refactoring: IsInitialBlockDownload -> CChainState

We introduce CChainState.m_cached_finished_ibd because the static state it
replaces would've been shared across all CChainState instances.

Author: jamesob

src/interfaces/chain.cpp

@@ -321,8 +321,8 @@ class ChainImpl : public Chain
     CFeeRate relayDustFee() override { return ::dustRelayFee; }
     bool getPruneMode() override { return ::fPruneMode; }
     bool p2pEnabled() override { return g_connman != nullptr; }
-    bool isReadyToBroadcast() override { return !::fImporting && !::fReindex && !IsInitialBlockDownload(); }
-    bool isInitialBlockDownload() override { return IsInitialBlockDownload(); }
+    bool isReadyToBroadcast() override { return !::fImporting && !::fReindex && !isInitialBlockDownload(); }
+    bool isInitialBlockDownload() override { return ::ChainstateActive().IsInitialBlockDownload(); }
     bool shutdownRequested() override { return ShutdownRequested(); }
     int64_t getAdjustedTime() override { return GetAdjustedTime(); }
     void initMessage(const std::string& message) override { ::uiInterface.InitMessage(message); }

src/interfaces/node.cpp

@@ -197,7 +197,7 @@ class NodeImpl : public Node
         }
         return GuessVerificationProgress(Params().TxData(), tip);
     }
-    bool isInitialBlockDownload() override { return IsInitialBlockDownload(); }
+    bool isInitialBlockDownload() override { return ::ChainstateActive().IsInitialBlockDownload(); }
     bool getReindex() override { return ::fReindex; }
     bool getImporting() override { return ::fImporting; }
     void setNetworkActive(bool active) override

src/net_processing.cpp

@@ -1240,7 +1240,7 @@ void PeerLogicValidation::BlockChecked(const CBlock& block, const CValidationSta
     //    the tip yet so we have no way to check this directly here. Instead we
     //    just check that there are currently no other blocks in flight.
     else if (state.IsValid() &&
-             !IsInitialBlockDownload() &&
+             !::ChainstateActive().IsInitialBlockDownload() &&
              mapBlocksInFlight.count(hash) == mapBlocksInFlight.size()) {
         if (it != mapBlockSource.end()) {
             MaybeSetPeerAsAnnouncingHeaderAndIDs(it->second.first, connman);
@@ -1728,7 +1728,7 @@ bool static ProcessHeadersMessage(CNode *pfrom, CConnman *connman, const std::ve
         }
         // If we're in IBD, we want outbound peers that will serve us a useful
         // chain. Disconnect peers that are on chains with insufficient work.
-        if (IsInitialBlockDownload() && nCount != MAX_HEADERS_RESULTS) {
+        if (::ChainstateActive().IsInitialBlockDownload() && nCount != MAX_HEADERS_RESULTS) {
             // When nCount < MAX_HEADERS_RESULTS, we know we have no more
             // headers to fetch from this peer.
             if (nodestate->pindexBestKnownBlock && nodestate->pindexBestKnownBlock->nChainWork < nMinimumChainWork) {
@@ -1994,7 +1994,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
         if (!pfrom->fInbound)
         {
             // Advertise our address
-            if (fListen && !IsInitialBlockDownload())
+            if (fListen && !::ChainstateActive().IsInitialBlockDownload())
             {
                 CAddress addr = GetLocalAddress(&pfrom->addr, pfrom->GetLocalServices());
                 FastRandomContext insecure_rand;
@@ -2229,7 +2229,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
                 pfrom->AddInventoryKnown(inv);
                 if (fBlocksOnly) {
                     LogPrint(BCLog::NET, "transaction (%s) inv sent in violation of protocol peer=%d\n", inv.hash.ToString(), pfrom->GetId());
-                } else if (!fAlreadyHave && !fImporting && !fReindex && !IsInitialBlockDownload()) {
+                } else if (!fAlreadyHave && !fImporting && !fReindex && !::ChainstateActive().IsInitialBlockDownload()) {
                     RequestTx(State(pfrom->GetId()), inv.hash, nNow);
                 }
             }
@@ -2387,7 +2387,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
         }
 
         LOCK(cs_main);
-        if (IsInitialBlockDownload() && !pfrom->fWhitelisted) {
+        if (::ChainstateActive().IsInitialBlockDownload() && !pfrom->fWhitelisted) {
             LogPrint(BCLog::NET, "Ignoring getheaders from peer=%d because node is in initial block download\n", pfrom->GetId());
             return true;
         }
@@ -2609,7 +2609,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
 
         if (!LookupBlockIndex(cmpctblock.header.hashPrevBlock)) {
             // Doesn't connect (or is genesis), instead of DoSing in AcceptBlockHeader, request deeper headers
-            if (!IsInitialBlockDownload())
+            if (!::ChainstateActive().IsInitialBlockDownload())
                 connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::GETHEADERS, ::ChainActive().GetLocator(pindexBestHeader), uint256()));
             return true;
         }
@@ -3525,7 +3525,7 @@ bool PeerLogicValidation::SendMessages(CNode* pto)
 
