Merge bitcoin/bitcoin#24138: index: Commit MuHash and best block together for coinstatsindex

691d45fdc83ec14f87a400f548553168ac70263f Add coinstatsindex_unclean_shutdown test (Ryan Ofsky)
eb6cc05da32c5bde122725a0bc907d3767a791cd index: Commit DB_MUHASH and DB_BEST_BLOCK to disk together (Martin Zumsande)

Pull request description:

  Fixes #24076

  Coinstatsindex currently writes the MuHash (`DB_MUHASH`) to disk in `CoinStatsIndex::WriteBlock()` and `CoinStatsIndex::ReverseBlock()`, but the best synced block is written in `BaseIndex::Commit()`. These are called at different points in time, both during the ThreadSync phase, and also after the initial sync is finished and validation callbacks (`BlockConnected()` vs `ChainStateFlushed()`) perform the syncing.

  As a result, the index DB is temporarily in an inconsistent state, and if bitcoind is terminated uncleanly (so that there is no time to call `Commit()` by receiving an interrupt or by flushing the chainstate) this leads to problems:
  On the next startup, `Init()` will read the best block and a MuHash that corresponds to a different (higher) block. Indexing will  be picked up at the the best block processing some blocks again, but since MuHash is a rolling hash, it will process some utxos twice and the muhashes for all future blocks will be wrong, as was observed in #24076.

  Fix this by always committing `DB_MUHASH` together with `DB_BEST_BLOCK`.

  Note that the block data for the index is still written at different times, but this does not corrupt the index - at worst, these entries will be processed another time and overwritten after an unclean shutdown and restart.

ACKs for top commit:
  ryanofsky:
    Code review ACK 691d45fdc83ec14f87a400f548553168ac70263f. Only change since last review is adding test
  fjahr:
    ACK 691d45fdc83ec14f87a400f548553168ac70263f

Tree-SHA512: e1c3b5f06fa4baacd1b070abb0f8111fe2ea4a001ca8b8bf892e96597cf8b5d5ea10fa8fb837cfbf46648f052c742d912add4ce26d4406294fc5fc20809a0e1b

2 files changed, 14 insertions, 0 deletions

diff --git a/src/test/util/validation.cpp b/src/test/util/validation.cpp
index 1aed492c3c..49535855f9 100644
--- a/src/test/util/validation.cpp
+++ b/src/test/util/validation.cpp
@@ -7,6 +7,7 @@
 #include <util/check.h>
 #include <util/time.h>
 #include <validation.h>
+#include <validationinterface.h>
 
 void TestChainState::ResetIbd()
 {
@@ -20,3 +21,8 @@ void TestChainState::JumpOutOfIbd()
     m_cached_finished_ibd = true;
     Assert(!IsInitialBlockDownload());
 }
+
+void ValidationInterfaceTest::BlockConnected(CValidationInterface& obj, const std::shared_ptr<const CBlock>& block, const CBlockIndex* pindex)
+{
+    obj.BlockConnected(block, pindex);
+}
diff --git a/src/test/util/validation.h b/src/test/util/validation.h
index b13aa0be60..b0bc717b6c 100644
--- a/src/test/util/validation.h
+++ b/src/test/util/validation.h
@@ -7,6 +7,8 @@
 
 #include <validation.h>
 
+class CValidationInterface;
+
 struct TestChainState : public CChainState {
     /** Reset the ibd cache to its initial state */
     void ResetIbd();
@@ -14,4 +16,10 @@ struct TestChainState : public CChainState {
     void JumpOutOfIbd();
 };
 
+class ValidationInterfaceTest
+{
+public:
+    static void BlockConnected(CValidationInterface& obj, const std::shared_ptr<const CBlock>& block, const CBlockIndex* pindex);
+};
+
 #endif // BITCOIN_TEST_UTIL_VALIDATION_H