test: adjust chainstate tests to use recognized snapshot base

In future commits, loading the block index while making use of a
snapshot is contingent on the snapshot being recognized by chainparams.

Ensure all existing unittests that use snapshots use a recognized
snapshot (at height 110).

Co-authored-by: Ryan Ofsky <ryan@ofsky.org>

src/test/validation_chainstatemanager_tests.cpp

@@ -30,12 +30,12 @@ using node::BlockManager;
 using node::KernelNotifications;
 using node::SnapshotMetadata;
 
-BOOST_FIXTURE_TEST_SUITE(validation_chainstatemanager_tests, ChainTestingSetup)
+BOOST_FIXTURE_TEST_SUITE(validation_chainstatemanager_tests, TestingSetup)
 
 //! Basic tests for ChainstateManager.
 //!
 //! First create a legacy (IBD) chainstate, then create a snapshot chainstate.
-BOOST_AUTO_TEST_CASE(chainstatemanager)
+BOOST_FIXTURE_TEST_CASE(chainstatemanager, TestChain100Setup)
 {
     ChainstateManager& manager = *m_node.chainman;
     CTxMemPool& mempool = *m_node.mempool;
@@ -46,14 +46,8 @@ BOOST_AUTO_TEST_CASE(chainstatemanager)
 
     // Create a legacy (IBD) chainstate.
     //
-    Chainstate& c1 = WITH_LOCK(::cs_main, return manager.InitializeChainstate(&mempool));
+    Chainstate& c1 = manager.ActiveChainstate();
     chainstates.push_back(&c1);
-    c1.InitCoinsDB(
-        /*cache_size_bytes=*/1 << 23, /*in_memory=*/true, /*should_wipe=*/false);
-    WITH_LOCK(::cs_main, c1.InitCoinsCache(1 << 23));
-    c1.LoadGenesisBlock();
-    BlockValidationState val_state;
-    BOOST_CHECK(c1.ActivateBestChain(val_state, nullptr));
 
     BOOST_CHECK(!manager.IsSnapshotActive());
     BOOST_CHECK(WITH_LOCK(::cs_main, return !manager.IsSnapshotValidated()));
@@ -63,8 +57,9 @@ BOOST_AUTO_TEST_CASE(chainstatemanager)
     auto& active_chain = WITH_LOCK(manager.GetMutex(), return manager.ActiveChain());
     BOOST_CHECK_EQUAL(&active_chain, &c1.m_chain);
 
-    BOOST_CHECK_EQUAL(WITH_LOCK(manager.GetMutex(), return manager.ActiveHeight()), 0);
+    // Get to a valid assumeutxo tip (per chainparams);
-
+    mineBlocks(10);
+    BOOST_CHECK_EQUAL(WITH_LOCK(manager.GetMutex(), return manager.ActiveHeight()), 110);
     auto active_tip = WITH_LOCK(manager.GetMutex(), return manager.ActiveTip());
     auto exp_tip = c1.m_chain.Tip();
     BOOST_CHECK_EQUAL(active_tip, exp_tip);
@@ -77,16 +72,19 @@ BOOST_AUTO_TEST_CASE(chainstatemanager)
     Chainstate& c2 = WITH_LOCK(::cs_main, return manager.ActivateExistingSnapshot(
         &mempool, snapshot_blockhash));
     chainstates.push_back(&c2);
-
-    BOOST_CHECK_EQUAL(manager.SnapshotBlockhash().value(), snapshot_blockhash);
-
     c2.InitCoinsDB(
         /*cache_size_bytes=*/1 << 23, /*in_memory=*/true, /*should_wipe=*/false);
-    WITH_LOCK(::cs_main, c2.InitCoinsCache(1 << 23));
+    {
-    c2.m_chain.SetTip(*active_tip);
+        LOCK(::cs_main);
+        c2.InitCoinsCache(1 << 23);
+        c2.CoinsTip().SetBestBlock(active_tip->GetBlockHash());
+        c2.setBlockIndexCandidates.insert(manager.m_blockman.LookupBlockIndex(active_tip->GetBlockHash()));
+        c2.LoadChainTip();
+    }
     BlockValidationState _;
     BOOST_CHECK(c2.ActivateBestChain(_, nullptr));
 
