update PeerNetwork to work with multiloops

3 files changed, 194 insertions, 162 deletions

diff --git a/include/salticidae/conn.h b/include/salticidae/conn.h
index 26d19fe..1364d4d 100644
--- a/include/salticidae/conn.h
+++ b/include/salticidae/conn.h
@@ -61,7 +61,7 @@ class ConnPool {
     /** The handle to a bi-directional connection. */
     using conn_t = ArcObj<Conn>;
     /** The type of callback invoked when connection status is changed. */
-    using conn_callback_t = std::function<void(Conn &)>;
+    using conn_callback_t = std::function<void(Conn &, bool)>;
 
     /** Abstraction for a bi-directional connection. */
     class Conn {
@@ -72,7 +72,7 @@ class ConnPool {
             PASSIVE, /**< the connection is established by accept() */
         };
     
-        private:
+        protected:
         size_t seg_buff_size;
         conn_t self_ref;
         int fd;
@@ -109,14 +109,10 @@ class ConnPool {
         /** Get the handle to itself. */
         conn_t self() { return self_ref; }
         operator std::string() const;
-        int get_fd() const { return fd; }
         const NetAddr &get_addr() const { return addr; }
         ConnMode get_mode() const { return mode; }
         ConnPool *get_pool() const { return cpool; }
-        SegBuffer &get_recv_buffer() { return recv_buffer; }
         MPSCWriteBuffer &get_send_buffer() { return send_buffer; }
-        /** Set the buffer size used for send/receive data. */
-        void set_seg_buff_size(size_t size) { seg_buff_size = size; }
 
         /** Write data to the connection (non-blocking). The data will be sent
          * whenever I/O is available. */
@@ -124,11 +120,6 @@ class ConnPool {
             send_buffer.push(std::move(data));
         }
 
-        ///** Move the send buffer from the other (old) connection. */
-        //void move_send_buffer(conn_t other) {
-        //    send_buffer = std::move(other->send_buffer);
-        //}
-
         protected:
         /** Close the IO and clear all on-going or planned events. */
         virtual void on_close() {
@@ -143,13 +134,9 @@ class ConnPool {
         /** Called when new data is available. */
         virtual void on_read() {}
         /** Called when the underlying connection is established. */
-        virtual void on_setup() {
-            cpool->update_conn(self());
-        }
+        virtual void on_setup() {}
         /** Called when the underlying connection breaks. */
-        virtual void on_teardown() {
-            cpool->update_conn(self());
-        }
+        virtual void on_teardown() {}
     };
 
     private:
@@ -165,14 +152,13 @@ class ConnPool {
     /* owned by the dispatcher */
     std::unordered_map<int, conn_t> pool;
     int listen_fd;  /**< for accepting new network connections */
-    int dlisten_fd[2]; /**< for control command sent to the dispatcher */
     Event ev_listen;
     Event ev_dlisten;
     std::mutex cp_mlock;
 
-    void update_conn(const conn_t &conn) {
-        auto ptr = new conn_t(conn);
-        write(mlisten_fd[1], &ptr, sizeof(ptr));
+    void update_conn(const conn_t &conn, bool connected) {
+        auto dcmd = new UserConn(conn, connected);
+        write(mlisten_fd[1], &dcmd, sizeof(dcmd));
     }
 
     struct Worker;
@@ -269,31 +255,22 @@ class ConnPool {
     void accept_client(evutil_socket_t, short);
     conn_t add_conn(const conn_t &conn);
     conn_t _connect(const NetAddr &addr);
-    void _listen(NetAddr listen_addr);
     void _post_terminate(int fd);
 
+    protected:
     class DispatchCmd {
         public:
         virtual ~DispatchCmd() = default;
         virtual void exec(ConnPool *cpool) = 0;
     };
 
-    // TODO: the following two are untested
-    class DspListen: public DispatchCmd {
-        const NetAddr addr;
-        public:
-        DspListen(const NetAddr &addr): addr(addr) {}
-        void exec(ConnPool *cpool) override {
-            cpool->_listen(addr);
-        }
-    };
-
+    private:
     class DspConnect: public DispatchCmd {
         const NetAddr addr;
         public:
         DspConnect(const NetAddr &addr): addr(addr) {}
         void exec(ConnPool *cpool) override {
-            cpool->update_conn(cpool->_connect(addr));
+            cpool->update_conn(cpool->_connect(addr), true);
         }
     };
 
@@ -318,6 +295,18 @@ class ConnPool {
         }
     };
 
