Merge #9665: Use cached [compact] blocks to respond to getdata messages

b49ad44 Add comment about cs_most_recent_block coverage (Matt Corallo)
c47f5b7 Cache witness-enabled state with recent-compact-block-cache (Matt Corallo)
efc135f Use cached [compact] blocks to respond to getdata messages (Matt Corallo)

Tree-SHA512: ffc478bddbf14b8ed304a3041f47746520ce545bdeffa9652eff2ccb25c8b0d5194abe72568c10f9c1b246ee361176ba217767af834752a2ca7263d292005e87

1 files changed, 36 insertions, 18 deletions

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index d881b8ddda..2e7b99baa4 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -774,10 +774,12 @@ void PeerLogicValidation::BlockConnected(const std::shared_ptr<const CBlock>& pb
     }
 }
 
+// All of the following cache a recent block, and are protected by cs_most_recent_block
 static CCriticalSection cs_most_recent_block;
 static std::shared_ptr<const CBlock> most_recent_block;
 static std::shared_ptr<const CBlockHeaderAndShortTxIDs> most_recent_compact_block;
 static uint256 most_recent_block_hash;
+static bool fWitnessesPresentInMostRecentCompactBlock;
 
 void PeerLogicValidation::NewPoWValidBlock(const CBlockIndex *pindex, const std::shared_ptr<const CBlock>& pblock) {
     std::shared_ptr<const CBlockHeaderAndShortTxIDs> pcmpctblock = std::make_shared<const CBlockHeaderAndShortTxIDs> (*pblock, true);
@@ -798,6 +800,7 @@ void PeerLogicValidation::NewPoWValidBlock(const CBlockIndex *pindex, const std:
         most_recent_block_hash = hashBlock;
         most_recent_block = pblock;
         most_recent_compact_block = pcmpctblock;
+        fWitnessesPresentInMostRecentCompactBlock = fWitnessEnabled;
     }
 
