Merge #17164: p2p: Avoid allocating memory for addrKnown where we don't need it

b6d2183858 Minor refactoring to remove implied m_addr_relay_peer. (User)
a552e8477c added asserts to check m_addr_known when it's used (User)
090b75c14b p2p: Avoid allocating memory for addrKnown where we don't need it (User)

Pull request description:

  We should allocate memory for addrKnown filter only for those peers which are expected to participate in address relay.

  Currently, we do it for all peers (including SPV and block-relay-only),  which results in extra RAM where it's not needed.

  Upd:
  In future, we would still allow SPVs to ask for addrs, so allocation still will be done by default.
  However, they will be able to opt-out via [this proposal](https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2019-October/017428.html) and then we could save some more memory.
  This PR still saves memory for block-relay-only peers immediately after merging.

Top commit has no ACKs.

Tree-SHA512: e84d93b2615556d466f5ca0e543580fde763911a3bfea3127c493ddfaba8f05c8605cb94ff795d165af542b594400995a2c51338185c298581408687e7812463

src/bloom.h

@@ -115,9 +115,6 @@ public:
 class CRollingBloomFilter
 {
 public:
-    // A random bloom filter calls GetRand() at creation time.
-    // Don't create global CRollingBloomFilter objects, as they may be
-    // constructed before the randomizer is properly initialized.
     CRollingBloomFilter(const unsigned int nElements, const double nFPRate);
 
     void insert(const std::vector<unsigned char>& vKey);

src/net.cpp

@@ -2666,11 +2666,10 @@ CNode::CNode(NodeId idIn, ServiceFlags nLocalServicesIn, int nMyStartingHeightIn
     addrBind(addrBindIn),
     fInbound(fInboundIn),
     nKeyedNetGroup(nKeyedNetGroupIn),
-    addrKnown(5000, 0.001),
     // Don't relay addr messages to peers that we connect to as block-relay-only
     // peers (to prevent adversaries from inferring these links from addr
     // traffic).
-    m_addr_relay_peer(!block_relay_only),
+    m_addr_known{block_relay_only ? nullptr : MakeUnique<CRollingBloomFilter>(5000, 0.001)},
     id(idIn),
     nLocalHostNonce(nLocalHostNonceIn),
     nLocalServices(nLocalServicesIn),

src/net.h

@@ -776,13 +776,12 @@ public:
 
     // flood relay
     std::vector<CAddress> vAddrToSend;
-    CRollingBloomFilter addrKnown;
+    const std::unique_ptr<CRollingBloomFilter> m_addr_known;
     bool fGetAddr{false};
     int64_t nNextAddrSend GUARDED_BY(cs_sendProcessing){0};
     int64_t nNextLocalAddrSend GUARDED_BY(cs_sendProcessing){0};
 
-    const bool m_addr_relay_peer;
+    bool IsAddrRelayPeer() const { return m_addr_known != nullptr; }
-    bool IsAddrRelayPeer() const { return m_addr_relay_peer; }
 
     // List of block ids we still have announce.
     // There is no final sorting before sending, as they are always sent immediately
@@ -931,7 +930,8 @@ public:
 
     void AddAddressKnown(const CAddress& _addr)
     {
-        addrKnown.insert(_addr.GetKey());
+        assert(m_addr_known);
+        m_addr_known->insert(_addr.GetKey());
     }
 
     void PushAddress(const CAddress& _addr, FastRandomContext &insecure_rand)
@@ -939,7 +939,8 @@ public:
         // Known checking here is only to save space from duplicates.
         // SendMessages will filter it again for knowns that were added
         // after addresses were pushed.
-        if (_addr.IsValid() && !addrKnown.contains(_addr.GetKey())) {
+        assert(m_addr_known);
+        if (_addr.IsValid() && !m_addr_known->contains(_addr.GetKey())) {
             if (vAddrToSend.size() >= MAX_ADDR_TO_SEND) {
                 vAddrToSend[insecure_rand.randrange(vAddrToSend.size())] = _addr;
             } else {

src/net_processing.cpp

@@ -1340,7 +1340,7 @@ static void RelayAddress(const CAddress& addr, bool fReachable, CConnman* connma
 
     // Relay to a limited number of other nodes
     // Use deterministic randomness to send to the same nodes for 24 hours
-    // at a time so the addrKnowns of the chosen nodes prevent repeats
+    // at a time so the m_addr_knowns of the chosen nodes prevent repeats
     uint64_t hashAddr = addr.GetHash();
     const CSipHasher hasher = connman->GetDeterministicRandomizer(RANDOMIZER_ID_ADDRESS_RELAY).Write(hashAddr << 32).Write((GetTime() + hashAddr) / (24*60*60));
     FastRandomContext insecure_rand;
@@ -3587,11 +3587,12 @@ bool PeerLogicValidation::SendMessages(CNode* pto)
             pto->nNextAddrSend = PoissonNextSend(nNow, AVG_ADDRESS_BROADCAST_INTERVAL);
             std::vector<CAddress> vAddr;
             vAddr.reserve(pto->vAddrToSend.size());
+            assert(pto->m_addr_known);
             for (const CAddress& addr : pto->vAddrToSend)
             {
-                if (!pto->addrKnown.contains(addr.GetKey()))
+                if (!pto->m_addr_known->contains(addr.GetKey()))
                 {
-                    pto->addrKnown.insert(addr.GetKey());
+                    pto->m_addr_known->insert(addr.GetKey());
                     vAddr.push_back(addr);
                     // receiver rejects addr messages larger than 1000
                     if (vAddr.size() >= 1000)