Merge pull request #442 from OffchainLabs/gcproc-rand-offset

add random offset to trie-time-limit

Author: tsahee

core/blockchain.go

@@ -160,8 +160,9 @@ type CacheConfig struct {
 	SnapshotRestoreMaxGas uint64 // Rollback up to this much gas to restore snapshot (otherwise snapshot recalculated from nothing)
 
 	// Arbitrum: configure GC window
-	TriesInMemory uint64        // Height difference before which a trie may not be garbage-collected
-	TrieRetention time.Duration // Time limit before which a trie may not be garbage-collected
+	TriesInMemory             uint64        // Height difference before which a trie may not be garbage-collected
+	TrieRetention             time.Duration // Time limit before which a trie may not be garbage-collected
+	TrieTimeLimitRandomOffset time.Duration // Range of random offset of each commit due to TrieTimeLimit period
 
 	MaxNumberOfBlocksToSkipStateSaving uint32
 	MaxAmountOfGasToSkipStateSaving    uint64
@@ -203,6 +204,7 @@ var defaultCacheConfig = &CacheConfig{
 	// Arbitrum Config Options
 	TriesInMemory:                      state.DefaultTriesInMemory,
 	TrieRetention:                      30 * time.Minute,
+	TrieTimeLimitRandomOffset:          0,
 	MaxNumberOfBlocksToSkipStateSaving: 0,
 	MaxAmountOfGasToSkipStateSaving:    0,
 
@@ -295,8 +297,10 @@ type BlockChain struct {
 	vmConfig   vm.Config
 	logger     *tracing.Hooks
 
+	// Arbitrum:
 	numberOfBlocksToSkipStateSaving      uint32
 	amountOfGasInBlocksToSkipStateSaving uint64
+	gcprocRandOffset                     time.Duration // random offset for gcproc time
 }
 
 type trieGcEntry struct {
@@ -376,6 +380,8 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, chainConfig *par
 	bc.prefetcher = newStatePrefetcher(chainConfig, bc.hc)
 	bc.processor = NewStateProcessor(chainConfig, bc.hc)
 
+	bc.gcprocRandOffset = bc.generateGcprocRandOffset()
+
 	bc.genesisBlock = bc.GetBlockByNumber(0)
 	if bc.genesisBlock == nil {
 		return nil, ErrNoGenesis
@@ -1627,8 +1633,9 @@ func (bc *BlockChain) writeBlockWithState(block *types.Block, receipts []*types.
 		}
 		flushInterval := time.Duration(bc.flushInterval.Load())
 		// If we exceeded out time allowance, flush an entire trie to disk
+		// The time threshold can be offset by gcprocRandOffset if TrieTimeLimitRandomOffset > 0; the offset is re-generated after each full trie flush
 		// In case of archive node that skips some trie commits we don't flush tries here
-		if bc.gcproc > flushInterval && prevEntry != nil && !archiveNode {
+		if bc.gcproc+bc.gcprocRandOffset > flushInterval && prevEntry != nil && !archiveNode {
 			// If the header is missing (canonical chain behind), we're reorging a low
 			// diff sidechain. Suspend committing until this operation is completed.
 			header := bc.GetHeaderByNumber(prevNum)
@@ -1644,6 +1651,7 @@ func (bc *BlockChain) writeBlockWithState(block *types.Block, receipts []*types.
 				bc.triedb.Commit(header.Root, true)
 				bc.lastWrite = prevNum
 				bc.gcproc = 0
+				bc.gcprocRandOffset = bc.generateGcprocRandOffset()
 			}
 		}
 		if prevEntry != nil {

core/blockchain_arbitrum.go

@@ -19,6 +19,7 @@ package core
 
 import (
 	"fmt"
+	"math/rand/v2"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -29,6 +30,13 @@ import (
 	"github.com/ethereum/go-ethereum/rpc"
 )
 
+func (bc *BlockChain) generateGcprocRandOffset() time.Duration {
+	if bc.cacheConfig.TrieTimeLimitRandomOffset > 0 {
+		return time.Duration(rand.Int64N(int64(bc.cacheConfig.TrieTimeLimitRandomOffset)))
+	}
+	return 0
+}
+
 func (bc *BlockChain) FlushTrieDB(capLimit common.StorageSize) error {
 	if bc.triedb.Scheme() == rawdb.PathScheme {
 		return nil
@@ -53,6 +61,7 @@ func (bc *BlockChain) FlushTrieDB(capLimit common.StorageSize) error {
 			}
 
 			bc.gcproc = 0
+			bc.gcprocRandOffset = bc.generateGcprocRandOffset()
 			bc.lastWrite = blockNumber
 		}
 	}