Merge #8637: Compact Block Tweaks (rebase of #8235)

3ac6de0 Align constant names for maximum compact block / blocktxn depth (Pieter Wuille)
b2e93a3 Add cmpctblock to debug help list (instagibbs)
fe998e9 More agressively filter compact block requests (Matt Corallo)
02a337d Dont remove a "preferred" cmpctblock peer if they provide a block (Matt Corallo)

3 files changed, 21 insertions, 6 deletions

diff --git a/src/init.cpp b/src/init.cpp
index eefef7ba0b..685188c458 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -423,7 +423,7 @@ std::string HelpMessage(HelpMessageMode mode)
         strUsage += HelpMessageOpt("-limitdescendantsize=<n>", strprintf("Do not accept transactions if any ancestor would have more than <n> kilobytes of in-mempool descendants (default: %u).", DEFAULT_DESCENDANT_SIZE_LIMIT));
         strUsage += HelpMessageOpt("-bip9params=deployment:start:end", "Use given start/end times for specified BIP9 deployment (regtest-only)");
     }
-    string debugCategories = "addrman, alert, bench, coindb, db, http, libevent, lock, mempool, mempoolrej, net, proxy, prune, rand, reindex, rpc, selectcoins, tor, zmq"; // Don't translate these and qt below
+    string debugCategories = "addrman, alert, bench, cmpctblock, coindb, db, http, libevent, lock, mempool, mempoolrej, net, proxy, prune, rand, reindex, rpc, selectcoins, tor, zmq"; // Don't translate these and qt below
     if (mode == HMM_BITCOIN_QT)
         debugCategories += ", qt";
     strUsage += HelpMessageOpt("-debug=<category>", strprintf(_("Output debugging information (default: %u, supplying <category> is optional)"), 0) + ". " +
diff --git a/src/main.cpp b/src/main.cpp
index d14a1bed3a..9f3116e358 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -485,9 +485,13 @@ void MaybeSetPeerAsAnnouncingHeaderAndIDs(const CNodeState* nodestate, CNode* pf
         return;
     }
     if (nodestate->fProvidesHeaderAndIDs) {
-        BOOST_FOREACH(const NodeId nodeid, lNodesAnnouncingHeaderAndIDs)
-            if (nodeid == pfrom->GetId())
+        for (std::list<NodeId>::iterator it = lNodesAnnouncingHeaderAndIDs.begin(); it != lNodesAnnouncingHeaderAndIDs.end(); it++) {
+            if (*it == pfrom->GetId()) {
+                lNodesAnnouncingHeaderAndIDs.erase(it);
+                lNodesAnnouncingHeaderAndIDs.push_back(pfrom->GetId());
                 return;
+            }
+        }
         bool fAnnounceUsingCMPCTBLOCK = false;
         uint64_t nCMPCTBLOCKVersion = (pfrom->GetLocalServices() & NODE_WITNESS) ? 2 : 1;
         if (lNodesAnnouncingHeaderAndIDs.size() >= 3) {
@@ -4875,7 +4879,7 @@ void static ProcessGetData(CNode* pfrom, const Consensus::Params& consensusParam
                         // and we don't feel like constructing the object for them, so
                         // instead we respond with the full, non-compact block.
                         bool fPeerWantsWitness = State(pfrom->GetId())->fWantsCmpctWitness;
-                        if (mi->second->nHeight >= chainActive.Height() - 10) {
+                        if (CanDirectFetch(consensusParams) && mi->second->nHeight >= chainActive.Height() - MAX_CMPCTBLOCK_DEPTH) {
                             CBlockHeaderAndShortTxIDs cmpctblock(block, fPeerWantsWitness);
                             pfrom->PushMessageWithFlag(fPeerWantsWitness ? 0 : SERIALIZE_TRANSACTION_NO_WITNESS, NetMsgType::CMPCTBLOCK, cmpctblock);
                         } else
@@ -5403,8 +5407,8 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
             return true;
         }
 
-        if (it->second->nHeight < chainActive.Height() - 15) {
-            LogPrint("net", "Peer %d sent us a getblocktxn for a block > 15 deep", pfrom->id);
+        if (it->second->nHeight < chainActive.Height() - MAX_BLOCKTXN_DEPTH) {
+            LogPrint("net", "Peer %d sent us a getblocktxn for a block > %i deep", pfrom->id, MAX_BLOCKTXN_DEPTH);
             return true;
         }
 
@@ -5733,6 +5737,12 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
                     return true;
                 }
 
+                if (!fAlreadyInFlight && mapBlocksInFlight.size() == 1 && pindex->pprev->IsValid(BLOCK_VALID_CHAIN)) {
+                    // We seem to be rather well-synced, so it appears pfrom was the first to provide us
+                    // with this block! Let's get them to announce using compact blocks in the future.
+                    MaybeSetPeerAsAnnouncingHeaderAndIDs(nodestate, pfrom, connman);
+                }
+
                 BlockTransactionsRequest req;
                 for (size_t i = 0; i < cmpctblock.BlockTxCount(); i++) {
                     if (!partialBlock.IsTxAvailable(i))
diff --git a/src/main.h b/src/main.h
index 2646d8f86b..db58b27487 100644
--- a/src/main.h
+++ b/src/main.h
@@ -90,6 +90,11 @@ static const unsigned int BLOCK_STALLING_TIMEOUT = 2;
 /** Number of headers sent in one getheaders result. We rely on the assumption that if a peer sends
  *  less than this number, we reached its tip. Changing this value is a protocol upgrade. */
 static const unsigned int MAX_HEADERS_RESULTS = 2000;
+/** Maximum depth of blocks we're willing to serve as compact blocks to peers
+ *  when requested. For older blocks, a regular BLOCK response will be sent. */
+static const int MAX_CMPCTBLOCK_DEPTH = 5;
+/** Maximum depth of blocks we're willing to respond to GETBLOCKTXN requests for. */
+static const int MAX_BLOCKTXN_DEPTH = 10;
 /** Size of the "block download window": how far ahead of our current height do we fetch?
  *  Larger windows tolerate larger download speed differences between peer, but increase the potential
  *  degree of disordering of blocks on disk (which make reindexing and in the future perhaps pruning