Merge #10279: Add a CChainState class to validation.cpp to take another step towards clarifying internal interfaces

22fddde Avoid calling GetSerializeSize on each tx in a block if !fTxIndex (Matt Corallo)
2862aca Move some additional variables into CChainState private (Matt Corallo)
fd4d80a Create initial CChainState to hold chain state information (Matt Corallo)
e104f0f Move block writing out of AcceptBlock (Matt Corallo)
50701ba Move txindex/undo data disk location stuff out of ConnectBlock (Matt Corallo)
93a34cf Make DisconnectBlock unaware of where undo data resides on disk (Matt Corallo)

Pull request description:

  CChainState should eventually, essentially, be our exposed "libconsensus", but we're probably a few releases away, so the real goal is to clarify our internal interfaces. The main split was a big step, but validation.cpp is still a somewhat ranomly-mixed bag of functions that are pure functions which validate inputs (which should probably either merge with their callers or move into another file in consensus/), read/write data from disk, manipulate our current chain state (which moves into CChainState), and do mempool transaction validation.

  Obviously this is only a small step, but some effort is made to clean up what functions the functions in CChainState call, and obviously as things are added its easy to keep clear "CChainState::* cannot call anything except via callbacks through CValidationInterface, pure functions, or disk read/write things". Right now there are some glaring violations in mempool callbacks, and general flushing logic needs cleaning up (FlushStateToDisk maybe shouldnt be called, and there should be an API towards setDirtyBlockIndex, but I'll leave that for after @sipa's current changesets land).

Tree-SHA512: 69b8ec191b36b19c9492b4dee74c8057621fb6ec98ad219e8da0b2ed5c3ad711b10b5af9ff1117e8807ccf88918eeeab573be8448baecc9a59f099c53095985b

2 files changed, 315 insertions, 172 deletions

diff --git a/src/validation.cpp b/src/validation.cpp
index 986052771c..946a916e82 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -59,48 +59,7 @@
 /**
  * Global state
  */
-
-CCriticalSection cs_main;
-
-BlockMap mapBlockIndex;
-CChain chainActive;
-CBlockIndex *pindexBestHeader = nullptr;
-CWaitableCriticalSection csBestBlock;
-CConditionVariable cvBlockChange;
-int nScriptCheckThreads = 0;
-std::atomic_bool fImporting(false);
-std::atomic_bool fReindex(false);
-bool fTxIndex = false;
-bool fHavePruned = false;
-bool fPruneMode = false;
-bool fIsBareMultisigStd = DEFAULT_PERMIT_BAREMULTISIG;
-bool fRequireStandard = true;
-bool fCheckBlockIndex = false;
-bool fCheckpointsEnabled = DEFAULT_CHECKPOINTS_ENABLED;
-size_t nCoinCacheUsage = 5000 * 300;
-uint64_t nPruneTarget = 0;
-int64_t nMaxTipAge = DEFAULT_MAX_TIP_AGE;
-bool fEnableReplacement = DEFAULT_ENABLE_REPLACEMENT;
-
-uint256 hashAssumeValid;
-arith_uint256 nMinimumChainWork;
-
-CFeeRate minRelayTxFee = CFeeRate(DEFAULT_MIN_RELAY_TX_FEE);
-CAmount maxTxFee = DEFAULT_TRANSACTION_MAXFEE;
-
-CBlockPolicyEstimator feeEstimator;
-CTxMemPool mempool(&feeEstimator);
-
-static void CheckBlockIndex(const Consensus::Params& consensusParams);
-
-/** Constant stuff for coinbase transactions we create: */
-CScript COINBASE_FLAGS;
-
-const std::string strMessageMagic = "Bitcoin Signed Message:\n";
-
-// Internal stuff
 namespace {
-
     struct CBlockIndexWorkComparator
     {
         bool operator()(const CBlockIndex *pa, const CBlockIndex *pb) const {
@@ -121,28 +80,39 @@ namespace {
             return false;
         }
     };
+} // anon namespace
+
+enum DisconnectResult
+{
+    DISCONNECT_OK,      // All good.
+    DISCONNECT_UNCLEAN, // Rolled back, but UTXO set was inconsistent with block.
+    DISCONNECT_FAILED   // Something else went wrong.
+};
 
-    CBlockIndex *pindexBestInvalid;
+class ConnectTrace;
 
+/**
+ * CChainState stores and provides an API to update our local knowledge of the
+ * current best chain and header tree.
+ *
+ * It generally provides access to the current block tree, as well as functions
+ * to provide new data, which it will appropriately validate and incorporate in
+ * its state as necessary.
+ *
+ * Eventually, the API here is targeted at being exposed externally as a
+ * consumable libconsensus library, so any functions added must only call
+ * other class member functions, pure functions in other parts of the consensus
+ * library, callbacks via the validation interface, or read/write-to-disk
+ * functions (eventually this will also be via callbacks).
+ */
+class CChainState {
+private:
     /**
      * The set of all CBlockIndex entries with BLOCK_VALID_TRANSACTIONS (for itself and all ancestors) and
      * as good as our current tip or better. Entries may be failed, though, and pruning nodes may be
      * missing the data for the block.
      */
     std::set<CBlockIndex*, CBlockIndexWorkComparator> setBlockIndexCandidates;
-    /** All pairs A->B, where A (or one of its ancestors) misses transactions, but B has transactions.
-     * Pruned nodes may have entries where B is missing data.
-     */
-    std::multimap<CBlockIndex*, CBlockIndex*> mapBlocksUnlinked;
-
-    CCriticalSection cs_LastBlockFile;
-    std::vector<CBlockFileInfo> vinfoBlockFile;
-    int nLastBlockFile = 0;
-    /** Global flag to indicate we should check to see if there are
-     *  block/undo files that should be deleted.  Set on startup
-     *  or if we allocate more file space when we're in prune mode
-     */
-    bool fCheckForPruning = false;
 
     /**
      * Every received block is assigned a unique and increasing identifier, so we
@@ -176,6 +146,113 @@ namespace {
       */
     std::set<CBlockIndex*> g_failed_blocks;
 
