rpc/rest: Take and reuse local Chain/ChainState obj

In all rest/rpc-related modules, if there are multiple calls to
ActiveChain{,State}(), and the calls fall under the same ::cs_main lock,
we can simply take a local reference and use/reuse it instead of calling
ActiveChain{,State}() again and again.

4 files changed, 39 insertions, 29 deletions

diff --git a/src/rest.cpp b/src/rest.cpp
index eea0d67882..9b9f414e6c 100644
--- a/src/rest.cpp
+++ b/src/rest.cpp
@@ -182,13 +182,14 @@ static bool rest_headers(const std::any& context,
     {
         ChainstateManager& chainman = EnsureAnyChainman(context);
         LOCK(cs_main);
-        tip = chainman.ActiveChain().Tip();
+        CChain& active_chain = chainman.ActiveChain();
+        tip = active_chain.Tip();
         const CBlockIndex* pindex = chainman.m_blockman.LookupBlockIndex(hash);
-        while (pindex != nullptr && chainman.ActiveChain().Contains(pindex)) {
+        while (pindex != nullptr && active_chain.Contains(pindex)) {
             headers.push_back(pindex);
             if (headers.size() == (unsigned long)count)
                 break;
-            pindex = chainman.ActiveChain().Next(pindex);
+            pindex = active_chain.Next(pindex);
         }
     }
 
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 4785a272c0..053b6913dc 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -1009,6 +1009,8 @@ static RPCHelpMan pruneblockchain()
 
     ChainstateManager& chainman = EnsureAnyChainman(request.context);
     LOCK(cs_main);
+    CChainState& active_chainstate = chainman.ActiveChainstate();
+    CChain& active_chain = active_chainstate.m_chain;
 
     int heightParam = request.params[0].get_int();
     if (heightParam < 0)
@@ -1018,7 +1020,7 @@ static RPCHelpMan pruneblockchain()
     // too low to be a block time (corresponds to timestamp from Sep 2001).
     if (heightParam > 1000000000) {
         // Add a 2 hour buffer to include blocks which might have had old timestamps
-        CBlockIndex* pindex = chainman.ActiveChain().FindEarliestAtLeast(heightParam - TIMESTAMP_WINDOW, 0);
+        CBlockIndex* pindex = active_chain.FindEarliestAtLeast(heightParam - TIMESTAMP_WINDOW, 0);
         if (!pindex) {
             throw JSONRPCError(RPC_INVALID_PARAMETER, "Could not find block with at least the specified timestamp.");
         }
@@ -1026,7 +1028,7 @@ static RPCHelpMan pruneblockchain()
     }
 
     unsigned int height = (unsigned int) heightParam;
-    unsigned int chainHeight = (unsigned int) chainman.ActiveChain().Height();
+    unsigned int chainHeight = (unsigned int) active_chain.Height();
     if (chainHeight < Params().PruneAfterHeight())
         throw JSONRPCError(RPC_MISC_ERROR, "Blockchain is too short for pruning.");
     else if (height > chainHeight)
@@ -1036,8 +1038,8 @@ static RPCHelpMan pruneblockchain()
         height = chainHeight - MIN_BLOCKS_TO_KEEP;
     }
 
-    PruneBlockFilesManual(chainman.ActiveChainstate(), height);
-    const CBlockIndex* block = chainman.ActiveChain().Tip();
+    PruneBlockFilesManual(active_chainstate, height);
+    const CBlockIndex* block = active_chain.Tip();
     CHECK_NONFATAL(block);
     while (block->pprev && (block->pprev->nStatus & BLOCK_HAVE_DATA)) {
         block = block->pprev;
@@ -1363,8 +1365,9 @@ RPCHelpMan getblockchaininfo()
 {
     ChainstateManager& chainman = EnsureAnyChainman(request.context);
     LOCK(cs_main);
+    CChainState& active_chainstate = chainman.ActiveChainstate();
 
-    const CBlockIndex* tip = chainman.ActiveChain().Tip();
+    const CBlockIndex* tip = active_chainstate.m_chain.Tip();
     CHECK_NONFATAL(tip);
     const int height = tip->nHeight;
     UniValue obj(UniValue::VOBJ);
@@ -1375,7 +1378,7 @@ RPCHelpMan getblockchaininfo()
     obj.pushKV("difficulty",            (double)GetDifficulty(tip));
     obj.pushKV("mediantime",            (int64_t)tip->GetMedianTimePast());
     obj.pushKV("verificationprogress",  GuessVerificationProgress(Params().TxData(), tip));
-    obj.pushKV("initialblockdownload",  chainman.ActiveChainstate().IsInitialBlockDownload());
+    obj.pushKV("initialblockdownload",  active_chainstate.IsInitialBlockDownload());
     obj.pushKV("chainwork",             tip->nChainWork.GetHex());
     obj.pushKV("size_on_disk",          CalculateCurrentUsage());
     obj.pushKV("pruned",                fPruneMode);
@@ -1457,6 +1460,7 @@ static RPCHelpMan getchaintips()
 {
     ChainstateManager& chainman = EnsureAnyChainman(request.context);
     LOCK(cs_main);
+    CChain& active_chain = chainman.ActiveChain();
 