+    class UserConn: public DispatchCmd {
+        conn_t conn;
+        bool connected;
+        public:
+        UserConn(const conn_t &conn, bool connected):
+            conn(conn), connected(connected) {}
+        void exec(ConnPool *cpool) override {
+            if (cpool->conn_cb)
+                cpool->conn_cb(*conn, connected);
+        }
+    };
+
     void post_terminate(int fd) {
         auto dcmd = new DspPostTerm(fd);
         write(dlisten_fd[1], &dcmd, sizeof(dcmd));
@@ -330,6 +319,7 @@ class ConnPool {
     protected:
     EventContext ec;
     EventContext dispatcher_ec;
+    int dlisten_fd[2]; /**< for control command sent to the dispatcher */
     std::mutex dsp_ec_mlock;
     /** Should be implemented by derived class to return a new Conn object. */
     virtual Conn *create_conn() = 0;
@@ -352,11 +342,10 @@ class ConnPool {
             throw ConnPoolError(std::string("failed to create dispatcher pipe"));
 
         ev_mlisten = Event(ec, mlisten_fd[0], EV_READ | EV_PERSIST, [this](int fd, short) {
-            conn_t *conn_ptr;
-            read(fd, &conn_ptr, sizeof(conn_ptr));
-            if (conn_cb)
-                conn_cb(**conn_ptr);
-            delete conn_ptr;
+            DispatchCmd *dcmd;
+            read(fd, &dcmd, sizeof(dcmd));
+            dcmd->exec(this);
+            delete dcmd;
         });
         ev_mlisten.add();
 
@@ -414,15 +403,7 @@ class ConnPool {
     /** Listen for passive connections (connection initiated from remote).
      * Does not need to be called if do not want to accept any passive
      * connections. */
-    void listen(NetAddr listen_addr, bool blocking = true) {
-        if (blocking)
-            _listen(listen_addr);
-        else
-        {
-            auto dcmd = new DspListen(listen_addr);
-            write(dlisten_fd[1], &dcmd, sizeof(dcmd));
-        }
-    }
+    void listen(NetAddr listen_addr);
 
     template<typename Func>
     void reg_conn_handler(Func cb) { conn_cb = cb; }
diff --git a/include/salticidae/network.h b/include/salticidae/network.h
index d82772f..8f8940b 100644
--- a/include/salticidae/network.h
+++ b/include/salticidae/network.h
@@ -77,8 +77,8 @@ class MsgNetwork: public ConnPool {
 
         protected:
 #ifdef SALTICIDAE_MSG_STAT
-        mutable size_t nsent;
-        mutable size_t nrecv;
+        mutable std::atomic<size_t> nsent;
+        mutable std::atomic<size_t> nrecv;
 #endif
 
         public:
@@ -107,7 +107,8 @@ class MsgNetwork: public ConnPool {
 #ifdef SALTICIDAE_MSG_STAT
     class msg_stat_by_opcode_t:
             public std::unordered_map<typename Msg::opcode_t,
-                                        std::pair<uint32_t, size_t>> {
+                        std::pair<std::atomic<uint32_t>,
+                                std::atomic<size_t>>> {
         public:
         void add(const Msg &msg) {
             auto &p = this->operator[](msg.get_opcode());
@@ -259,6 +260,7 @@ class PeerNetwork: public MsgNetwork<OpcodeType> {
         friend PeerNetwork;
         NetAddr peer_id;
         Event ev_timeout;
+        void reset_timeout(double timeout);
 
         public:
         Conn() = default;
@@ -292,6 +294,7 @@ class PeerNetwork: public MsgNetwork<OpcodeType> {
         bool ping_timer_ok;
         bool pong_msg_ok;
         bool connected;
+        std::mutex mlock;
 
         Peer() = delete;
         Peer(NetAddr addr, conn_t conn, const EventContext &ec):
@@ -314,7 +317,7 @@ class PeerNetwork: public MsgNetwork<OpcodeType> {
     };
 
     std::unordered_map <NetAddr, BoxObj<Peer>> id2peer;
-    std::vector<NetAddr> peer_list;
+    std::mutex pn_mlock;
 
     IdentityMode id_mode;
     double retry_conn_delay;
@@ -350,7 +353,6 @@ class PeerNetwork: public MsgNetwork<OpcodeType> {
 
     void msg_ping(MsgPing &&msg, Conn &conn);
     void msg_pong(MsgPong &&msg, Conn &conn);
-    void reset_conn_timeout(Conn &conn);
     bool check_new_conn(Conn &conn, uint16_t port);
     void start_active_conn(const NetAddr &paddr);
 
