From 5c0411220e69b49f4bf7c9e86bc23c5aaf9dcf20 Mon Sep 17 00:00:00 2001
From: tuyennhv <vutuyen2636@gmail.com>
Date: Mon, 19 Jul 2021 23:26:22 +0700
Subject: [PATCH] Improve rotateEpochs and exitQueueEndChurn (#2831)

* Improve rotateEpochs()

* Improve exitQueueEndChurn in EpochProcess

* EpochProcess: no need to push validator to array manually
---
 .../src/allForks/stateTransition.ts           |  2 +-
 .../src/allForks/util/epochContext.ts         |  8 +------
 .../src/allForks/util/epochProcess.ts         | 23 +++++++++++--------
 3 files changed, 15 insertions(+), 18 deletions(-)

diff --git a/packages/beacon-state-transition/src/allForks/stateTransition.ts b/packages/beacon-state-transition/src/allForks/stateTransition.ts
index 8b8551b2e244..bd176d55934c 100644
--- a/packages/beacon-state-transition/src/allForks/stateTransition.ts
+++ b/packages/beacon-state-transition/src/allForks/stateTransition.ts
@@ -144,7 +144,7 @@ function processSlotsWithTransientCache(
         metrics?.registerValidatorStatuses(process.currentEpoch, process.statuses);
 
         postState.slot++;
-        rotateEpochs(postState.epochCtx, postState, postState.validators);
+        rotateEpochs(postState.epochCtx, postState, process.indicesBounded);
       } finally {
         if (timer) timer();
       }
diff --git a/packages/beacon-state-transition/src/allForks/util/epochContext.ts b/packages/beacon-state-transition/src/allForks/util/epochContext.ts
index a6d4986579c2..cec2d902da4f 100644
--- a/packages/beacon-state-transition/src/allForks/util/epochContext.ts
+++ b/packages/beacon-state-transition/src/allForks/util/epochContext.ts
@@ -36,7 +36,6 @@ import {
 } from "../../util";
 import {computeEpochShuffling, IEpochShuffling} from "./epochShuffling";
 import {MutableVector} from "@chainsafe/persistent-ts";
-import {CachedValidatorList} from "./cachedValidatorList";
 import {computeBaseRewardPerIncrement} from "../../altair/misc";
 
 export type AttesterDuty = {
@@ -204,17 +203,12 @@ export function computeSyncParticipantReward(config: IBeaconConfig, totalActiveB
 export function rotateEpochs(
   epochCtx: EpochContext,
   state: allForks.BeaconState,
-  validators: CachedValidatorList<phase0.Validator>
+  indicesBounded: [ValidatorIndex, Epoch, Epoch][]
 ): void {
   epochCtx.previousShuffling = epochCtx.currentShuffling;
   epochCtx.currentShuffling = epochCtx.nextShuffling;
   const currEpoch = epochCtx.currentShuffling.epoch;
   const nextEpoch = currEpoch + 1;
-  const indicesBounded: [ValidatorIndex, Epoch, Epoch][] = validators.map((v, i) => [
-    i,
-    v.activationEpoch,
-    v.exitEpoch,
-  ]);
   epochCtx.nextShuffling = computeEpochShuffling(state, indicesBounded, nextEpoch);
   epochCtx.proposers = computeProposers(state, epochCtx.currentShuffling);
 
diff --git a/packages/beacon-state-transition/src/allForks/util/epochProcess.ts b/packages/beacon-state-transition/src/allForks/util/epochProcess.ts
index 13a790868244..db5e9795c54a 100644
--- a/packages/beacon-state-transition/src/allForks/util/epochProcess.ts
+++ b/packages/beacon-state-transition/src/allForks/util/epochProcess.ts
@@ -54,6 +54,8 @@ export interface IEpochProcess {
   statuses: IAttesterStatus[];
   validators: phase0.Validator[];
   balances?: BigUint64Array;
+  // to be used for rotateEpochs()
+  indicesBounded: [ValidatorIndex, Epoch, Epoch][];
 }
 
 export function createIEpochProcess(): IEpochProcess {
@@ -77,6 +79,7 @@ export function createIEpochProcess(): IEpochProcess {
     churnLimit: 0,
     statuses: [],
     validators: [],
+    indicesBounded: [],
   };
 }
 
@@ -96,7 +99,8 @@ export function prepareEpochProcessState<T extends allForks.BeaconState>(state:
 
   let activeCount = 0;
 
-  validators.forEach((v, i) => {
+  out.validators = validators.persistent.toArray();
+  out.validators.forEach((v, i) => {
     const status = createIAttesterStatus();
 
     if (v.slashed) {
@@ -118,8 +122,13 @@ export function prepareEpochProcessState<T extends allForks.BeaconState>(state:
       activeCount += 1;
     }
 
-    if (v.exitEpoch !== FAR_FUTURE_EPOCH && v.exitEpoch > exitQueueEnd) {
-      exitQueueEnd = v.exitEpoch;
+    if (v.exitEpoch !== FAR_FUTURE_EPOCH) {
+      if (v.exitEpoch > exitQueueEnd) {
+        exitQueueEnd = v.exitEpoch;
+        exitQueueEndChurn = 1;
+      } else if (v.exitEpoch === exitQueueEnd) {
+        exitQueueEndChurn += 1;
+      }
     }
 
     if (v.activationEligibilityEpoch === FAR_FUTURE_EPOCH && v.effectiveBalance === MAX_EFFECTIVE_BALANCE) {
@@ -135,7 +144,7 @@ export function prepareEpochProcessState<T extends allForks.BeaconState>(state:
     }
 
     out.statuses.push(status);
-    out.validators.push(v);
+    out.indicesBounded.push([i, v.activationEpoch, v.exitEpoch]);
   });
 
   if (out.totalActiveStake < EFFECTIVE_BALANCE_INCREMENT) {
@@ -150,12 +159,6 @@ export function prepareEpochProcessState<T extends allForks.BeaconState>(state:
     (a, b) => out.validators[a].activationEligibilityEpoch - out.validators[b].activationEligibilityEpoch || a - b
   );
 
-  for (const validator of out.validators) {
-    if (validator.exitEpoch === exitQueueEnd) {
-      exitQueueEndChurn += 1;
-    }
-  }
-
   const churnLimit = getChurnLimit(config, activeCount);
   if (exitQueueEndChurn >= churnLimit) {
     exitQueueEnd += 1;