feat: switch to compounding from consolidation requests (#7122)

* New compound switching logic

* clean up

* fix: remove newCompoundingValidators in EpochTransitionCache

* Bump spec version

* Address comment

* address comment

* Lint

---------

Co-authored-by: Tuyen Nguyen <[email protected]>

packages/state-transition/src/block/processConsolidationRequest.ts

@@ -3,31 +3,38 @@ import {FAR_FUTURE_EPOCH, MIN_ACTIVATION_BALANCE, PENDING_CONSOLIDATIONS_LIMIT}
 
 import {CachedBeaconStateElectra} from "../types.js";
 import {getConsolidationChurnLimit, isActiveValidator} from "../util/validator.js";
-import {hasExecutionWithdrawalCredential} from "../util/electra.js";
+import {hasExecutionWithdrawalCredential, switchToCompoundingValidator} from "../util/electra.js";
 import {computeConsolidationEpochAndUpdateChurn} from "../util/epoch.js";
+import {hasEth1WithdrawalCredential} from "../util/capella.js";
 
+// TODO Electra: Clean up necessary as there is a lot of overlap with isValidSwitchToCompoundRequest
 export function processConsolidationRequest(
   state: CachedBeaconStateElectra,
   consolidationRequest: electra.ConsolidationRequest
 ): void {
-  // If the pending consolidations queue is full, consolidation requests are ignored
-  if (state.pendingConsolidations.length >= PENDING_CONSOLIDATIONS_LIMIT) {
+  const {sourcePubkey, targetPubkey, sourceAddress} = consolidationRequest;
+  const sourceIndex = state.epochCtx.getValidatorIndex(sourcePubkey);
+  const targetIndex = state.epochCtx.getValidatorIndex(targetPubkey);
+
+  if (sourceIndex === null || targetIndex === null) {
     return;
   }
 
-  // If there is too little available consolidation churn limit, consolidation requests are ignored
-  if (getConsolidationChurnLimit(state.epochCtx) <= MIN_ACTIVATION_BALANCE) {
+  if (isValidSwitchToCompoundRequest(state, consolidationRequest)) {
+    switchToCompoundingValidator(state, sourceIndex);
+    // Early return since we have already switched validator to compounding
     return;
   }
 
-  const {sourcePubkey, targetPubkey} = consolidationRequest;
-  const sourceIndex = state.epochCtx.getValidatorIndex(sourcePubkey);
-  const targetIndex = state.epochCtx.getValidatorIndex(targetPubkey);
-
-  if (sourceIndex === null || targetIndex === null) {
+  // If the pending consolidations queue is full, consolidation requests are ignored
+  if (state.pendingConsolidations.length >= PENDING_CONSOLIDATIONS_LIMIT) {
     return;
   }
 
+  // If there is too little available consolidation churn limit, consolidation requests are ignored
+  if (getConsolidationChurnLimit(state.epochCtx) <= MIN_ACTIVATION_BALANCE) {
+    return;
+  }
   // Verify that source != target, so a consolidation cannot be used as an exit.
   if (sourceIndex === targetIndex) {
     return;
@@ -46,7 +53,7 @@ export function processConsolidationRequest(
     return;
   }
 
-  if (Buffer.compare(sourceWithdrawalAddress, consolidationRequest.sourceAddress) !== 0) {
+  if (Buffer.compare(sourceWithdrawalAddress, sourceAddress) !== 0) {
     return;
   }
 
@@ -70,4 +77,55 @@ export function processConsolidationRequest(
     targetIndex,
   });
   state.pendingConsolidations.push(pendingConsolidation);
+
+  // Churn any target excess active balance of target and raise its max
+  if (hasEth1WithdrawalCredential(targetValidator.withdrawalCredentials)) {
+    switchToCompoundingValidator(state, targetIndex);
+  }
+}
+
+/**
+ * Determine if we should set consolidation target validator to compounding credential
+ */
+function isValidSwitchToCompoundRequest(
+  state: CachedBeaconStateElectra,
+  consolidationRequest: electra.ConsolidationRequest
+): boolean {
+  const {sourcePubkey, targetPubkey, sourceAddress} = consolidationRequest;
+  const sourceIndex = state.epochCtx.getValidatorIndex(sourcePubkey);
+  const targetIndex = state.epochCtx.getValidatorIndex(targetPubkey);
+
+  // Verify pubkey exists
+  if (sourceIndex === null) {
+    return false;
+  }
+
+  // Switch to compounding requires source and target be equal
+  if (sourceIndex !== targetIndex) {
+    return false;
+  }
+
+  const sourceValidator = state.validators.getReadonly(sourceIndex);
+  const sourceWithdrawalAddress = sourceValidator.withdrawalCredentials.subarray(12);
+  // Verify request has been authorized
+  if (Buffer.compare(sourceWithdrawalAddress, sourceAddress) !== 0) {
+    return false;
+  }
+
+  // Verify source withdrawal credentials
+  if (!hasEth1WithdrawalCredential(sourceValidator.withdrawalCredentials)) {
+    return false;
+  }
+
+  // Verify the source is active
+  if (!isActiveValidator(sourceValidator, state.epochCtx.epoch)) {
+    return false;
+  }
+
+  // Verify exit for source has not been initiated
+  if (sourceValidator.exitEpoch !== FAR_FUTURE_EPOCH) {
+    return false;
+  }
+
+  return true;
 }

packages/state-transition/src/cache/epochTransitionCache.ts

@@ -139,12 +139,6 @@ export interface EpochTransitionCache {
    */
   validators: phase0.Validator[];
 