@@ -380,12 +382,11 @@ class PeerNetwork: public MsgNetwork<OpcodeType> {
     void add_peer(const NetAddr &paddr);
     const conn_t get_peer_conn(const NetAddr &paddr) const;
     template<typename MsgType>
-    void send_msg(const MsgType &msg, const Peer *peer);
+    void _send_msg(const MsgType &msg, const Peer *peer);
     template<typename MsgType>
     void send_msg(const MsgType &msg, const NetAddr &paddr);
     void listen(NetAddr listen_addr);
     bool has_peer(const NetAddr &paddr) const;
-    const std::vector<NetAddr> &all_peers() const;
     conn_t connect(const NetAddr &addr) {
         return static_pointer_cast<Conn>(ConnPool::connect(addr));
     }
@@ -395,9 +396,9 @@ class PeerNetwork: public MsgNetwork<OpcodeType> {
 template<typename OpcodeType>
 void MsgNetwork<OpcodeType>::Conn::on_read() {
     ConnPool::Conn::on_read();
-    auto &recv_buffer = get_recv_buffer();
+    auto &recv_buffer = this->recv_buffer;
     auto mn = get_net();
-    while (get_fd() != -1)
+    while (fd != -1)
     {
         if (msg_state == Conn::HEADER)
         {
@@ -426,23 +427,22 @@ void MsgNetwork<OpcodeType>::Conn::on_read() {
     }
 }
 
-template<typename O, O _, O __>
-void PeerNetwork<O, _, __>::Peer::reset_conn(conn_t new_conn) {
-    if (conn != new_conn)
-    {
-        if (conn)
-        {
-            //SALTICIDAE_LOG_DEBUG("moving send buffer");
-            //new_conn->move_send_buffer(conn);
-            SALTICIDAE_LOG_INFO("terminating old connection %s", std::string(*conn).c_str());
-            conn->terminate();
-        }
-        addr = new_conn->get_addr();
-        conn = new_conn;
-    }
-    clear_all_events();
+template<typename OpcodeType>
+template<typename MsgType>
+void MsgNetwork<OpcodeType>::send_msg(const MsgType &_msg, Conn &conn) {
+    Msg msg(_msg);
+    bytearray_t msg_data = msg.serialize();
+    SALTICIDAE_LOG_DEBUG("wrote message %s to %s",
+                std::string(msg).c_str(),
+                std::string(conn).c_str());
+    conn.write(std::move(msg_data));
+#ifdef SALTICIDAE_MSG_STAT
+    conn.nsent++;
+    sent_by_opcode.add(msg);
+#endif
 }
 
+/* begin: functions invoked by the dispatcher */
 template<typename O, O _, O __>
 void PeerNetwork<O, _, __>::Conn::on_setup() {
     MsgNet::Conn::on_setup();
@@ -452,9 +452,14 @@ void PeerNetwork<O, _, __>::Conn::on_setup() {
         SALTICIDAE_LOG_INFO("peer ping-pong timeout");
         this->terminate();
     });
+    if (this->get_mode() == Conn::ConnMode::ACTIVE)
+    {
+        peer_id = this->get_addr();
+        if (id_mode == IP_BASED) peer_id.port = 0;
+    }
     /* the initial ping-pong to set up the connection */
     auto &conn = static_cast<Conn &>(*this);
-    pn->reset_conn_timeout(conn);
+    conn->reset_timeout(pn->conn_timeout);
     pn->MsgNet::send_msg(MsgPing(pn->listen_port), conn);
 }
 
@@ -462,9 +467,11 @@ template<typename O, O _, O __>
 void PeerNetwork<O, _, __>::Conn::on_teardown() {
     MsgNet::Conn::on_teardown();
     auto pn = get_net();
+    mutex_lg_t _pn_lg(pn->pn_mlock);
     auto it = pn->id2peer.find(peer_id);
     if (it == pn->id2peer.end()) return;
     auto p = it->second.get();
+    mutex_lg_t _p_lg(p->mlock);
     if (this != p->conn.get()) return;
     p->ev_ping_timer.del();
     p->connected = false;
@@ -472,14 +479,69 @@ void PeerNetwork<O, _, __>::Conn::on_teardown() {
     SALTICIDAE_LOG_INFO("connection lost %s for %s",
             std::string(*this).c_str(),
             std::string(peer_id).c_str());
-    p->ev_retry_timer = Event(pn->ec, -1, 0,
+    // try to reconnect
+    p->ev_retry_timer = Event(pn->dispatcher_ec, -1, 0,
             [pn, peer_id = this->peer_id](evutil_socket_t, short) {
+        mutex_lg_t _pn_lg(pn->pn_mlock);
         pn->start_active_conn(peer_id);
     });
     p->ev_retry_timer.add_with_timeout(pn->gen_conn_timeout());
 }
 
