refactor: remove unused assumeutxo methods

After feedback from Russ, I realized that there are some extraneous assumeutxo methods
that are not necessary and probably just overly confusing. These include

- `Validated*()`
- `IsBackgroundIBD()`

and they can be removed.

src/test/validation_chainstatemanager_tests.cpp

@@ -44,7 +44,6 @@ BOOST_AUTO_TEST_CASE(chainstatemanager)
 
     BOOST_CHECK(!manager.IsSnapshotActive());
     BOOST_CHECK(!manager.IsSnapshotValidated());
-    BOOST_CHECK(!manager.IsBackgroundIBD(&c1));
     auto all = manager.GetAll();
     BOOST_CHECK_EQUAL_COLLECTIONS(all.begin(), all.end(), chainstates.begin(), chainstates.end());
 
@@ -57,9 +56,6 @@ BOOST_AUTO_TEST_CASE(chainstatemanager)
     auto exp_tip = c1.m_chain.Tip();
     BOOST_CHECK_EQUAL(active_tip, exp_tip);
 
-    auto& validated_cs = manager.ValidatedChainstate();
-    BOOST_CHECK_EQUAL(&validated_cs, &c1);
-
     BOOST_CHECK(!manager.SnapshotBlockhash().has_value());
 
     // Create a snapshot-based chainstate.
@@ -81,8 +77,8 @@ BOOST_AUTO_TEST_CASE(chainstatemanager)
 
     BOOST_CHECK(manager.IsSnapshotActive());
     BOOST_CHECK(!manager.IsSnapshotValidated());
-    BOOST_CHECK(manager.IsBackgroundIBD(&c1));
-    BOOST_CHECK(!manager.IsBackgroundIBD(&c2));
+    BOOST_CHECK_EQUAL(&c2, &manager.ActiveChainstate());
+    BOOST_CHECK(&c1 != &manager.ActiveChainstate());
     auto all2 = manager.GetAll();
     BOOST_CHECK_EQUAL_COLLECTIONS(all2.begin(), all2.end(), chainstates.begin(), chainstates.end());
 
@@ -99,16 +95,6 @@ BOOST_AUTO_TEST_CASE(chainstatemanager)
     // CCoinsViewCache instances.
     BOOST_CHECK(exp_tip != exp_tip2);
 
-    auto& validated_cs2 = manager.ValidatedChainstate();
-    BOOST_CHECK_EQUAL(&validated_cs2, &c1);
-
-    auto& validated_chain = manager.ValidatedChain();
-    BOOST_CHECK_EQUAL(&validated_chain, &c1.m_chain);
-
-    auto validated_tip = manager.ValidatedTip();
-    exp_tip = c1.m_chain.Tip();
-    BOOST_CHECK_EQUAL(validated_tip, exp_tip);
-
     // Let scheduler events finish running to avoid accessing memory that is going to be unloaded
     SyncWithValidationInterfaceQueue();
 
@@ -321,27 +307,27 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_activate_snapshot, TestChain100Setup)
     {
         LOCK(::cs_main);
         size_t coins_in_active{0};
-        size_t coins_in_ibd{0};
-        size_t coins_missing_ibd{0};
+        size_t coins_in_background{0};
+        size_t coins_missing_from_background{0};
 
         for (CChainState* chainstate : chainman.GetAll()) {
             BOOST_TEST_MESSAGE("Checking coins in " << chainstate->ToString());
             CCoinsViewCache& coinscache = chainstate->CoinsTip();
-            bool is_ibd = chainman.IsBackgroundIBD(chainstate);
+            bool is_background = chainstate != &chainman.ActiveChainstate();
 
             for (CTransactionRef& txn : m_coinbase_txns) {
                 COutPoint op{txn->GetHash(), 0};
                 if (coinscache.HaveCoin(op)) {
-                    (is_ibd ? coins_in_ibd : coins_in_active)++;
-                } else if (is_ibd) {
-                    coins_missing_ibd++;
+                    (is_background ? coins_in_background : coins_in_active)++;
+                } else if (is_background) {
+                    coins_missing_from_background++;
                 }
             }
         }
 
         BOOST_CHECK_EQUAL(coins_in_active, initial_total_coins + new_coins);
-        BOOST_CHECK_EQUAL(coins_in_ibd, initial_total_coins);
-        BOOST_CHECK_EQUAL(coins_missing_ibd, new_coins);
+        BOOST_CHECK_EQUAL(coins_in_background, initial_total_coins);
+        BOOST_CHECK_EQUAL(coins_missing_from_background, new_coins);
     }
 
     // Snapshot should refuse to load after one has already loaded.

src/validation.cpp

@@ -5007,22 +5007,6 @@ bool ChainstateManager::IsSnapshotActive() const
     return m_snapshot_chainstate && m_active_chainstate == m_snapshot_chainstate.get();
 }
 
-CChainState& ChainstateManager::ValidatedChainstate() const
-{
-    LOCK(::cs_main);
-    if (m_snapshot_chainstate && IsSnapshotValidated()) {
-        return *m_snapshot_chainstate.get();
-    }
-    assert(m_ibd_chainstate);
-    return *m_ibd_chainstate.get();
-}
-
-bool ChainstateManager::IsBackgroundIBD(CChainState* chainstate) const
-{
-    LOCK(::cs_main);
-    return (m_snapshot_chainstate && chainstate == m_ibd_chainstate.get());
-}
-
 void ChainstateManager::Unload()
 {
     for (CChainState* chainstate : this->GetAll()) {

src/validation.h

@@ -862,12 +862,6 @@ private:
  * *Background IBD chainstate*: an IBD chainstate for which the
  *    IBD process is happening in the background while use of the
  *    active (snapshot) chainstate allows the rest of the system to function.
- *
- * *Validated chainstate*: the most-work chainstate which has been validated
- *   locally via initial block download. This will be the snapshot chainstate
- *   if a snapshot was loaded and all blocks up to the snapshot starting point
- *   have been downloaded and validated (via background validation), otherwise
- *   it will be the IBD chainstate.
  */
 class ChainstateManager
 {
@@ -986,19 +980,6 @@ public:
     //! Is there a snapshot in use and has it been fully validated?
     bool IsSnapshotValidated() const { return m_snapshot_validated; }
 
-    //! @returns true if this chainstate is being used to validate an active
-    //!          snapshot in the background.
-    bool IsBackgroundIBD(CChainState* chainstate) const;
-
-    //! Return the most-work chainstate that has been fully validated.
-    //!
-    //! During background validation of a snapshot, this is the IBD chain. After
-    //! background validation has completed, this is the snapshot chain.
-    CChainState& ValidatedChainstate() const;
-
-    CChain& ValidatedChain() const { return ValidatedChainstate().m_chain; }
-    CBlockIndex* ValidatedTip() const { return ValidatedChain().Tip(); }
-
     /**
      * Process an incoming block. This only returns after the best known valid
      * block is made active. Note that it does not, however, guarantee that the