fix(consensus): fix private chain initialization #1987

wanwiset25 · 2026-01-26T06:56:05Z

Proposed changes

Revert to using masternodes list from snapshot during vote verification.
This is due to epochInfo.Masternodes requires target block to be downloaded in database but during voting sometimes vote messages arrive before block download. Causing delay in minting blocks.
Chain initialization underflow, tempTCEpoch should have lowest value of 0.

ref: #1628 #1850

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This PR has sufficient test coverage (unit/integration test) OR I have provided reason in the PR description for not having test coverage
Tested in private network from genesis.
Provide an end-to-end test plan in the PR description on how to manually test it on the devnet/testnet.
Tested the backwards compatibility.
Tested with XDC nodes running this version co-exist with those running the previous version.
Relevant documentation has been updated as part of this PR
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coderabbitai · 2026-01-26T06:56:15Z

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Copilot

Pull request overview

Fixes consensus v2 edge cases by switching vote signature verification back to using snapshot-derived masternode lists (to avoid requiring the proposed block header to be present) and tightening epoch/chain initialization logic to prevent underflow during TC epoch resolution.

Changes:

Verify vote signatures against snapshot.NextEpochCandidates instead of epochInfo.Masternodes.
Adjust TC epoch lookup loop to avoid going below epoch 0 (intended).
Improve error messages and enrich mining logs with round context; minor gaslimit handling tweak for genesis parent.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
consensus/XDPoS/utils/pool.go	Adds `Pool.Inspect()` helper to log pool contents.
consensus/XDPoS/engines/engine_v2/vote.go	Changes vote verification to use snapshot candidates; adds additional logging.
consensus/XDPoS/engines/engine_v2/verifyHeader.go	Minor whitespace-only change.
consensus/XDPoS/engines/engine_v2/utils.go	Improves `GetBlockByEpochNumber` error messages with context.
consensus/XDPoS/engines/engine_v2/timeout.go	Modifies TC epoch selection loop condition to address underflow.
consensus/XDPoS/engines/engine_v2/mining.go	Adds `round` to “your turn” info logs.
consensus/XDPoS/engines/engine_v2/engine.go	Aligns gaslimit verification behavior around genesis parent handling.

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Copilot · 2026-01-26T07:00:45Z

consensus/XDPoS/engines/engine_v2/vote.go

+	log.Warn("[VerifyVoteMessage] check", "verified", verified, "error", err, "votedBlockHash", vote.ProposedBlockInfo.Hash.Hex(), "number", vote.ProposedBlockInfo.Number, "round", vote.ProposedBlockInfo.Round)
+


This log.Warn("[VerifyVoteMessage] check", ...) runs for every vote verification (including successful ones), which can create extremely noisy logs on busy networks and hide actionable warnings. Consider removing it or lowering to Debug/Trace, and/or only logging when err != nil or !verified.

Copilot · 2026-01-26T07:00:45Z

consensus/XDPoS/engines/engine_v2/timeout.go

 	}
 	log.Info("[getTCEpochInfo] Init epochInfo", "number", epochBlockInfo.Number, "round", epochRound, "tcRound", timeoutRound, "tcEpoch", tempTCEpoch)
-	for epochBlockInfo.Round > timeoutRound {
+	for epochBlockInfo.Round > timeoutRound || tempTCEpoch > 0 {


The loop condition epochBlockInfo.Round > timeoutRound || tempTCEpoch > 0 does not prevent tempTCEpoch-- from underflowing when tempTCEpoch == 0 but epochBlockInfo.Round > timeoutRound is still true (e.g., if timeoutRound is very small). This can wrap tempTCEpoch to math.MaxUint64 and cause incorrect epoch lookups. Guard the decrement (break when tempTCEpoch == 0) or change the loop logic so the decrement only happens when tempTCEpoch > 0 (e.g., use && plus a final iteration that can reach epoch 0 safely).

