update implementation

core/blockchain.go

@@ -140,8 +140,8 @@ type CacheConfig struct {
 	StateHistory        uint64        // Number of blocks from head whose state histories are reserved.
 	StateScheme         string        // Scheme used to store ethereum states and merkle tree nodes on top
 
-	EnableDiskRootInterval bool          // Enable update disk root when time threshold is reached. Disabled by default
-	DiskRootThreshold      time.Duration // Time threshold after which to flush the layers to disk
+	AllowForceUpdate bool // Enable update disk root when commit threshold is reached. Disabled by default
+	CommitThreshold  int  // Number of commits threshold after which to flush the layers to disk
 
 	SnapshotNoBuild bool // Whether the background generation is allowed
 	SnapshotWait    bool // Wait for snapshot construction on startup. TODO(karalabe): This is a dirty hack for testing, nuke it
@@ -163,6 +163,8 @@ func (c *CacheConfig) triedbConfig(isVerkle bool) *triedb.Config {
 			StateHistory:     c.StateHistory,
 			CleanCacheSize:   c.TrieCleanLimit * 1024 * 1024,
 			DirtyCacheSize:   c.TrieDirtyLimit * 1024 * 1024,
+			AllowForceUpdate: c.AllowForceUpdate,
+			CommitThreshold:  c.CommitThreshold,
 		}
 	}
 	return config
@@ -177,8 +179,8 @@ var defaultCacheConfig = &CacheConfig{
 	SnapshotLimit:    256,
 	SnapshotWait:     true,
 	StateScheme:      rawdb.HashScheme,
-	EnableDiskRootInterval: false,
-	DiskRootThreshold:      60 * time.Minute,
+	AllowForceUpdate: false,
+	CommitThreshold:  128,
 }
 
 // DefaultCacheConfigWithScheme returns a deep copied default cache config with
@@ -450,8 +452,8 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, genesis *Genesis
 			Recovery:         recover,
 			NoBuild:          bc.cacheConfig.SnapshotNoBuild,
 			AsyncBuild:       !bc.cacheConfig.SnapshotWait,
-			EnableDiskRootInterval: bc.cacheConfig.EnableDiskRootInterval,
-			DiskRootThreshold:      bc.cacheConfig.DiskRootThreshold,
+			AllowForceUpdate: bc.cacheConfig.AllowForceUpdate,
+			CommitThreshold:  bc.cacheConfig.CommitThreshold,
 		}
 		bc.snaps, _ = snapshot.New(snapconfig, bc.db, bc.triedb, head.Root)
 	}

core/blockchain_repair_test.go

@@ -1820,7 +1820,7 @@ func testRepairWithScheme(t *testing.T, tt *rewindTest, snapshots bool, scheme s
 			t.Fatalf("Failed to flush trie state: %v", err)
 		}
 		if snapshots {
-			if err := chain.snaps.Cap(canonblocks[tt.commitBlock-1].Root(), 0); err != nil {
+			if err := chain.snaps.Cap(canonblocks[tt.commitBlock-1].Root(), 0, false); err != nil {
 				t.Fatalf("Failed to flatten snapshots: %v", err)
 			}
 		}
@@ -1950,7 +1950,7 @@ func testIssue23496(t *testing.T, scheme string) {
 	if _, err := chain.InsertChain(blocks[1:2]); err != nil {
 		t.Fatalf("Failed to import canonical chain start: %v", err)
 	}
-	if err := chain.snaps.Cap(blocks[1].Root(), 0); err != nil {
+	if err := chain.snaps.Cap(blocks[1].Root(), 0, false); err != nil {
 		t.Fatalf("Failed to flatten snapshots: %v", err)
 	}
 

core/blockchain_sethead_test.go

@@ -2023,7 +2023,7 @@ func testSetHeadWithScheme(t *testing.T, tt *rewindTest, snapshots bool, scheme
 	if tt.commitBlock > 0 {
 		chain.triedb.Commit(canonblocks[tt.commitBlock-1].Root(), false)
 		if snapshots {
-			if err := chain.snaps.Cap(canonblocks[tt.commitBlock-1].Root(), 0); err != nil {
+			if err := chain.snaps.Cap(canonblocks[tt.commitBlock-1].Root(), 0, false); err != nil {
 				t.Fatalf("Failed to flatten snapshots: %v", err)
 			}
 		}