         // Address refresh broadcast
         int64_t nNow = GetTimeMicros();
-        if (!IsInitialBlockDownload() && pto->nNextLocalAddrSend < nNow) {
+        if (!::ChainstateActive().IsInitialBlockDownload() && pto->nNextLocalAddrSend < nNow) {
             AdvertiseLocal(pto);
             pto->nNextLocalAddrSend = PoissonNextSend(nNow, AVG_LOCAL_ADDRESS_BROADCAST_INTERVAL);
         }
@@ -3926,7 +3926,7 @@ bool PeerLogicValidation::SendMessages(CNode* pto)
         // Message: getdata (blocks)
         //
         std::vector<CInv> vGetData;
-        if (!pto->fClient && ((fFetch && !pto->m_limited_node) || !IsInitialBlockDownload()) && state.nBlocksInFlight < MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
+        if (!pto->fClient && ((fFetch && !pto->m_limited_node) || !::ChainstateActive().IsInitialBlockDownload()) && state.nBlocksInFlight < MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
             std::vector<const CBlockIndex*> vToDownload;
             NodeId staller = -1;
             FindNextBlocksToDownload(pto->GetId(), MAX_BLOCKS_IN_TRANSIT_PER_PEER - state.nBlocksInFlight, vToDownload, staller, consensusParams);

src/rpc/blockchain.cpp

@@ -1342,7 +1342,7 @@ UniValue getblockchaininfo(const JSONRPCRequest& request)
     obj.pushKV("difficulty",            (double)GetDifficulty(tip));
     obj.pushKV("mediantime",            (int64_t)tip->GetMedianTimePast());
     obj.pushKV("verificationprogress",  GuessVerificationProgress(Params().TxData(), tip));
-    obj.pushKV("initialblockdownload",  IsInitialBlockDownload());
+    obj.pushKV("initialblockdownload",  ::ChainstateActive().IsInitialBlockDownload());
     obj.pushKV("chainwork",             tip->nChainWork.GetHex());
     obj.pushKV("size_on_disk",          CalculateCurrentUsage());
     obj.pushKV("pruned",                fPruneMode);

src/rpc/mining.cpp

@@ -442,7 +442,7 @@ static UniValue getblocktemplate(const JSONRPCRequest& request)
     if (g_connman->GetNodeCount(CConnman::CONNECTIONS_ALL) == 0)
         throw JSONRPCError(RPC_CLIENT_NOT_CONNECTED, PACKAGE_NAME " is not connected!");
 
-    if (IsInitialBlockDownload())
+    if (::ChainstateActive().IsInitialBlockDownload())
         throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, PACKAGE_NAME " is in initial sync and waiting for blocks...");
 
     static unsigned int nTransactionsUpdatedLast;

src/validation.cpp

@@ -321,7 +321,7 @@ static void LimitMempoolSize(CTxMemPool& pool, size_t limit, unsigned long age)
 static bool IsCurrentForFeeEstimation() EXCLUSIVE_LOCKS_REQUIRED(cs_main)
 {
     AssertLockHeld(cs_main);
-    if (IsInitialBlockDownload())
+    if (::ChainstateActive().IsInitialBlockDownload())
         return false;
     if (::ChainActive().Tip()->GetBlockTime() < (GetTime() - MAX_FEE_ESTIMATION_TIP_AGE))
         return false;
@@ -1022,27 +1022,30 @@ CAmount GetBlockSubsidy(int nHeight, const Consensus::Params& consensusParams)
     return nSubsidy;
 }
 
-bool IsInitialBlockDownload()
+// Note that though this is marked const, we may end up modifying `m_cached_finished_ibd`, which
+// is a performance-related implementation detail. This function must be marked
+// `const` so that `CValidationInterface` clients (which are given a `const CChainState*`)
+// can call it.
+//
+bool CChainState::IsInitialBlockDownload() const
 {
-    // Once this function has returned false, it must remain false.
-    static std::atomic<bool> latchToFalse{false};
     // Optimization: pre-test latch before taking the lock.
-    if (latchToFalse.load(std::memory_order_relaxed))
+    if (m_cached_finished_ibd.load(std::memory_order_relaxed))
         return false;
 