+public:
+    CChain chainActive;
+    BlockMap mapBlockIndex;
+    std::multimap<CBlockIndex*, CBlockIndex*> mapBlocksUnlinked;
+    CBlockIndex *pindexBestInvalid = nullptr;
+
+    bool LoadBlockIndex(const Consensus::Params& consensus_params, CBlockTreeDB& blocktree);
+
+    bool ActivateBestChain(CValidationState &state, const CChainParams& chainparams, std::shared_ptr<const CBlock> pblock);
+
+    bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex);
+    bool AcceptBlock(const std::shared_ptr<const CBlock>& pblock, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex, bool fRequested, const CDiskBlockPos* dbp, bool* fNewBlock);
+
+    // Block (dis)connection on a given view:
+    DisconnectResult DisconnectBlock(const CBlock& block, const CBlockIndex* pindex, CCoinsViewCache& view);
+    bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pindex,
+                    CCoinsViewCache& view, const CChainParams& chainparams, bool fJustCheck = false);
+
+    // Block disconnection on our pcoinsTip:
+    bool DisconnectTip(CValidationState& state, const CChainParams& chainparams, DisconnectedBlockTransactions *disconnectpool);
+
+    // Manual block validity manipulation:
+    bool PreciousBlock(CValidationState& state, const CChainParams& params, CBlockIndex *pindex);
+    bool InvalidateBlock(CValidationState& state, const CChainParams& chainparams, CBlockIndex *pindex);
+    bool ResetBlockFailureFlags(CBlockIndex *pindex);
+
+    bool ReplayBlocks(const CChainParams& params, CCoinsView* view);
+    bool RewindBlockIndex(const CChainParams& params);
+    bool LoadGenesisBlock(const CChainParams& chainparams);
+
+    void PruneBlockIndexCandidates();
+
+    void UnloadBlockIndex();
+
+private:
+    bool ActivateBestChainStep(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexMostWork, const std::shared_ptr<const CBlock>& pblock, bool& fInvalidFound, ConnectTrace& connectTrace);
+    bool ConnectTip(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexNew, const std::shared_ptr<const CBlock>& pblock, ConnectTrace& connectTrace, DisconnectedBlockTransactions &disconnectpool);
+
+    CBlockIndex* AddToBlockIndex(const CBlockHeader& block);
+    /** Create a new block index entry for a given block hash */
+    CBlockIndex * InsertBlockIndex(const uint256& hash);
+    void CheckBlockIndex(const Consensus::Params& consensusParams);
+
+    void InvalidBlockFound(CBlockIndex *pindex, const CValidationState &state);
+    CBlockIndex* FindMostWorkChain();
+    bool ReceivedBlockTransactions(const CBlock &block, CValidationState& state, CBlockIndex *pindexNew, const CDiskBlockPos& pos, const Consensus::Params& consensusParams);
+
+
+    bool RollforwardBlock(const CBlockIndex* pindex, CCoinsViewCache& inputs, const CChainParams& params);
+} g_chainstate;
+
+
+
+CCriticalSection cs_main;
+
+BlockMap& mapBlockIndex = g_chainstate.mapBlockIndex;
+CChain& chainActive = g_chainstate.chainActive;
+CBlockIndex *pindexBestHeader = nullptr;
+CWaitableCriticalSection csBestBlock;
+CConditionVariable cvBlockChange;
+int nScriptCheckThreads = 0;
+std::atomic_bool fImporting(false);
+std::atomic_bool fReindex(false);
+bool fTxIndex = false;
+bool fHavePruned = false;
+bool fPruneMode = false;
+bool fIsBareMultisigStd = DEFAULT_PERMIT_BAREMULTISIG;
+bool fRequireStandard = true;
+bool fCheckBlockIndex = false;
+bool fCheckpointsEnabled = DEFAULT_CHECKPOINTS_ENABLED;
+size_t nCoinCacheUsage = 5000 * 300;
+uint64_t nPruneTarget = 0;
+int64_t nMaxTipAge = DEFAULT_MAX_TIP_AGE;
+bool fEnableReplacement = DEFAULT_ENABLE_REPLACEMENT;
+
+uint256 hashAssumeValid;
+arith_uint256 nMinimumChainWork;
+
+CFeeRate minRelayTxFee = CFeeRate(DEFAULT_MIN_RELAY_TX_FEE);
+CAmount maxTxFee = DEFAULT_TRANSACTION_MAXFEE;
+
+CBlockPolicyEstimator feeEstimator;
+CTxMemPool mempool(&feeEstimator);
+
+/** Constant stuff for coinbase transactions we create: */
+CScript COINBASE_FLAGS;
+
+const std::string strMessageMagic = "Bitcoin Signed Message:\n";
+
+// Internal stuff
+namespace {
+    CBlockIndex *&pindexBestInvalid = g_chainstate.pindexBestInvalid;
+
+    /** All pairs A->B, where A (or one of its ancestors) misses transactions, but B has transactions.
+     * Pruned nodes may have entries where B is missing data.
+     */
+    std::multimap<CBlockIndex*, CBlockIndex*>& mapBlocksUnlinked = g_chainstate.mapBlocksUnlinked;
+
+    CCriticalSection cs_LastBlockFile;
+    std::vector<CBlockFileInfo> vinfoBlockFile;
+    int nLastBlockFile = 0;
+    /** Global flag to indicate we should check to see if there are
+     *  block/undo files that should be deleted.  Set on startup
+     *  or if we allocate more file space when we're in prune mode
+     */
+    bool fCheckForPruning = false;
+
     /** Dirty block index entries. */
     std::set<CBlockIndex*> setDirtyBlockIndex;
 
@@ -1201,7 +1278,7 @@ void static InvalidChainFound(CBlockIndex* pindexNew)
     CheckForkWarningConditions();
 }
 
-void static InvalidBlockFound(CBlockIndex *pindex, const CValidationState &state) {
+void CChainState::InvalidBlockFound(CBlockIndex *pindex, const CValidationState &state) {
     if (!state.CorruptionPossible()) {
         pindex->nStatus |= BLOCK_FAILED_VALID;
         g_failed_blocks.insert(pindex);
@@ -1384,8 +1461,13 @@ bool UndoWriteToDisk(const CBlockUndo& blockundo, CDiskBlockPos& pos, const uint
     return true;
 }
 
-bool UndoReadFromDisk(CBlockUndo& blockundo, const CDiskBlockPos& pos, const uint256& hashBlock)
+static bool UndoReadFromDisk(CBlockUndo& blockundo, const CBlockIndex *pindex)
 {
+    CDiskBlockPos pos = pindex->GetUndoPos();
+    if (pos.IsNull()) {
+        return error("%s: no undo data available", __func__);
+    }
+
     // Open history file to read
     CAutoFile filein(OpenUndoFile(pos, true), SER_DISK, CLIENT_VERSION);
     if (filein.IsNull())
@@ -1395,7 +1477,7 @@ bool UndoReadFromDisk(CBlockUndo& blockundo, const CDiskBlockPos& pos, const uin
     uint256 hashChecksum;
     CHashVerifier<CAutoFile> verifier(&filein); // We need a CHashVerifier as reserializing may lose data
     try {
-        verifier << hashBlock;
+        verifier << pindex->pprev->GetBlockHash();
         verifier >> blockundo;
         filein >> hashChecksum;
     }
@@ -1430,13 +1512,6 @@ bool AbortNode(CValidationState& state, const std::string& strMessage, const std
 
