From 2e3b05ccdd32f0827f30d70e6329b981b129a4ce Mon Sep 17 00:00:00 2001
From: Gregory Maxwell <greg@xiph.org>
Date: Wed, 25 Nov 2015 21:25:30 -0800
Subject: [PATCH] Replace setInventoryKnown with a rolling bloom filter.

Mruset setInventoryKnown was reduced to a remarkably small 1000
 entries as a side effect of sendbuffer size reductions in 2012.

This removes setInventoryKnown filtering from merkleBlock responses
 because false positives there are especially unattractive and
 also because I'm not sure if there aren't race conditions around
 the relay pool that would cause some transactions there to
 be suppressed. (Also, ProcessGetData was accessing
 setInventoryKnown without taking the required lock.)
---
 src/main.cpp | 9 ++++-----
 src/net.cpp  | 3 ++-
 src/net.h    | 6 +++---
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index 6f3359893e6bf..f90478033637c 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -5159,8 +5159,7 @@ void static ProcessGetData(CNode* pfrom)
                             // however we MUST always provide at least what the remote peer needs
                             typedef std::pair<unsigned int, uint256> PairType;
                             for (PairType& pair : merkleBlock.vMatchedTxn)
-                                if (!pfrom->setInventoryKnown.count(CInv(MSG_TX, pair.second)))
-                                    pfrom->PushMessage(NetMsgType::TX, block.vtx[pair.first]);
+                                pfrom->PushMessage(NetMsgType::TX, block.vtx[pair.first]);
                         }
                         // else
                         // no response
@@ -6398,7 +6397,7 @@ bool SendMessages(CNode* pto)
             vInv.reserve(pto->vInventoryToSend.size());
             vInvWait.reserve(pto->vInventoryToSend.size());
             for (const CInv& inv : pto->vInventoryToSend) {
-                if (pto->setInventoryKnown.count(inv))
+                if (pto->setInventoryKnown.contains(inv.hash))
                     continue;
 
                 // trickle out tx inv to protect privacy
@@ -6417,8 +6416,8 @@ bool SendMessages(CNode* pto)
                     }
                 }
 
-                // returns true if wasn't already contained in the set
-                if (pto->setInventoryKnown.insert(inv).second) {
+                if (!pto->setInventoryKnown.contains(inv.hash)) {
+                    pto->setInventoryKnown.insert(inv.hash);
                     vInv.push_back(inv);
                     if (vInv.size() >= 1000) {
                         pto->PushMessage(NetMsgType::INV, vInv);
diff --git a/src/net.cpp b/src/net.cpp
index 341bd52067490..35546ae264eda 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -2319,7 +2319,7 @@ unsigned int SendBufferSize() { return 1000 * GetArg("-maxsendbuffer", 1 * 1000)
 CNode::CNode(SOCKET hSocketIn, CAddress addrIn, std::string addrNameIn, bool fInboundIn) :
     ssSend(SER_NETWORK, INIT_PROTO_VERSION),
     addrKnown(5000, 0.001),
-    setInventoryKnown(SendBufferSize() / 1000)
+    setInventoryKnown(50000, 0.000001)
 {
     nServices = NODE_NONE;
     nServicesExpected = NODE_NONE;
@@ -2347,6 +2347,7 @@ CNode::CNode(SOCKET hSocketIn, CAddress addrIn, std::string addrNameIn, bool fIn
     nSendOffset = 0;
     hashContinue = UINT256_ZERO;
     nStartingHeight = -1;
+    setInventoryKnown.reset();
     fGetAddr = false;
     nNextLocalAddrSend = 0;
     nNextAddrSend = 0;
diff --git a/src/net.h b/src/net.h
index a8d2334ad5894..ac67e77bca79a 100644
--- a/src/net.h
+++ b/src/net.h
@@ -387,7 +387,7 @@ class CNode
     int64_t nNextLocalAddrSend;
 
     // inventory based relay
-    mruset<CInv> setInventoryKnown;
+    CRollingBloomFilter setInventoryKnown;
     std::vector<CInv> vInventoryToSend;
     RecursiveMutex cs_inventory;
     std::multimap<int64_t, CInv> mapAskFor;
@@ -487,7 +487,7 @@ class CNode
     {
         {
             LOCK(cs_inventory);
-            setInventoryKnown.insert(inv);
+            setInventoryKnown.insert(inv.hash);
         }
     }
 
@@ -495,7 +495,7 @@ class CNode
     {
         {
             LOCK(cs_inventory);
-            if (!setInventoryKnown.count(inv))
+            if (!setInventoryKnown.contains(inv.hash))
                 vInventoryToSend.push_back(inv);
         }
     }