Node migration

[reubenr0d]

Problem

In the current state of the Tenderizer, if we need to migrate stake to a new node, we need to perform a rescue withdrawal, set the new node and then stake. However in this workflow claimingRewards and stakes need to be paused while the resuce withdrawal is thawing. The goal of this issue is to make the necessary changes such that new deposits/stakes and immediately staked towards the new node, and we can start claiming rewards for the same, while the withdrawal for the previous node is still processing.

Proposed solution

node storage

• On calling setNode() apart from setting node we also store oldNode so that can be used to process the rescue withdrawal.
• In rescueUnlock(), processUnstake(), processWithdraw() we use node as oldNode == address(0) ? node : oldNode
• In processWithdraw() we set oldNode back to zero address, indicating that the withdrawal from the older node has been processed, and future unlocks will be processed from node as usual

currentPrincipal

• In rescueUnlock(), cpAtResuce = currentPricnple
• In Graph._processNewStake(), rewards = int256(stake) + int256(cpAtRescue) - int256(currentPrincipal_);
• In _claimRewards(),

  if (oldNode == address(0) && cpAtRescue > 0) {
   _stake(node, cpAtRescue);
   cpAtRescue = 0;
  }

  However this requires us to also change _stake() to accept the node.

• In Tenderizer.claimRewards(), _stake(steak.balanceOf(address(this)) - cpAtRescue);

[kyriediculous]

I personally think adding address node to the locks might be cleaner, this value would be populated by the global node state variable at the time of execution.

So a migration process could look like this.

1. rescueUnlock + processUnstake from node A a. amount equals total amount staked to node A b. Set pendingMigration to amount from (a)
2. setNodeto node B, we can receive and stake deposits to node B already
3. processWithdraw+ rescueWithdraw a. Set pendingMigration to 0
4. claimRewards to restake migrated funds

[kyriediculous]

One thing that could be useful is to wrap the "rescue" functions into a "migrate" function which handles the state updates for uint256 pendingMIgration

[reubenr0d]

Migration workflow

• upgrade contracts with code changes described above
• rescueUnlock()
• processUnstake()
• setNode()
• processWithdraw()
• rescueWithdraw()
• claimRewards()