 } // namespace
 
-enum DisconnectResult
-{
-    DISCONNECT_OK,      // All good.
-    DISCONNECT_UNCLEAN, // Rolled back, but UTXO set was inconsistent with block.
-    DISCONNECT_FAILED   // Something else went wrong.
-};
-
 /**
  * Restore the UTXO in a Coin at a given COutPoint
  * @param undo The Coin to be restored.
@@ -1473,17 +1548,12 @@ int ApplyTxInUndo(Coin&& undo, CCoinsViewCache& view, const COutPoint& out)
 
 /** Undo the effects of this block (with given index) on the UTXO set represented by coins.
  *  When FAILED is returned, view is left in an indeterminate state. */
-static DisconnectResult DisconnectBlock(const CBlock& block, const CBlockIndex* pindex, CCoinsViewCache& view)
+DisconnectResult CChainState::DisconnectBlock(const CBlock& block, const CBlockIndex* pindex, CCoinsViewCache& view)
 {
     bool fClean = true;
 
     CBlockUndo blockUndo;
-    CDiskBlockPos pos = pindex->GetUndoPos();
-    if (pos.IsNull()) {
-        error("DisconnectBlock(): no undo data available");
-        return DISCONNECT_FAILED;
-    }
-    if (!UndoReadFromDisk(blockUndo, pos, pindex->pprev->GetBlockHash())) {
+    if (!UndoReadFromDisk(blockUndo, pindex)) {
         error("DisconnectBlock(): failure reading undo data");
         return DISCONNECT_FAILED;
     }
@@ -1560,6 +1630,45 @@ void static FlushBlockFile(bool fFinalize = false)
 
 static bool FindUndoPos(CValidationState &state, int nFile, CDiskBlockPos &pos, unsigned int nAddSize);
 
+static bool WriteUndoDataForBlock(const CBlockUndo& blockundo, CValidationState& state, CBlockIndex* pindex, const CChainParams& chainparams)
+{
+    // Write undo information to disk
+    if (pindex->GetUndoPos().IsNull()) {
+        CDiskBlockPos _pos;
+        if (!FindUndoPos(state, pindex->nFile, _pos, ::GetSerializeSize(blockundo, SER_DISK, CLIENT_VERSION) + 40))
+            return error("ConnectBlock(): FindUndoPos failed");
+        if (!UndoWriteToDisk(blockundo, _pos, pindex->pprev->GetBlockHash(), chainparams.MessageStart()))
+            return AbortNode(state, "Failed to write undo data");
+
+        // update nUndoPos in block index
+        pindex->nUndoPos = _pos.nPos;
+        pindex->nStatus |= BLOCK_HAVE_UNDO;
+        setDirtyBlockIndex.insert(pindex);
+    }
+
+    return true;
+}
+
+static bool WriteTxIndexDataForBlock(const CBlock& block, CValidationState& state, CBlockIndex* pindex)
+{
+    if (!fTxIndex) return true;
+
+    CDiskTxPos pos(pindex->GetBlockPos(), GetSizeOfCompactSize(block.vtx.size()));
+    std::vector<std::pair<uint256, CDiskTxPos> > vPos;
+    vPos.reserve(block.vtx.size());
+    for (const CTransactionRef& tx : block.vtx)
+    {
+        vPos.push_back(std::make_pair(tx->GetHash(), pos));
+        pos.nTxOffset += ::GetSerializeSize(*tx, SER_DISK, CLIENT_VERSION);
+    }
+
+    if (!pblocktree->WriteTxIndex(vPos)) {
+        return AbortNode(state, "Failed to write transaction index");
+    }
+
+    return true;
+}
+
 static CCheckQueue<CScriptCheck> scriptcheckqueue(128);
 
 void ThreadScriptCheck() {
@@ -1660,8 +1769,8 @@ static int64_t nBlocksTotal = 0;
 /** Apply the effects of this block (with given index) on the UTXO set represented by coins.
  *  Validity checks that depend on the UTXO set are also done; ConnectBlock()
  *  can fail if those validity checks fail (among other reasons). */
-static bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pindex,
-                  CCoinsViewCache& view, const CChainParams& chainparams, bool fJustCheck = false)
+bool CChainState::ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pindex,
+                  CCoinsViewCache& view, const CChainParams& chainparams, bool fJustCheck)
 {
     AssertLockHeld(cs_main);
     assert(pindex);
@@ -1787,9 +1896,6 @@ static bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockInd
     CAmount nFees = 0;
     int nInputs = 0;
     int64_t nSigOpsCost = 0;
-    CDiskTxPos pos(pindex->GetBlockPos(), GetSizeOfCompactSize(block.vtx.size()));
-    std::vector<std::pair<uint256, CDiskTxPos> > vPos;
-    vPos.reserve(block.vtx.size());
     blockundo.vtxundo.reserve(block.vtx.size() - 1);
     std::vector<PrecomputedTransactionData> txdata;
     txdata.reserve(block.vtx.size()); // Required so that pointers to individual PrecomputedTransactionData don't get invalidated
@@ -1850,9 +1956,6 @@ static bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockInd
             blockundo.vtxundo.push_back(CTxUndo());
         }
         UpdateCoins(tx, view, i == 0 ? undoDummy : blockundo.vtxundo.back(), pindex->nHeight);
-
-        vPos.push_back(std::make_pair(tx.GetHash(), pos));
-        pos.nTxOffset += ::GetSerializeSize(tx, SER_DISK, CLIENT_VERSION);
     }
     int64_t nTime3 = GetTimeMicros(); nTimeConnect += nTime3 - nTime2;
     LogPrint(BCLog::BENCH, "      - Connect %u transactions: %.2fms (%.3fms/tx, %.3fms/txin) [%.2fs (%.2fms/blk)]\n", (unsigned)block.vtx.size(), MILLI * (nTime3 - nTime2), MILLI * (nTime3 - nTime2) / block.vtx.size(), nInputs <= 1 ? 0 : MILLI * (nTime3 - nTime2) / (nInputs-1), nTimeConnect * MICRO, nTimeConnect * MILLI / nBlocksTotal);
@@ -1872,28 +1975,16 @@ static bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockInd
     if (fJustCheck)
         return true;
 
