In Chapter 6: Exchange Rate Providers, we saw how the SelfPeggingAsset (SPA) Pool gets external price information to keep its calculations fair. Remember back in Chapter 1 we also mentioned a parameter called A
(Amplification)? This parameter is very important for pools dealing with assets that should trade closely, like two different stablecoins. A higher A
makes the pool act more like a 1:1 exchange when trades are small and the pool is balanced, reducing slippage.
But what happens if the pool administrators decide they need to change this A
value?
Imagine the ‘A’ parameter is like a big, important dial controlling how sensitive the pool’s pricing is. Maybe the pool needs to become more sensitive (lower A) or less sensitive (higher A) due to changing market conditions or to optimize performance.
If you just instantly flipped this ‘A’ dial to a new setting, it could be very disruptive:
We need a way to turn this dial slowly and predictably, giving everyone time to adjust. This is exactly what the RampAController is designed for.
The RampAController
is a dedicated smart contract that manages the gradual adjustment, or “ramping,” of the A
parameter for a specific SPA Pool.
Think of it like a programmable motor attached to that important ‘A’ dial:
RampAController
) with a target ‘A’ value and a future time when the dial should reach that target.RampAController
.RampAController
looks at its programmed schedule and the current time, calculates the exact position the dial should be at right now, and reports that value back to the pool.This ensures the change is smooth, transparent, and happens over a defined period, preventing the problems of an instant switch.
Changing the ‘A’ parameter is usually an administrative task performed by the owner or governor of the SPA. Regular users don’t typically interact with the RampAController
directly, but they benefit from the smooth transitions it enables.
Use Case: Gradually increase ‘A’ from 100 to 200 over the next 3 days.
1. Starting the Ramp:
Goal: Tell the controller linked to the pool to start moving ‘A’ from its current value (let’s assume it’s 100) towards 200, finishing in exactly 3 days.
Action: The pool owner which is governance for now , calls the rampA
function on the RampAController
contract associated with that specific pool.
Inputs:
_futureA
): 200_futureTime
): The exact timestamp (seconds since the epoch) corresponding to 3 days from now.Interaction (Conceptual):
// --- Conceptual Snippet ---
// Assume 'rampController' is the RampAController instance for the pool
// Assume 'poolOwner' is the authorized address
// Calculate the timestamp for 3 days from now
uint256 threeDaysFromNow = block.timestamp + 3 days;
// Pool owner calls rampA
rampController.rampA(
200, // The target A value
threeDaysFromNow // The time when A should reach 200
);
// The controller is now actively ramping A!
Explanation:
rampA
with the new target value and the end time.