 template<typename O, O _, O __>
+void PeerNetwork<O, _, __>::Peer::reset_conn(conn_t new_conn) {
+    if (conn != new_conn)
+    {
+        if (conn)
+        {
+            //SALTICIDAE_LOG_DEBUG("moving send buffer");
+            //new_conn->move_send_buffer(conn);
+            SALTICIDAE_LOG_INFO("terminating old connection %s", std::string(*conn).c_str());
+            conn->terminate();
+        }
+        addr = new_conn->get_addr();
+        conn = new_conn;
+    }
+    clear_all_events();
+}
+
+template<typename O, O _, O __>
+void PeerNetwork<O, _, __>::Conn::reset_timeout(double timeout) {
+    assert(ev_timeout);
+    ev_timeout.del();
+    ev_timeout.add_with_timeout(timeout);
+    SALTICIDAE_LOG_INFO("reset timeout %.2f", timeout);
+}
+
+template<typename O, O _, O __>
+void PeerNetwork<O, _, __>::Peer::reset_ping_timer() {
+    assert(ev_ping_timer);
+    ev_ping_timer.del();
+    ev_ping_timer.add_with_timeout(
+        gen_rand_timeout(conn->get_net()->ping_period));
+}
+
+template<typename O, O _, O __>
+void PeerNetwork<O, _, __>::Peer::send_ping() {
+    auto pn = conn->get_net();
+    ping_timer_ok = false;
+    pong_msg_ok = false;
+    conn->reset_timeout(pn->conn_timeout);
+    pn->_send_msg(MsgPing(pn->listen_port), this);
+}
+
+template<typename O, O _, O __>
+void PeerNetwork<O, _, __>::Peer::ping_timer(evutil_socket_t, short) {
+    mutex_lg_t _p_lg(mlock);
+    ping_timer_ok = true;
+    if (pong_msg_ok)
+    {
+        reset_ping_timer();
+        send_ping();
+    }
+}
+
+template<typename O, O _, O __>
 bool PeerNetwork<O, _, __>::check_new_conn(Conn &conn, uint16_t port) {
     if (conn.peer_id.is_null())
     {   /* passive connections can eventually have ids after getting the port
@@ -489,6 +551,7 @@ bool PeerNetwork<O, _, __>::check_new_conn(Conn &conn, uint16_t port) {
         conn.peer_id.port = port;
     }
     auto p = id2peer.find(conn.peer_id)->second.get();
+    mutex_lg_t _p_lg(p->mlock);
     if (p->connected)
     {
         if (conn.self() != p->conn)
@@ -509,31 +572,77 @@ bool PeerNetwork<O, _, __>::check_new_conn(Conn &conn, uint16_t port) {
 }
 
 template<typename O, O _, O __>
+class PeerNetworkPing: public ConnPool::DispatchCmd {
+    using conn_t = typename PeerNetwork<O, _, __>::conn_t;
+    conn_t conn;
+    uint16_t port;
+    public:
+    PeerNetworkPing(const conn_t &conn, uint16_t port):
+        conn(conn), port(port) {}
+    void exec(ConnPool *cpool) override {
+        auto pn = static_cast<PeerNetwork<O, _, __> *>(cpool);
+        mutex_lg_t _pn_lg(pn->pn_mlock);
+        if (pn->check_new_conn(conn, port)) return;
+        auto p = pn->id2peer.find(conn.peer_id)->second.get();
+        mutex_lg_t _p_lg(p->mlock);
+        pn->_send_msg(MsgPong(this->listen_port), p);
+    }
+};
+
+template<typename O, O _, O __>
+class PeerNetworkPong: public ConnPool::DispatchCmd {
+    using conn_t = typename PeerNetwork<O, _, __>::conn_t;
+    conn_t conn;
+    uint16_t port;
+    public:
+    PeerNetworkPong(const conn_t &conn, uint16_t port):
+        conn(conn), port(port) {}
+    void exec(ConnPool *cpool) override {
+        auto pn = static_cast<PeerNetwork<O, _, __> *>(cpool);
+        mutex_lg_t _pn_lg(pn->pn_mlock);
+        auto it = pn->id2peer.find(conn->peer_id);
+        if (it == pn->id2peer.end())
+        {
+            SALTICIDAE_LOG_WARN("pong message discarded");
+            return;
+        }
+        if (pn->check_new_conn(conn, port)) return;
+        auto p = it->second.get();
+        mutex_lg_t _p_lg(p->mlock);
+        p->pong_msg_ok = true;
+        if (p->ping_timer_ok)
+        {
+            p->reset_ping_timer();
+            p->send_ping();
+        }
+    }
+};
+/* end: functions invoked by the dispatcher */
+
+/* this function could be both invoked by the dispatcher and the user loop */
+template<typename O, O _, O __>
+void PeerNetwork<O, _, __>::start_active_conn(const NetAddr &addr) {
+    auto p = id2peer.find(addr)->second.get();
+    mutex_lg_t _p_lg(p->mlock);
+    if (p->connected) return;
+    auto conn = static_pointer_cast<Conn>(connect(addr));
+    assert(p->conn == nullptr);
+    p->conn = conn;
+}
+
+/* begin: functions invoked by the user loop */
+template<typename O, O _, O __>
 void PeerNetwork<O, _, __>::msg_ping(MsgPing &&msg, Conn &conn) {
     uint16_t port = msg.port;
     SALTICIDAE_LOG_INFO("ping from %s, port %u", std::string(conn).c_str(), ntohs(port));
-    if (check_new_conn(conn, port)) return;
-    auto p = id2peer.find(conn.peer_id)->second.get();
-    send_msg(MsgPong(this->listen_port), p);
+    auto dcmd = new PeerNetworkPing<O, _, __>(conn.self(), port);
+    write(this->dlisten_fd[1], &dcmd, sizeof(dcmd));
 }
 