-    // Write undo information to disk
-    if (pindex->GetUndoPos().IsNull() || !pindex->IsValid(BLOCK_VALID_SCRIPTS))
-    {
-        if (pindex->GetUndoPos().IsNull()) {
-            CDiskBlockPos _pos;
-            if (!FindUndoPos(state, pindex->nFile, _pos, ::GetSerializeSize(blockundo, SER_DISK, CLIENT_VERSION) + 40))
-                return error("ConnectBlock(): FindUndoPos failed");
-            if (!UndoWriteToDisk(blockundo, _pos, pindex->pprev->GetBlockHash(), chainparams.MessageStart()))
-                return AbortNode(state, "Failed to write undo data");
-
-            // update nUndoPos in block index
-            pindex->nUndoPos = _pos.nPos;
-            pindex->nStatus |= BLOCK_HAVE_UNDO;
-        }
+    if (!WriteUndoDataForBlock(blockundo, state, pindex, chainparams))
+        return false;
 
+    if (!pindex->IsValid(BLOCK_VALID_SCRIPTS)) {
         pindex->RaiseValidity(BLOCK_VALID_SCRIPTS);
         setDirtyBlockIndex.insert(pindex);
     }
 
-    if (fTxIndex)
-        if (!pblocktree->WriteTxIndex(vPos))
-            return AbortNode(state, "Failed to write transaction index");
+    if (!WriteTxIndexDataForBlock(block, state, pindex))
+        return false;
 
     assert(pindex->phashBlock);
     // add this block to the view's block chain
@@ -2045,10 +2136,8 @@ static void DoWarning(const std::string& strWarning)
     }
 }
 
-/** Update chainActive and related internal data structures. */
-void static UpdateTip(CBlockIndex *pindexNew, const CChainParams& chainParams) {
-    chainActive.SetTip(pindexNew);
-
+/** Check warning conditions and do some notifications on new chain tip set. */
+void static UpdateTip(const CBlockIndex *pindexNew, const CChainParams& chainParams) {
     // New best block
     mempool.AddTransactionsUpdated(1);
 
@@ -2058,7 +2147,7 @@ void static UpdateTip(CBlockIndex *pindexNew, const CChainParams& chainParams) {
     if (!IsInitialBlockDownload())
     {
         int nUpgraded = 0;
-        const CBlockIndex* pindex = chainActive.Tip();
+        const CBlockIndex* pindex = pindexNew;
         for (int bit = 0; bit < VERSIONBITS_NUM_BITS; bit++) {
             WarningBitsConditionChecker checker(bit);
             ThresholdState state = checker.GetStateFor(pindex, chainParams.GetConsensus(), warningcache[bit]);
@@ -2089,10 +2178,10 @@ void static UpdateTip(CBlockIndex *pindexNew, const CChainParams& chainParams) {
         }
     }
     LogPrintf("%s: new best=%s height=%d version=0x%08x log2_work=%.8g tx=%lu date='%s' progress=%f cache=%.1fMiB(%utxo)", __func__,
-      chainActive.Tip()->GetBlockHash().ToString(), chainActive.Height(), chainActive.Tip()->nVersion,
-      log(chainActive.Tip()->nChainWork.getdouble())/log(2.0), (unsigned long)chainActive.Tip()->nChainTx,
-      DateTimeStrFormat("%Y-%m-%d %H:%M:%S", chainActive.Tip()->GetBlockTime()),
-      GuessVerificationProgress(chainParams.TxData(), chainActive.Tip()), pcoinsTip->DynamicMemoryUsage() * (1.0 / (1<<20)), pcoinsTip->GetCacheSize());
+      pindexNew->GetBlockHash().ToString(), pindexNew->nHeight, pindexNew->nVersion,
+      log(pindexNew->nChainWork.getdouble())/log(2.0), (unsigned long)pindexNew->nChainTx,
+      DateTimeStrFormat("%Y-%m-%d %H:%M:%S", pindexNew->GetBlockTime()),
+      GuessVerificationProgress(chainParams.TxData(), pindexNew), pcoinsTip->DynamicMemoryUsage() * (1.0 / (1<<20)), pcoinsTip->GetCacheSize());
     if (!warningMessages.empty())
         LogPrintf(" warning='%s'", boost::algorithm::join(warningMessages, ", "));
     LogPrintf("\n");
@@ -2109,7 +2198,7 @@ void static UpdateTip(CBlockIndex *pindexNew, const CChainParams& chainParams) {
   * disconnectpool (note that the caller is responsible for mempool consistency
   * in any case).
   */
-bool static DisconnectTip(CValidationState& state, const CChainParams& chainparams, DisconnectedBlockTransactions *disconnectpool)
+bool CChainState::DisconnectTip(CValidationState& state, const CChainParams& chainparams, DisconnectedBlockTransactions *disconnectpool)
 {
     CBlockIndex *pindexDelete = chainActive.Tip();
     assert(pindexDelete);
@@ -2146,7 +2235,8 @@ bool static DisconnectTip(CValidationState& state, const CChainParams& chainpara
         }
     }
 
-    // Update chainActive and related variables.
+    chainActive.SetTip(pindexDelete->pprev);
+
     UpdateTip(pindexDelete->pprev, chainparams);
     // Let wallets know transactions went from 1-confirmed to
     // 0-confirmed or conflicted:
@@ -2231,7 +2321,7 @@ public:
  *
  * The block is added to connectTrace if connection succeeds.
  */
-bool static ConnectTip(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexNew, const std::shared_ptr<const CBlock>& pblock, ConnectTrace& connectTrace, DisconnectedBlockTransactions &disconnectpool)
+bool CChainState::ConnectTip(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexNew, const std::shared_ptr<const CBlock>& pblock, ConnectTrace& connectTrace, DisconnectedBlockTransactions &disconnectpool)
 {
     assert(pindexNew->pprev == chainActive.Tip());
     // Read block from disk.
@@ -2275,6 +2365,7 @@ bool static ConnectTip(CValidationState& state, const CChainParams& chainparams,
     mempool.removeForBlock(blockConnecting.vtx, pindexNew->nHeight);
     disconnectpool.removeForBlock(blockConnecting.vtx);
     // Update chainActive & related variables.
+    chainActive.SetTip(pindexNew);
     UpdateTip(pindexNew, chainparams);
 
     int64_t nTime6 = GetTimeMicros(); nTimePostConnect += nTime6 - nTime5; nTimeTotal += nTime6 - nTime1;
@@ -2289,7 +2380,7 @@ bool static ConnectTip(CValidationState& state, const CChainParams& chainparams,
  * Return the tip of the chain with the most work in it, that isn't
  * known to be invalid (it's however far from certain to be valid).
  */
-static CBlockIndex* FindMostWorkChain() {
+CBlockIndex* CChainState::FindMostWorkChain() {
     do {
         CBlockIndex *pindexNew = nullptr;
 
