[refactor] Move ComputeBlockVersion into VersionBitsCache

This also changes ComputeBlockVersion to take the versionbits cache
mutex once, rather than once for each versionbits deployment.

Author: ajtowns

src/miner.cpp

@@ -121,7 +121,7 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& sc
     assert(pindexPrev != nullptr);
     nHeight = pindexPrev->nHeight + 1;
 
-    pblock->nVersion = ComputeBlockVersion(pindexPrev, chainparams.GetConsensus());
+    pblock->nVersion = g_versionbitscache.ComputeBlockVersion(pindexPrev, chainparams.GetConsensus());
     // -regtest only: allow overriding block.nVersion with
     // -blockversion=N to test forking scenarios
     if (chainparams.MineBlocksOnDemand())

src/test/versionbits_tests.cpp

@@ -15,6 +15,11 @@
 /* Define a virtual block time, one block per 10 minutes after Nov 14 2014, 0:55:36am */
 static int32_t TestTime(int nHeight) { return 1415926536 + 600 * nHeight; }
 
+static int32_t ComputeBlockVersion(const CBlockIndex* pindexPrev, const Consensus::Params& params)
+{
+    return g_versionbitscache.ComputeBlockVersion(pindexPrev, params);
+}
+
 static const std::string StateName(ThresholdState state)
 {
     switch (state) {

src/validation.cpp

@@ -1627,7 +1627,7 @@ class WarningBitsConditionChecker : public AbstractThresholdConditionChecker
         return pindex->nHeight >= params.MinBIP9WarningHeight &&
                ((pindex->nVersion & VERSIONBITS_TOP_MASK) == VERSIONBITS_TOP_BITS) &&
                ((pindex->nVersion >> bit) & 1) != 0 &&
-               ((ComputeBlockVersion(pindex->pprev, params) >> bit) & 1) == 0;
+               ((g_versionbitscache.ComputeBlockVersion(pindex->pprev, params) >> bit) & 1) == 0;
     }
 };
 

src/versionbits.cpp

@@ -212,16 +212,16 @@ uint32_t VersionBitsCache::Mask(const Consensus::Params& params, Consensus::Depl
     return VersionBitsConditionChecker(pos).Mask(params);
 }
 
-extern VersionBitsCache g_versionbitscache; // removed in next commit
-
-int32_t ComputeBlockVersion(const CBlockIndex* pindexPrev, const Consensus::Params& params)
+int32_t VersionBitsCache::ComputeBlockVersion(const CBlockIndex* pindexPrev, const Consensus::Params& params)
 {
+    LOCK(m_mutex);
     int32_t nVersion = VERSIONBITS_TOP_BITS;
 
     for (int i = 0; i < (int)Consensus::MAX_VERSION_BITS_DEPLOYMENTS; i++) {
-        ThresholdState state = g_versionbitscache.State(pindexPrev, params, static_cast<Consensus::DeploymentPos>(i));
+        Consensus::DeploymentPos pos = static_cast<Consensus::DeploymentPos>(i);
+        ThresholdState state = VersionBitsConditionChecker(pos).GetStateFor(pindexPrev, params, m_caches[pos]);
         if (state == ThresholdState::LOCKED_IN || state == ThresholdState::STARTED) {
-            nVersion |= g_versionbitscache.Mask(params, static_cast<Consensus::DeploymentPos>(i));
+            nVersion |= Mask(params, pos);
         }
     }
 

src/versionbits.h

@@ -93,12 +93,11 @@ class VersionBitsCache
     /** Get the block height at which the BIP9 deployment switched into the state for the block after pindexPrev. */
     int StateSinceHeight(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos);
 
+    /** Determine what nVersion a new block should use
+     */
+    int32_t ComputeBlockVersion(const CBlockIndex* pindexPrev, const Consensus::Params& params);
+
     void Clear();
 };
 
-/**
- * Determine what nVersion a new block should use.
- */
-int32_t ComputeBlockVersion(const CBlockIndex* pindexPrev, const Consensus::Params& params);
-
 #endif // BITCOIN_VERSIONBITS_H