core: track and improve tx indexing/unindexing (#21331)

* core: add background indexer to waitgroup

* core: make indexer stopable

* core/rawdb: add unit tests

* core/rawdb: fix lint

* core/rawdb: fix tests

* core/rawdb: fix linter

core/blockchain.go

@@ -345,6 +345,8 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, chainConfig *par
 	go bc.update()
 	if txLookupLimit != nil {
 		bc.txLookupLimit = *txLookupLimit
+
+		bc.wg.Add(1)
 		go bc.maintainTxIndex(txIndexBlock)
 	}
 	// If periodic cache journal is required, spin it up.
@@ -2230,6 +2232,8 @@ func (bc *BlockChain) update() {
 // sync, Geth will automatically construct the missing indices and delete
 // the extra indices.
 func (bc *BlockChain) maintainTxIndex(ancients uint64) {
+	defer bc.wg.Done()
+
 	// Before starting the actual maintenance, we need to handle a special case,
 	// where user might init Geth with an external ancient database. If so, we
 	// need to reindex all necessary transactions before starting to process any
@@ -2239,7 +2243,7 @@ func (bc *BlockChain) maintainTxIndex(ancients uint64) {
 		if bc.txLookupLimit != 0 && ancients > bc.txLookupLimit {
 			from = ancients - bc.txLookupLimit
 		}
-		rawdb.IndexTransactions(bc.db, from, ancients)
+		rawdb.IndexTransactions(bc.db, from, ancients, bc.quit)
 	}
 	// indexBlocks reindexes or unindexes transactions depending on user configuration
 	indexBlocks := func(tail *uint64, head uint64, done chan struct{}) {
@@ -2253,24 +2257,24 @@ func (bc *BlockChain) maintainTxIndex(ancients uint64) {
 				rawdb.WriteTxIndexTail(bc.db, 0)
 			} else {
 				// Prune all stale tx indices and record the tx index tail
-				rawdb.UnindexTransactions(bc.db, 0, head-bc.txLookupLimit+1)
+				rawdb.UnindexTransactions(bc.db, 0, head-bc.txLookupLimit+1, bc.quit)
 			}
 			return
 		}
 		// If a previous indexing existed, make sure that we fill in any missing entries
 		if bc.txLookupLimit == 0 || head < bc.txLookupLimit {
 			if *tail > 0 {
-				rawdb.IndexTransactions(bc.db, 0, *tail)
+				rawdb.IndexTransactions(bc.db, 0, *tail, bc.quit)
 			}
 			return
 		}
 		// Update the transaction index to the new chain state
 		if head-bc.txLookupLimit+1 < *tail {
 			// Reindex a part of missing indices and rewind index tail to HEAD-limit
-			rawdb.IndexTransactions(bc.db, head-bc.txLookupLimit+1, *tail)
+			rawdb.IndexTransactions(bc.db, head-bc.txLookupLimit+1, *tail, bc.quit)
 		} else {
 			// Unindex a part of stale indices and forward index tail to HEAD-limit
-			rawdb.UnindexTransactions(bc.db, *tail, head-bc.txLookupLimit+1)
+			rawdb.UnindexTransactions(bc.db, *tail, head-bc.txLookupLimit+1, bc.quit)
 		}
 	}
 	// Any reindexing done, start listening to chain events and moving the index window
@@ -2294,6 +2298,10 @@ func (bc *BlockChain) maintainTxIndex(ancients uint64) {
 		case <-done:
 			done = nil
 		case <-bc.quit:
+			if done != nil {
+				log.Info("Waiting background transaction indexer to exit")
+				<-done
+			}
 			return
 		}
 	}