refactor: async burning (#1001)

* refactor: burning

* chore: fmt

* chore: update storage report

* chore: update readme

* refactor: add burnableShares for epm storage

* chore: update storage report

README.md

@@ -102,6 +102,14 @@ surya mdreport surya_report.md ./src/contracts/**/*.sol
 make bindings
 ```
 
+### Generate updated Storage Report
+
+To update the storage reports in `/docs/storage-report` run:
+
+```bash
+make storage-report
+```
+
 ## Deployments
 
 ### Current Mainnet Deployment

docs/core/AllocationManager.md

@@ -623,7 +623,7 @@ Once slashing is processed for a strategy, [slashed stake is burned via the `Del
     * If the `allocation` now has a `currentMagnitude` of 0:
         * Removes `strategy` from the `allocatedStrategies[operator][operatorSetKey]` list
         * If this list now has a length of 0, remove `operatorSetKey` from `allocatedSets[operator]`
-    * Calls [`DelegationManager.burnOperatorShares`](./DelegationManager.md#burnoperatorshares)
+    * Calls [`DelegationManager.slashOperatorShares`](./DelegationManager.md#slashoperatorshares)
 * Emit an `OperatorSlashed` event
 
 *Requirements*:

docs/storage-report/EigenPodManager.md

@@ -32,7 +32,9 @@
 |---------------------------------+----------------------------------------------------------------------------+------+--------+-------+--------------------------------------------------------|
 | _beaconChainSlashingFactor      | mapping(address => struct IEigenPodManagerTypes.BeaconChainSlashingFactor) | 157  | 0      | 32    | src/contracts/pods/EigenPodManager.sol:EigenPodManager |
 |---------------------------------+----------------------------------------------------------------------------+------+--------+-------+--------------------------------------------------------|
-| __gap                           | uint256[43]                                                                | 158  | 0      | 1376  | src/contracts/pods/EigenPodManager.sol:EigenPodManager |
+| burnableETHShares               | uint256                                                                    | 158  | 0      | 32    | src/contracts/pods/EigenPodManager.sol:EigenPodManager |
+|---------------------------------+----------------------------------------------------------------------------+------+--------+-------+--------------------------------------------------------|
+| __gap                           | uint256[42]                                                                | 159  | 0      | 1344  | src/contracts/pods/EigenPodManager.sol:EigenPodManager |
 |---------------------------------+----------------------------------------------------------------------------+------+--------+-------+--------------------------------------------------------|
 | _status                         | uint256                                                                    | 201  | 0      | 32    | src/contracts/pods/EigenPodManager.sol:EigenPodManager |
 |---------------------------------+----------------------------------------------------------------------------+------+--------+-------+--------------------------------------------------------|

docs/storage-report/EigenPodManagerStorage.md

@@ -16,6 +16,8 @@
 |---------------------------------+----------------------------------------------------------------------------+------+--------+-------+----------------------------------------------------------------------|
 | _beaconChainSlashingFactor      | mapping(address => struct IEigenPodManagerTypes.BeaconChainSlashingFactor) | 6    | 0      | 32    | src/contracts/pods/EigenPodManagerStorage.sol:EigenPodManagerStorage |
 |---------------------------------+----------------------------------------------------------------------------+------+--------+-------+----------------------------------------------------------------------|
-| __gap                           | uint256[43]                                                                | 7    | 0      | 1376  | src/contracts/pods/EigenPodManagerStorage.sol:EigenPodManagerStorage |
+| burnableETHShares               | uint256                                                                    | 7    | 0      | 32    | src/contracts/pods/EigenPodManagerStorage.sol:EigenPodManagerStorage |
+|---------------------------------+----------------------------------------------------------------------------+------+--------+-------+----------------------------------------------------------------------|
+| __gap                           | uint256[42]                                                                | 8    | 0      | 1344  | src/contracts/pods/EigenPodManagerStorage.sol:EigenPodManagerStorage |