@@ -2344,7 +2435,7 @@ static CBlockIndex* FindMostWorkChain() {
 }
 
 /** Delete all entries in setBlockIndexCandidates that are worse than the current tip. */
-static void PruneBlockIndexCandidates() {
+void CChainState::PruneBlockIndexCandidates() {
     // Note that we can't delete the current block itself, as we may need to return to it later in case a
     // reorganization to a better block fails.
     std::set<CBlockIndex*, CBlockIndexWorkComparator>::iterator it = setBlockIndexCandidates.begin();
@@ -2359,7 +2450,7 @@ static void PruneBlockIndexCandidates() {
  * Try to make some progress towards making pindexMostWork the active block.
  * pblock is either nullptr or a pointer to a CBlock corresponding to pindexMostWork.
  */
-static bool ActivateBestChainStep(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexMostWork, const std::shared_ptr<const CBlock>& pblock, bool& fInvalidFound, ConnectTrace& connectTrace)
+bool CChainState::ActivateBestChainStep(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexMostWork, const std::shared_ptr<const CBlock>& pblock, bool& fInvalidFound, ConnectTrace& connectTrace)
 {
     AssertLockHeld(cs_main);
     const CBlockIndex *pindexOldTip = chainActive.Tip();
@@ -2466,7 +2557,7 @@ static void NotifyHeaderTip() {
  * or an activated best chain. pblock is either nullptr or a pointer to a block
  * that is already loaded (to avoid loading it again from disk).
  */
-bool ActivateBestChain(CValidationState &state, const CChainParams& chainparams, std::shared_ptr<const CBlock> pblock) {
+bool CChainState::ActivateBestChain(CValidationState &state, const CChainParams& chainparams, std::shared_ptr<const CBlock> pblock) {
     // Note that while we're often called here from ProcessNewBlock, this is
     // far from a guarantee. Things in the P2P/RPC will often end up calling
     // us in the middle of ProcessNewBlock - do not assume pblock is set
@@ -2536,9 +2627,11 @@ bool ActivateBestChain(CValidationState &state, const CChainParams& chainparams,
 
     return true;
 }
+bool ActivateBestChain(CValidationState &state, const CChainParams& chainparams, std::shared_ptr<const CBlock> pblock) {
+    return g_chainstate.ActivateBestChain(state, chainparams, std::move(pblock));
+}
 
-
-bool PreciousBlock(CValidationState& state, const CChainParams& params, CBlockIndex *pindex)
+bool CChainState::PreciousBlock(CValidationState& state, const CChainParams& params, CBlockIndex *pindex)
 {
     {
         LOCK(cs_main);
@@ -2564,10 +2657,13 @@ bool PreciousBlock(CValidationState& state, const CChainParams& params, CBlockIn
         }
     }
 
-    return ActivateBestChain(state, params);
+    return ActivateBestChain(state, params, std::shared_ptr<const CBlock>());
+}
+bool PreciousBlock(CValidationState& state, const CChainParams& params, CBlockIndex *pindex) {
+    return g_chainstate.PreciousBlock(state, params, pindex);
 }
 
-bool InvalidateBlock(CValidationState& state, const CChainParams& chainparams, CBlockIndex *pindex)
+bool CChainState::InvalidateBlock(CValidationState& state, const CChainParams& chainparams, CBlockIndex *pindex)
 {
     AssertLockHeld(cs_main);
 
@@ -2626,8 +2722,11 @@ bool InvalidateBlock(CValidationState& state, const CChainParams& chainparams, C
     uiInterface.NotifyBlockTip(IsInitialBlockDownload(), pindex->pprev);
     return true;
 }
+bool InvalidateBlock(CValidationState& state, const CChainParams& chainparams, CBlockIndex *pindex) {
+    return g_chainstate.InvalidateBlock(state, chainparams, pindex);
+}
 
-bool ResetBlockFailureFlags(CBlockIndex *pindex) {
+bool CChainState::ResetBlockFailureFlags(CBlockIndex *pindex) {
     AssertLockHeld(cs_main);
 
     int nHeight = pindex->nHeight;
@@ -2660,8 +2759,11 @@ bool ResetBlockFailureFlags(CBlockIndex *pindex) {
     }
     return true;
 }
+bool ResetBlockFailureFlags(CBlockIndex *pindex) {
+    return g_chainstate.ResetBlockFailureFlags(pindex);
+}
 
-static CBlockIndex* AddToBlockIndex(const CBlockHeader& block)
+CBlockIndex* CChainState::AddToBlockIndex(const CBlockHeader& block)
 {
     // Check for duplicate
     uint256 hash = block.GetHash();
@@ -2696,7 +2798,7 @@ static CBlockIndex* AddToBlockIndex(const CBlockHeader& block)
 }
 
 /** Mark a block as having its data received and checked (up to BLOCK_VALID_TRANSACTIONS). */
-static bool ReceivedBlockTransactions(const CBlock &block, CValidationState& state, CBlockIndex *pindexNew, const CDiskBlockPos& pos, const Consensus::Params& consensusParams)
+bool CChainState::ReceivedBlockTransactions(const CBlock &block, CValidationState& state, CBlockIndex *pindexNew, const CDiskBlockPos& pos, const Consensus::Params& consensusParams)
 {
     pindexNew->nTx = block.vtx.size();
     pindexNew->nChainTx = 0;
@@ -2744,7 +2846,7 @@ static bool ReceivedBlockTransactions(const CBlock &block, CValidationState& sta
     return true;
 }
 
-static bool FindBlockPos(CValidationState &state, CDiskBlockPos &pos, unsigned int nAddSize, unsigned int nHeight, uint64_t nTime, bool fKnown = false)
+static bool FindBlockPos(CDiskBlockPos &pos, unsigned int nAddSize, unsigned int nHeight, uint64_t nTime, bool fKnown = false)
 {
     LOCK(cs_LastBlockFile);
 