     /*
      * Idea: The set of chain tips is the active chain tip, plus orphan blocks which do not have another orphan building off of them.
@@ -1470,7 +1474,7 @@ static RPCHelpMan getchaintips()
     std::set<const CBlockIndex*> setPrevs;
 
     for (const std::pair<const uint256, CBlockIndex*>& item : chainman.BlockIndex()) {
-        if (!chainman.ActiveChain().Contains(item.second)) {
+        if (!active_chain.Contains(item.second)) {
             setOrphans.insert(item.second);
             setPrevs.insert(item.second->pprev);
         }
@@ -1483,7 +1487,7 @@ static RPCHelpMan getchaintips()
     }
 
     // Always report the currently active tip.
-    setTips.insert(chainman.ActiveChain().Tip());
+    setTips.insert(active_chain.Tip());
 
     /* Construct the output array.  */
     UniValue res(UniValue::VARR);
@@ -1492,11 +1496,11 @@ static RPCHelpMan getchaintips()
         obj.pushKV("height", block->nHeight);
         obj.pushKV("hash", block->phashBlock->GetHex());
 
-        const int branchLen = block->nHeight - chainman.ActiveChain().FindFork(block)->nHeight;
+        const int branchLen = block->nHeight - active_chain.FindFork(block)->nHeight;
         obj.pushKV("branchlen", branchLen);
 
         std::string status;
-        if (chainman.ActiveChain().Contains(block)) {
+        if (active_chain.Contains(block)) {
             // This block is part of the currently active chain.
             status = "active";
         } else if (block->nStatus & BLOCK_FAILED_MASK) {
@@ -1903,11 +1907,12 @@ static RPCHelpMan getblockstats()
 {
     ChainstateManager& chainman = EnsureAnyChainman(request.context);
     LOCK(cs_main);
+    CChain& active_chain = chainman.ActiveChain();
 
     CBlockIndex* pindex;
     if (request.params[0].isNum()) {
         const int height = request.params[0].get_int();
-        const int current_tip = chainman.ActiveChain().Height();
+        const int current_tip = active_chain.Height();
         if (height < 0) {
             throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Target block height %d is negative", height));
         }
@@ -1915,14 +1920,14 @@ static RPCHelpMan getblockstats()
             throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Target block height %d after current tip %d", height, current_tip));
         }
 
-        pindex = chainman.ActiveChain()[height];
+        pindex = active_chain[height];
     } else {
         const uint256 hash(ParseHashV(request.params[0], "hash_or_height"));
         pindex = chainman.m_blockman.LookupBlockIndex(hash);
         if (!pindex) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
         }
-        if (!chainman.ActiveChain().Contains(pindex)) {
+        if (!active_chain.Contains(pindex)) {
             throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Block is not in chain %s", Params().NetworkIDString()));
         }
     }
@@ -2307,10 +2312,11 @@ static RPCHelpMan scantxoutset()
         {
             ChainstateManager& chainman = EnsureChainman(node);
             LOCK(cs_main);
-            chainman.ActiveChainstate().ForceFlushStateToDisk();
-            pcursor = std::unique_ptr<CCoinsViewCursor>(chainman.ActiveChainstate().CoinsDB().Cursor());
+            CChainState& active_chainstate = chainman.ActiveChainstate();
+            active_chainstate.ForceFlushStateToDisk();
+            pcursor = std::unique_ptr<CCoinsViewCursor>(active_chainstate.CoinsDB().Cursor());
             CHECK_NONFATAL(pcursor);
-            tip = chainman.ActiveChain().Tip();
+            tip = active_chainstate.m_chain.Tip();
             CHECK_NONFATAL(tip);
         }
         bool res = FindScriptPubKey(g_scan_progress, g_should_abort_scan, count, pcursor.get(), needles, coins, node.rpc_interruption_point);
diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index 15e03194a3..0cef310c50 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -608,6 +608,8 @@ static RPCHelpMan getblocktemplate()
     UniValue lpval = NullUniValue;
     std::set<std::string> setClientRules;
     int64_t nMaxVersionPreVB = -1;
+    CChainState& active_chainstate = chainman.ActiveChainstate();
+    CChain& active_chain = active_chainstate.m_chain;
     if (!request.params[0].isNull())
     {
         const UniValue& oparam = request.params[0].get_obj();
@@ -642,12 +644,12 @@ static RPCHelpMan getblocktemplate()
                 return "duplicate-inconclusive";
             }
 
