core/filtermaps: fix deadlock in filtermap callback

core/filtermaps/filtermaps.go

@@ -85,11 +85,17 @@ type FilterMaps struct {
 	// fields written by the indexer and read by matcher backend. Indexer can
 	// read them without a lock and write them under indexLock write lock.
 	// Matcher backend can read them under indexLock read lock.
-	indexLock           sync.RWMutex
-	indexedRange        filterMapsRange
-	cleanedEpochsBefore uint32     // all unindexed data cleaned before this point
-	indexedView         *ChainView // always consistent with the log index
-	hasTempRange        bool
+	indexLock    sync.RWMutex
+	indexedRange filterMapsRange
+	indexedView  *ChainView // always consistent with the log index
+	hasTempRange bool
+
+	// cleanedEpochsBefore indicates that all unindexed data before this point
+	// has been cleaned.
+	//
+	// This field is only accessed and modified within tryUnindexTail, so no
+	// explicit locking is required.
+	cleanedEpochsBefore uint32
 
 	// also accessed by indexer and matcher backend but no locking needed.
 	filterMapCache *lru.Cache[uint32, filterMap]
@@ -248,15 +254,16 @@ func NewFilterMaps(db ethdb.KeyValueStore, initView *ChainView, historyCutoff, f
 		},
 		// deleting last unindexed epoch might have been interrupted by shutdown
 		cleanedEpochsBefore: max(rs.MapsFirst>>params.logMapsPerEpoch, 1) - 1,
-		historyCutoff:       historyCutoff,
-		finalBlock:          finalBlock,
-		matcherSyncCh:       make(chan *FilterMapsMatcherBackend),
-		matchers:            make(map[*FilterMapsMatcherBackend]struct{}),
-		filterMapCache:      lru.NewCache[uint32, filterMap](cachedFilterMaps),
-		lastBlockCache:      lru.NewCache[uint32, lastBlockOfMap](cachedLastBlocks),
-		lvPointerCache:      lru.NewCache[uint64, uint64](cachedLvPointers),
-		baseRowsCache:       lru.NewCache[uint64, [][]uint32](cachedBaseRows),
-		renderSnapshots:     lru.NewCache[uint64, *renderedMap](cachedRenderSnapshots),
+
+		historyCutoff:   historyCutoff,
+		finalBlock:      finalBlock,
+		matcherSyncCh:   make(chan *FilterMapsMatcherBackend),
+		matchers:        make(map[*FilterMapsMatcherBackend]struct{}),
+		filterMapCache:  lru.NewCache[uint32, filterMap](cachedFilterMaps),
+		lastBlockCache:  lru.NewCache[uint32, lastBlockOfMap](cachedLastBlocks),
+		lvPointerCache:  lru.NewCache[uint64, uint64](cachedLvPointers),
+		baseRowsCache:   lru.NewCache[uint64, [][]uint32](cachedBaseRows),
+		renderSnapshots: lru.NewCache[uint64, *renderedMap](cachedRenderSnapshots),
 	}
 
 	// Set initial indexer target.
@@ -444,6 +451,7 @@ func (f *FilterMaps) safeDeleteWithLogs(deleteFn func(db ethdb.KeyValueStore, ha
 
 // setRange updates the indexed chain view and covered range and also adds the
 // changes to the given batch.
+//
 // Note that this function assumes that the index write lock is being held.
 func (f *FilterMaps) setRange(batch ethdb.KeyValueWriter, newView *ChainView, newRange filterMapsRange, isTempRange bool) {
 	f.indexedView = newView
@@ -477,6 +485,7 @@ func (f *FilterMaps) setRange(batch ethdb.KeyValueWriter, newView *ChainView, ne
 // Note that this function assumes that the log index structure is consistent
 // with the canonical chain at the point where the given log value index points.
 // If this is not the case then an invalid result or an error may be returned.
+//
 // Note that this function assumes that the indexer read lock is being held when
 // called from outside the indexerLoop goroutine.
 func (f *FilterMaps) getLogByLvIndex(lvIndex uint64) (*types.Log, error) {
@@ -655,6 +664,7 @@ func (f *FilterMaps) mapRowIndex(mapIndex, rowIndex uint32) uint64 {
 // getBlockLvPointer returns the starting log value index where the log values
 // generated by the given block are located. If blockNumber is beyond the current
 // head then the first unoccupied log value index is returned.
+//
 // Note that this function assumes that the indexer read lock is being held when
 // called from outside the indexerLoop goroutine.
 func (f *FilterMaps) getBlockLvPointer(blockNumber uint64) (uint64, error) {
@@ -762,7 +772,7 @@ func (f *FilterMaps) deleteTailEpoch(epoch uint32) (bool, error) {
 		return false, errors.New("invalid tail epoch number")
 	}
 	// remove index data
-	if err := f.safeDeleteWithLogs(func(db ethdb.KeyValueStore, hashScheme bool, stopCb func(bool) bool) error {
+	deleteFn := func(db ethdb.KeyValueStore, hashScheme bool, stopCb func(bool) bool) error {
 		first := f.mapRowIndex(firstMap, 0)
 		count := f.mapRowIndex(firstMap+f.mapsPerEpoch, 0) - first
 		if err := rawdb.DeleteFilterMapRows(f.db, common.NewRange(first, count), hashScheme, stopCb); err != nil {
@@ -786,10 +796,13 @@ func (f *FilterMaps) deleteTailEpoch(epoch uint32) (bool, error) {
 			f.lvPointerCache.Remove(blockNumber)
 		}
 		return nil
-	}, fmt.Sprintf("Deleting tail epoch #%d", epoch), func() bool {
+	}
+	action := fmt.Sprintf("Deleting tail epoch #%d", epoch)
+	stopFn := func() bool {
 		f.processEvents()
 		return f.stop || !f.targetHeadIndexed()
-	}); err == nil {
+	}
+	if err := f.safeDeleteWithLogs(deleteFn, action, stopFn); err == nil {
 		// everything removed; mark as cleaned and report success
 		if f.cleanedEpochsBefore == epoch {
 			f.cleanedEpochsBefore = epoch + 1
@@ -808,6 +821,9 @@ func (f *FilterMaps) deleteTailEpoch(epoch uint32) (bool, error) {
 }
 