@@ -2793,7 +2895,7 @@ static bool FindBlockPos(CValidationState &state, CDiskBlockPos &pos, unsigned i
                 }
             }
             else
-                return state.Error("out of disk space");
+                return error("out of disk space");
         }
     }
 
@@ -3101,7 +3203,7 @@ static bool ContextualCheckBlock(const CBlock& block, CValidationState& state, c
     return true;
 }
 
-static bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex)
+bool CChainState::AcceptBlockHeader(const CBlockHeader& block, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex)
 {
     AssertLockHeld(cs_main);
     // Check for duplicate
@@ -3168,7 +3270,7 @@ bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& headers, CValidatio
         LOCK(cs_main);
         for (const CBlockHeader& header : headers) {
             CBlockIndex *pindex = nullptr; // Use a temp pindex instead of ppindex to avoid a const_cast
-            if (!AcceptBlockHeader(header, state, chainparams, &pindex)) {
+            if (!g_chainstate.AcceptBlockHeader(header, state, chainparams, &pindex)) {
                 if (first_invalid) *first_invalid = header;
                 return false;
             }
@@ -3182,7 +3284,26 @@ bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& headers, CValidatio
 }
 
 /** Store block on disk. If dbp is non-nullptr, the file is known to already reside on disk */
-static bool AcceptBlock(const std::shared_ptr<const CBlock>& pblock, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex, bool fRequested, const CDiskBlockPos* dbp, bool* fNewBlock)
+static CDiskBlockPos SaveBlockToDisk(const CBlock& block, int nHeight, const CChainParams& chainparams, const CDiskBlockPos* dbp) {
+    unsigned int nBlockSize = ::GetSerializeSize(block, SER_DISK, CLIENT_VERSION);
+    CDiskBlockPos blockPos;
+    if (dbp != nullptr)
+        blockPos = *dbp;
+    if (!FindBlockPos(blockPos, nBlockSize+8, nHeight, block.GetBlockTime(), dbp != nullptr)) {
+        error("%s: FindBlockPos failed", __func__);
+        return CDiskBlockPos();
+    }
+    if (dbp == nullptr) {
+        if (!WriteBlockToDisk(block, blockPos, chainparams.MessageStart())) {
+            AbortNode("Failed to write block");
+            return CDiskBlockPos();
+        }
+    }
+    return blockPos;
+}
+
+/** Store block on disk. If dbp is non-nullptr, the file is known to already reside on disk */
+bool CChainState::AcceptBlock(const std::shared_ptr<const CBlock>& pblock, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex, bool fRequested, const CDiskBlockPos* dbp, bool* fNewBlock)
 {
     const CBlock& block = *pblock;
 
@@ -3242,19 +3363,13 @@ static bool AcceptBlock(const std::shared_ptr<const CBlock>& pblock, CValidation
     if (!IsInitialBlockDownload() && chainActive.Tip() == pindex->pprev)
         GetMainSignals().NewPoWValidBlock(pindex, pblock);
 
-    int nHeight = pindex->nHeight;
-
     // Write block to history file
     try {
-        unsigned int nBlockSize = ::GetSerializeSize(block, SER_DISK, CLIENT_VERSION);
-        CDiskBlockPos blockPos;
-        if (dbp != nullptr)
-            blockPos = *dbp;
-        if (!FindBlockPos(state, blockPos, nBlockSize+8, nHeight, block.GetBlockTime(), dbp != nullptr))
-            return error("AcceptBlock(): FindBlockPos failed");
-        if (dbp == nullptr)
-            if (!WriteBlockToDisk(block, blockPos, chainparams.MessageStart()))
-                AbortNode(state, "Failed to write block");
+        CDiskBlockPos blockPos = SaveBlockToDisk(block, pindex->nHeight, chainparams, dbp);
+        if (blockPos.IsNull()) {
+            state.Error(strprintf("%s: Failed to find position to write new block to disk", __func__));
+            return false;
+        }
         if (!ReceivedBlockTransactions(block, state, pindex, blockPos, chainparams.GetConsensus()))
             return error("AcceptBlock(): ReceivedBlockTransactions failed");
     } catch (const std::runtime_error& e) {
@@ -3264,6 +3379,8 @@ static bool AcceptBlock(const std::shared_ptr<const CBlock>& pblock, CValidation
     if (fCheckForPruning)
         FlushStateToDisk(chainparams, state, FLUSH_STATE_NONE); // we just allocated more disk space for block files
 
+    CheckBlockIndex(chainparams.GetConsensus());
+
     return true;
 }
 
@@ -3281,9 +3398,8 @@ bool ProcessNewBlock(const CChainParams& chainparams, const std::shared_ptr<cons
 
         if (ret) {
             // Store to disk
-            ret = AcceptBlock(pblock, state, chainparams, &pindex, fForceProcessing, nullptr, fNewBlock);
+            ret = g_chainstate.AcceptBlock(pblock, state, chainparams, &pindex, fForceProcessing, nullptr, fNewBlock);
         }
-        CheckBlockIndex(chainparams.GetConsensus());
         if (!ret) {
             GetMainSignals().BlockChecked(*pblock, state);
             return error("%s: AcceptBlock FAILED (%s)", __func__, state.GetDebugMessage());
@@ -3293,7 +3409,7 @@ bool ProcessNewBlock(const CChainParams& chainparams, const std::shared_ptr<cons
     NotifyHeaderTip();
 
     CValidationState state; // Only used to report errors, not invalidity - ignore it
-    if (!ActivateBestChain(state, chainparams, pblock))
+    if (!g_chainstate.ActivateBestChain(state, chainparams, pblock))
         return error("%s: ActivateBestChain failed", __func__);
 
     return true;
@@ -3315,7 +3431,7 @@ bool TestBlockValidity(CValidationState& state, const CChainParams& chainparams,
         return error("%s: Consensus::CheckBlock: %s", __func__, FormatStateMessage(state));
     if (!ContextualCheckBlock(block, state, chainparams.GetConsensus(), pindexPrev))
         return error("%s: Consensus::ContextualCheckBlock: %s", __func__, FormatStateMessage(state));
-    if (!ConnectBlock(block, state, &indexDummy, viewNew, chainparams, true))
+    if (!g_chainstate.ConnectBlock(block, state, &indexDummy, viewNew, chainparams, true))
         return false;
     assert(state.IsValid());
 
@@ -3523,7 +3639,7 @@ fs::path GetBlockPosFilename(const CDiskBlockPos &pos, const char *prefix)
     return GetDataDir() / "blocks" / strprintf("%s%05u.dat", prefix, pos.nFile);
 }
 