core/blockchain_snapshot_test.go

@@ -108,7 +108,7 @@ func (basic *snapshotTestBasic) prepare(t *testing.T) (*BlockChain, []*types.Blo
 			// Flushing the entire snap tree into the disk, the
 			// relevant (a) snapshot root and (b) snapshot generator
 			// will be persisted atomically.
-			chain.snaps.Cap(blocks[point-1].Root(), 0)
+			chain.snaps.Cap(blocks[point-1].Root(), 0, false)
 			diskRoot, blockRoot := chain.snaps.DiskRoot(), blocks[point-1].Root()
 			if !bytes.Equal(diskRoot.Bytes(), blockRoot.Bytes()) {
 				t.Fatalf("Failed to flush disk layer change, want %x, got %x", blockRoot, diskRoot)

core/state/pruner/pruner.go

@@ -192,7 +192,7 @@ func prune(snaptree *snapshot.Tree, root common.Hash, maindb ethdb.Database, sta
 	// Pruning is done, now drop the "useless" layers from the snapshot.
 	// Firstly, flushing the target layer into the disk. After that all
 	// diff layers below the target will all be merged into the disk.
-	if err := snaptree.Cap(root, 0); err != nil {
+	if err := snaptree.Cap(root, 0, false); err != nil {
 		return err
 	}
 	// Secondly, flushing the snapshot journal into the disk. All diff

core/state/snapshot/difflayer.go

@@ -77,8 +77,10 @@ var (
 	bloomAccountHasherOffset  = 0
 	bloomStorageHasherOffset  = 0
 
-	// Setting a minimum to prevent very low input from user
-	minTimeThreshold = 1 * time.Minute
+	// Count for number of commits before force disk update
+	// after the first 128 layers, the 129 layers would be committed
+	// to disk.
+	defaultCommitThreshold = 128
 )
 
 func init() {

core/state/snapshot/disklayer_test.go

@@ -133,7 +133,7 @@ func TestDiskMerge(t *testing.T) {
 	}); err != nil {
 		t.Fatalf("failed to update snapshot tree: %v", err)
 	}
-	if err := snaps.Cap(diffRoot, 0); err != nil {
+	if err := snaps.Cap(diffRoot, 0, false); err != nil {
 		t.Fatalf("failed to flatten snapshot tree: %v", err)
 	}
 	// Retrieve all the data through the disk layer and validate it
@@ -356,7 +356,7 @@ func TestDiskPartialMerge(t *testing.T) {
 		}); err != nil {
 			t.Fatalf("test %d: failed to update snapshot tree: %v", i, err)
 		}
-		if err := snaps.Cap(diffRoot, 0); err != nil {
+		if err := snaps.Cap(diffRoot, 0, false); err != nil {
 			t.Fatalf("test %d: failed to flatten snapshot tree: %v", i, err)
 		}
 		// Retrieve all the data through the disk layer and validate it
@@ -467,7 +467,7 @@ func TestDiskGeneratorPersistence(t *testing.T) {
 	}, nil); err != nil {
 		t.Fatalf("failed to update snapshot tree: %v", err)
 	}
-	if err := snaps.Cap(diffRoot, 0); err != nil {
+	if err := snaps.Cap(diffRoot, 0, false); err != nil {
 		t.Fatalf("failed to flatten snapshot tree: %v", err)
 	}
 	blob := rawdb.ReadSnapshotGenerator(db)
@@ -489,7 +489,7 @@ func TestDiskGeneratorPersistence(t *testing.T) {
 	}
 	diskLayer := snaps.layers[snaps.diskRoot()].(*diskLayer)
 	diskLayer.genMarker = nil // Construction finished
-	if err := snaps.Cap(diffTwoRoot, 0); err != nil {
+	if err := snaps.Cap(diffTwoRoot, 0, false); err != nil {
 		t.Fatalf("failed to flatten snapshot tree: %v", err)
 	}
 	blob = rawdb.ReadSnapshotGenerator(db)

core/state/snapshot/iterator_test.go

@@ -248,7 +248,7 @@ func TestAccountIteratorTraversal(t *testing.T) {
 		aggregatorMemoryLimit = limit
 	}()
 	aggregatorMemoryLimit = 0 // Force pushing the bottom-most layer into disk
-	snaps.Cap(common.HexToHash("0x04"), 2)
+	snaps.Cap(common.HexToHash("0x04"), 2, false)
 	verifyIterator(t, 7, head.(*diffLayer).newBinaryAccountIterator(), verifyAccount)
 