 ╰---------------------------------+----------------------------------------------------------------------------+------+--------+-------+----------------------------------------------------------------------╯
 

docs/storage-report/StrategyManager.md

@@ -44,6 +44,8 @@
 |----------------------------------------------------------+------------------------------------------------------------+------+--------+-------+--------------------------------------------------------|
 | __deprecated_thirdPartyTransfersForbidden                | mapping(contract IStrategy => bool)                        | 211  | 0      | 32    | src/contracts/core/StrategyManager.sol:StrategyManager |
 |----------------------------------------------------------+------------------------------------------------------------+------+--------+-------+--------------------------------------------------------|
-| __gap                                                    | uint256[39]                                                | 212  | 0      | 1248  | src/contracts/core/StrategyManager.sol:StrategyManager |
+| burnableShares                                           | mapping(contract IStrategy => uint256)                     | 212  | 0      | 32    | src/contracts/core/StrategyManager.sol:StrategyManager |
+|----------------------------------------------------------+------------------------------------------------------------+------+--------+-------+--------------------------------------------------------|
+| __gap                                                    | uint256[38]                                                | 213  | 0      | 1216  | src/contracts/core/StrategyManager.sol:StrategyManager |
 ╰----------------------------------------------------------+------------------------------------------------------------+------+--------+-------+--------------------------------------------------------╯
 

docs/storage-report/StrategyManagerStorage.md

@@ -24,6 +24,8 @@
 |----------------------------------------------------------+------------------------------------------------------------+------+--------+-------+----------------------------------------------------------------------|
 | __deprecated_thirdPartyTransfersForbidden                | mapping(contract IStrategy => bool)                        | 10   | 0      | 32    | src/contracts/core/StrategyManagerStorage.sol:StrategyManagerStorage |
 |----------------------------------------------------------+------------------------------------------------------------+------+--------+-------+----------------------------------------------------------------------|
-| __gap                                                    | uint256[39]                                                | 11   | 0      | 1248  | src/contracts/core/StrategyManagerStorage.sol:StrategyManagerStorage |
+| burnableShares                                           | mapping(contract IStrategy => uint256)                     | 11   | 0      | 32    | src/contracts/core/StrategyManagerStorage.sol:StrategyManagerStorage |
+|----------------------------------------------------------+------------------------------------------------------------+------+--------+-------+----------------------------------------------------------------------|
+| __gap                                                    | uint256[38]                                                | 12   | 0      | 1216  | src/contracts/core/StrategyManagerStorage.sol:StrategyManagerStorage |
 ╰----------------------------------------------------------+------------------------------------------------------------+------+--------+-------+----------------------------------------------------------------------╯
 

src/contracts/core/AllocationManager.sol

@@ -132,8 +132,8 @@ contract AllocationManager is
 
             _updateMaxMagnitude(params.operator, params.strategies[i], info.maxMagnitude);
 
-            // 6. Decrease and burn operators shares in the DelegationManager
-            delegation.burnOperatorShares({
+            // 6. Slash operators shares in the DelegationManager
+            delegation.slashOperatorShares({
                 operator: params.operator,
                 strategy: params.strategies[i],
                 prevMaxMagnitude: prevMaxMagnitude,

src/contracts/core/DelegationManager.sol

@@ -275,7 +275,7 @@ contract DelegationManager is
     }
 
     /// @inheritdoc IDelegationManager
-    function burnOperatorShares(
+    function slashOperatorShares(
         address operator,
