core: only fire one chain head per batch (#15123)

* core: only fire one chain head per batch

* miner: announce chan events synchronously

2 files changed, 33 insertions, 22 deletions

diff --git a/core/blockchain.go b/core/blockchain.go
index 25be8d762..235c1f3da 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -854,9 +854,22 @@ func (bc *BlockChain) WriteBlockAndState(block *types.Block, receipts []*types.R
 	return status, nil
 }
 
-// InsertChain will attempt to insert the given chain in to the canonical chain or, otherwise, create a fork. If an error is returned
-// it will return the index number of the failing block as well an error describing what went wrong (for possible errors see core/errors.go).
+// InsertChain attempts to insert the given batch of blocks in to the canonical
+// chain or, otherwise, create a fork. If an error is returned it will return
+// the index number of the failing block as well an error describing what went
+// wrong.
+//
+// After insertion is done, all accumulated events will be fired.
 func (bc *BlockChain) InsertChain(chain types.Blocks) (int, error) {
+	n, events, logs, err := bc.insertChain(chain)
+	bc.PostChainEvents(events, logs)
+	return n, err
+}
+
+// insertChain will execute the actual chain insertion and event aggregation. The
+// only reason this method exists as a separate one is to make locking cleaner
+// with deferred statements.
+func (bc *BlockChain) insertChain(chain types.Blocks) (int, []interface{}, []*types.Log, error) {
 	// Do a sanity check that the provided chain is actually ordered and linked
 	for i := 1; i < len(chain); i++ {
 		if chain[i].NumberU64() != chain[i-1].NumberU64()+1 || chain[i].ParentHash() != chain[i-1].Hash() {
@@ -864,7 +877,7 @@ func (bc *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 			log.Error("Non contiguous block insert", "number", chain[i].Number(), "hash", chain[i].Hash(),
 				"parent", chain[i].ParentHash(), "prevnumber", chain[i-1].Number(), "prevhash", chain[i-1].Hash())
 
-			return 0, fmt.Errorf("non contiguous insert: item %d is #%d [%x…], item %d is #%d [%x…] (parent [%x…])", i-1, chain[i-1].NumberU64(),
+			return 0, nil, nil, fmt.Errorf("non contiguous insert: item %d is #%d [%x…], item %d is #%d [%x…] (parent [%x…])", i-1, chain[i-1].NumberU64(),
 				chain[i-1].Hash().Bytes()[:4], i, chain[i].NumberU64(), chain[i].Hash().Bytes()[:4], chain[i].ParentHash().Bytes()[:4])
 		}
 	}
@@ -881,6 +894,7 @@ func (bc *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 	var (
 		stats         = insertStats{startTime: mclock.Now()}
 		events        = make([]interface{}, 0, len(chain))
+		lastCanon     *types.Block
 		coalescedLogs []*types.Log
 	)
 	// Start the parallel header verifier
@@ -904,7 +918,7 @@ func (bc *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 		// If the header is a banned one, straight out abort
 		if BadHashes[block.Hash()] {
 			bc.reportBlock(block, nil, ErrBlacklistedHash)
-			return i, ErrBlacklistedHash
+			return i, events, coalescedLogs, ErrBlacklistedHash
 		}
 		// Wait for the block's verification to complete
 		bstart := time.Now()
@@ -925,7 +939,7 @@ func (bc *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 				// if given.
 				max := big.NewInt(time.Now().Unix() + maxTimeFutureBlocks)
 				if block.Time().Cmp(max) > 0 {
-					return i, fmt.Errorf("future block: %v > %v", block.Time(), max)
+					return i, events, coalescedLogs, fmt.Errorf("future block: %v > %v", block.Time(), max)
 				}
 				bc.futureBlocks.Add(block.Hash(), block)
 				stats.queued++
@@ -939,7 +953,7 @@ func (bc *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 			}
 
 			bc.reportBlock(block, nil, err)
-			return i, err
+			return i, events, coalescedLogs, err
 		}
 		// Create a new statedb using the parent block and report an
 		// error if it fails.
@@ -951,40 +965,35 @@ func (bc *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 		}
 		state, err := state.New(parent.Root(), bc.stateCache)
 		if err != nil {
-			return i, err
+			return i, events, coalescedLogs, err
 		}
 		// Process block using the parent state as reference point.
 		receipts, logs, usedGas, err := bc.processor.Process(block, state, bc.vmConfig)
 		if err != nil {
 			bc.reportBlock(block, receipts, err)
-			return i, err
+			return i, events, coalescedLogs, err
 		}
 		// Validate the state using the default validator
 		err = bc.Validator().ValidateState(block, parent, state, receipts, usedGas)
 		if err != nil {
 			bc.reportBlock(block, receipts, err)
-			return i, err
+			return i, events, coalescedLogs, err
 		}
-
 		// Write the block to the chain and get the status.
 		status, err := bc.WriteBlockAndState(block, receipts, state)
 		if err != nil {
-			return i, err
+			return i, events, coalescedLogs, err
 		}
 		switch status {
 		case CanonStatTy:
 			log.Debug("Inserted new block", "number", block.Number(), "hash", block.Hash(), "uncles", len(block.Uncles()),
 				"txs", len(block.Transactions()), "gas", block.GasUsed(), "elapsed", common.PrettyDuration(time.Since(bstart)))
-			// coalesce logs for later processing
+
 			coalescedLogs = append(coalescedLogs, logs...)
 			blockInsertTimer.UpdateSince(bstart)
 			events = append(events, ChainEvent{block, block.Hash(), logs})
-			// We need some control over the mining operation. Acquiring locks and waiting
-			// for the miner to create new block takes too long and in most cases isn't
-			// even necessary.
-			if bc.LastBlockHash() == block.Hash() {
-				events = append(events, ChainHeadEvent{block})
-			}
+			lastCanon = block
+
 		case SideStatTy:
 			log.Debug("Inserted forked block", "number", block.Number(), "hash", block.Hash(), "diff", block.Difficulty(), "elapsed",
 				common.PrettyDuration(time.Since(bstart)), "txs", len(block.Transactions()), "gas", block.GasUsed(), "uncles", len(block.Uncles()))
@@ -996,9 +1005,11 @@ func (bc *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 		stats.usedGas += usedGas.Uint64()
 		stats.report(chain, i)
 	}
-	go bc.PostChainEvents(events, coalescedLogs)
-
-	return 0, nil
+	// Append a single chain head event if we've progressed the chain
+	if lastCanon != nil && bc.LastBlockHash() == lastCanon.Hash() {
+		events = append(events, ChainHeadEvent{lastCanon})
+	}
+	return 0, events, coalescedLogs, nil
 }
 
 // insertStats tracks and reports on block insertion.
diff --git a/core/blockchain_test.go b/core/blockchain_test.go
index 470974a0a..700a30a16 100644
--- a/core/blockchain_test.go
+++ b/core/blockchain_test.go
@@ -935,7 +935,7 @@ func TestReorgSideEvent(t *testing.T) {
 		}
 		gen.AddTx(tx)
 	})
-	chainSideCh := make(chan ChainSideEvent)
+	chainSideCh := make(chan ChainSideEvent, 64)
 	blockchain.SubscribeChainSideEvent(chainSideCh)
 	if _, err := blockchain.InsertChain(replacementBlocks); err != nil {
 		t.Fatalf("failed to insert chain: %v", err)