     connman->ForEachNode([this, &pcmpctblock, pindex, &msgMaker, fWitnessEnabled, &hashBlock](CNode* pnode) {
@@ -990,6 +993,15 @@ void static ProcessGetData(CNode* pfrom, const Consensus::Params& consensusParam
             {
                 bool send = false;
                 BlockMap::iterator mi = mapBlockIndex.find(inv.hash);
+                std::shared_ptr<const CBlock> a_recent_block;
+                std::shared_ptr<const CBlockHeaderAndShortTxIDs> a_recent_compact_block;
+                bool fWitnessesPresentInARecentCompactBlock;
+                {
+                    LOCK(cs_most_recent_block);
+                    a_recent_block = most_recent_block;
+                    a_recent_compact_block = most_recent_compact_block;
+                    fWitnessesPresentInARecentCompactBlock = fWitnessesPresentInMostRecentCompactBlock;
+                }
                 if (mi != mapBlockIndex.end())
                 {
                     if (mi->second->nChainTx && !mi->second->IsValid(BLOCK_VALID_SCRIPTS) &&
@@ -999,11 +1011,6 @@ void static ProcessGetData(CNode* pfrom, const Consensus::Params& consensusParam
                         // before ActivateBestChain but after AcceptBlock).
                         // In this case, we need to run ActivateBestChain prior to checking the relay
                         // conditions below.
-                        std::shared_ptr<const CBlock> a_recent_block;
-                        {
-                            LOCK(cs_most_recent_block);
-                            a_recent_block = most_recent_block;
-                        }
                         CValidationState dummy;
                         ActivateBestChain(dummy, Params(), a_recent_block);
                     }
@@ -1037,14 +1044,20 @@ void static ProcessGetData(CNode* pfrom, const Consensus::Params& consensusParam
                 // it's available before trying to send.
                 if (send && (mi->second->nStatus & BLOCK_HAVE_DATA))
                 {
-                    // Send block from disk
-                    CBlock block;
-                    if (!ReadBlockFromDisk(block, (*mi).second, consensusParams))
-                        assert(!"cannot load block from disk");
+                    std::shared_ptr<const CBlock> pblock;
+                    if (a_recent_block && a_recent_block->GetHash() == (*mi).second->GetBlockHash()) {
+                        pblock = a_recent_block;
+                    } else {
+                        // Send block from disk
+                        std::shared_ptr<CBlock> pblockRead = std::make_shared<CBlock>();
+                        if (!ReadBlockFromDisk(*pblockRead, (*mi).second, consensusParams))
+                            assert(!"cannot load block from disk");
+                        pblock = pblockRead;
+                    }
                     if (inv.type == MSG_BLOCK)
-                        connman.PushMessage(pfrom, msgMaker.Make(SERIALIZE_TRANSACTION_NO_WITNESS, NetMsgType::BLOCK, block));
+                        connman.PushMessage(pfrom, msgMaker.Make(SERIALIZE_TRANSACTION_NO_WITNESS, NetMsgType::BLOCK, *pblock));
                     else if (inv.type == MSG_WITNESS_BLOCK)
-                        connman.PushMessage(pfrom, msgMaker.Make(NetMsgType::BLOCK, block));
+                        connman.PushMessage(pfrom, msgMaker.Make(NetMsgType::BLOCK, *pblock));
                     else if (inv.type == MSG_FILTERED_BLOCK)
                     {
                         bool sendMerkleBlock = false;
@@ -1053,7 +1066,7 @@ void static ProcessGetData(CNode* pfrom, const Consensus::Params& consensusParam
                             LOCK(pfrom->cs_filter);
                             if (pfrom->pfilter) {
                                 sendMerkleBlock = true;
-                                merkleBlock = CMerkleBlock(block, *pfrom->pfilter);
+                                merkleBlock = CMerkleBlock(*pblock, *pfrom->pfilter);
                             }
                         }
                         if (sendMerkleBlock) {
@@ -1066,7 +1079,7 @@ void static ProcessGetData(CNode* pfrom, const Consensus::Params& consensusParam
                             // however we MUST always provide at least what the remote peer needs
                             typedef std::pair<unsigned int, uint256> PairType;
                             BOOST_FOREACH(PairType& pair, merkleBlock.vMatchedTxn)
-                                connman.PushMessage(pfrom, msgMaker.Make(SERIALIZE_TRANSACTION_NO_WITNESS, NetMsgType::TX, *block.vtx[pair.first]));
+                                connman.PushMessage(pfrom, msgMaker.Make(SERIALIZE_TRANSACTION_NO_WITNESS, NetMsgType::TX, *pblock->vtx[pair.first]));
                         }
                         // else
                             // no response
@@ -1080,10 +1093,15 @@ void static ProcessGetData(CNode* pfrom, const Consensus::Params& consensusParam
                         bool fPeerWantsWitness = State(pfrom->GetId())->fWantsCmpctWitness;
                         int nSendFlags = fPeerWantsWitness ? 0 : SERIALIZE_TRANSACTION_NO_WITNESS;
                         if (CanDirectFetch(consensusParams) && mi->second->nHeight >= chainActive.Height() - MAX_CMPCTBLOCK_DEPTH) {
-                            CBlockHeaderAndShortTxIDs cmpctblock(block, fPeerWantsWitness);
-                            connman.PushMessage(pfrom, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, cmpctblock));
-                        } else
-                            connman.PushMessage(pfrom, msgMaker.Make(nSendFlags, NetMsgType::BLOCK, block));
+                            if ((fPeerWantsWitness || !fWitnessesPresentInARecentCompactBlock) && a_recent_compact_block && a_recent_compact_block->header.GetHash() == mi->second->GetBlockHash()) {
+                                connman.PushMessage(pfrom, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, *a_recent_compact_block));
+                            } else {
+                                CBlockHeaderAndShortTxIDs cmpctblock(*pblock, fPeerWantsWitness);
+                                connman.PushMessage(pfrom, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, cmpctblock));
+                            }
+                        } else {
+                            connman.PushMessage(pfrom, msgMaker.Make(nSendFlags, NetMsgType::BLOCK, *pblock));
+                        }
                     }
 
                     // Trigger the peer node to send a getblocks request for the next batch of inventory
@@ -2974,7 +2992,7 @@ bool SendMessages(CNode* pto, CConnman& connman, const std::atomic<bool>& interr
                     {
                         LOCK(cs_most_recent_block);
                         if (most_recent_block_hash == pBestIndex->GetBlockHash()) {
-                            if (state.fWantsCmpctWitness)
+                            if (state.fWantsCmpctWitness || !fWitnessesPresentInMostRecentCompactBlock)
                                 connman.PushMessage(pto, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, *most_recent_compact_block));
                             else {
                                 CBlockHeaderAndShortTxIDs cmpctblock(*most_recent_block, state.fWantsCmpctWitness);