 	it, _ = snaps.AccountIterator(common.HexToHash("0x04"), common.Hash{})
@@ -296,7 +296,7 @@ func TestStorageIteratorTraversal(t *testing.T) {
 		aggregatorMemoryLimit = limit
 	}()
 	aggregatorMemoryLimit = 0 // Force pushing the bottom-most layer into disk
-	snaps.Cap(common.HexToHash("0x04"), 2)
+	snaps.Cap(common.HexToHash("0x04"), 2, false)
 	verifyIterator(t, 6, head.(*diffLayer).newBinaryStorageIterator(common.HexToHash("0xaa")), verifyStorage)
 
 	it, _ = snaps.StorageIterator(common.HexToHash("0x04"), common.HexToHash("0xaa"), common.Hash{})
@@ -384,7 +384,7 @@ func TestAccountIteratorTraversalValues(t *testing.T) {
 		aggregatorMemoryLimit = limit
 	}()
 	aggregatorMemoryLimit = 0 // Force pushing the bottom-most layer into disk
-	snaps.Cap(common.HexToHash("0x09"), 2)
+	snaps.Cap(common.HexToHash("0x09"), 2, false)
 
 	it, _ = snaps.AccountIterator(common.HexToHash("0x09"), common.Hash{})
 	for it.Next() {
@@ -483,7 +483,7 @@ func TestStorageIteratorTraversalValues(t *testing.T) {
 		aggregatorMemoryLimit = limit
 	}()
 	aggregatorMemoryLimit = 0 // Force pushing the bottom-most layer into disk
-	snaps.Cap(common.HexToHash("0x09"), 2)
+	snaps.Cap(common.HexToHash("0x09"), 2, false)
 
 	it, _ = snaps.StorageIterator(common.HexToHash("0x09"), common.HexToHash("0xaa"), common.Hash{})
 	for it.Next() {
@@ -541,7 +541,7 @@ func TestAccountIteratorLargeTraversal(t *testing.T) {
 		aggregatorMemoryLimit = limit
 	}()
 	aggregatorMemoryLimit = 0 // Force pushing the bottom-most layer into disk
-	snaps.Cap(common.HexToHash("0x80"), 2)
+	snaps.Cap(common.HexToHash("0x80"), 2, false)
 
 	verifyIterator(t, 200, head.(*diffLayer).newBinaryAccountIterator(), verifyAccount)
 
@@ -580,7 +580,7 @@ func TestAccountIteratorFlattening(t *testing.T) {
 	it, _ := snaps.AccountIterator(common.HexToHash("0x04"), common.Hash{})
 	defer it.Release()
 
-	if err := snaps.Cap(common.HexToHash("0x04"), 1); err != nil {
+	if err := snaps.Cap(common.HexToHash("0x04"), 1, false); err != nil {
 		t.Fatalf("failed to flatten snapshot stack: %v", err)
 	}
 	//verifyIterator(t, 7, it)

core/state/snapshot/snapshot.go

@@ -22,7 +22,6 @@ import (
 	"errors"
 	"fmt"
 	"sync"
-	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/rawdb"
@@ -155,8 +154,19 @@ type Config struct {
 	Recovery         bool // Indicator that the snapshots is in the recovery mode
 	NoBuild          bool // Indicator that the snapshots generation is disallowed
 	AsyncBuild       bool // The snapshot generation is allowed to be constructed asynchronously
-	EnableDiskRootInterval bool          // The disk root is allowed to update after a time threshold
-	DiskRootThreshold      time.Duration // The threshold to update disk root
+	AllowForceUpdate bool // Enable forcing snap root generation on a commit count
+	CommitThreshold  int  // Number of commit after which to attempt snap root update
+}
+
+// sanitize checks the provided user configurations and changes anything that's
+// unreasonable or unworkable.
+func (c *Config) sanitize() Config {
+	conf := *c
+
+	if conf.CommitThreshold == 0 {
+		conf.CommitThreshold = defaultCommitThreshold
+	}
+	return conf
 }
 
 // Tree is an Ethereum state snapshot tree. It consists of one persistent base
@@ -174,7 +184,7 @@ type Tree struct {
 	triedb        *triedb.Database         // In-memory cache to access the trie through
 	layers        map[common.Hash]snapshot // Collection of all known layers
 	lock          sync.RWMutex
-	baseTime time.Time // Reference to calculate the time threshold
+	commitCounter int // Counter for number of commits
 
