Merge bitcoin/bitcoin#28427: index: coinstats reorg, fail when block cannot be reversed

c0bf667 index: add [nodiscard] attribute to functions writing to the db (furszy)
eef5955 index: coinstats reorg, fail when block cannot be reversed (furszy)

Pull request description:

  Found it while reviewing bitcoin/bitcoin#24230 (comment).

  During a reorg, continuing execution when a block cannot be reversed leaves the
  coinstats index in an inconsistent state.
  This was surely overlooked when 'CustomRewind' was implemented.

ACKs for top commit:
  ryanofsky:
    Code review ACK c0bf667. Only change since last review is new commit adding [[nodiscard]]

Tree-SHA512: f4fc8522508d23e4fff09a29c935971819b1bd3b2a260e08e2e2b72f9340980d74fbec742a58fe216baf61d27de057c7c8300e8fa075f8507cd1227f128af909

Author: fanquake

src/index/blockfilterindex.cpp

@@ -261,7 +261,7 @@ bool BlockFilterIndex::CustomAppend(const interfaces::BlockInfo& block)
     return true;
 }
 
-static bool CopyHeightIndexToHashIndex(CDBIterator& db_it, CDBBatch& batch,
+[[nodiscard]] static bool CopyHeightIndexToHashIndex(CDBIterator& db_it, CDBBatch& batch,
                                        const std::string& index_name,
                                        int start_height, int stop_height)
 {

src/index/coinstatsindex.cpp

@@ -235,7 +235,7 @@ bool CoinStatsIndex::CustomAppend(const interfaces::BlockInfo& block)
     return m_db->Write(DBHeightKey(block.height), value);
 }
 
-static bool CopyHeightIndexToHashIndex(CDBIterator& db_it, CDBBatch& batch,
+[[nodiscard]] static bool CopyHeightIndexToHashIndex(CDBIterator& db_it, CDBBatch& batch,
                                        const std::string& index_name,
                                        int start_height, int stop_height)
 {
@@ -288,7 +288,9 @@ bool CoinStatsIndex::CustomRewind(const interfaces::BlockKey& current_tip, const
                              __func__, iter_tip->GetBlockHash().ToString());
             }
 
-            ReverseBlock(block, iter_tip);
+            if (!ReverseBlock(block, iter_tip)) {
+                return false; // failure cause logged internally
+            }
 
             iter_tip = iter_tip->GetAncestor(iter_tip->nHeight - 1);
         } while (new_tip_index != iter_tip);

src/index/coinstatsindex.h

@@ -38,7 +38,7 @@ class CoinStatsIndex final : public BaseIndex
     CAmount m_total_unspendables_scripts{0};
     CAmount m_total_unspendables_unclaimed_rewards{0};
 
-    bool ReverseBlock(const CBlock& block, const CBlockIndex* pindex);
+    [[nodiscard]] bool ReverseBlock(const CBlock& block, const CBlockIndex* pindex);
 
     bool AllowPrune() const override { return true; }
 

src/index/txindex.cpp

@@ -27,7 +27,7 @@ class TxIndex::DB : public BaseIndex::DB
     bool ReadTxPos(const uint256& txid, CDiskTxPos& pos) const;
 
     /// Write a batch of transaction positions to the DB.
-    bool WriteTxs(const std::vector<std::pair<uint256, CDiskTxPos>>& v_pos);
+    [[nodiscard]] bool WriteTxs(const std::vector<std::pair<uint256, CDiskTxPos>>& v_pos);
 };
 
 TxIndex::DB::DB(size_t n_cache_size, bool f_memory, bool f_wipe) :