 // exportCheckpoints exports epoch checkpoints in the format used by checkpoints.go.
+//
+// Note: acquiring the indexLock read lock is unnecessary here, as this function
+// is always called within the indexLoop.
 func (f *FilterMaps) exportCheckpoints() {
 	finalLvPtr, err := f.getBlockLvPointer(f.finalBlock + 1)
 	if err != nil {

core/filtermaps/indexer.go

@@ -43,6 +43,8 @@ func (f *FilterMaps) indexerLoop() {
 	log.Info("Started log indexer")
 
 	for !f.stop {
+		// Note: acquiring the indexLock read lock is unnecessary here,
+		// as the `indexedRange` is accessed within the indexerLoop.
 		if !f.indexedRange.initialized {
 			if f.targetView.HeadNumber() == 0 {
 				// initialize when chain head is available
@@ -105,7 +107,7 @@ type targetUpdate struct {
 	historyCutoff, finalBlock uint64
 }
 
-// SetTargetView sets a new target chain view for the indexer to render.
+// SetTarget sets a new target chain view for the indexer to render.
 // Note that SetTargetView never blocks.
 func (f *FilterMaps) SetTarget(targetView *ChainView, historyCutoff, finalBlock uint64) {
 	if targetView == nil {
@@ -178,6 +180,8 @@ func (f *FilterMaps) processSingleEvent(blocking bool) bool {
 	if f.stop {
 		return false
 	}
+	// Note: acquiring the indexLock read lock is unnecessary here,
+	// as this function is always called within the indexLoop.
 	if !f.hasTempRange {
 		for _, mb := range f.matcherSyncRequests {
 			mb.synced()

core/filtermaps/matcher_backend.go

@@ -111,17 +111,17 @@ func (fm *FilterMapsMatcherBackend) GetLogByLvIndex(ctx context.Context, lvIndex
 // synced signals to the matcher that has triggered a synchronisation that it
 // has been finished and the log index is consistent with the chain head passed
 // as a parameter.
+//
 // Note that if the log index head was far behind the chain head then it might not
 // be synced up to the given head in a single step. Still, the latest chain head
 // should be passed as a parameter and the existing log index should be consistent
 // with that chain.
+//
+// Note: acquiring the indexLock read lock is unnecessary here, as this function
+// is always called within the indexLoop.
 func (fm *FilterMapsMatcherBackend) synced() {
-	fm.f.indexLock.RLock()
 	fm.f.matchersLock.Lock()
-	defer func() {
-		fm.f.matchersLock.Unlock()
-		fm.f.indexLock.RUnlock()
-	}()
+	defer fm.f.matchersLock.Unlock()
 
 	indexedBlocks := fm.f.indexedRange.blocks
 	if !fm.f.indexedRange.headIndexed && !indexedBlocks.IsEmpty() {
@@ -154,6 +154,8 @@ func (fm *FilterMapsMatcherBackend) SyncLogIndex(ctx context.Context) (SyncRange
 	case <-ctx.Done():
 		return SyncRange{}, ctx.Err()
 	case <-fm.f.disabledCh:
+		// Note: acquiring the indexLock read lock is unnecessary here,
+		// as the indexer has already been terminated.
 		return SyncRange{IndexedView: fm.f.indexedView}, nil
 	}
 	select {
@@ -162,6 +164,8 @@ func (fm *FilterMapsMatcherBackend) SyncLogIndex(ctx context.Context) (SyncRange
 	case <-ctx.Done():
 		return SyncRange{}, ctx.Err()
 	case <-fm.f.disabledCh:
+		// Note: acquiring the indexLock read lock is unnecessary here,
+		// as the indexer has already been terminated.
 		return SyncRange{IndexedView: fm.f.indexedView}, nil
 	}
 }
@@ -170,7 +174,9 @@ func (fm *FilterMapsMatcherBackend) SyncLogIndex(ctx context.Context) (SyncRange
 // valid range with the current indexed range. This function should be called
 // whenever a part of the log index has been removed, before adding new blocks
 // to it.
-// Note that this function assumes that the index read lock is being held.
+//
+// Note: acquiring the indexLock read lock is unnecessary here, as this function
+// is always called within the indexLoop.
 func (f *FilterMaps) updateMatchersValidRange() {
 	f.matchersLock.Lock()
 	defer f.matchersLock.Unlock()