triedb/pathdb: pause the pruning if indexer is active

triedb/pathdb/history_index_pruner.go

@@ -59,16 +59,21 @@ type indexPruner struct {
 	closed  chan struct{}
 	wg      sync.WaitGroup
 	log     log.Logger
+
+	pauseReq chan chan struct{} // Pause request; caller sends ack channel, pruner closes it when paused
+	resumeCh chan struct{}      // Resume signal sent by caller after indexSingle/unindexSingle completes
 }
 
 // newIndexPruner creates and starts a new index pruner for the given history type.
 func newIndexPruner(disk ethdb.KeyValueStore, typ historyType) *indexPruner {
 	p := &indexPruner{
-		disk:    disk,
-		typ:     typ,
-		trigger: make(chan struct{}, 1),
-		closed:  make(chan struct{}),
-		log:     log.New("type", typ.String()),
+		disk:     disk,
+		typ:      typ,
+		trigger:  make(chan struct{}, 1),
+		closed:   make(chan struct{}),
+		log:      log.New("type", typ.String()),
+		pauseReq: make(chan chan struct{}),
+		resumeCh: make(chan struct{}),
 	}
 	p.wg.Add(1)
 	go p.run()
@@ -95,6 +100,27 @@ func (p *indexPruner) prune(newTail uint64) {
 	}
 }
 
+// pause requests the pruner to flush all pending writes and pause. It blocks
+// until the pruner has acknowledged the pause. This must be paired with a
+// subsequent call to resume.
+func (p *indexPruner) pause() {
+	ack := make(chan struct{})
+	select {
+	case p.pauseReq <- ack:
+		<-ack // wait for the pruner to flush and acknowledge
+	case <-p.closed:
+	}
+}
+
+// resume unblocks a previously paused pruner, allowing it to continue
+// processing.
+func (p *indexPruner) resume() {
+	select {
+	case p.resumeCh <- struct{}{}:
+	case <-p.closed:
+	}
+}
+
 // close shuts down the pruner and waits for it to finish.
 func (p *indexPruner) close() {
 	select {
@@ -124,6 +150,15 @@ func (p *indexPruner) run() {
 				p.lastRun = tail
 			}
 
+		case ack := <-p.pauseReq:
+			// Pruner is idle, acknowledge immediately and wait for resume.
+			close(ack)
+			select {
+			case <-p.resumeCh:
+			case <-p.closed:
+				return
+			}
+
 		case <-p.closed:
 			return
 		}
@@ -175,55 +210,79 @@ func (p *indexPruner) process(tail uint64) error {
 func (p *indexPruner) prunePrefix(prefix []byte, elemType elementType, tail uint64) (int, error) {
 	var (
 		pruned int
-		start  []byte // iterator seek position
+		opened = time.Now()
+		it     = p.disk.NewIterator(prefix, nil)
 		batch  = p.disk.NewBatchWithSize(ethdb.IdealBatchSize)
 	)
 	for {
-		var (
-			reopen bool
-			opened = time.Now()
-			it     = p.disk.NewIterator(prefix, start)
-		)
-		for it.Next() {
-			// Check termination
-			select {
-			case <-p.closed:
-				it.Release()
-				if batch.ValueSize() > 0 {
-					return pruned, batch.Write()
-				}
-				return pruned, nil
-			default:
+		// Terminate if iterator is exhausted
+		if !it.Next() {
+			it.Release()
+			break
+		}
+		// Periodically release the iterator so the LSM compactor
+		// is not blocked by the read snapshot we hold.
+		if time.Since(opened) >= iteratorReopenInterval {
+			start := common.CopyBytes(it.Key()[len(prefix):])
+			it.Release()
+			it = p.disk.NewIterator(prefix, start)
+		}
+		// Check termination or pause request
+		select {
+		case <-p.closed:
+			// Terminate the process if indexer is closed
+			it.Release()
+			if batch.ValueSize() > 0 {
+				return pruned, batch.Write()
 			}
+			return pruned, nil
 
-			key, value := it.Key(), it.Value()
-			ident, bsize := p.identFromKey(key, prefix, elemType)
-			n, err := p.pruneEntry(batch, ident, value, bsize, tail)
-			if err != nil {
-				p.log.Warn("Failed to prune index entry", "ident", ident, "err", err)
-				continue
-			}
-			pruned += n
+		case ack := <-p.pauseReq:
+			// Save the current position so that after resume the
+			// iterator can be re-opened from where it left off.
+			key := it.Key()
+			start := common.CopyBytes(key[len(prefix):])
+			it.Release()
 
-			if batch.ValueSize() >= ethdb.IdealBatchSize {
+			// Flush all pending writes before acknowledging the pause.
+			if batch.ValueSize() > 0 {
 				if err := batch.Write(); err != nil {
-					it.Release()
+					close(ack)
 					return 0, err
 				}
 				batch.Reset()
 			}
-			// Periodically release the iterator so the LSM compactor
-			// is not blocked by the read snapshot we hold.
-			if time.Since(opened) >= iteratorReopenInterval {
-				reopen = true
-				start = common.CopyBytes(key[len(prefix):])
-				break
-			}
-		}
-		it.Release()
+			close(ack)
 
-		if !reopen {
-			break
+			// Block until resumed or closed
+			select {
+			case <-p.resumeCh:
+				it = p.disk.NewIterator(prefix, start)
+			case <-p.closed:
+				return pruned, nil
+			}
+
+		default:
+			// Keep processing
+		}
+
+		// Prune the index data block
+		key, value := it.Key(), it.Value()
+		ident, bsize := p.identFromKey(key, prefix, elemType)
+		n, err := p.pruneEntry(batch, ident, value, bsize, tail)
+		if err != nil {
+			p.log.Warn("Failed to prune index entry", "ident", ident, "err", err)
+			continue
+		}
+		pruned += n
+
+		// Flush the batch if there are too many accumulated
+		if batch.ValueSize() >= ethdb.IdealBatchSize {
+			if err := batch.Write(); err != nil {
+				it.Release()
+				return 0, err
+			}
+			batch.Reset()
 		}
 	}
 	if batch.ValueSize() > 0 {

triedb/pathdb/history_indexer.go

@@ -805,6 +805,8 @@ func (i *historyIndexer) extend(historyID uint64) error {
 	case <-i.initer.closed:
 		return errors.New("indexer is closed")
 	case <-i.initer.done:
+		i.pruner.pause()
+		defer i.pruner.resume()
 		return indexSingle(historyID, i.disk, i.freezer, i.typ)
 	case i.initer.interrupt <- signal:
 		return <-signal.result
@@ -822,6 +824,8 @@ func (i *historyIndexer) shorten(historyID uint64) error {
 	case <-i.initer.closed:
 		return errors.New("indexer is closed")
 	case <-i.initer.done:
+		i.pruner.pause()
+		defer i.pruner.resume()
 		return unindexSingle(historyID, i.disk, i.freezer, i.typ)
 	case i.initer.interrupt <- signal:
 		return <-signal.result