core: fix pruner panic when importing low-diff-large-sidechain

1 files changed, 17 insertions, 11 deletions

diff --git a/core/blockchain.go b/core/blockchain.go
index fa1c254b3..0d2d71b4d 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -972,20 +972,26 @@ func (bc *BlockChain) WriteBlockWithState(block *types.Block, receipts []*types.
 				triedb.Cap(limit - ethdb.IdealBatchSize)
 			}
 			// Find the next state trie we need to commit
-			header := bc.GetHeaderByNumber(current - triesInMemory)
-			chosen := header.Number.Uint64()
+			chosen := current - triesInMemory
 
 			// If we exceeded out time allowance, flush an entire trie to disk
 			if bc.gcproc > bc.cacheConfig.TrieTimeLimit {
-				// If we're exceeding limits but haven't reached a large enough memory gap,
-				// warn the user that the system is becoming unstable.
-				if chosen < lastWrite+triesInMemory && bc.gcproc >= 2*bc.cacheConfig.TrieTimeLimit {
-					log.Info("State in memory for too long, committing", "time", bc.gcproc, "allowance", bc.cacheConfig.TrieTimeLimit, "optimum", float64(chosen-lastWrite)/triesInMemory)
+				// If the header is missing (canonical chain behind), we're reorging a low
+				// diff sidechain. Suspend committing until this operation is completed.
+				header := bc.GetHeaderByNumber(chosen)
+				if header == nil {
+					log.Warn("Reorg in progress, trie commit postponed", "number", chosen)
+				} else {
+					// If we're exceeding limits but haven't reached a large enough memory gap,
+					// warn the user that the system is becoming unstable.
+					if chosen < lastWrite+triesInMemory && bc.gcproc >= 2*bc.cacheConfig.TrieTimeLimit {
+						log.Info("State in memory for too long, committing", "time", bc.gcproc, "allowance", bc.cacheConfig.TrieTimeLimit, "optimum", float64(chosen-lastWrite)/triesInMemory)
+					}
+					// Flush an entire trie and restart the counters
+					triedb.Commit(header.Root, true)
+					lastWrite = chosen
+					bc.gcproc = 0
 				}
-				// Flush an entire trie and restart the counters
-				triedb.Commit(header.Root, true)
-				lastWrite = chosen
-				bc.gcproc = 0
 			}
 			// Garbage collect anything below our required write retention
 			for !bc.triegc.Empty() {
@@ -1317,7 +1323,7 @@ func (bc *BlockChain) insertSidechain(block *types.Block, it *insertIterator) (i
 			if err := bc.WriteBlockWithoutState(block, externTd); err != nil {
 				return it.index, nil, nil, err
 			}
-			log.Debug("Inserted sidechain block", "number", block.Number(), "hash", block.Hash(),
+			log.Debug("Injected sidechain block", "number", block.Number(), "hash", block.Hash(),
 				"diff", block.Difficulty(), "elapsed", common.PrettyDuration(time.Since(start)),
 				"txs", len(block.Transactions()), "gas", block.GasUsed(), "uncles", len(block.Uncles()),
 				"root", block.Root())