         IStrategy strategy,
         uint64 prevMaxMagnitude,
@@ -307,11 +307,9 @@ contract DelegationManager is
             sharesToDecrease: operatorSharesSlashed
         });
 
-        // NOTE: native ETH shares will be burned by a different mechanism in a future release
-        if (strategy != beaconChainETHStrategy) {
-            strategyManager.burnShares(strategy, totalDepositSharesToBurn);
-            emit OperatorSharesBurned(operator, strategy, totalDepositSharesToBurn);
-        }
+        IShareManager shareManager = _getShareManager(strategy);
+        // NOTE: for beaconChainETHStrategy, increased burnable shares currently have no mechanism for burning
+        shareManager.increaseBurnableShares(strategy, totalDepositSharesToBurn);
     }
 
     /**

src/contracts/core/StrategyManager.sol

@@ -140,8 +140,19 @@ contract StrategyManager is
         strategy.withdraw(staker, token, shares);
     }
 
+    /// @inheritdoc IShareManager
+    function increaseBurnableShares(IStrategy strategy, uint256 addedSharesToBurn) external onlyDelegationManager {
+        burnableShares[strategy] += addedSharesToBurn;
+        emit BurnableSharesIncreased(strategy, addedSharesToBurn);
+    }
+
     /// @inheritdoc IStrategyManager
-    function burnShares(IStrategy strategy, uint256 sharesToBurn) external onlyDelegationManager {
+    function burnShares(
+        IStrategy strategy
+    ) external nonReentrant {
+        uint256 sharesToBurn = burnableShares[strategy];
+        burnableShares[strategy] = 0;
+        emit BurnableSharesDecreased(strategy, sharesToBurn);
         // burning shares is functionally the same as withdrawing but with different destination address
         strategy.withdraw(DEFAULT_BURN_ADDRESS, strategy.underlyingToken(), sharesToBurn);
     }

src/contracts/core/StrategyManagerStorage.sol

@@ -69,6 +69,9 @@ abstract contract StrategyManagerStorage is IStrategyManager {
     /// @dev Do not remove, deprecated storage.
     mapping(IStrategy strategy => bool) private __deprecated_thirdPartyTransfersForbidden;
 
+    /// @notice Returns the amount of `shares` that have been slashed on EigenLayer but not burned yet.
+    mapping(IStrategy strategy => uint256) public burnableShares;
+
     // Construction
 
     /**
@@ -85,5 +88,5 @@ abstract contract StrategyManagerStorage is IStrategyManager {
      * variables without shifting down storage in the inheritance chain.
      * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
      */
-    uint256[39] private __gap;
+    uint256[38] private __gap;
 }

src/contracts/interfaces/IDelegationManager.sol

@@ -148,9 +148,6 @@ interface IDelegationManagerEvents is IDelegationManagerTypes {
     /// @notice Emitted whenever an operator's shares are decreased for a given strategy. Note that shares is the delta in the operator's shares.
     event OperatorSharesDecreased(address indexed operator, address staker, IStrategy strategy, uint256 shares);
 
-    /// @notice Emitted whenever an operator's shares are burned for a given strategy
-    event OperatorSharesBurned(address indexed operator, IStrategy strategy, uint256 shares);
-
     /// @notice Emitted when @param staker delegates to @param operator.
     event StakerDelegated(address indexed staker, address indexed operator);
 
@@ -353,8 +350,8 @@ interface IDelegationManager is ISignatureUtils, IDelegationManagerErrors, IDele
     ) external;
 
     /**
-     * @notice Decreases the operators shares in storage after a slash and burns the corresponding Strategy shares
-     * by calling into the StrategyManager or EigenPodManager to burn the shares.
+     * @notice Decreases the operators shares in storage after a slash and increases the burnable shares by calling
+     * into either the StrategyManager or EigenPodManager (if the strategy is beaconChainETH).
      * @param operator The operator to decrease shares for
      * @param strategy The strategy to decrease shares for
      * @param prevMaxMagnitude the previous maxMagnitude of the operator
@@ -363,7 +360,7 @@ interface IDelegationManager is ISignatureUtils, IDelegationManagerErrors, IDele
      * @dev Note: Assumes `prevMaxMagnitude <= newMaxMagnitude`. This invariant is maintained in
      * the AllocationManager.
      */
-    function burnOperatorShares(
+    function slashOperatorShares(
         address operator,
         IStrategy strategy,
         uint64 prevMaxMagnitude,

src/contracts/interfaces/IEigenPodManager.sol

@@ -54,6 +54,9 @@ interface IEigenPodManagerEvents {
     event BeaconChainSlashingFactorDecreased(