-            CBlockIndex* const pindexPrev = chainman.ActiveChain().Tip();
+            CBlockIndex* const pindexPrev = active_chain.Tip();
             // TestBlockValidity only supports blocks built on the current Tip
             if (block.hashPrevBlock != pindexPrev->GetBlockHash())
                 return "inconclusive-not-best-prevblk";
             BlockValidationState state;
-            TestBlockValidity(state, Params(), chainman.ActiveChainstate(), block, pindexPrev, false, true);
+            TestBlockValidity(state, Params(), active_chainstate, block, pindexPrev, false, true);
             return BIP22ValidationResult(state);
         }
 
@@ -677,7 +679,7 @@ static RPCHelpMan getblocktemplate()
             throw JSONRPCError(RPC_CLIENT_NOT_CONNECTED, PACKAGE_NAME " is not connected!");
         }
 
-        if (chainman.ActiveChainstate().IsInitialBlockDownload()) {
+        if (active_chainstate.IsInitialBlockDownload()) {
             throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, PACKAGE_NAME " is in initial sync and waiting for blocks...");
         }
     }
@@ -703,7 +705,7 @@ static RPCHelpMan getblocktemplate()
         else
         {
             // NOTE: Spec does not specify behaviour for non-string longpollid, but this makes testing easier
-            hashWatchedChain = chainman.ActiveChain().Tip()->GetBlockHash();
+            hashWatchedChain = active_chain.Tip()->GetBlockHash();
             nTransactionsUpdatedLastLP = nTransactionsUpdatedLast;
         }
 
@@ -748,7 +750,7 @@ static RPCHelpMan getblocktemplate()
     static CBlockIndex* pindexPrev;
     static int64_t nStart;
     static std::unique_ptr<CBlockTemplate> pblocktemplate;
-    if (pindexPrev != chainman.ActiveChain().Tip() ||
+    if (pindexPrev != active_chain.Tip() ||
         (mempool.GetTransactionsUpdated() != nTransactionsUpdatedLast && GetTime() - nStart > 5))
     {
         // Clear pindexPrev so future calls make a new block, despite any failures from here on
@@ -756,12 +758,12 @@ static RPCHelpMan getblocktemplate()
 
         // Store the pindexBest used before CreateNewBlock, to avoid races
         nTransactionsUpdatedLast = mempool.GetTransactionsUpdated();
-        CBlockIndex* pindexPrevNew = chainman.ActiveChain().Tip();
+        CBlockIndex* pindexPrevNew = active_chain.Tip();
         nStart = GetTime();
 
         // Create new block
         CScript scriptDummy = CScript() << OP_TRUE;
-        pblocktemplate = BlockAssembler(chainman.ActiveChainstate(), mempool, Params()).CreateNewBlock(scriptDummy);
+        pblocktemplate = BlockAssembler(active_chainstate, mempool, Params()).CreateNewBlock(scriptDummy);
         if (!pblocktemplate)
             throw JSONRPCError(RPC_OUT_OF_MEMORY, "Out of memory");
 
@@ -897,7 +899,7 @@ static RPCHelpMan getblocktemplate()
     result.pushKV("transactions", transactions);
     result.pushKV("coinbaseaux", aux);
     result.pushKV("coinbasevalue", (int64_t)pblock->vtx[0]->vout[0].nValue);
-    result.pushKV("longpollid", chainman.ActiveChain().Tip()->GetBlockHash().GetHex() + ToString(nTransactionsUpdatedLast));
+    result.pushKV("longpollid", active_chain.Tip()->GetBlockHash().GetHex() + ToString(nTransactionsUpdatedLast));
     result.pushKV("target", hashTarget.GetHex());
     result.pushKV("mintime", (int64_t)pindexPrev->GetMedianTimePast()+1);
     result.pushKV("mutable", aMutable);
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 5947755819..19e9c75e32 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -268,12 +268,13 @@ static RPCHelpMan gettxoutproof()
         }
     } else {
         LOCK(cs_main);
+        CChainState& active_chainstate = chainman.ActiveChainstate();
 
         // Loop through txids and try to find which block they're in. Exit loop once a block is found.
         for (const auto& tx : setTxids) {
-            const Coin& coin = AccessByTxid(chainman.ActiveChainstate().CoinsTip(), tx);
+            const Coin& coin = AccessByTxid(active_chainstate.CoinsTip(), tx);
             if (!coin.IsSpent()) {
-                pblockindex = chainman.ActiveChain()[coin.nHeight];
+                pblockindex = active_chainstate.m_chain[coin.nHeight];
                 break;
             }
         }