-CBlockIndex * InsertBlockIndex(uint256 hash)
+CBlockIndex * CChainState::InsertBlockIndex(const uint256& hash)
 {
     if (hash.IsNull())
         return nullptr;
@@ -3541,9 +3657,9 @@ CBlockIndex * InsertBlockIndex(uint256 hash)
     return pindexNew;
 }
 
-bool static LoadBlockIndexDB(const CChainParams& chainparams)
+bool CChainState::LoadBlockIndex(const Consensus::Params& consensus_params, CBlockTreeDB& blocktree)
 {
-    if (!pblocktree->LoadBlockIndexGuts(chainparams.GetConsensus(), InsertBlockIndex))
+    if (!blocktree.LoadBlockIndexGuts(consensus_params, [this](const uint256& hash){ return this->InsertBlockIndex(hash); }))
         return false;
 
     boost::this_thread::interruption_point();
@@ -3590,6 +3706,14 @@ bool static LoadBlockIndexDB(const CChainParams& chainparams)
             pindexBestHeader = pindex;
     }
 
+    return true;
+}
+
+bool static LoadBlockIndexDB(const CChainParams& chainparams)
+{
+    if (!g_chainstate.LoadBlockIndex(chainparams.GetConsensus(), *pblocktree))
+        return false;
+
     // Load block file info
     pblocktree->ReadLastBlockFile(nLastBlockFile);
     vinfoBlockFile.resize(nLastBlockFile + 1);
@@ -3662,7 +3786,7 @@ bool LoadChainTip(const CChainParams& chainparams)
         return false;
     chainActive.SetTip(it->second);
 
-    PruneBlockIndexCandidates();
+    g_chainstate.PruneBlockIndexCandidates();
 
     LogPrintf("Loaded best chain: hashBestChain=%s height=%d date=%s progress=%f\n",
         chainActive.Tip()->GetBlockHash().ToString(), chainActive.Height(),
@@ -3727,16 +3851,16 @@ bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview,
         // check level 2: verify undo validity
         if (nCheckLevel >= 2 && pindex) {
             CBlockUndo undo;
-            CDiskBlockPos pos = pindex->GetUndoPos();
-            if (!pos.IsNull()) {
-                if (!UndoReadFromDisk(undo, pos, pindex->pprev->GetBlockHash()))
+            if (!pindex->GetUndoPos().IsNull()) {
+                if (!UndoReadFromDisk(undo, pindex)) {
                     return error("VerifyDB(): *** found bad undo data at %d, hash=%s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
+                }
             }
         }
         // check level 3: check for inconsistencies during memory-only disconnect of tip blocks
         if (nCheckLevel >= 3 && pindex == pindexState && (coins.DynamicMemoryUsage() + pcoinsTip->DynamicMemoryUsage()) <= nCoinCacheUsage) {
             assert(coins.GetBestBlock() == pindex->GetBlockHash());
-            DisconnectResult res = DisconnectBlock(block, pindex, coins);
+            DisconnectResult res = g_chainstate.DisconnectBlock(block, pindex, coins);
             if (res == DISCONNECT_FAILED) {
                 return error("VerifyDB(): *** irrecoverable inconsistency in block data at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
             }
@@ -3764,7 +3888,7 @@ bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview,
             CBlock block;
             if (!ReadBlockFromDisk(block, pindex, chainparams.GetConsensus()))
                 return error("VerifyDB(): *** ReadBlockFromDisk failed at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
-            if (!ConnectBlock(block, state, pindex, coins, chainparams))
+            if (!g_chainstate.ConnectBlock(block, state, pindex, coins, chainparams))
                 return error("VerifyDB(): *** found unconnectable block at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
         }
     }
@@ -3776,7 +3900,7 @@ bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview,
 }
 
 /** Apply the effects of a block on the utxo cache, ignoring that it may already have been applied. */
-static bool RollforwardBlock(const CBlockIndex* pindex, CCoinsViewCache& inputs, const CChainParams& params)
+bool CChainState::RollforwardBlock(const CBlockIndex* pindex, CCoinsViewCache& inputs, const CChainParams& params)
 {
     // TODO: merge with ConnectBlock
     CBlock block;
@@ -3796,7 +3920,7 @@ static bool RollforwardBlock(const CBlockIndex* pindex, CCoinsViewCache& inputs,
     return true;
 }
 
-bool ReplayBlocks(const CChainParams& params, CCoinsView* view)
+bool CChainState::ReplayBlocks(const CChainParams& params, CCoinsView* view)
 {
     LOCK(cs_main);
 
@@ -3861,7 +3985,11 @@ bool ReplayBlocks(const CChainParams& params, CCoinsView* view)
     return true;
 }
 
-bool RewindBlockIndex(const CChainParams& params)
+bool ReplayBlocks(const CChainParams& params, CCoinsView* view) {
+    return g_chainstate.ReplayBlocks(params, view);
+}
+
+bool CChainState::RewindBlockIndex(const CChainParams& params)
 {
     LOCK(cs_main);
 
@@ -3942,10 +4070,21 @@ bool RewindBlockIndex(const CChainParams& params)
         PruneBlockIndexCandidates();
 
         CheckBlockIndex(params.GetConsensus());
+    }
 
+    return true;
+}
+
+bool RewindBlockIndex(const CChainParams& params) {
+    if (!g_chainstate.RewindBlockIndex(params)) {
+        return false;
+    }
+
+    if (chainActive.Tip() != nullptr) {
         // FlushStateToDisk can possibly read chainActive. Be conservative
         // and skip it here, we're about to -reindex-chainstate anyway, so
         // it'll get called a bunch real soon.
+        CValidationState state;
         if (!FlushStateToDisk(params, state, FLUSH_STATE_ALWAYS)) {
             return false;
         }
@@ -3954,13 +4093,18 @@ bool RewindBlockIndex(const CChainParams& params)
     return true;
 }
 