+    BOOST_CHECK_EQUAL(manager.SnapshotBlockhash().value(), snapshot_blockhash);
     BOOST_CHECK(manager.IsSnapshotActive());
     BOOST_CHECK(WITH_LOCK(::cs_main, return !manager.IsSnapshotValidated()));
     BOOST_CHECK_EQUAL(&c2, &manager.ActiveChainstate());
@@ -97,13 +95,15 @@ BOOST_AUTO_TEST_CASE(chainstatemanager)
     auto& active_chain2 = WITH_LOCK(manager.GetMutex(), return manager.ActiveChain());
     BOOST_CHECK_EQUAL(&active_chain2, &c2.m_chain);
 
-    BOOST_CHECK_EQUAL(WITH_LOCK(manager.GetMutex(), return manager.ActiveHeight()), 0);
+    BOOST_CHECK_EQUAL(WITH_LOCK(manager.GetMutex(), return manager.ActiveHeight()), 110);
+    mineBlocks(1);
+    BOOST_CHECK_EQUAL(WITH_LOCK(manager.GetMutex(), return manager.ActiveHeight()), 111);
+    BOOST_CHECK_EQUAL(WITH_LOCK(manager.GetMutex(), return c1.m_chain.Height()), 110);
 
     auto active_tip2 = WITH_LOCK(manager.GetMutex(), return manager.ActiveTip());
-    auto exp_tip2 = c2.m_chain.Tip();
+    BOOST_CHECK_EQUAL(active_tip, active_tip2->pprev);
-    BOOST_CHECK_EQUAL(active_tip2, exp_tip2);
+    BOOST_CHECK_EQUAL(active_tip, c1.m_chain.Tip());
-
+    BOOST_CHECK_EQUAL(active_tip2, c2.m_chain.Tip());
-    BOOST_CHECK_EQUAL(exp_tip, exp_tip2);
 
     // Let scheduler events finish running to avoid accessing memory that is going to be unloaded
     SyncWithValidationInterfaceQueue();
@@ -125,9 +125,6 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_rebalance_caches, TestChain100Setup)
     //
     Chainstate& c1 = manager.ActiveChainstate();
     chainstates.push_back(&c1);
-    c1.InitCoinsDB(
-        /*cache_size_bytes=*/1 << 23, /*in_memory=*/true, /*should_wipe=*/false);
-
     {
         LOCK(::cs_main);
         c1.InitCoinsCache(1 << 23);
@@ -431,13 +428,20 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_loadblockindex, TestChain100Setup)
 
     int num_indexes{0};
     int num_assumed_valid{0};
+    // Blocks in range [assumed_valid_start_idx, last_assumed_valid_idx) will be
+    // marked as assumed-valid and not having data.
     const int expected_assumed_valid{20};
-    const int last_assumed_valid_idx{40};
+    const int last_assumed_valid_idx{111};
     const int assumed_valid_start_idx = last_assumed_valid_idx - expected_assumed_valid;
 
+    // Mine to height 120, past the hardcoded regtest assumeutxo snapshot at
+    // height 110
+    mineBlocks(20);
+
     CBlockIndex* validated_tip{nullptr};
     CBlockIndex* assumed_base{nullptr};
     CBlockIndex* assumed_tip{WITH_LOCK(chainman.GetMutex(), return chainman.ActiveChain().Tip())};
+    BOOST_CHECK_EQUAL(assumed_tip->nHeight, 120);
 
     auto reload_all_block_indexes = [&]() {
         // For completeness, we also reset the block sequence counters to
@@ -463,7 +467,7 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_loadblockindex, TestChain100Setup)
         LOCK(::cs_main);
         auto index = cs1.m_chain[i];
 
-        // Blocks with heights in range [20, 40) are marked ASSUMED_VALID
+        // Blocks with heights in range [91, 110] are marked ASSUMED_VALID
         if (i < last_assumed_valid_idx && i >= assumed_valid_start_idx) {
             index->nStatus = BlockStatus::BLOCK_VALID_TREE | BlockStatus::BLOCK_ASSUMED_VALID;
         }
@@ -497,10 +501,36 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_loadblockindex, TestChain100Setup)
     // Set tip of the assume-valid-based chain to the assume-valid block
     cs2.m_chain.SetTip(*assumed_base);
 
