Add update of validator refresh interval

KIPs/kip-163.md

@@ -15,12 +15,14 @@ Introducing a new CnStakingV3 with public delegation.
 
 ## Abstract
 
-The new CnStakingV3 will be compatible with public delegation. The public delegation will support `delegation` and `redelegation` for general users.
+The new CnStakingV3 will be compatible with public delegation. The public delegation will support `delegation` and `redelegation` for general users. Also, the staking information interval will be changed to 1 block, which is currently 86,400 blocks.
 
 ## Motivation
 
 In KIP-81, Klaytn introduced CnStakingV2. However, it’s difficult for general users to delegate their KLAY if a validator doesn’t provide public delegation services. For example, users can delegate to `SwapScanner` and `KommuneDAO` since they provide their own public delegation services. This narrowed the delegation options to a small number of GC members. In addition, Klaytn expects various GC members to join in the merged chain; there is a strong need to introduce a new CnStakingV3 with public delegation.
 
+The `redelegation` can make massive staking changes in a short period, which can lead to non-negligible errors in the validator set and reward distribution with current 86,400 blocks interval. To prevent this, the staking information intervl will be changed to 1 block.
+
 ## Specification
 
 The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in RFC 2119.
@@ -29,23 +31,25 @@ The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL
 
 CnStakingV3 is basically an upgraded version of CnStakingV2, so it must be compatible with the existing core contracts like `AddressBook`, `StakingTracker` and so on. The notifying changes include the followings:
 
--   CnStakingV3 supports public delegation natively, allowing it to receive delegations and re-delegation from general users.
+- CnStakingV3 supports public delegation natively, allowing it to receive delegations and re-delegation from general users.
 
--   Re-delegation is supported between CnStakingV3 enabling public delegation and re-delegation.
+- Re-delegation is supported between CnStakingV3 enabling public delegation and re-delegation.
 
 A GC member can enable public delegation from CnStakingV3. If it is enabled, all staking functionalities must be proxied via a public delegation contract defined in this proposal, namely `PublicDelegation`. When users want to delegate their KLAY, they stake KLAY to `PublicDelegation` and receive `shares` in return, which represent users' assets.
 
 `PublicDelegation` shall be implemented based on an interest-bearing token model, especially ERC-4626. However, `shares` must not be transferable.
 
+Staking information for block `N` will come from block `N-1` instead of `CalcStakingBlockNumber(N)` from `FORK_BLOCK`.
+
 ### Smart Contracts Overview
 
 This KIP contains upgraded and newly implemented smart contracts. The overall structure is shown in below diagram.
 
--   CnStakingV3: an upgraded version of CnStakingV2. It can enable public delegation and use re-delegation between CNs enable public delegation.
+- CnStakingV3: an upgraded version of CnStakingV2. It can enable public delegation and use re-delegation between CNs enable public delegation.
 
--   IKIP163: an interface that a public delegation must implement to be compatible with CnStakingV3.
+- IKIP163: an interface that a public delegation must implement to be compatible with CnStakingV3.
 
--   PublicDelegation: a public delegation contract provided by Klaytn. Note that it will be only compatible with CnStakingV3.
+- PublicDelegation: a public delegation contract provided by Klaytn. Note that it will be only compatible with CnStakingV3.
 
 Henceforth, CnStakingV3 shall be denoted as CNv3, and Public Delegation as PD.
 
@@ -114,10 +118,10 @@ Deploys and sets a PD to CnV3. The `PublicDelegation` will be deployed via `_pdF
 
 The function validates the following requirement(s):
 
--   The function MUST revert if PD is not enabled.
--   The function MUST revert if CnV3 already initialized.
--   The function MUST revert if `_pdArgs` isn’t encoded correctly.
--   The function MUST revert if PD deployment fails.
+- The function MUST revert if PD is not enabled.
+- The function MUST revert if CnV3 already initialized.
+- The function MUST revert if `_pdArgs` isn’t encoded correctly.
+- The function MUST revert if PD deployment fails.
 
 The function emits `SetPublicDelegation` event.
 
@@ -129,12 +133,12 @@ Requests CNv3 to redelegate `_user`’s `_value` of KLAY to `_targetCnV3`. CNv3
 
 The function validates the following requirement(s):
 
--   The function MUST revert if CNv3 does not allow PD, or if the caller is not PD.
--   The function MUST revert if CNv3 does not allow redelegation.
--   The function MUST revert if `_targetCnV3` is itself.
--   The function MUST revert if `_targetCnV3` isn’t a valid CNv3 staking contract registered in AddressBook.
--   The function MUST revert if `_value` is larger than total staking amount.
--   The function MUST revert if `lastRedelegation[_user] != 0 && lastRedelegation[_user] + lockup <= block.timestamp`.
+- The function MUST revert if CNv3 does not allow PD, or if the caller is not PD.
+- The function MUST revert if CNv3 does not allow redelegation.
+- The function MUST revert if `_targetCnV3` is itself.
+- The function MUST revert if `_targetCnV3` isn’t a valid CNv3 staking contract registered in AddressBook.
+- The function MUST revert if `_value` is larger than total staking amount.
+- The function MUST revert if `lastRedelegation[_user] != 0 && lastRedelegation[_user] + lockup <= block.timestamp`.
 
