAX, CustomError::Default);
    ctx.accounts.counter.count = new_count;
});

let diff = compute_usage_cost!({
    require!(new_count <= u64::MAX, CustomError::Default);
});
msg!("diff value: {}", diff);