Merge bitcoin#19733: Move comment about BaseIndex::DB from TxIndex::DB

8ed2f1e Remove unused includes (Marcin Jachymiak)
cf095a5 Move comment about BaseIndex::DB from TxIndex::DB (Marcin Jachymiak)

Pull request description:

  Moves a comment about the `BaseIndex::DB` from the `TxIndex::DB` into the correct place. Originally part of bitcoin#14053.

ACKs for top commit:
  fanquake:
    ACK 8ed2f1e

Tree-SHA512: cb4e2b916c7ab996961cc2e1d910bc4b8a1700eb32b70fc1657ca720117a7a84f7337fe5e4fb30e047aa92c31eaa976eaaa5cb8f861877f2ff6f4a59bb94f4e9

src/index/base.h

@@ -22,6 +22,13 @@ class CBlockIndex;
 class BaseIndex : public CValidationInterface
 {
 protected:
+    /**
+     * The database stores a block locator of the chain the database is synced to
+     * so that the index can efficiently determine the point it last stopped at.
+     * A locator is used instead of a simple hash of the chain tip because blocks
+     * and block index entries may not be flushed to disk until after this database
+     * is updated.
+    */
     class DB : public CDBWrapper
     {
     public:

src/index/txindex.cpp

@@ -7,6 +7,7 @@
 #include <ui_interface.h>
 #include <util/system.h>
 #include <validation.h>
+#include <serialize.h>
 
 #include <boost/thread.hpp>
 
@@ -39,15 +40,7 @@ struct CDiskTxPos : public FlatFilePos
     }
 };
 
-/**
- * Access to the txindex database (indexes/txindex/)
- *
- * The database stores a block locator of the chain the database is synced to
- * so that the TxIndex can efficiently determine the point it last stopped at.
- * A locator is used instead of a simple hash of the chain tip because blocks
- * and block index entries may not be flushed to disk until after this database
- * is updated.
- */
+/** Access to the txindex database (indexes/txindex/) */
 class TxIndex::DB : public BaseIndex::DB
 {
 public: