feat: add block time metric (#707)

* feat: add block time metric

* chore: auto version bump [bot]

* trigger ci

---------

Co-authored-by: Thegaram <[email protected]>

core/blockchain.go

@@ -53,6 +53,7 @@ var (
 	headBlockGauge     = metrics.NewRegisteredGauge("chain/head/block", nil)
 	headHeaderGauge    = metrics.NewRegisteredGauge("chain/head/header", nil)
 	headFastBlockGauge = metrics.NewRegisteredGauge("chain/head/receipt", nil)
+	headTimeGapGauge   = metrics.NewRegisteredGauge("chain/head/timegap", nil)
 
 	l2BaseFeeGauge = metrics.NewRegisteredGauge("chain/fees/l2basefee", nil)
 
@@ -1255,6 +1256,12 @@ func (bc *BlockChain) writeBlockWithState(block *types.Block, receipts []*types.
 		l2BaseFeeGauge.Update(0)
 	}
 
+	parent := bc.GetHeaderByHash(block.ParentHash())
+	// block.Time is guaranteed to be larger than parent.Time,
+	// and the time gap should fit into int64.
+	gap := int64(block.Time() - parent.Time)
+	headTimeGapGauge.Update(gap)
+
 	// Calculate the total difficulty of the block
 	ptd := bc.GetTd(block.ParentHash(), block.NumberU64()-1)
 	if ptd == nil {

params/version.go

@@ -24,7 +24,7 @@ import (
 const (
 	VersionMajor = 5         // Major version component of the current release
 	VersionMinor = 2         // Minor version component of the current release
-	VersionPatch = 5         // Patch version component of the current release
+	VersionPatch = 6         // Patch version component of the current release
 	VersionMeta  = "mainnet" // Version metadata to append to the version string
 )