core,eth: add debug_setTrieFlushInterval to change trie flush frequency (#24785)

This PR makes it possible to modify the flush interval time via RPC. On one extreme, `0s`, it would act as an archive node. If set to `1h`, means that after one hour of effective block processing time, the trie would be flushed. If one block takes 200ms, this means that a flush would occur every `5*3600=18000`  blocks -- however, if the memory size of the cached states grows too large, it will flush sooner. 

Essentially, this makes it possible to configure the node to be more or less "archive:ish", and without restarting the node while reconfiguring it.

core/blockchain.go

@@ -169,12 +169,14 @@ type BlockChain struct {
 	chainConfig *params.ChainConfig // Chain & network configuration
 	cacheConfig *CacheConfig        // Cache configuration for pruning
 
-	db         ethdb.Database // Low level persistent database to store final content in
+	db            ethdb.Database // Low level persistent database to store final content in
-	snaps      *snapshot.Tree // Snapshot tree for fast trie leaf access
+	snaps         *snapshot.Tree // Snapshot tree for fast trie leaf access
-	triegc     *prque.Prque   // Priority queue mapping block numbers to tries to gc
+	triegc        *prque.Prque   // Priority queue mapping block numbers to tries to gc
-	gcproc     time.Duration  // Accumulates canonical block processing for trie dumping
+	gcproc        time.Duration  // Accumulates canonical block processing for trie dumping
-	triedb     *trie.Database // The database handler for maintaining trie nodes.
+	lastWrite     uint64         // Last block when the state was flushed
-	stateCache state.Database // State database to reuse between imports (contains state cache)
+	flushInterval int64          // Time interval (processing time) after which to flush a state
+	triedb        *trie.Database // The database handler for maintaining trie nodes.
+	stateCache    state.Database // State database to reuse between imports (contains state cache)
 
 	// txLookupLimit is the maximum number of blocks from head whose tx indices
 	// are reserved:
@@ -258,6 +260,7 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, genesis *Genesis
 		cacheConfig:   cacheConfig,
 		db:            db,
 		triedb:        triedb,
+		flushInterval: int64(cacheConfig.TrieTimeLimit),
 		triegc:        prque.New(nil),
 		quit:          make(chan struct{}),
 		chainmu:       syncx.NewClosableMutex(),
@@ -1248,8 +1251,6 @@ func (bc *BlockChain) InsertReceiptChain(blockChain types.Blocks, receiptChain [
 	return 0, nil
 }
 
-var lastWrite uint64
-
 // writeBlockWithoutState writes only the block and its metadata to the database,
 // but does not write any state. This is used to construct competing side forks
 // up to the point where they exceed the canonical total difficulty.
@@ -1311,53 +1312,55 @@ func (bc *BlockChain) writeBlockWithState(block *types.Block, receipts []*types.
 	// If we're running an archive node, always flush
 	if bc.cacheConfig.TrieDirtyDisabled {
 		return bc.triedb.Commit(root, false, nil)
-	} else {
+	}
-		// Full but not archive node, do proper garbage collection
+	// Full but not archive node, do proper garbage collection
-		bc.triedb.Reference(root, common.Hash{}) // metadata reference to keep trie alive
+	bc.triedb.Reference(root, common.Hash{}) // metadata reference to keep trie alive
-		bc.triegc.Push(root, -int64(block.NumberU64()))
+	bc.triegc.Push(root, -int64(block.NumberU64()))
 
