Merge bitcoin/bitcoin#21523: validation: run VerifyDB on all chainstates

844ad0eccaa1dbfefc30d19804d95d67c3d5f06d doc: IsSnapshotActive (James O'Beirne)
9b604c0207b526c008617cdca210f35db5e344db validation: prepare VerifyDB for assumeutxo (James O'Beirne)
7901647d722bcc5b0554ad73b14481cbe73608e4 refactor: rename active_chainstate in VerifyDB (James O'Beirne)

Pull request description:

  This is part of the [assumeutxo project](https://github.com/bitcoin/bitcoin/projects/11) (parent PR: #15606)

  ---

  ~~Pretty cut and dry; parameterizes `CVerifyDB` methods so that we can run the verify procedure on multiple chainstates.~~

  Two minor tweaks to ensure that `VerifyDB` can be run on multiple chainstates and a corresponding rename.

ACKs for top commit:
  fjahr:
    Code review re-ACK 844ad0eccaa1dbfefc30d19804d95d67c3d5f06d
  MarcoFalke:
    review ACK 844ad0eccaa1dbfefc30d19804d95d67c3d5f06d 🐥

Tree-SHA512: 26a398cf4dabc1aa0850743921dba0452b4813848a3c777586dc981716737e98e17b8110254a5c41af95dd236e0c00dc8b4eee891d69bef825a5e1911fc499d0

4 files changed, 41 insertions, 26 deletions

diff --git a/src/init.cpp b/src/init.cpp
index 24d67f48dc..3f9838f2e0 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1525,11 +1525,8 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
                             break;
                         }
 
-                        // Only verify the DB of the active chainstate. This is fixed in later
-                        // work when we allow VerifyDB to be parameterized by chainstate.
-                        if (&::ChainstateActive() == chainstate &&
-                            !CVerifyDB().VerifyDB(
-                                chainparams, *chainstate, &chainstate->CoinsDB(),
+                        if (!CVerifyDB().VerifyDB(
+                                *chainstate, chainparams, chainstate->CoinsDB(),
                                 args.GetArg("-checklevel", DEFAULT_CHECKLEVEL),
                                 args.GetArg("-checkblocks", DEFAULT_CHECKBLOCKS))) {
                             strLoadError = _("Corrupted block database detected");
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index e7fd97ee1f..d36814716b 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -1239,7 +1239,8 @@ static RPCHelpMan verifychain()
     LOCK(cs_main);
 
     CChainState& active_chainstate = chainman.ActiveChainstate();
-    return CVerifyDB().VerifyDB(Params(), active_chainstate, &active_chainstate.CoinsTip(), check_level, check_depth);
+    return CVerifyDB().VerifyDB(
+        active_chainstate, Params(), active_chainstate.CoinsTip(), check_level, check_depth);
 },
     };
 }
diff --git a/src/validation.cpp b/src/validation.cpp
index 09b7bb4398..1ddafa5613 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -4101,38 +4101,46 @@ CVerifyDB::~CVerifyDB()
     uiInterface.ShowProgress("", 100, false);
 }
 
-bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CChainState& active_chainstate, CCoinsView *coinsview, int nCheckLevel, int nCheckDepth)
+bool CVerifyDB::VerifyDB(
+    CChainState& chainstate,
+    const CChainParams& chainparams,
+    CCoinsView& coinsview,
+    int nCheckLevel, int nCheckDepth)
 {
     AssertLockHeld(cs_main);
 
-    assert(std::addressof(::ChainstateActive()) == std::addressof(active_chainstate));
-    if (active_chainstate.m_chain.Tip() == nullptr || active_chainstate.m_chain.Tip()->pprev == nullptr)
+    assert(std::addressof(::ChainstateActive()) == std::addressof(chainstate));
+    if (chainstate.m_chain.Tip() == nullptr || chainstate.m_chain.Tip()->pprev == nullptr)
         return true;
 
