From 4da209290831720b0f61754b92dabefd5cb35b6d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A9ter=20Szil=C3=A1gyi?= <peterke@gmail.com>
Date: Fri, 8 Feb 2019 11:11:31 +0200
Subject: core: fix pruner panic when importing low-diff-large-sidechain

---
 core/blockchain_test.go | 43 +++++++++++++++++++++++++------------------
 1 file changed, 25 insertions(+), 18 deletions(-)

(limited to 'core/blockchain_test.go')

diff --git a/core/blockchain_test.go b/core/blockchain_test.go
index 641f1ecd4..504ad0eaf 100644
--- a/core/blockchain_test.go
+++ b/core/blockchain_test.go
@@ -1487,16 +1487,22 @@ func BenchmarkBlockChain_1x1000Executions(b *testing.B) {
 // Tests that importing a very large side fork, which is larger than the canon chain,
 // but where the difficulty per block is kept low: this means that it will not
 // overtake the 'canon' chain until after it's passed canon by about 200 blocks.
-func TestLargeOldSidechainWithALowTdChain(t *testing.T) {
-
+//
+// Details at:
+//  - https://github.com/ethereum/go-ethereum/issues/18977
+//  - https://github.com/ethereum/go-ethereum/pull/18988
+func TestLowDiffLongChain(t *testing.T) {
 	// Generate a canonical chain to act as the main dataset
 	engine := ethash.NewFaker()
-
 	db := ethdb.NewMemDatabase()
 	genesis := new(Genesis).MustCommit(db)
-	// We must use a pretty long chain to ensure that the fork
-	// doesn't overtake us until after at least 128 blocks post tip
-	blocks, _ := generateChain(params.TestChainConfig, genesis, engine, db, 6*triesInMemory, func(i int, b *BlockGen) { b.SetCoinbase(common.Address{1}) }, makeHeaderWithLargeDifficulty)
+
+	// We must use a pretty long chain to ensure that the fork doesn't overtake us
+	// until after at least 128 blocks post tip
+	blocks, _ := GenerateChain(params.TestChainConfig, genesis, engine, db, 6*triesInMemory, func(i int, b *BlockGen) {
+		b.SetCoinbase(common.Address{1})
+		b.OffsetTime(-9)
+	})
 
 	// Import the canonical chain
 	diskdb := ethdb.NewMemDatabase()
@@ -1506,19 +1512,14 @@ func TestLargeOldSidechainWithALowTdChain(t *testing.T) {
 	if err != nil {
 		t.Fatalf("failed to create tester chain: %v", err)
 	}
-	for i := 0; i < len(blocks); i++ {
-		if _, err := chain.InsertChain(blocks[i : i+1]); err != nil {
-			t.Fatalf("block %d: failed to insert into chain: %v", i, err)
-		}
+	if n, err := chain.InsertChain(blocks); err != nil {
+		t.Fatalf("block %d: failed to insert into chain: %v", n, err)
 	}
-	// Dereference all the recent tries and ensure no past trie is left in
-	for i := 0; i < triesInMemory; i++ {
-		chain.stateCache.TrieDB().Dereference(blocks[len(blocks)-1-i].Root())
-	}
-
 	// Generate fork chain, starting from an early block
 	parent := blocks[10]
-	fork, _ := generateChain(params.TestChainConfig, parent, engine, db, 256+6*triesInMemory, func(i int, b *BlockGen) { b.SetCoinbase(common.Address{2}) }, makeHeaderWithSmallDifficulty)
+	fork, _ := GenerateChain(params.TestChainConfig, parent, engine, db, 8*triesInMemory, func(i int, b *BlockGen) {
+		b.SetCoinbase(common.Address{2})
+	})
 
 	// And now import the fork
 	if i, err := chain.InsertChain(fork); err != nil {
@@ -1528,6 +1529,12 @@ func TestLargeOldSidechainWithALowTdChain(t *testing.T) {
 	if got := fork[len(fork)-1].Hash(); got != head.Hash() {
 		t.Fatalf("head wrong, expected %x got %x", head.Hash(), got)
 	}
-	td := chain.GetTd(head.Hash(), head.NumberU64())
-	fmt.Printf("td %v", td)
+	// Sanity check that all the canonical numbers are present
+	header := chain.CurrentHeader()
+	for number := head.NumberU64(); number > 0; number-- {
+		if hash := chain.GetHeaderByNumber(number).Hash(); hash != header.Hash() {
+			t.Fatalf("header %d: canonical hash mismatch: have %x, want %x", number, hash, header.Hash())
+		}
+		header = chain.GetHeader(header.ParentHash, number-1)
+	}
 }
-- 
cgit v1.2.3