 	// Test hooks
 	onFlatten func() // Hook invoked when the bottom most diff layers are flattened
@@ -203,13 +213,9 @@ func New(config Config, diskdb ethdb.KeyValueStore, triedb *triedb.Database, roo
 		diskdb: diskdb,
 		triedb: triedb,
 		layers: make(map[common.Hash]snapshot),
-		baseTime: time.Now(),
 	}
 
-	// If user provided threshold smaller than minimum, set to minimum
-	if config.DiskRootThreshold < minTimeThreshold {
-		config.DiskRootThreshold = minTimeThreshold
-	}
+	config = config.sanitize()
 
 	// Attempt to load a previously persisted snapshot and rebuild one if failed
 	head, disabled, err := loadSnapshot(diskdb, triedb, root, config.CacheSize, config.Recovery, config.NoBuild)
@@ -393,7 +399,7 @@ func (t *Tree) Update(blockRoot common.Hash, parentRoot common.Hash, destructs m
 // which may or may not overflow and cascade to disk. Since this last layer's
 // survival is only known *after* capping, we need to omit it from the count if
 // we want to ensure that *at least* the requested number of diff layers remain.
-func (t *Tree) Cap(root common.Hash, layers int) error {
+func (t *Tree) Cap(root common.Hash, layers int, force bool) error {
 	// Retrieve the head snapshot to cap from
 	snap := t.Snapshot(root)
 	if snap == nil {
@@ -427,7 +433,7 @@ func (t *Tree) Cap(root common.Hash, layers int) error {
 		t.layers = map[common.Hash]snapshot{base.root: base}
 		return nil
 	}
-	persisted := t.cap(diff, layers)
+	persisted := t.cap(diff, layers, force)
 
 	// Remove any layer that is stale or links into a stale layer
 	children := make(map[common.Hash][]common.Hash)
@@ -477,7 +483,7 @@ func (t *Tree) Cap(root common.Hash, layers int) error {
 // which may or may not overflow and cascade to disk. Since this last layer's
 // survival is only known *after* capping, we need to omit it from the count if
 // we want to ensure that *at least* the requested number of diff layers remain.
-func (t *Tree) cap(diff *diffLayer, layers int) *diskLayer {
+func (t *Tree) cap(diff *diffLayer, layers int, force bool) *diskLayer {
 	// Dive until we run out of layers or reach the persistent database
 	for i := 0; i < layers-1; i++ {
 		// If we still have diff layers below, continue down
@@ -511,7 +517,7 @@ func (t *Tree) cap(diff *diffLayer, layers int) *diskLayer {
 			t.onFlatten()
 		}
 		diff.parent = flattened
-		if (flattened.memory < aggregatorMemoryLimit) && !t.isPastThreshold() {
+		if (flattened.memory < aggregatorMemoryLimit) && !force {
 			// Accumulator layer is smaller than the limit, so we can abort, unless
 			// there's a snapshot being generated currently. In that case, the trie
 			// will move from underneath the generator so we **must** merge all the
@@ -530,9 +536,6 @@ func (t *Tree) cap(diff *diffLayer, layers int) *diskLayer {
 	base := diffToDisk(bottom)
 	bottom.lock.RUnlock()
 
-	// Reset the time reference for next update
-	t.baseTime = time.Now()
-
 	t.layers[base.root] = base
 	diff.parent = base
 	return base
@@ -900,8 +903,19 @@ func (t *Tree) Size() (diffs common.StorageSize, buf common.StorageSize) {
 	return size, 0
 }
 
-// Check if time threshold is enabled and if the time elapsed is more than the threshold.
-// if false, we can abort else we proceed to update the disk root
-func (t *Tree) isPastThreshold() bool {
-	return (t.config.EnableDiskRootInterval && (time.Since(t.baseTime) > t.config.DiskRootThreshold))
+// Checks the config to compare if count of commits is above threshold
+func (t *Tree) CompareThreshold() bool {
+	if !t.config.AllowForceUpdate {
+		return false
+	}
+
+	log.Debug("Snapshot Commit counters", "counter", t.commitCounter, "threshold", t.config.CommitThreshold)
+	if t.commitCounter > t.config.CommitThreshold {
+		t.commitCounter = 0
+		return true
+	}
+
+	t.commitCounter++
+
+	return false
 }