Suggested change

for epochBlockInfo.Round > timeoutRound || tempTCEpoch > 0 {

for epochBlockInfo.Round > timeoutRound || tempTCEpoch > 0 {

if tempTCEpoch == 0 {

break

}

Copilot · 2026-01-26T07:00:46Z

consensus/XDPoS/engines/engine_v2/verifyHeader.go

 	if err != nil && parent.Number.Uint64() != 0 { // skip genesis block
 		return err
 	}
+


There is trailing whitespace on this blank line; running gofmt should remove it. Some CI/lint setups will fail on whitespace-only diffs.

Copilot · 2026-01-26T07:00:46Z

consensus/XDPoS/utils/pool.go

+	p.lock.RLock()
+	defer p.lock.RUnlock()
+
+	for poolKey, objMap := range p.objList {
+		log.Info("[Inspect] Pool Key:", "poolKey", poolKey, "numObjects", len(objMap))
+		for objHash, obj := range objMap {
+			log.Info("[Inspect]   Object Hash:", "objHash", objHash.Hex(), "signer", obj.GetSigner().Hex())
+		}
+	}


Inspect() holds the pool's read lock while emitting per-object log.Info calls. Logging can be slow and will block writers for the duration of the iteration, which can impact consensus responsiveness under load. Consider copying the minimal data you need (keys/counts/signer) under the lock, then releasing the lock before logging (or lower the log level / make it conditional).

Suggested change

p.lock.RLock()

defer p.lock.RUnlock()

for poolKey, objMap := range p.objList {

log.Info("[Inspect] Pool Key:", "poolKey", poolKey, "numObjects", len(objMap))

for objHash, obj := range objMap {

log.Info("[Inspect] Object Hash:", "objHash", objHash.Hex(), "signer", obj.GetSigner().Hex())

}

}

type poolInfo struct {

poolKey string

numObjects int

}

type objInfo struct {

poolKey string

objHash string

signer string

}

p.lock.RLock()

poolInfos := make([]poolInfo, 0, len(p.objList))

var objInfos []objInfo

for poolKey, objMap := range p.objList {

poolInfos = append(poolInfos, poolInfo{

poolKey: poolKey,

numObjects: len(objMap),

})

for objHash, obj := range objMap {

objInfos = append(objInfos, objInfo{

poolKey: poolKey,

objHash: objHash.Hex(),

signer: obj.GetSigner().Hex(),

})

}

}

p.lock.RUnlock()

for _, info := range poolInfos {

log.Info("[Inspect] Pool Key:", "poolKey", info.poolKey, "numObjects", info.numObjects)

}

for _, info := range objInfos {

log.Info("[Inspect] Object Hash:", "objHash", info.objHash, "signer", info.signer)

}

Copilot · 2026-01-26T07:00:46Z

consensus/XDPoS/engines/engine_v2/vote.go

+	snapshot, err := x.getSnapshot(chain, vote.GapNumber, true)
 	if err != nil {
-		log.Error("[VerifyVoteMessage] Fail to get epochInfo when verifying vote message!", "blockNum", vote.ProposedBlockInfo.Number, "blockHash", vote.ProposedBlockInfo.Hash, "voteHash", vote.Hash(), "voteGapNumber", vote.GapNumber, "err", err)
+		log.Error("[VerifyVoteMessage] fail to get snapshot for a vote message", "blockNum", vote.ProposedBlockInfo.Number, "blockHash", vote.ProposedBlockInfo.Hash, "voteHash", vote.Hash(), "error", err.Error())
 		return false, err
 	}


VerifyVoteMessage now always calls getSnapshot and returns an error if the gap header/snapshot isn't available. This breaks the previously supported timing condition where votes can arrive before required chain data is present (and will also make the existing TestVerifyVoteMessage_HeaderNotPresent fail). Consider deferring verification when the gap header/snapshot isn't available yet (return (false, nil) and log at Debug/Trace) instead of logging an error and returning a hard failure.

gzliudan · 2026-01-26T09:25:10Z

consensus/XDPoS/engines/engine_v2/vote.go

+	snapshot, err := x.getSnapshot(chain, vote.GapNumber, true)
 	if err != nil {
-		log.Error("[VerifyVoteMessage] Fail to get epochInfo when verifying vote message!", "blockNum", vote.ProposedBlockInfo.Number, "blockHash", vote.ProposedBlockInfo.Hash, "voteHash", vote.Hash(), "voteGapNumber", vote.GapNumber, "err", err)
+		log.Error("[VerifyVoteMessage] fail to get snapshot for a vote message", "blockNum", vote.ProposedBlockInfo.Number, "blockHash", vote.ProposedBlockInfo.Hash, "voteHash", vote.Hash(), "error", err.Error())


does "error", err work in this line ?