+    // Sanity check test variables.
+    BOOST_CHECK_EQUAL(num_indexes, 121); // 121 total blocks, including genesis
+    BOOST_CHECK_EQUAL(assumed_tip->nHeight, 120);  // original chain has height 120
+    BOOST_CHECK_EQUAL(validated_tip->nHeight, 90); // current cs1 chain has height 90
+    BOOST_CHECK_EQUAL(assumed_base->nHeight, 110); // current cs2 chain has height 110
+
+    // Regenerate cs1.setBlockIndexCandidates and cs2.setBlockIndexCandidate and
+    // check contents below.
     reload_all_block_indexes();
 
-    // The fully validated chain should have the current validated tip
+    // The fully validated chain should only have the current validated tip and
-    // and the assumed valid base as candidates.
+    // the assumed valid base as candidates, blocks 90 and 110. Specifically:
+    //
+    // - It does not have blocks 0-89 because they contain less work than the
+    //   chain tip.
+    //
+    // - It has block 90 because it has data and equal work to the chain tip,
+    //   (since it is the chain tip).
+    //
+    // - It does not have blocks 91-109 because they do not contain data.
+    //
+    // - It has block 110 even though it does not have data, because
+    //   LoadBlockIndex has a special case to always add the snapshot block as a
+    //   candidate. The special case is only actually intended to apply to the
+    //   snapshot chainstate cs2, not the background chainstate cs1, but it is
+    //   written broadly and applies to both.
+    //
+    // - It does not have any blocks after height 110 because cs1 is a background
+    //   chainstate, and only blocks where are ancestors of the snapshot block
+    //   are added as candidates for the background chainstate.
     BOOST_CHECK_EQUAL(cs1.setBlockIndexCandidates.size(), 2);
     BOOST_CHECK_EQUAL(cs1.setBlockIndexCandidates.count(validated_tip), 1);
     BOOST_CHECK_EQUAL(cs1.setBlockIndexCandidates.count(assumed_base), 1);
@@ -508,8 +538,25 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_loadblockindex, TestChain100Setup)
     // The assumed-valid tolerant chain has the assumed valid base as a
     // candidate, but otherwise has none of the assumed-valid (which do not
     // HAVE_DATA) blocks as candidates.
+    //
+    // Specifically:
+    // - All blocks below height 110 are not candidates, because cs2 chain tip
+    //   has height 110 and they have less work than it does.
+    //
+    // - Block 110 is a candidate even though it does not have data, because it
+    //   is the snapshot block, which is assumed valid.
+    //
+    // - Blocks 111-120 are added because they have data.
+
+    // Check that block 90 is absent
     BOOST_CHECK_EQUAL(cs2.setBlockIndexCandidates.count(validated_tip), 0);
+    // Check that block 109 is absent
+    BOOST_CHECK_EQUAL(cs2.setBlockIndexCandidates.count(assumed_base->pprev), 0);
+    // Check that block 110 is present
+    BOOST_CHECK_EQUAL(cs2.setBlockIndexCandidates.count(assumed_base), 1);
+    // Check that block 120 is present
     BOOST_CHECK_EQUAL(cs2.setBlockIndexCandidates.count(assumed_tip), 1);
+    // Check that 11 blocks total are present.
     BOOST_CHECK_EQUAL(cs2.setBlockIndexCandidates.size(), num_indexes - last_assumed_valid_idx + 1);
 }
 

src/validation.cpp

@@ -3539,7 +3539,8 @@ void Chainstate::ResetBlockFailureFlags(CBlockIndex *pindex) {
 void Chainstate::TryAddBlockIndexCandidate(CBlockIndex* pindex)
 {
     AssertLockHeld(cs_main);
-    // The block only is a candidate for the most-work-chain if it has more work than our current tip.
+    // The block only is a candidate for the most-work-chain if it has the same
+    // or more work than our current tip.
     if (m_chain.Tip() != nullptr && setBlockIndexCandidates.value_comp()(pindex, m_chain.Tip())) {
         return;
     }