 The function emits `Redelegation` event.
 
@@ -146,11 +150,11 @@ Handles redelegation request from departure CNv3. This CNv3 will stake msg.value
 
 The function validates the following requirement(s):
 
--   The function MUST revert if CNv3 does not allow PD.
--   The function MUST revert if CNv3 does not allow redelegation.
--   The function MUST revert if departure CNv3 isn’t a valid CNv3 staking contract registered in AddressBook.
--   The function MUST revert if balance after calling `stakeFor` is lower than expected.
-    -   In `stakeFor`, PD will stake `msg.value` back to CNv3. It means CNv3 can compute deterministic balance changes.
+- The function MUST revert if CNv3 does not allow PD.
+- The function MUST revert if CNv3 does not allow redelegation.
+- The function MUST revert if departure CNv3 isn’t a valid CNv3 staking contract registered in AddressBook.
+- The function MUST revert if balance after calling `stakeFor` is lower than expected.
+  - In `stakeFor`, PD will stake `msg.value` back to CNv3. It means CNv3 can compute deterministic balance changes.
 
 The function emits `HandleRedelegation` event.
 
@@ -205,8 +209,8 @@ When block reward is auto-compounding, the commission is calculated and paid aut
 
 Since PD is a type of token contract, its name and symbol will be determined as follows:
 
--   Name: `{gcName} Public Delegated KLAY` (ex. `KF Public Delegated KLAY`)
--   Symbol: `{gcName}-pdKLAY` (ex. `KF-pdKLAY`)
+- Name: `{gcName} Public Delegated KLAY` (ex. `KF Public Delegated KLAY`)
+- Symbol: `{gcName}-pdKLAY` (ex. `KF-pdKLAY`)
 
 ##### Interface
 
@@ -350,20 +354,20 @@ interface IPublicDelegation is IKIP163 {
 
 The PublicDelegation has constants related to commission.
 
--   `MAX_COMMISSION_RATE`: Max commission rate. It will be 3,000. (= 30%)
--   `COMMISSION_DENOMINATOR`: Commission denominator. It will be 10,000.
+- `MAX_COMMISSION_RATE`: Max commission rate. It will be 3,000. (= 30%)
+- `COMMISSION_DENOMINATOR`: Commission denominator. It will be 10,000.
 
 ##### Methods
 
 All math for managing a user's staking follows ERC4626 standard. Note that PD isn’t based on ERC20 assets, but native KLAY.
 
--   `totalAssets()`: Total assets managed by PD. It contains reward.
--   `maxRedeem(address owner)`: Max reedeemable shares of owner.
--   `maxWithdraw(address owner)`: Max withdrawable KLAY of owner.
--   `convertToAssets(uint256 shares)`: Expected KLAY when convert shares.
--   `previewDeposit(uint256 assets)`: Expected shares when deposit assets of KLAY.
--   `previewWithdraw(uint256 assets)`: Expected shares to withdraw assets of KLAY.
--   `previewRedeem(uint256 shares)`: Expected KLAY when redeem shares.
+- `totalAssets()`: Total assets managed by PD. It contains reward.
+- `maxRedeem(address owner)`: Max reedeemable shares of owner.
+- `maxWithdraw(address owner)`: Max withdrawable KLAY of owner.
+- `convertToAssets(uint256 shares)`: Expected KLAY when convert shares.
+- `previewDeposit(uint256 assets)`: Expected shares when deposit assets of KLAY.
+- `previewWithdraw(uint256 assets)`: Expected shares to withdraw assets of KLAY.
+- `previewRedeem(uint256 shares)`: Expected KLAY when redeem shares.
 
 To enable auto-compounding, PD stakes cumulative KLAY rewards to CNv3 automatically when the below functions are called or call `sweep` function explicitly.
 
@@ -375,7 +379,7 @@ It updates commission receiver address of PD. Previously accumulated commission
 
 The function validates the following requirement(s):
 
--   The function MUST revert if caller is not an owner.
+- The function MUST revert if caller is not an owner.
 
 The function emits `UpdateCommissionTo` event.
 
@@ -387,8 +391,8 @@ It updates commission rate of PD. Previously accumulated rewards must follow pre
 
 The function validates the following requirement(s):
 
--   The function MUST revert if caller is not an owner.
--   The function MUST revert if `_commissionRate` is higher than `MAX_COMMISSION_RATE`.
+- The function MUST revert if caller is not an owner.
+- The function MUST revert if `_commissionRate` is higher than `MAX_COMMISSION_RATE`.
 
 The function emits `UpdateCommissionRate` event.
 
@@ -405,8 +409,8 @@ Call `delegate` with `msg.value` to CNv3 internally. It must mint corresponding
 
 The function validates the following requirement(s):
 
--   The function MUST revert if user would receive 0 shares.
--   The function MUST revert if delegate call reverts.
+- The function MUST revert if user would receive 0 shares.
+- The function MUST revert if delegate call reverts.
 
 The function emits `Staked` event.
 
