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Context

For developers looking to support custom liquidity mining, subscriber contracts receive notifications about a position. Rewards can be issued proportional to the liquidity's fee revenue, without the need of custodying the position.

Guide

1. Inherit ISubscriber​

Please see ISubscriber for the interface definition

import {ISubscriber} from "v4-periphery/src/interfaces/ISubscriber.sol";

contract MySubscriber is ISubscriber {
    // Implement the ISubscriber interface
}

Developers should implement each function, and do proper accounting for rewards -- rewards should be proportional to a position's liquidity or fee-revenue.

2. A note on unsubscribe()​

Unsubscribe has a gas limit to prevent griefing. The value is determined at deployment, and is readable via unsubscribeGasLimit() on PositionManager

If notifyUnsubscribe() reverts, the position will still successfully unsubscribe.

3. Opt-in to a subscriber contract​

To opt-in to a subscriber contract, call subscribe() on the PositionManager contract.

import {IPositionManager} from "v4-periphery/src/interfaces/IPositionManager.sol";

IPositionManager posm = IPositionManager(<address>);
ISubscriber mySubscriber = ISubscriber(<address>);

bytes memory optionalData = ...;
posm.subscribe(tokenId, mySubscriber, optionalData);
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