core/state/snapshot/snapshot_test.go

@@ -114,7 +114,7 @@ func TestDiskLayerExternalInvalidationFullFlatten(t *testing.T) {
 		t.Errorf("pre-cap layer count mismatch: have %d, want %d", n, 2)
 	}
 	// Commit the diff layer onto the disk and ensure it's persisted
-	if err := snaps.Cap(common.HexToHash("0x02"), 0); err != nil {
+	if err := snaps.Cap(common.HexToHash("0x02"), 0, false); err != nil {
 		t.Fatalf("failed to merge diff layer onto disk: %v", err)
 	}
 	// Since the base layer was modified, ensure that data retrievals on the external reference fail
@@ -164,7 +164,7 @@ func TestDiskLayerExternalInvalidationPartialFlatten(t *testing.T) {
 	defer func(memcap uint64) { aggregatorMemoryLimit = memcap }(aggregatorMemoryLimit)
 	aggregatorMemoryLimit = 0
 
-	if err := snaps.Cap(common.HexToHash("0x03"), 1); err != nil {
+	if err := snaps.Cap(common.HexToHash("0x03"), 1, false); err != nil {
 		t.Fatalf("failed to merge accumulator onto disk: %v", err)
 	}
 	// Since the base layer was modified, ensure that data retrievals on the external reference fail
@@ -219,14 +219,14 @@ func TestDiffLayerExternalInvalidationPartialFlatten(t *testing.T) {
 
 	// Doing a Cap operation with many allowed layers should be a no-op
 	exp := len(snaps.layers)
-	if err := snaps.Cap(common.HexToHash("0x04"), 2000); err != nil {
+	if err := snaps.Cap(common.HexToHash("0x04"), 2000, false); err != nil {
 		t.Fatalf("failed to flatten diff layer into accumulator: %v", err)
 	}
 	if got := len(snaps.layers); got != exp {
 		t.Errorf("layers modified, got %d exp %d", got, exp)
 	}
 	// Flatten the diff layer into the bottom accumulator
-	if err := snaps.Cap(common.HexToHash("0x04"), 1); err != nil {
+	if err := snaps.Cap(common.HexToHash("0x04"), 1, false); err != nil {
 		t.Fatalf("failed to flatten diff layer into accumulator: %v", err)
 	}
 	// Since the accumulator diff layer was modified, ensure that data retrievals on the external reference fail
@@ -297,11 +297,11 @@ func TestPostCapBasicDataAccess(t *testing.T) {
 		t.Error(err)
 	}
 	// Cap to a bad root should fail
-	if err := snaps.Cap(common.HexToHash("0x1337"), 0); err == nil {
+	if err := snaps.Cap(common.HexToHash("0x1337"), 0, false); err == nil {
 		t.Errorf("expected error, got none")
 	}
 	// Now, merge the a-chain
-	snaps.Cap(common.HexToHash("0xa3"), 0)
+	snaps.Cap(common.HexToHash("0xa3"), 0, false)
 
 	// At this point, a2 got merged into a1. Thus, a1 is now modified, and as a1 is
 	// the parent of b2, b2 should no longer be able to iterate into parent.
@@ -325,7 +325,7 @@ func TestPostCapBasicDataAccess(t *testing.T) {
 	}
 	// Now, merge it again, just for fun. It should now error, since a3
 	// is a disk layer
-	if err := snaps.Cap(common.HexToHash("0xa3"), 0); err == nil {
+	if err := snaps.Cap(common.HexToHash("0xa3"), 0, false); err == nil {
 		t.Error("expected error capping the disk layer, got none")
 	}
 }
@@ -357,10 +357,8 @@ func TestForceSnapRootCaps(t *testing.T) {
 		layers: map[common.Hash]snapshot{
 			base.root: base,
 		},
-		baseTime: time.Now(),
 		config: Config{
-			EnableDiskRootInterval: true,
-			DiskRootThreshold:      30 * time.Minute,
+			CommitThreshold: 10,
 		},
 	}
 
@@ -377,7 +375,7 @@ func TestForceSnapRootCaps(t *testing.T) {
 	}
 
 	// Now capping without time threshold reached
-	if err := snaps.Cap(head, 128); err != nil {
+	if err := snaps.Cap(head, 128, false); err != nil {
 		t.Error("Error while capping layers", err)
 	}
 
@@ -393,12 +391,8 @@ func TestForceSnapRootCaps(t *testing.T) {
 		t.Errorf("Unexpected number of layers after flatten - count: %d, expected: 130", newLayers)
 	}
 
