core/headerchain.go

Type	MOD
Upstream Lines	659
Changed	+26 -1

Add TD tracking and PoW total difficulty management

diff --git a/core/headerchain.go b/core/headerchain.go
index a33222e9f..b4260e4d4 100644
--- a/core/headerchain.go
+++ b/core/headerchain.go
@@ -19,6 +19,7 @@ package core
 import (
    "errors"
    "fmt"
+   "math/big"
    "sync/atomic"
    "time"

@@ -35,6 +36,7 @@ import (

 const (
    headerCacheLimit = 512
+   tdCacheLimit     = 1024 // ETC: cache for TD
    numberCacheLimit = 2048
 )

@@ -63,7 +65,8 @@ type HeaderChain struct {
    currentHeaderHash common.Hash                  // Hash of the current head of the header chain (prevent recomputing all the time)

    headerCache *lru.Cache[common.Hash, *types.Header]
-   numberCache *lru.Cache[common.Hash, uint64] // most recent block numbers
+   tdCache     *lru.Cache[common.Hash, *big.Int] // ETC: TD cache for PoW chains
+   numberCache *lru.Cache[common.Hash, uint64]   // most recent block numbers

    procInterrupt func() bool
    engine        consensus.Engine
@@ -76,6 +79,7 @@ func NewHeaderChain(chainDb ethdb.Database, config *params.ChainConfig, engine c
        config:        config,
        chainDb:       chainDb,
        headerCache:   lru.NewCache[common.Hash, *types.Header](headerCacheLimit),
+       tdCache:       lru.NewCache[common.Hash, *big.Int](tdCacheLimit),
        numberCache:   lru.NewCache[common.Hash, uint64](numberCacheLimit),
        procInterrupt: procInterrupt,
        engine:        engine,
@@ -196,6 +200,15 @@ func (hc *HeaderChain) WriteHeaders(headers []*types.Header) (int, error) {
    if !hc.HasHeader(headers[0].ParentHash, headers[0].Number.Uint64()-1) {
        return 0, consensus.ErrUnknownAncestor
    }
+   // Get parent TD for chain sync. For PoW chains (ETC), parent TD must
+   // exist — reject headers without it (cf. core-geth WriteHeaders).
+   // Post-merge chains don't use TD so nil is acceptable. Gate on IsPow()
+   // rather than Ethash != nil so PoS configs that retain an Ethash block
+   // (upstream merge configs) aren't tripped by a missing TD.
+   parentTd := hc.GetTd(headers[0].ParentHash, headers[0].Number.Uint64()-1)
+   if parentTd == nil && hc.config.IsPow() {
+       return 0, consensus.ErrUnknownAncestor
+   }
    var (
        inserted    []rawdb.NumberHash // Ephemeral lookup of number/hash for the chain
        parentKnown = true             // Set to true to force hc.HasHeader check the first iteration
@@ -212,12 +225,22 @@ func (hc *HeaderChain) WriteHeaders(headers []*types.Header) (int, error) {
            hash = header.Hash()
        }
        number := header.Number.Uint64()
+       // Advance the running TD for every header, regardless of whether it
+       // is already known. Otherwise a batch shaped like [known, new] would
+       // persist the new header's TD without the known sibling's difficulty.
+       if parentTd != nil {
+           parentTd = new(big.Int).Add(parentTd, header.Difficulty)
+       }

        // If the parent was not present, store it
        // If the header is already known, skip it, otherwise store
        alreadyKnown := parentKnown && hc.HasHeader(hash, number)
        if !alreadyKnown {
            rawdb.WriteHeader(batch, header)
+           if parentTd != nil {
+               rawdb.WriteTd(batch, hash, number, parentTd)
+               hc.tdCache.Add(hash, new(big.Int).Set(parentTd))
+           }
            inserted = append(inserted, rawdb.NumberHash{Number: number, Hash: hash})
            hc.headerCache.Add(hash, header)
            hc.numberCache.Add(hash, number)
@@ -598,6 +621,7 @@ func (hc *HeaderChain) setHead(headBlock uint64, headTime uint64, updateFn Updat
                if delFn != nil {
                    delFn(batch, hash, num)
                }
+               hc.deleteTd(batch, hash, num)
                // Remove the hash->number mapping along with the header itself
                rawdb.DeleteHeader(batch, hash, num)
            }
@@ -638,6 +662,7 @@ func (hc *HeaderChain) setHead(headBlock uint64, headTime uint64, updateFn Updat
    }
    // Clear out any stale content from the caches
    hc.headerCache.Purge()
+   hc.tdCache.Purge()
    hc.numberCache.Purge()
 }

← Back to Total Difficulty (TD)