-		if current := block.NumberU64(); current > TriesInMemory {
+	current := block.NumberU64()
-			// If we exceeded our memory allowance, flush matured singleton nodes to disk
+	// Flush limits are not considered for the first TriesInMemory blocks.
-			var (
+	if current <= TriesInMemory {
-				nodes, imgs = bc.triedb.Size()
+		return nil
-				limit       = common.StorageSize(bc.cacheConfig.TrieDirtyLimit) * 1024 * 1024
+	}
-			)
+	// If we exceeded our memory allowance, flush matured singleton nodes to disk
-			if nodes > limit || imgs > 4*1024*1024 {
+	var (
-				bc.triedb.Cap(limit - ethdb.IdealBatchSize)
+		nodes, imgs = bc.triedb.Size()
-			}
+		limit       = common.StorageSize(bc.cacheConfig.TrieDirtyLimit) * 1024 * 1024
-			// Find the next state trie we need to commit
+	)
-			chosen := current - TriesInMemory
+	if nodes > limit || imgs > 4*1024*1024 {
-
+		bc.triedb.Cap(limit - ethdb.IdealBatchSize)
-			// If we exceeded out time allowance, flush an entire trie to disk
+	}
-			if bc.gcproc > bc.cacheConfig.TrieTimeLimit {
+	// Find the next state trie we need to commit
-				// If the header is missing (canonical chain behind), we're reorging a low
+	chosen := current - TriesInMemory
-				// diff sidechain. Suspend committing until this operation is completed.
+	flushInterval := time.Duration(atomic.LoadInt64(&bc.flushInterval))
-				header := bc.GetHeaderByNumber(chosen)
+	// If we exceeded time allowance, flush an entire trie to disk
-				if header == nil {
+	if bc.gcproc > flushInterval {
-					log.Warn("Reorg in progress, trie commit postponed", "number", chosen)
+		// If the header is missing (canonical chain behind), we're reorging a low
-				} else {
+		// diff sidechain. Suspend committing until this operation is completed.
-					// If we're exceeding limits but haven't reached a large enough memory gap,
+		header := bc.GetHeaderByNumber(chosen)
-					// warn the user that the system is becoming unstable.
+		if header == nil {
-					if chosen < lastWrite+TriesInMemory && bc.gcproc >= 2*bc.cacheConfig.TrieTimeLimit {
+			log.Warn("Reorg in progress, trie commit postponed", "number", chosen)
-						log.Info("State in memory for too long, committing", "time", bc.gcproc, "allowance", bc.cacheConfig.TrieTimeLimit, "optimum", float64(chosen-lastWrite)/TriesInMemory)
+		} else {
-					}
+			// If we're exceeding limits but haven't reached a large enough memory gap,
-					// Flush an entire trie and restart the counters
+			// warn the user that the system is becoming unstable.
-					bc.triedb.Commit(header.Root, true, nil)
+			if chosen < bc.lastWrite+TriesInMemory && bc.gcproc >= 2*flushInterval {
-					lastWrite = chosen
+				log.Info("State in memory for too long, committing", "time", bc.gcproc, "allowance", flushInterval, "optimum", float64(chosen-bc.lastWrite)/TriesInMemory)
-					bc.gcproc = 0
-				}
-			}
-			// Garbage collect anything below our required write retention
-			for !bc.triegc.Empty() {
-				root, number := bc.triegc.Pop()
-				if uint64(-number) > chosen {
-					bc.triegc.Push(root, number)
-					break
-				}
-				bc.triedb.Dereference(root.(common.Hash))
 			}
+			// Flush an entire trie and restart the counters
+			bc.triedb.Commit(header.Root, true, nil)
+			bc.lastWrite = chosen
+			bc.gcproc = 0
 		}
 	}
+	// Garbage collect anything below our required write retention
+	for !bc.triegc.Empty() {
+		root, number := bc.triegc.Pop()
+		if uint64(-number) > chosen {
+			bc.triegc.Push(root, number)
+			break
+		}
+		bc.triedb.Dereference(root.(common.Hash))
+	}
 	return nil
 }
 
@@ -2436,3 +2439,10 @@ func (bc *BlockChain) SetBlockValidatorAndProcessorForTesting(v Validator, p Pro
 	bc.validator = v
 	bc.processor = p
 }
+
+// SetTrieFlushInterval configures how often in-memory tries are persisted to disk.
+// The interval is in terms of block processing time, not wall clock.
+// It is thread-safe and can be called repeatedly without side effects.
+func (bc *BlockChain) SetTrieFlushInterval(interval time.Duration) {
+	atomic.StoreInt64(&bc.flushInterval, int64(interval))
+}

eth/api.go

@@ -590,3 +590,14 @@ func (api *DebugAPI) GetAccessibleState(from, to rpc.BlockNumber) (uint64, error
 	}
 	return 0, errors.New("no state found")
 }
+
+// SetTrieFlushInterval configures how often in-memory tries are persisted
+// to disk. The value is in terms of block processing time, not wall clock.
+func (api *DebugAPI) SetTrieFlushInterval(interval string) error {
+	t, err := time.ParseDuration(interval)
+	if err != nil {
+		return err
+	}
+	api.eth.blockchain.SetTrieFlushInterval(t)
+	return nil
+}

internal/web3ext/web3ext.go

@@ -490,6 +490,11 @@ web3._extend({
 			call: 'debug_dbAncients',
 			params: 0
 		}),
+		new web3._extend.Method({
+			name: 'setTrieFlushInterval',
+			call: 'debug_setTrieFlushInterval',
+			params: 1
+		}),
 	],
 	properties: []
 });