refactoring: introduce ChainstateActive()

To be used once we move global functions (e.g. FlushStateToDisk()) into
CChainState methods.

Thanks to Marco Falke for suggestions

src/validation.cpp

@@ -80,6 +80,8 @@ bool CBlockIndexWorkComparator::operator()(const CBlockIndex *pa, const CBlockIn
 
 CChainState g_chainstate;
 
+CChainState& ChainstateActive() { return g_chainstate; }
+
 CChain& ChainActive() { return g_chainstate.m_chain; }
 
 /**
@@ -94,7 +96,7 @@ CChain& ChainActive() { return g_chainstate.m_chain; }
  */
 RecursiveMutex cs_main;
 
-BlockMap& mapBlockIndex = g_chainstate.mapBlockIndex;
+BlockMap& mapBlockIndex = ::ChainstateActive().mapBlockIndex;
 CBlockIndex *pindexBestHeader = nullptr;
 Mutex g_best_block_mutex;
 std::condition_variable g_best_block_cv;
@@ -125,12 +127,12 @@ CScript COINBASE_FLAGS;
 
 // Internal stuff
 namespace {
-    CBlockIndex *&pindexBestInvalid = g_chainstate.pindexBestInvalid;
+    CBlockIndex *&pindexBestInvalid = ::ChainstateActive().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;
+    std::multimap<CBlockIndex*, CBlockIndex*>& mapBlocksUnlinked = ::ChainstateActive().mapBlocksUnlinked;
 
     CCriticalSection cs_LastBlockFile;
     std::vector<CBlockFileInfo> vinfoBlockFile;
@@ -2627,7 +2629,7 @@ bool CChainState::ActivateBestChain(CValidationState &state, const CChainParams&
 }
 
 bool ActivateBestChain(CValidationState &state, const CChainParams& chainparams, std::shared_ptr<const CBlock> pblock) {
-    return g_chainstate.ActivateBestChain(state, chainparams, std::move(pblock));
+    return ::ChainstateActive().ActivateBestChain(state, chainparams, std::move(pblock));
 }
 
 bool CChainState::PreciousBlock(CValidationState& state, const CChainParams& params, CBlockIndex *pindex)
@@ -2659,7 +2661,7 @@ bool CChainState::PreciousBlock(CValidationState& state, const CChainParams& par
     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);
+    return ::ChainstateActive().PreciousBlock(state, params, pindex);
 }
 
 bool CChainState::InvalidateBlock(CValidationState& state, const CChainParams& chainparams, CBlockIndex *pindex)
@@ -2748,7 +2750,7 @@ bool CChainState::InvalidateBlock(CValidationState& state, const CChainParams& c
 }
 
 bool InvalidateBlock(CValidationState& state, const CChainParams& chainparams, CBlockIndex *pindex) {
-    return g_chainstate.InvalidateBlock(state, chainparams, pindex);
+    return ::ChainstateActive().InvalidateBlock(state, chainparams, pindex);
 }
 
 void CChainState::ResetBlockFailureFlags(CBlockIndex *pindex) {
@@ -2786,7 +2788,7 @@ void CChainState::ResetBlockFailureFlags(CBlockIndex *pindex) {
 }
 
 void ResetBlockFailureFlags(CBlockIndex *pindex) {
-    return g_chainstate.ResetBlockFailureFlags(pindex);
+    return ::ChainstateActive().ResetBlockFailureFlags(pindex);
 }
 
 CBlockIndex* CChainState::AddToBlockIndex(const CBlockHeader& block)
@@ -3324,7 +3326,7 @@ 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 (!g_chainstate.AcceptBlockHeader(header, state, chainparams, &pindex)) {
+            if (!::ChainstateActive().AcceptBlockHeader(header, state, chainparams, &pindex)) {
                 if (first_invalid) *first_invalid = header;
                 return false;
             }
@@ -3455,7 +3457,7 @@ bool ProcessNewBlock(const CChainParams& chainparams, const std::shared_ptr<cons
         bool ret = CheckBlock(*pblock, state, chainparams.GetConsensus());
         if (ret) {
             // Store to disk
-            ret = g_chainstate.AcceptBlock(pblock, state, chainparams, &pindex, fForceProcessing, nullptr, fNewBlock);
+            ret = ::ChainstateActive().AcceptBlock(pblock, state, chainparams, &pindex, fForceProcessing, nullptr, fNewBlock);
         }
         if (!ret) {
             GetMainSignals().BlockChecked(*pblock, state);
@@ -3466,7 +3468,7 @@ bool ProcessNewBlock(const CChainParams& chainparams, const std::shared_ptr<cons
     NotifyHeaderTip();
 
     CValidationState state; // Only used to report errors, not invalidity - ignore it
-    if (!g_chainstate.ActivateBestChain(state, chainparams, pblock))
+    if (!::ChainstateActive().ActivateBestChain(state, chainparams, pblock))
         return error("%s: ActivateBestChain failed (%s)", __func__, FormatStateMessage(state));
 
     return true;
@@ -3490,7 +3492,7 @@ 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 (!g_chainstate.ConnectBlock(block, state, &indexDummy, viewNew, chainparams, true))
+    if (!::ChainstateActive().ConnectBlock(block, state, &indexDummy, viewNew, chainparams, true))
         return false;
     assert(state.IsValid());
 
