[net_processing] Move peer_map to PeerManager

src/net_processing.h

@@ -39,6 +39,40 @@ struct CNodeStateStats {
     std::vector<int> vHeightInFlight;
 };
 
+/**
+ * Data structure for an individual peer. This struct is not protected by
+ * cs_main since it does not contain validation-critical data.
+ *
+ * Memory is owned by shared pointers and this object is destructed when
+ * the refcount drops to zero.
+ *
+ * TODO: move most members from CNodeState to this structure.
+ * TODO: move remaining application-layer data members from CNode to this structure.
+ */
+struct Peer {
+    /** Same id as the CNode object for this peer */
+    const NodeId m_id{0};
+
+    /** Protects misbehavior data members */
+    Mutex m_misbehavior_mutex;
+    /** Accumulated misbehavior score for this peer */
+    int m_misbehavior_score GUARDED_BY(m_misbehavior_mutex){0};
+    /** Whether this peer should be disconnected and marked as discouraged (unless it has the noban permission). */
+    bool m_should_discourage GUARDED_BY(m_misbehavior_mutex){false};
+
+    /** Set of txids to reconsider once their parent transactions have been accepted **/
+    std::set<uint256> m_orphan_work_set GUARDED_BY(g_cs_orphans);
+
+    /** Protects m_getdata_requests **/
+    Mutex m_getdata_requests_mutex;
+    /** Work queue of items requested by this peer **/
+    std::deque<CInv> m_getdata_requests GUARDED_BY(m_getdata_requests_mutex);
+
+    explicit Peer(NodeId id) : m_id(id) {}
+};
+
+using PeerRef = std::shared_ptr<Peer>;
+
 class PeerManager final : public CValidationInterface, public NetEventsInterface {
 public:
     PeerManager(const CChainParams& chainparams, CConnman& connman, BanMan* banman,
@@ -105,6 +139,10 @@ public:
     bool GetNodeStateStats(NodeId nodeid, CNodeStateStats& stats);
 
 private:
+    /** Get a shared pointer to the Peer object.
+     *  May return an empty shared_ptr if the Peer object can't be found. */
+    PeerRef GetPeerRef(NodeId id);
+
     /**
      * Potentially mark a node discouraged based on the contents of a BlockValidationState object
      *
@@ -153,6 +191,16 @@ private:
     TxRequestTracker m_txrequest GUARDED_BY(::cs_main);
 
     int64_t m_stale_tip_check_time; //!< Next time to check for stale tip
+
+    /** Protects m_peer_map */
+    Mutex m_peer_mutex;
+    /**
+     * Map of all Peer objects, keyed by peer id. This map is protected
+     * by the m_peer_mutex. Once a shared pointer reference is
+     * taken, the lock may be released. Individual fields are protected by
+     * their own locks.
+     */
+    std::map<NodeId, PeerRef> m_peer_map GUARDED_BY(m_peer_mutex);
 };
 
 /** Relay transaction to every node */