-	// Setting baseTime 100 min behind to trigger disk update
-	snaps.baseTime = time.Now().Add(time.Duration(-100) * time.Minute)
-
-	// Check if forceSnapshot disabled, time threshold should not trigger snapshot
-	snaps.config.EnableDiskRootInterval = false
-	if err := snaps.Cap(head, 128); err != nil {
+	// Check if forceSnapshot disabled, disk root should not update
+	if err := snaps.Cap(head, 128, false); err != nil {
 		t.Error("Error while capping layers", err)
 	}
 
@@ -408,9 +402,8 @@ func TestForceSnapRootCaps(t *testing.T) {
 		t.Errorf("Disk root should not have updated at this point - actual: %s, expected: %s", firstDiskRoot, base.root)
 	}
 
-	// Re-enable forceSnapshot, time threshold should trigger snapshot
-	snaps.config.EnableDiskRootInterval = true
-	if err := snaps.Cap(head, 128); err != nil {
+	// Re-enable forceSnapshot, disk root should update now
+	if err := snaps.Cap(head, 128, true); err != nil {
 		t.Error("Error while capping layers", err)
 	}
 
@@ -425,6 +418,23 @@ func TestForceSnapRootCaps(t *testing.T) {
 	if newLayers := len(snaps.layers); newLayers != 129 {
 		t.Errorf("Unexpected number of layers after flatten - count: %d, expected: 130", newLayers)
 	}
+
+	// validate compareThreshold method when enabled
+	snaps.commitCounter = 5
+	if compare := snaps.CompareThreshold(); compare {
+		t.Errorf("Incorrect CompareThreshold return - actual: %t, expected: false", compare)
+	}
+
+	snaps.commitCounter = 200
+	if compare := snaps.CompareThreshold(); !compare {
+		t.Errorf("Incorrect CompareThreshold return - actual: %t, expected: true", compare)
+	}
+
+	// validate compareThreshold method when disabled
+	snaps.config.AllowForceUpdate = false
+	if compare := snaps.CompareThreshold(); compare {
+		t.Errorf("Incorrect CompareThreshold return - actual: %t, expected: false", compare)
+	}
 }
 
 // TestSnaphots tests the functionality for retrieving the snapshot
@@ -462,7 +472,7 @@ func TestSnaphots(t *testing.T) {
 		head = makeRoot(uint64(i + 2))
 		snaps.Update(head, last, nil, setAccount(fmt.Sprintf("%d", i+2)), nil)
 		last = head
-		snaps.Cap(head, 128) // 130 layers (128 diffs + 1 accumulator + 1 disk)
+		snaps.Cap(head, 128, false) // 130 layers (128 diffs + 1 accumulator + 1 disk)
 	}
 	var cases = []struct {
 		headRoot     common.Hash
@@ -497,7 +507,7 @@ func TestSnaphots(t *testing.T) {
 	defer func(memcap uint64) { aggregatorMemoryLimit = memcap }(aggregatorMemoryLimit)
 	aggregatorMemoryLimit = 0
 
-	snaps.Cap(head, 128) // 129 (128 diffs + 1 overflown accumulator + 1 disk)
+	snaps.Cap(head, 128, false) // 129 (128 diffs + 1 overflown accumulator + 1 disk)
 
 	cases = []struct {
 		headRoot     common.Hash
@@ -576,7 +586,7 @@ func TestReadStateDuringFlattening(t *testing.T) {
 		}
 	}
 	// Cap the snap tree, which will mark the bottom-most layer as stale.
-	snaps.Cap(common.HexToHash("0xa3"), 1)
+	snaps.Cap(common.HexToHash("0xa3"), 1, false)
 	select {
 	case account := <-result:
 		if account == nil {

core/state/statedb.go

@@ -1276,7 +1276,7 @@ func (s *StateDB) Commit(block uint64, deleteEmptyObjects bool) (common.Hash, er
 			// - head layer is paired with HEAD state
 			// - head-1 layer is paired with HEAD-1 state
 			// - head-127 layer(bottom-most diff layer) is paired with HEAD-127 state
-			if err := s.snaps.Cap(root, TriesInMemory); err != nil {
+			if err := s.snaps.Cap(root, TriesInMemory, s.snaps.CompareThreshold()); err != nil {
 				log.Warn("Failed to cap snapshot tree", "root", root, "layers", TriesInMemory, "err", err)
 			}
 		}

eth/backend.go

@@ -199,8 +199,8 @@ func New(stack *node.Node, config *ethconfig.Config) (*Ethereum, error) {
 			Preimages:           config.Preimages,
 			StateHistory:        config.StateHistory,
 			StateScheme:         scheme,
-			EnableDiskRootInterval: config.EnableDiskRootInterval,
-			DiskRootThreshold:      config.DiskRootThreshold,
+			AllowForceUpdate:    config.AllowForceUpdate,
+			CommitThreshold:     config.CommitThreshold,
 		}
 	)
 	if config.VMTrace != "" {

eth/ethconfig/config.go

@@ -59,8 +59,8 @@ var Defaults = Config{
 	TrieDirtyCache:     256,
 	TrieTimeout:        60 * time.Minute,
 	SnapshotCache:      102,
-	EnableDiskRootInterval: false,
-	DiskRootThreshold:      60 * time.Minute,
+	AllowForceUpdate:   false,
+	CommitThreshold:    128,
 	FilterLogCacheSize: 32,
 	Miner:              miner.DefaultConfig,
 	TxPool:             legacypool.DefaultConfig,
@@ -126,8 +126,8 @@ type Config struct {
 	TrieTimeout      time.Duration
 	SnapshotCache    int
 	Preimages        bool
-	EnableDiskRootInterval bool
-	DiskRootThreshold      time.Duration
+	AllowForceUpdate bool
+	CommitThreshold  int
 
 	// This is the number of blocks for which logs will be cached in the filter system.
 	FilterLogCacheSize int

eth/ethconfig/gen_config.go

@@ -44,8 +44,8 @@ func (c Config) MarshalTOML() (interface{}, error) {
 		TrieTimeout             time.Duration
 		SnapshotCache           int
 		Preimages               bool
-		EnableDiskRootInterval  bool
-		DiskRootThreshold       time.Duration
+		AllowForceUpdate        bool
+		CommitThreshold         int
 		FilterLogCacheSize      int
 		Miner                   miner.Config
 		TxPool                  legacypool.Config
@@ -89,8 +89,8 @@ func (c Config) MarshalTOML() (interface{}, error) {
 	enc.TrieTimeout = c.TrieTimeout
 	enc.SnapshotCache = c.SnapshotCache
 	enc.Preimages = c.Preimages
-	enc.EnableDiskRootInterval = c.EnableDiskRootInterval
-	enc.DiskRootThreshold = c.DiskRootThreshold
+	enc.AllowForceUpdate = c.AllowForceUpdate
+	enc.CommitThreshold = c.CommitThreshold
 	enc.FilterLogCacheSize = c.FilterLogCacheSize
 	enc.Miner = c.Miner
 	enc.TxPool = c.TxPool
@@ -138,8 +138,8 @@ func (c *Config) UnmarshalTOML(unmarshal func(interface{}) error) error {
 		TrieTimeout             *time.Duration
 		SnapshotCache           *int
 		Preimages               *bool
-		EnableDiskRootInterval  *bool
-		DiskRootThreshold       *time.Duration
+		AllowForceUpdate        *bool
+		CommitThreshold         *int
 		FilterLogCacheSize      *int
 		Miner                   *miner.Config
 		TxPool                  *legacypool.Config
@@ -240,11 +240,11 @@ func (c *Config) UnmarshalTOML(unmarshal func(interface{}) error) error {
 	if dec.Preimages != nil {
 		c.Preimages = *dec.Preimages
 	}
-	if dec.EnableDiskRootInterval != nil {
-		c.EnableDiskRootInterval = *dec.EnableDiskRootInterval
+	if dec.AllowForceUpdate != nil {
+		c.AllowForceUpdate = *dec.AllowForceUpdate
 	}
-	if dec.DiskRootThreshold != nil {
-		c.DiskRootThreshold = *dec.DiskRootThreshold
+	if dec.CommitThreshold != nil {
+		c.CommitThreshold = *dec.CommitThreshold
 	}
 	if dec.FilterLogCacheSize != nil {
 		c.FilterLogCacheSize = *dec.FilterLogCacheSize

triedb/pathdb/database.go

@@ -50,6 +50,12 @@ const (
 	// Do not increase the buffer size arbitrarily, otherwise the system
 	// pause time will increase when the database writes happen.
 	DefaultBufferSize = 64 * 1024 * 1024
+
+	// Count for number of commits before force disk update
+	// after the first 128 layers, the 129th layer would be
+	// flattened and committed to disk forming the default
+	// 128 diff layers + 1 disk layer
+	defaultCommitThreshold = 128
 )
 
 var (
@@ -94,6 +100,8 @@ type Config struct {
 	CleanCacheSize   int    // Maximum memory allowance (in bytes) for caching clean nodes
 	DirtyCacheSize   int    // Maximum memory allowance (in bytes) for caching dirty nodes
 	ReadOnly         bool   // Flag whether the database is opened in read only mode.
+	AllowForceUpdate bool   // Enable forcing snap root generation on a commit count
+	CommitThreshold  int    // Number of commit after which to attempt root update
 }
 