         address staker, uint64 prevBeaconChainSlashingFactor, uint64 newBeaconChainSlashingFactor
     );
+
+    /// @notice Emitted when an operator is slashed and shares to be burned are increased
+    event BurnableETHSharesIncreased(uint256 shares);
 }
 
 interface IEigenPodManagerTypes {
@@ -161,4 +164,7 @@ interface IEigenPodManager is
     function beaconChainSlashingFactor(
         address staker
     ) external view returns (uint64);
+
+    /// @notice Returns the accumulated amount of beacon chain ETH Strategy shares
+    function burnableETHShares() external view returns (uint256);
 }

src/contracts/interfaces/IShareManager.sol

@@ -37,4 +37,13 @@ interface IShareManager {
     /// @dev strategy must be beaconChainETH when talking to the EigenPodManager
     /// @dev returns 0 if the user has negative shares
     function stakerDepositShares(address user, IStrategy strategy) external view returns (uint256 depositShares);
+
+    /**
+     * @notice Increase the amount of burnable shares for a given Strategy. This is called by the DelegationManager
+     * when an operator is slashed in EigenLayer.
+     * @param strategy The strategy to burn shares in.
+     * @param addedSharesToBurn The amount of added shares to burn.
+     * @dev This function is only called by the DelegationManager when an operator is slashed.
+     */
+    function increaseBurnableShares(IStrategy strategy, uint256 addedSharesToBurn) external;
 }

src/contracts/interfaces/IStrategyManager.sol

@@ -43,6 +43,12 @@ interface IStrategyManagerEvents {
 
     /// @notice Emitted when a strategy is removed from the approved list of strategies for deposit
     event StrategyRemovedFromDepositWhitelist(IStrategy strategy);
+
+    /// @notice Emitted when an operator is slashed and shares to be burned are increased
+    event BurnableSharesIncreased(IStrategy strategy, uint256 shares);
+
+    /// @notice Emitted when shares are burned
+    event BurnableSharesDecreased(IStrategy strategy, uint256 shares);
 }
 
 /**
@@ -109,12 +115,13 @@ interface IStrategyManager is IStrategyManagerErrors, IStrategyManagerEvents, IS
     ) external returns (uint256 shares);
 
     /**
-     * @notice Burns Strategy shares for the given strategy by calling into the strategy to transfer to the default burn address.
+     * @notice Burns Strategy shares for the given strategy by calling into the strategy to transfer
+     * to the default burn address.
      * @param strategy The strategy to burn shares in.
-     * @param sharesToBurn The amount of shares to burn.
-     * @dev This function is only called by the DelegationManager when an operator is slashed.
      */
-    function burnShares(IStrategy strategy, uint256 sharesToBurn) external;
+    function burnShares(
+        IStrategy strategy
+    ) external;
 
     /**
      * @notice Owner-only function to change the `strategyWhitelister` address.

src/contracts/pods/EigenPodManager.sol

@@ -219,6 +219,12 @@ contract EigenPodManager is
         }
     }
 
+    /// @inheritdoc IShareManager
+    function increaseBurnableShares(IStrategy, uint256 addedSharesToBurn) external onlyDelegationManager {
+        burnableETHShares += addedSharesToBurn;
+        emit BurnableETHSharesIncreased(addedSharesToBurn);
+    }
+
     // INTERNAL FUNCTIONS
 
     function _deployPod() internal returns (IEigenPod) {

src/contracts/pods/EigenPodManagerStorage.sol

@@ -78,6 +78,9 @@ abstract contract EigenPodManagerStorage is IEigenPodManager {
     /// Note: this is specifically updated when the staker's beacon chain balance decreases
     mapping(address staker => BeaconChainSlashingFactor) internal _beaconChainSlashingFactor;
 
+    /// @notice Returns the amount of `shares` that have been slashed on EigenLayer but not burned yet.
+    uint256 public burnableETHShares;
+
     constructor(IETHPOSDeposit _ethPOS, IBeacon _eigenPodBeacon, IDelegationManager _delegationManager) {
         ethPOS = _ethPOS;
         eigenPodBeacon = _eigenPodBeacon;
@@ -89,5 +92,5 @@ abstract contract EigenPodManagerStorage is IEigenPodManager {
      * variables without shifting down storage in the inheritance chain.
      * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
      */
-    uint256[43] private __gap;
+    uint256[42] private __gap;
 }

src/test/mocks/DelegationManagerMock.sol

@@ -25,7 +25,7 @@ contract DelegationManagerMock is Test {
         isOperator[operator] = _isOperatorReturnValue;
     }
 
-    function burnOperatorShares(
+    function slashOperatorShares(
         address operator,
         IStrategy strategy,
         uint64 prevMaxMagnitude,