gzliudan · 2026-01-26T09:27:15Z

consensus/XDPoS/engines/engine_v2/engine.go

 	// Ensure gas settings are bounded
-	if err := misc.VerifyGaslimit(parent.GasLimit, header.GasLimit); err != nil {
+	err = misc.VerifyGaslimit(parent.GasLimit, header.GasLimit)
+	if err != nil && parent.Number.Uint64() != 0 { // skip genesis block


parent.Number.Sign() != 0 has better performance than parent.Number.Uint64() != 0

fixed in another PR

Copilot AI review requested due to automatic review settings January 26, 2026 06:56

Copilot started reviewing on behalf of wanwiset25 January 26, 2026 06:56 View session

Copilot AI reviewed Jan 26, 2026

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wanwiset25 force-pushed the fix-privchain-initialization branch 2 times, most recently from ecfb357 to 233f6ec Compare January 26, 2026 08:10

gzliudan reviewed Jan 26, 2026

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benjamin202410 approved these changes Feb 5, 2026

View reviewed changes

wanwiset25 force-pushed the fix-privchain-initialization branch 2 times, most recently from 20d3ebc to 01d7c1d Compare February 9, 2026 09:17

wanwiset25 added 3 commits February 10, 2026 11:25

revert: use masternodes from snapshot to verify vote

aaba209

fix underflow during chain initialization

bd3fc3f

add previously removed test

92a712d

wanwiset25 force-pushed the fix-privchain-initialization branch from 12f3998 to 92a712d Compare February 10, 2026 04:25

rename snapshot > snap for consistency

294c144

wanwiset25 requested review from AnilChinchawale, anunay-xin and wgr523 February 10, 2026 11:08

anunay-xin approved these changes Feb 10, 2026

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gzliudan changed the title ~~consensus: fix private chain initialization~~ fix(consensus): fix private chain initialization Feb 11, 2026

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fix(consensus): fix private chain initialization #1987

fix(consensus): fix private chain initialization #1987

wanwiset25 commented Jan 26, 2026 •

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		log.Warn("[VerifyVoteMessage] check", "verified", verified, "error", err, "votedBlockHash", vote.ProposedBlockInfo.Hash.Hex(), "number", vote.ProposedBlockInfo.Number, "round", vote.ProposedBlockInfo.Round)

-	p.lock.RLock()
-	defer p.lock.RUnlock()
-	for poolKey, objMap := range p.objList {
-		log.Info("[Inspect] Pool Key:", "poolKey", poolKey, "numObjects", len(objMap))
-		for objHash, obj := range objMap {
-			log.Info("[Inspect]   Object Hash:", "objHash", objHash.Hex(), "signer", obj.GetSigner().Hex())
-		}
-	}
+	type poolInfo struct {
+		poolKey    string
+		numObjects int
+	}
+	type objInfo struct {
+		poolKey string
+		objHash string
+		signer  string
+	}
+	p.lock.RLock()
+	poolInfos := make([]poolInfo, 0, len(p.objList))
+	var objInfos []objInfo
+	for poolKey, objMap := range p.objList {
+		poolInfos = append(poolInfos, poolInfo{
+			poolKey:    poolKey,
+			numObjects: len(objMap),
+		})
+		for objHash, obj := range objMap {
+			objInfos = append(objInfos, objInfo{
+				poolKey: poolKey,
+				objHash: objHash.Hex(),
+				signer:  obj.GetSigner().Hex(),
+			})
+		}
+	}
+	p.lock.RUnlock()
+	for _, info := range poolInfos {
+		log.Info("[Inspect] Pool Key:", "poolKey", info.poolKey, "numObjects", info.numObjects)
+	}
+	for _, info := range objInfos {
+		log.Info("[Inspect]   Object Hash:", "objHash", info.objHash, "signer", info.signer)
+	}

fix(consensus): fix private chain initialization #1987

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