-  /**
-   * This is for electra only
-   * Validators that're switched to compounding during processPendingConsolidations(), not available in beforeProcessEpoch()
-   */
-  newCompoundingValidators?: Set<ValidatorIndex>;
-
   /**
    * balances array will be populated by processRewardsAndPenalties() and consumed by processEffectiveBalanceUpdates().
    * processRewardsAndPenalties() already has a regular Javascript array of balances.
@@ -518,8 +512,6 @@ export function beforeProcessEpoch(
     inclusionDelays,
     flags,
     validators,
-    // will be assigned in processPendingConsolidations()
-    newCompoundingValidators: undefined,
     // Will be assigned in processRewardsAndPenalties()
     balances: undefined,
   };

packages/state-transition/src/epoch/processEffectiveBalanceUpdates.ts

@@ -46,7 +46,6 @@ export function processEffectiveBalanceUpdates(
   // so it's recycled here for performance.
   const balances = cache.balances ?? state.balances.getAll();
   const currentEpochValidators = cache.validators;
-  const newCompoundingValidators = cache.newCompoundingValidators ?? new Set();
 
   let numUpdate = 0;
   for (let i = 0, len = balances.length; i < len; i++) {
@@ -61,9 +60,9 @@ export function processEffectiveBalanceUpdates(
       effectiveBalanceLimit = MAX_EFFECTIVE_BALANCE;
     } else {
       // from electra, effectiveBalanceLimit is per validator
-      const isCompoundingValidator =
-        hasCompoundingWithdrawalCredential(currentEpochValidators[i].withdrawalCredentials) ||
-        newCompoundingValidators.has(i);
+      const isCompoundingValidator = hasCompoundingWithdrawalCredential(
+        currentEpochValidators[i].withdrawalCredentials
+      );
       effectiveBalanceLimit = isCompoundingValidator ? MAX_EFFECTIVE_BALANCE_ELECTRA : MIN_ACTIVATION_BALANCE;
     }
 

packages/state-transition/src/epoch/processPendingConsolidations.ts

@@ -1,8 +1,6 @@
-import {ValidatorIndex} from "@lodestar/types";
 import {CachedBeaconStateElectra, EpochTransitionCache} from "../types.js";
 import {decreaseBalance, increaseBalance} from "../util/balance.js";
 import {getActiveBalance} from "../util/validator.js";
-import {switchToCompoundingValidator} from "../util/electra.js";
 
 /**
  * Starting from Electra:
@@ -22,7 +20,6 @@ export function processPendingConsolidations(state: CachedBeaconStateElectra, ca
   let nextPendingConsolidation = 0;
   const validators = state.validators;
   const cachedBalances = cache.balances;
-  const newCompoundingValidators = new Set<ValidatorIndex>();
 
   for (const pendingConsolidation of state.pendingConsolidations.getAllReadonly()) {
     const {sourceIndex, targetIndex} = pendingConsolidation;
@@ -36,9 +33,6 @@ export function processPendingConsolidations(state: CachedBeaconStateElectra, ca
     if (sourceValidator.withdrawableEpoch > nextEpoch) {
       break;
     }
-    // Churn any target excess active balance of target and raise its max
-    switchToCompoundingValidator(state, targetIndex);
-    newCompoundingValidators.add(targetIndex);
     // Move active balance to target. Excess balance is withdrawable.
     const activeBalance = getActiveBalance(state, sourceIndex);
     decreaseBalance(state, sourceIndex, activeBalance);
@@ -51,6 +45,5 @@ export function processPendingConsolidations(state: CachedBeaconStateElectra, ca
     nextPendingConsolidation++;
   }
 
-  cache.newCompoundingValidators = newCompoundingValidators;
   state.pendingConsolidations = state.pendingConsolidations.sliceFrom(nextPendingConsolidation);
 }

packages/state-transition/src/util/electra.ts

@@ -17,15 +17,13 @@ export function hasExecutionWithdrawalCredential(withdrawalCredentials: Uint8Arr
 export function switchToCompoundingValidator(state: CachedBeaconStateElectra, index: ValidatorIndex): void {
   const validator = state.validators.get(index);
 
-  if (hasEth1WithdrawalCredential(validator.withdrawalCredentials)) {
-    // directly modifying the byte leads to ssz missing the modification resulting into
-    // wrong root compute, although slicing can be avoided but anyway this is not going
-    // to be a hot path so its better to clean slice and avoid side effects
-    const newWithdrawalCredentials = validator.withdrawalCredentials.slice();
-    newWithdrawalCredentials[0] = COMPOUNDING_WITHDRAWAL_PREFIX;
-    validator.withdrawalCredentials = newWithdrawalCredentials;
-    queueExcessActiveBalance(state, index);
-  }
+  // directly modifying the byte leads to ssz missing the modification resulting into
+  // wrong root compute, although slicing can be avoided but anyway this is not going
+  // to be a hot path so its better to clean slice and avoid side effects
+  const newWithdrawalCredentials = validator.withdrawalCredentials.slice();
+  newWithdrawalCredentials[0] = COMPOUNDING_WITHDRAWAL_PREFIX;
+  validator.withdrawalCredentials = newWithdrawalCredentials;
+  queueExcessActiveBalance(state, index);
 }
 
 export function queueExcessActiveBalance(state: CachedBeaconStateElectra, index: ValidatorIndex): void {