validation: change UpdateTip for multiple chainstates

Summary:
Only perform certain behavior (namely that related to servicing
the getblocktemplate RPC call) for the active chainstate when
calling UpdateTip.

Co-authored-by: Jon Atack <jon@atack.com>

This is a backport of [[bitcoin/bitcoin#21526 | core#21526]] [3/12]
bitcoin/bitcoin@b217020
Depends on D12277

Notes:
 - the main difference from the source material is that we do not have the code handling BIP9 deployments in `UpdateTip`. As a result, there is no need for the `warning_messages` arguments in `UpdateTipLog`
 - the  `const` qualifier for the  `CblockIndex *pindexNew` argument in `UpdateTip` was missed in D1972

Test Plan: `ninja all check-all`

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D12278

src/validation.cpp

@@ -2117,7 +2117,39 @@ void CChainState::PruneAndFlush() {
     }
 }
 
-void CChainState::UpdateTip(CBlockIndex *pindexNew) {
+static void UpdateTipLog(const CCoinsViewCache &coins_tip,
+                         const CBlockIndex *tip, const CChainParams &params,
+                         const std::string &func_name,
+                         const std::string &prefix)
+    EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
+    AssertLockHeld(::cs_main);
+    LogPrintf("%s%s: new best=%s height=%d version=0x%08x log2_work=%f tx=%ld "
+              "date='%s' progress=%f cache=%.1fMiB(%utxo)\n",
+              prefix, func_name, tip->GetBlockHash().ToString(), tip->nHeight,
+              tip->nVersion, log(tip->nChainWork.getdouble()) / log(2.0),
+              tip->GetChainTxCount(),
+              FormatISO8601DateTime(tip->GetBlockTime()),
+              GuessVerificationProgress(params.TxData(), tip),
+              coins_tip.DynamicMemoryUsage() * (1.0 / (1 << 20)),
+              coins_tip.GetCacheSize());
+}
+
+void CChainState::UpdateTip(const CBlockIndex *pindexNew) {
+    const auto &coins_tip = CoinsTip();
+
+    // The remainder of the function isn't relevant if we are not acting on
+    // the active chainstate, so return if need be.
+    if (this != &m_chainman.ActiveChainstate()) {
+        // Only log every so often so that we don't bury log messages at the
+        // tip.
+        constexpr int BACKGROUND_LOG_INTERVAL = 2000;
+        if (pindexNew->nHeight % BACKGROUND_LOG_INTERVAL == 0) {
+            UpdateTipLog(coins_tip, pindexNew, m_params, __func__,
+                         "[background validation] ");
+        }
+        return;
+    }
+
     // New best block
     if (m_mempool) {
         m_mempool->AddTransactionsUpdated(1);
@@ -2129,16 +2161,7 @@ void CChainState::UpdateTip(CBlockIndex *pindexNew) {
         g_best_block_cv.notify_all();
     }
 
-    LogPrintf("%s: new best=%s height=%d version=0x%08x log2_work=%f tx=%ld "
-              "date='%s' progress=%f cache=%.1fMiB(%utxo)\n",
-              __func__, pindexNew->GetBlockHash().ToString(),
-              pindexNew->nHeight, pindexNew->nVersion,
-              log(pindexNew->nChainWork.getdouble()) / log(2.0),
-              pindexNew->GetChainTxCount(),
-              FormatISO8601DateTime(pindexNew->GetBlockTime()),
-              GuessVerificationProgress(m_params.TxData(), pindexNew),
-              CoinsTip().DynamicMemoryUsage() * (1.0 / (1 << 20)),
-              CoinsTip().GetCacheSize());
+    UpdateTipLog(coins_tip, pindexNew, m_params, __func__, "");
 }
 
 /**

src/validation.h

@@ -1172,7 +1172,8 @@ class CChainState {
     /**
      * Check warning conditions and do some notifications on new chain tip set.
      */
-    void UpdateTip(CBlockIndex *pindexNew) EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
+    void UpdateTip(const CBlockIndex *pindexNew)
+        EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 
     friend ChainstateManager;
 };