@@ -424,9 +428,9 @@ Call `approveStakingWithdrawal` to CNv3 internally. It must burn corresponding s
 
 The function validates the following requirement(s):
 
--   The function MUST revert if user requests to withdraw 0 KLAY.
--   The function MUST revert if user withdraws more than staked.
--   The function MUST revert if `approveStakingWithdrawal` call reverts.
+- The function MUST revert if user requests to withdraw 0 KLAY.
+- The function MUST revert if user withdraws more than staked.
+- The function MUST revert if `approveStakingWithdrawal` call reverts.
 
 The functions emit `RequestWithdrawal` event.
 
@@ -442,8 +446,8 @@ Call `cancelApprovedStakingWithdrawal` to CNv3 internally. User’s shares must
 
 The function validates the following requirement(s):
 
--   The function MUST revert if a user attempts to withdraw another user’s request.
--   The function MUST revert if `cancelApprovedStakingWithdrawal` call reverts.
+- The function MUST revert if a user attempts to withdraw another user’s request.
+- The function MUST revert if `cancelApprovedStakingWithdrawal` call reverts.
 
 The function emits `RequestCancelWithdrawal` event.
 
@@ -460,8 +464,8 @@ Calls `withdrawApprovedStaking` to CNv3 internally. If the withdrawal was cancel
 
 The function validates the following requirement(s):
 
--   The function MUST revert if a user attempts to claim another user’s request.
--   The function MUST revert if `withdrawApprovedStaking` call reverts.
+- The function MUST revert if a user attempts to claim another user’s request.
+- The function MUST revert if `withdrawApprovedStaking` call reverts.
 
 The function emits `Claimed` if withdrew successfully.
 
@@ -479,14 +483,50 @@ Call `redelegate` to CNv3 internally. It must burn corresponding shares of users
 
 The function validates the following requirement(s):
 
--   The function MUST revert if `_targetCnV3` isn’t a valid CNv3 staking contract.
--   The function MUST revert if current CNv3 doesn’t allow redelegation.
--   The function MUST revert if a user redelegates more KLAY than staked.
--   The function MUST revert is a user redelegates 0 KLAY.
--   The function MUST revert if `redelegate` call reverts.
+- The function MUST revert if `_targetCnV3` isn’t a valid CNv3 staking contract.
+- The function MUST revert if current CNv3 doesn’t allow redelegation.
+- The function MUST revert if a user redelegates more KLAY than staked.
+- The function MUST revert is a user redelegates 0 KLAY.
+- The function MUST revert if `redelegate` call reverts.
 
 The functions emit `Redelegated` event.
 
+### Core Logic
+
+From `FORK_BLOCK`, the staking information for block `N` will be recorded in block `N-1` instead of `CalcStakingBlockNumber(N)`.
+
+#### Parameters
+
+| Constant     | Value |
+| ------------ | ----- |
+| `FORK_BLOCK` | TBD   |
+
+```go
+// In staking_manager.go
+func GetStakingInfo(blockNum uint64) *StakingInfo {
+	stakingBlockNumber := blockNum
+	var stakingInfo *StakingInfo
+	if isForkBlockEnabled(blockNum) {
+        // After `FORK_BLOCK`, staking information for block `N` will be recorded in block `N-1`.
+	    if blockNum > 0 {
+			stakingBlockNumber--
+		}
+		stakingInfo = GetStakingInfoForForkBlock(stakingBlockNumber)
+	} else {
+        // Before `FORK_BLOCK`, staking information for block `N` will be recorded in `CalcStakingBlockNumber(N)`.
+		stakingBlockNumber = params.CalcStakingBlockNumber(blockNum)
+		stakingInfo = GetStakingInfoOnStakingBlock(stakingBlockNumber)
+	}
+	return stakingInfo
+}
+```
+
+| Function                                 | Description                                                                                                                                |
+| ---------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ |
+| `GetStakingInfo(blockNum)`               | Returns staking information needed to handle block `blockNum`.                                                                             |
+| `GetStakingInfoForForkBlock(blockNum)`   | Returns staking information at block `blockNum`. If `blockNum` is before `FORK_BLOCK - 1`, return nil.                                     |
+| `GetStakingInfoOnStakingBlock(blockNum)` | Returns staking information at staking block `blockNum`. If `blockNum` is not a staking interval block nor after `FORK_BLOCK`, return nil. |
+
 ## Rationale
 
 ### Non-transferable shares in PublicDelegation
@@ -522,9 +562,9 @@ TBA
 
 ## References
 
--   [ERC4626](https://eips.ethereum.org/EIPS/eip-4626)
--   [Inflation Attack](https://blog.openzeppelin.com/a-novel-defense-against-erc4626-inflation-attacks)
--   [Cosmos Staking Module](https://docs.cosmos.network/v0.46/modules/staking/)
+- [ERC4626](https://eips.ethereum.org/EIPS/eip-4626)
+- [Inflation Attack](https://blog.openzeppelin.com/a-novel-defense-against-erc4626-inflation-attacks)
+- [Cosmos Staking Module](https://docs.cosmos.network/v0.46/modules/staking/)
 
 ## Copyright