@@ -3757,7 +3759,7 @@ bool CChainState::LoadBlockIndex(const Consensus::Params& consensus_params, CBlo
 
 bool static LoadBlockIndexDB(const CChainParams& chainparams) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
 {
-    if (!g_chainstate.LoadBlockIndex(chainparams.GetConsensus(), *pblocktree))
+    if (!::ChainstateActive().LoadBlockIndex(chainparams.GetConsensus(), *pblocktree))
         return false;
 
     // Load block file info
@@ -3832,7 +3834,7 @@ bool LoadChainTip(const CChainParams& chainparams)
     }
     ::ChainActive().SetTip(pindex);
 
-    g_chainstate.PruneBlockIndexCandidates();
+    ::ChainstateActive().PruneBlockIndexCandidates();
 
     LogPrintf("Loaded best chain: hashBestChain=%s height=%d date=%s progress=%f\n",
         ::ChainActive().Tip()->GetBlockHash().ToString(), ::ChainActive().Height(),
@@ -3905,7 +3907,7 @@ bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview,
         // check level 3: check for inconsistencies during memory-only disconnect of tip blocks
         if (nCheckLevel >= 3 && (coins.DynamicMemoryUsage() + pcoinsTip->DynamicMemoryUsage()) <= nCoinCacheUsage) {
             assert(coins.GetBestBlock() == pindex->GetBlockHash());
-            DisconnectResult res = g_chainstate.DisconnectBlock(block, pindex, coins);
+            DisconnectResult res = ::ChainstateActive().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());
             }
@@ -3940,7 +3942,7 @@ 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 (!g_chainstate.ConnectBlock(block, state, pindex, coins, chainparams))
+            if (!::ChainstateActive().ConnectBlock(block, state, pindex, coins, chainparams))
                 return error("VerifyDB(): *** found unconnectable block at %d, hash=%s (%s)", pindex->nHeight, pindex->GetBlockHash().ToString(), FormatStateMessage(state));
         }
     }
@@ -4039,7 +4041,7 @@ bool CChainState::ReplayBlocks(const CChainParams& params, CCoinsView* view)
 }
 
 bool ReplayBlocks(const CChainParams& params, CCoinsView* view) {
-    return g_chainstate.ReplayBlocks(params, view);
+    return ::ChainstateActive().ReplayBlocks(params, view);
 }
 
 //! Helper for CChainState::RewindBlockIndex
@@ -4172,7 +4174,7 @@ bool CChainState::RewindBlockIndex(const CChainParams& params)
 }
 
 bool RewindBlockIndex(const CChainParams& params) {
-    if (!g_chainstate.RewindBlockIndex(params)) {
+    if (!::ChainstateActive().RewindBlockIndex(params)) {
         return false;
     }
 
@@ -4222,7 +4224,7 @@ void UnloadBlockIndex()
     mapBlockIndex.clear();
     fHavePruned = false;
 
-    g_chainstate.UnloadBlockIndex();
+    ::ChainstateActive().UnloadBlockIndex();
 }
 
 bool LoadBlockIndex(const CChainParams& chainparams)
@@ -4274,7 +4276,7 @@ bool CChainState::LoadGenesisBlock(const CChainParams& chainparams)
 
 bool LoadGenesisBlock(const CChainParams& chainparams)
 {
-    return g_chainstate.LoadGenesisBlock(chainparams);
+    return ::ChainstateActive().LoadGenesisBlock(chainparams);
 }
 
 bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, FlatFilePos *dbp)
@@ -4339,7 +4341,7 @@ bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, FlatFi
                     CBlockIndex* pindex = LookupBlockIndex(hash);
                     if (!pindex || (pindex->nStatus & BLOCK_HAVE_DATA) == 0) {
                       CValidationState state;
-                      if (g_chainstate.AcceptBlock(pblock, state, chainparams, nullptr, true, dbp, nullptr)) {
+                      if (::ChainstateActive().AcceptBlock(pblock, state, chainparams, nullptr, true, dbp, nullptr)) {
                           nLoaded++;
                       }
                       if (state.IsError()) {
@@ -4376,7 +4378,7 @@ bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, FlatFi
                                     head.ToString());
                             LOCK(cs_main);
                             CValidationState dummy;
-                            if (g_chainstate.AcceptBlock(pblockrecursive, dummy, chainparams, nullptr, true, &it->second, nullptr))
+                            if (::ChainstateActive().AcceptBlock(pblockrecursive, dummy, chainparams, nullptr, true, &it->second, nullptr))
                             {
                                 nLoaded++;
                                 queue.push_back(pblockrecursive->GetHash());

src/validation.h

@@ -575,6 +575,9 @@ bool InvalidateBlock(CValidationState& state, const CChainParams& chainparams, C
 /** Remove invalidity status from a block and its descendants. */
 void ResetBlockFailureFlags(CBlockIndex* pindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
+/** @returns the most-work valid chainstate. */
+CChainState& ChainstateActive();
+
 /** @returns the most-work chain. */
 CChain& ChainActive();