 // sanitize checks the provided user configurations and changes anything that's
@@ -104,6 +112,11 @@ func (c *Config) sanitize() *Config {
 		log.Warn("Sanitizing invalid node buffer size", "provided", common.StorageSize(conf.DirtyCacheSize), "updated", common.StorageSize(maxBufferSize))
 		conf.DirtyCacheSize = maxBufferSize
 	}
+
+	if conf.CommitThreshold == 0 {
+		log.Warn("Sanitizing invalid commit threshold to default", "defaultThreshold", defaultCommitThreshold)
+		conf.CommitThreshold = defaultCommitThreshold
+	}
 	return &conf
 }
 
@@ -112,6 +125,7 @@ var Defaults = &Config{
 	StateHistory:     params.FullImmutabilityThreshold,
 	CleanCacheSize:   defaultCleanSize,
 	DirtyCacheSize:   DefaultBufferSize,
+	AllowForceUpdate: false,
 }
 
 // ReadOnly is the config in order to open database in read only mode.
@@ -141,6 +155,7 @@ type Database struct {
 	tree          *layerTree                   // The group for all known layers
 	freezer       ethdb.ResettableAncientStore // Freezer for storing trie histories, nil possible in tests
 	lock          sync.RWMutex                 // Lock to prevent mutations from happening at the same time
+	commitCounter int                          // Counter for number of commits
 }
 
 // New attempts to load an already existing layer from a persistent key-value
@@ -250,7 +265,7 @@ func (db *Database) Update(root common.Hash, parentRoot common.Hash, block uint6
 	// - head-1 layer is paired with HEAD-1 state
 	// - head-127 layer(bottom-most diff layer) is paired with HEAD-127 state
 	// - head-128 layer(disk layer) is paired with HEAD-128 state
-	return db.tree.cap(root, maxDiffLayers)
+	return db.tree.cap(root, maxDiffLayers, db.compareThreshold())
 }
 
 // Commit traverses downwards the layer tree from a specified layer with the
@@ -265,7 +280,7 @@ func (db *Database) Commit(root common.Hash, report bool) error {
 	if err := db.modifyAllowed(); err != nil {
 		return err
 	}
-	return db.tree.cap(root, 0)
+	return db.tree.cap(root, 0, false)
 }
 
 // Disable deactivates the database and invalidates all available state layers
@@ -524,3 +539,20 @@ func (db *Database) StorageHistory(address common.Address, slot common.Hash, sta
 func (db *Database) HistoryRange() (uint64, uint64, error) {
 	return historyRange(db.freezer)
 }
+
+// Checks the config to compare if count of commits is above threshold
+func (db *Database) compareThreshold() bool {
+	if !db.config.AllowForceUpdate {
+		return false
+	}
+
+	log.Debug("PathDB Commit counters", "counter", db.commitCounter, "threshold", db.config.CommitThreshold)
+	if db.commitCounter > db.config.CommitThreshold {
+		db.commitCounter = 0
+		return true
+	}
+
+	db.commitCounter++
+
+	return false
+}

triedb/pathdb/layertree.go

@@ -111,7 +111,7 @@ func (tree *layerTree) add(root common.Hash, parentRoot common.Hash, block uint6
 
 // cap traverses downwards the diff tree until the number of allowed diff layers
 // are crossed. All diffs beyond the permitted number are flattened downwards.
-func (tree *layerTree) cap(root common.Hash, layers int) error {
+func (tree *layerTree) cap(root common.Hash, layers int, force bool) error {
 	// Retrieve the head layer to cap from
 	root = types.TrieRootHash(root)
 	l := tree.get(root)
@@ -156,7 +156,7 @@ func (tree *layerTree) cap(root common.Hash, layers int) error {
 		// parent is linked correctly.
 		diff.lock.Lock()
 
-		base, err := parent.persist(false)
+		base, err := parent.persist(force)
 		if err != nil {
 			diff.lock.Unlock()
 			return err