     LOCK(cs_main);
-    if (latchToFalse.load(std::memory_order_relaxed))
+    if (m_cached_finished_ibd.load(std::memory_order_relaxed))
         return false;
     if (fImporting || fReindex)
         return true;
-    if (::ChainActive().Tip() == nullptr)
+    if (m_chain.Tip() == nullptr)
         return true;
-    if (::ChainActive().Tip()->nChainWork < nMinimumChainWork)
+    if (m_chain.Tip()->nChainWork < nMinimumChainWork)
         return true;
-    if (::ChainActive().Tip()->GetBlockTime() < (GetTime() - nMaxTipAge))
+    if (m_chain.Tip()->GetBlockTime() < (GetTime() - nMaxTipAge))
         return true;
     LogPrintf("Leaving InitialBlockDownload (latching to false)\n");
-    latchToFalse.store(true, std::memory_order_relaxed);
+    m_cached_finished_ibd.store(true, std::memory_order_relaxed);
     return false;
 }
 
@@ -1071,7 +1074,7 @@ static void CheckForkWarningConditions() EXCLUSIVE_LOCKS_REQUIRED(cs_main)
     AssertLockHeld(cs_main);
     // Before we get past initial download, we cannot reliably alert about forks
     // (we assume we don't get stuck on a fork before finishing our initial sync)
-    if (IsInitialBlockDownload())
+    if (::ChainstateActive().IsInitialBlockDownload())
         return;
 
     // If our best fork is no longer within 72 blocks (+/- 12 hours if no one mines it)
@@ -2101,7 +2104,7 @@ void static UpdateTip(const CBlockIndex *pindexNew, const CChainParams& chainPar
     }
 
     std::string warningMessages;
-    if (!IsInitialBlockDownload())
+    if (!::ChainstateActive().IsInitialBlockDownload())
     {
         int nUpgraded = 0;
         const CBlockIndex* pindex = pindexNew;
@@ -2492,7 +2495,7 @@ static void NotifyHeaderTip() LOCKS_EXCLUDED(cs_main) {
 
         if (pindexHeader != pindexHeaderOld) {
             fNotify = true;
-            fInitialBlockDownload = IsInitialBlockDownload();
+            fInitialBlockDownload = ::ChainstateActive().IsInitialBlockDownload();
             pindexHeaderOld = pindexHeader;
         }
     }
@@ -3621,7 +3624,7 @@ static void FindFilesToPrune(std::set<int>& setFilesToPrune, uint64_t nPruneAfte
         // To avoid excessive prune events negating the benefit of high dbcache
         // values, we should not prune too rapidly.
         // So when pruning in IBD, increase the buffer a bit to avoid a re-prune too soon.
-        if (IsInitialBlockDownload()) {
+        if (::ChainstateActive().IsInitialBlockDownload()) {
             // Since this is only relevant during IBD, we use a fixed 10%
             nBuffer += nPruneTarget / 10;
         }

src/validation.h

@@ -249,8 +249,6 @@ bool LoadChainTip(const CChainParams& chainparams) EXCLUSIVE_LOCKS_REQUIRED(cs_m
 void UnloadBlockIndex();
 /** Run an instance of the script checking thread */
 void ThreadScriptCheck(int worker_num);
-/** Check whether we are doing an initial block download (synchronizing from disk or network) */
-bool IsInitialBlockDownload();
 /** Retrieve a transaction (from memory pool, or from disk, if possible) */
 bool GetTransaction(const uint256& hash, CTransactionRef& tx, const Consensus::Params& params, uint256& hashBlock, const CBlockIndex* const blockIndex = nullptr);
 /**
@@ -503,6 +501,14 @@ class CChainState {
      */
     CCriticalSection m_cs_chainstate;
 
+    /**
+     * Whether this chainstate is undergoing initial block download.
+     *
+     * Mutable because we need to be able to mark IsInitialBlockDownload()
+     * const, which latches this for caching purposes.
+     */
+    mutable std::atomic<bool> m_cached_finished_ibd{false};
+
 public:
     //! The current chain of blockheaders we consult and build on.
     //! @see CChain, CBlockIndex.
@@ -565,6 +571,9 @@ class CChainState {
 
     void UnloadBlockIndex();
 
+    /** Check whether we are doing an initial block download (synchronizing from disk or network) */
+    bool IsInitialBlockDownload() const;
+
 private:
     bool ActivateBestChainStep(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexMostWork, const std::shared_ptr<const CBlock>& pblock, bool& fInvalidFound, ConnectTrace& connectTrace) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     bool ConnectTip(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexNew, const std::shared_ptr<const CBlock>& pblock, ConnectTrace& connectTrace, DisconnectedBlockTransactions &disconnectpool) EXCLUSIVE_LOCKS_REQUIRED(cs_main);