+void CChainState::UnloadBlockIndex() {
+    nBlockSequenceId = 1;
+    g_failed_blocks.clear();
+    setBlockIndexCandidates.clear();
+}
+
 // May NOT be used after any connections are up as much
 // of the peer-processing logic assumes a consistent
 // block index state
 void UnloadBlockIndex()
 {
     LOCK(cs_main);
-    setBlockIndexCandidates.clear();
     chainActive.SetTip(nullptr);
     pindexBestInvalid = nullptr;
     pindexBestHeader = nullptr;
@@ -3968,9 +4112,7 @@ void UnloadBlockIndex()
     mapBlocksUnlinked.clear();
     vinfoBlockFile.clear();
     nLastBlockFile = 0;
-    nBlockSequenceId = 1;
     setDirtyBlockIndex.clear();
-    g_failed_blocks.clear();
     setDirtyFileInfo.clear();
     versionbitscache.Clear();
     for (int b = 0; b < VERSIONBITS_NUM_BITS; b++) {
@@ -3982,6 +4124,8 @@ void UnloadBlockIndex()
     }
     mapBlockIndex.clear();
     fHavePruned = false;
+
+    g_chainstate.UnloadBlockIndex();
 }
 
 bool LoadBlockIndex(const CChainParams& chainparams)
@@ -4009,7 +4153,7 @@ bool LoadBlockIndex(const CChainParams& chainparams)
     return true;
 }
 
-bool LoadGenesisBlock(const CChainParams& chainparams)
+bool CChainState::LoadGenesisBlock(const CChainParams& chainparams)
 {
     LOCK(cs_main);
 
@@ -4022,15 +4166,11 @@ bool LoadGenesisBlock(const CChainParams& chainparams)
 
     try {
         CBlock &block = const_cast<CBlock&>(chainparams.GenesisBlock());
-        // Start new block file
-        unsigned int nBlockSize = ::GetSerializeSize(block, SER_DISK, CLIENT_VERSION);
-        CDiskBlockPos blockPos;
-        CValidationState state;
-        if (!FindBlockPos(state, blockPos, nBlockSize+8, 0, block.GetBlockTime()))
-            return error("%s: FindBlockPos failed", __func__);
-        if (!WriteBlockToDisk(block, blockPos, chainparams.MessageStart()))
+        CDiskBlockPos blockPos = SaveBlockToDisk(block, 0, chainparams, nullptr);
+        if (blockPos.IsNull())
             return error("%s: writing genesis block to disk failed", __func__);
         CBlockIndex *pindex = AddToBlockIndex(block);
+        CValidationState state;
         if (!ReceivedBlockTransactions(block, state, pindex, blockPos, chainparams.GetConsensus()))
             return error("%s: genesis block not accepted", __func__);
     } catch (const std::runtime_error& e) {
@@ -4040,6 +4180,11 @@ bool LoadGenesisBlock(const CChainParams& chainparams)
     return true;
 }
 
+bool LoadGenesisBlock(const CChainParams& chainparams)
+{
+    return g_chainstate.LoadGenesisBlock(chainparams);
+}
+
 bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, CDiskBlockPos *dbp)
 {
     // Map of disk positions for blocks with unknown parent (only used for reindex)
@@ -4100,7 +4245,7 @@ bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, CDiskB
                 if (mapBlockIndex.count(hash) == 0 || (mapBlockIndex[hash]->nStatus & BLOCK_HAVE_DATA) == 0) {
                     LOCK(cs_main);
                     CValidationState state;
-                    if (AcceptBlock(pblock, state, chainparams, nullptr, true, dbp, nullptr))
+                    if (g_chainstate.AcceptBlock(pblock, state, chainparams, nullptr, true, dbp, nullptr))
                         nLoaded++;
                     if (state.IsError())
                         break;
@@ -4134,7 +4279,7 @@ bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, CDiskB
                                     head.ToString());
                             LOCK(cs_main);
                             CValidationState dummy;
-                            if (AcceptBlock(pblockrecursive, dummy, chainparams, nullptr, true, &it->second, nullptr))
+                            if (g_chainstate.AcceptBlock(pblockrecursive, dummy, chainparams, nullptr, true, &it->second, nullptr))
                             {
                                 nLoaded++;
                                 queue.push_back(pblockrecursive->GetHash());
@@ -4157,7 +4302,7 @@ bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, CDiskB
     return nLoaded > 0;
 }
 
-void static CheckBlockIndex(const Consensus::Params& consensusParams)
+void CChainState::CheckBlockIndex(const Consensus::Params& consensusParams)
 {
     if (!fCheckBlockIndex) {
         return;
@@ -4499,7 +4644,7 @@ bool DumpMempool(void)
 }
 
 //! Guess how far we are in the verification process at the given block index
-double GuessVerificationProgress(const ChainTxData& data, CBlockIndex *pindex) {
+double GuessVerificationProgress(const ChainTxData& data, const CBlockIndex *pindex) {
     if (pindex == nullptr)
         return 0.0;
 
diff --git a/src/validation.h b/src/validation.h
index 49bff9f30c..4c8e041af0 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -159,7 +159,7 @@ extern CCriticalSection cs_main;
 extern CBlockPolicyEstimator feeEstimator;
 extern CTxMemPool mempool;
 typedef std::unordered_map<uint256, CBlockIndex*, BlockHasher> BlockMap;
-extern BlockMap mapBlockIndex;
+extern BlockMap& mapBlockIndex;
 extern uint64_t nLastBlockTx;
 extern uint64_t nLastBlockWeight;
 extern const std::string strMessageMagic;
@@ -281,7 +281,7 @@ bool ActivateBestChain(CValidationState& state, const CChainParams& chainparams,
 CAmount GetBlockSubsidy(int nHeight, const Consensus::Params& consensusParams);
 
 /** Guess verification progress (as a fraction between 0.0=genesis and 1.0=current tip). */
-double GuessVerificationProgress(const ChainTxData& data, CBlockIndex* pindex);
+double GuessVerificationProgress(const ChainTxData& data, const CBlockIndex* pindex);
 
 /** Calculate the amount of disk space the block & undo files currently use */
 uint64_t CalculateCurrentUsage();
@@ -296,8 +296,6 @@ void PruneOneBlockFile(const int fileNumber);
  */
 void UnlinkPrunedFiles(const std::set<int>& setFilesToPrune);
 
-/** Create a new block index entry for a given block hash */
-CBlockIndex * InsertBlockIndex(uint256 hash);
 /** Flush all state, indexes and buffers to disk. */
 void FlushStateToDisk();
 /** Prune block files and flush state to disk. */
@@ -443,7 +441,7 @@ bool InvalidateBlock(CValidationState& state, const CChainParams& chainparams, C
 bool ResetBlockFailureFlags(CBlockIndex *pindex);
 
 /** The currently-connected chain of blocks (protected by cs_main). */
-extern CChain chainActive;
+extern CChain& chainActive;
 
 /** Global variable that points to the coins database (protected by cs_main) */
 extern std::unique_ptr<CCoinsViewDB> pcoinsdbview;