     // Verify blocks in the best chain
-    if (nCheckDepth <= 0 || nCheckDepth > active_chainstate.m_chain.Height())
-        nCheckDepth = active_chainstate.m_chain.Height();
+    if (nCheckDepth <= 0 || nCheckDepth > chainstate.m_chain.Height())
+        nCheckDepth = chainstate.m_chain.Height();
     nCheckLevel = std::max(0, std::min(4, nCheckLevel));
     LogPrintf("Verifying last %i blocks at level %i\n", nCheckDepth, nCheckLevel);
-    CCoinsViewCache coins(coinsview);
+    CCoinsViewCache coins(&coinsview);
     CBlockIndex* pindex;
     CBlockIndex* pindexFailure = nullptr;
     int nGoodTransactions = 0;
     BlockValidationState state;
     int reportDone = 0;
     LogPrintf("[0%%]..."); /* Continued */
-    for (pindex = active_chainstate.m_chain.Tip(); pindex && pindex->pprev; pindex = pindex->pprev) {
-        const int percentageDone = std::max(1, std::min(99, (int)(((double)(active_chainstate.m_chain.Height() - pindex->nHeight)) / (double)nCheckDepth * (nCheckLevel >= 4 ? 50 : 100))));
+
+    bool is_snapshot_cs = !chainstate.m_from_snapshot_blockhash.IsNull();
+
+    for (pindex = chainstate.m_chain.Tip(); pindex && pindex->pprev; pindex = pindex->pprev) {
+        const int percentageDone = std::max(1, std::min(99, (int)(((double)(chainstate.m_chain.Height() - pindex->nHeight)) / (double)nCheckDepth * (nCheckLevel >= 4 ? 50 : 100))));
         if (reportDone < percentageDone/10) {
             // report every 10% step
             LogPrintf("[%d%%]...", percentageDone); /* Continued */
             reportDone = percentageDone/10;
         }
         uiInterface.ShowProgress(_("Verifying blocks...").translated, percentageDone, false);
-        if (pindex->nHeight <= active_chainstate.m_chain.Height()-nCheckDepth)
+        if (pindex->nHeight <= chainstate.m_chain.Height()-nCheckDepth)
             break;
-        if (fPruneMode && !(pindex->nStatus & BLOCK_HAVE_DATA)) {
-            // If pruning, only go back as far as we have data.
+        if ((fPruneMode || is_snapshot_cs) && !(pindex->nStatus & BLOCK_HAVE_DATA)) {
+            // If pruning or running under an assumeutxo snapshot, only go
+            // back as far as we have data.
             LogPrintf("VerifyDB(): block verification stopping at height %d (pruning, no data)\n", pindex->nHeight);
             break;
         }
@@ -4154,9 +4162,11 @@ bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CChainState& active_ch
             }
         }
         // check level 3: check for inconsistencies during memory-only disconnect of tip blocks
-        if (nCheckLevel >= 3 && (coins.DynamicMemoryUsage() + active_chainstate.CoinsTip().DynamicMemoryUsage()) <= active_chainstate.m_coinstip_cache_size_bytes) {
+        size_t curr_coins_usage = coins.DynamicMemoryUsage() + chainstate.CoinsTip().DynamicMemoryUsage();
+
+        if (nCheckLevel >= 3 && curr_coins_usage <= chainstate.m_coinstip_cache_size_bytes) {
             assert(coins.GetBestBlock() == pindex->GetBlockHash());
-            DisconnectResult res = active_chainstate.DisconnectBlock(block, pindex, coins);
+            DisconnectResult res = 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());
             }
@@ -4170,26 +4180,26 @@ bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CChainState& active_ch
         if (ShutdownRequested()) return true;
     }
     if (pindexFailure)
-        return error("VerifyDB(): *** coin database inconsistencies found (last %i blocks, %i good transactions before that)\n", active_chainstate.m_chain.Height() - pindexFailure->nHeight + 1, nGoodTransactions);
+        return error("VerifyDB(): *** coin database inconsistencies found (last %i blocks, %i good transactions before that)\n", chainstate.m_chain.Height() - pindexFailure->nHeight + 1, nGoodTransactions);
 
     // store block count as we move pindex at check level >= 4
-    int block_count = active_chainstate.m_chain.Height() - pindex->nHeight;
+    int block_count = chainstate.m_chain.Height() - pindex->nHeight;
 
     // check level 4: try reconnecting blocks
     if (nCheckLevel >= 4) {
-        while (pindex != active_chainstate.m_chain.Tip()) {
-            const int percentageDone = std::max(1, std::min(99, 100 - (int)(((double)(active_chainstate.m_chain.Height() - pindex->nHeight)) / (double)nCheckDepth * 50)));
+        while (pindex != chainstate.m_chain.Tip()) {
+            const int percentageDone = std::max(1, std::min(99, 100 - (int)(((double)(chainstate.m_chain.Height() - pindex->nHeight)) / (double)nCheckDepth * 50)));
             if (reportDone < percentageDone/10) {
                 // report every 10% step
                 LogPrintf("[%d%%]...", percentageDone); /* Continued */
                 reportDone = percentageDone/10;
             }
             uiInterface.ShowProgress(_("Verifying blocks...").translated, percentageDone, false);
-            pindex = active_chainstate.m_chain.Next(pindex);
+            pindex = chainstate.m_chain.Next(pindex);
             CBlock block;
             if (!ReadBlockFromDisk(block, pindex, chainparams.GetConsensus()))
                 return error("VerifyDB(): *** ReadBlockFromDisk failed at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
-            if (!active_chainstate.ConnectBlock(block, state, pindex, coins, chainparams))
+            if (!chainstate.ConnectBlock(block, state, pindex, coins, chainparams))
                 return error("VerifyDB(): *** found unconnectable block at %d, hash=%s (%s)", pindex->nHeight, pindex->GetBlockHash().ToString(), state.ToString());
             if (ShutdownRequested()) return true;
         }
diff --git a/src/validation.h b/src/validation.h
index 9ae2838ead..a5e6892aa9 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -329,7 +329,12 @@ class CVerifyDB {
 public:
     CVerifyDB();
     ~CVerifyDB();
-    bool VerifyDB(const CChainParams& chainparams, CChainState& active_chainstate, CCoinsView *coinsview, int nCheckLevel, int nCheckDepth) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    bool VerifyDB(
+        CChainState& chainstate,
+        const CChainParams& chainparams,
+        CCoinsView& coinsview,
+        int nCheckLevel,
+        int nCheckDepth) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 };
 
 enum DisconnectResult
@@ -913,6 +918,8 @@ public:
         return m_blockman.m_block_index;
     }
 
+    //! @returns true if a snapshot-based chainstate is in use. Also implies
+    //!          that a background validation chainstate is also in use.
     bool IsSnapshotActive() const;
 
     std::optional<uint256> SnapshotBlockhash() const;