[refactor] change per-peer workset to info map within orphanage

No change for now, moving from map of NodeId->workset to
NodeId->PeerOrphanInfo struct that holds the workset.

In future commits, we will start tracking more things per-peer in the
orphanage.

Author: glozow

src/txorphanage.cpp

@@ -103,7 +103,7 @@ int TxOrphanage::EraseTx(const Wtxid& wtxid)
 
 void TxOrphanage::EraseForPeer(NodeId peer)
 {
-    m_peer_work_set.erase(peer);
+    m_peer_orphanage_info.erase(peer);
 
     int nErased = 0;
     std::map<Wtxid, OrphanTx>::iterator iter = m_orphans.begin();
@@ -174,7 +174,7 @@ void TxOrphanage::AddChildrenToWorkSet(const CTransaction& tx, FastRandomContext
 
                 // Get this source peer's work set, emplacing an empty set if it didn't exist
                 // (note: if this peer wasn't still connected, we would have removed the orphan tx already)
-                std::set<Wtxid>& orphan_work_set = m_peer_work_set.try_emplace(announcer).first->second;
+                std::set<Wtxid>& orphan_work_set = m_peer_orphanage_info.try_emplace(announcer).first->second.m_work_set;
                 // Add this tx to the work set
                 orphan_work_set.insert(elem->first);
                 LogDebug(BCLog::TXPACKAGES, "added %s (wtxid=%s) to peer %d workset\n",
@@ -203,30 +203,29 @@ bool TxOrphanage::HaveTxFromPeer(const Wtxid& wtxid, NodeId peer) const
 
 CTransactionRef TxOrphanage::GetTxToReconsider(NodeId peer)
 {
-    auto work_set_it = m_peer_work_set.find(peer);
-    if (work_set_it != m_peer_work_set.end()) {
-        auto& work_set = work_set_it->second;
-        while (!work_set.empty()) {
-            Wtxid wtxid = *work_set.begin();
-            work_set.erase(work_set.begin());
-
-            const auto orphan_it = m_orphans.find(wtxid);
-            if (orphan_it != m_orphans.end()) {
-                return orphan_it->second.tx;
-            }
+    auto peer_it = m_peer_orphanage_info.find(peer);
+    if (peer_it == m_peer_orphanage_info.end()) return nullptr;
+
+    auto& work_set = peer_it->second.m_work_set;
+    while (!work_set.empty()) {
+        Wtxid wtxid = *work_set.begin();
+        work_set.erase(work_set.begin());
+
+        const auto orphan_it = m_orphans.find(wtxid);
+        if (orphan_it != m_orphans.end()) {
+            return orphan_it->second.tx;
         }
     }
     return nullptr;
 }
 
 bool TxOrphanage::HaveTxToReconsider(NodeId peer)
 {
-    auto work_set_it = m_peer_work_set.find(peer);
-    if (work_set_it != m_peer_work_set.end()) {
-        auto& work_set = work_set_it->second;
-        return !work_set.empty();
-    }
-    return false;
+    auto peer_it = m_peer_orphanage_info.find(peer);
+    if (peer_it == m_peer_orphanage_info.end()) return false;
+
+    auto& work_set = peer_it->second.m_work_set;
+    return !work_set.empty();
 }
 
 void TxOrphanage::EraseForBlock(const CBlock& block)

src/txorphanage.h

@@ -109,8 +109,14 @@ class TxOrphanage {
      *  -maxorphantx/DEFAULT_MAX_ORPHAN_TRANSACTIONS */
     std::map<Wtxid, OrphanTx> m_orphans;
 
-    /** Which peer provided the orphans that need to be reconsidered */
-    std::map<NodeId, std::set<Wtxid>> m_peer_work_set;
+    struct PeerOrphanInfo {
+        /** List of transactions that should be reconsidered: added to in AddChildrenToWorkSet,
+         * removed from one-by-one with each call to GetTxToReconsider. The wtxids may refer to
+         * transactions that are no longer present in orphanage; these are lazily removed in
+         * GetTxToReconsider. */
+        std::set<Wtxid> m_work_set;
+    };
+    std::map<NodeId, PeerOrphanInfo> m_peer_orphanage_info;
 
     using OrphanMap = decltype(m_orphans);