 template<typename O, O _, O __>
 void PeerNetwork<O, _, __>::msg_pong(MsgPong &&msg, Conn &conn) {
-    auto it = id2peer.find(conn.peer_id);
-    if (it == id2peer.end())
-    {
-        SALTICIDAE_LOG_WARN("pong message discarded");
-        return;
-    }
-    auto p = it->second.get();
-    uint16_t port = msg.port;
-    if (check_new_conn(conn, port)) return;
-    p->pong_msg_ok = true;
-    if (p->ping_timer_ok)
-    {
-        p->reset_ping_timer();
-        p->send_ping();
-    }
+    auto dcmd = new PeerNetworkPong<O, _, __>(conn.self(), msg.port);
+    write(this->dlisten_fd[1], &dcmd, sizeof(dcmd));
 }
 
 template<typename O, O _, O __>
@@ -545,30 +654,19 @@ void PeerNetwork<O, _, __>::listen(NetAddr listen_addr) {
 }
 
 template<typename O, O _, O __>
-void PeerNetwork<O, _, __>::start_active_conn(const NetAddr &addr) {
-    auto p = id2peer.find(addr)->second.get();
-    if (p->connected) return;
-    auto conn = static_pointer_cast<Conn>(connect(addr));
-    assert(p->conn == nullptr);
-    p->conn = conn;
-    conn->peer_id = addr;
-    if (id_mode == IP_BASED)
-        conn->peer_id.port = 0;
-}
-
-template<typename O, O _, O __>
 void PeerNetwork<O, _, __>::add_peer(const NetAddr &addr) {
+    mutex_lg_t _pn_lg(pn_mlock);
     auto it = id2peer.find(addr);
     if (it != id2peer.end())
         throw PeerNetworkError("peer already exists");
-    id2peer.insert(std::make_pair(addr, new Peer(addr, nullptr, this->ec)));
-    peer_list.push_back(addr);
+    id2peer.insert(std::make_pair(addr, new Peer(addr, nullptr, this->dispatcher_ec)));
     start_active_conn(addr);
 }
 
 template<typename O, O _, O __>
 const typename PeerNetwork<O, _, __>::conn_t
 PeerNetwork<O, _, __>::get_peer_conn(const NetAddr &paddr) const {
+    mutex_lg_t _pn_lg(pn_mlock);
     auto it = id2peer.find(paddr);
     if (it == id2peer.end())
         throw PeerNetworkError("peer does not exist");
@@ -577,27 +675,13 @@ PeerNetwork<O, _, __>::get_peer_conn(const NetAddr &paddr) const {
 
 template<typename O, O _, O __>
 bool PeerNetwork<O, _, __>::has_peer(const NetAddr &paddr) const {
+    mutex_lg_t _pn_lg(pn_mlock);
     return id2peer.count(paddr);
 }
 
-template<typename OpcodeType>
-template<typename MsgType>
-void MsgNetwork<OpcodeType>::send_msg(const MsgType &_msg, Conn &conn) {
-    Msg msg(_msg);
-    bytearray_t msg_data = msg.serialize();
-    SALTICIDAE_LOG_DEBUG("wrote message %s to %s",
-                std::string(msg).c_str(),
-                std::string(conn).c_str());
-    conn.write(std::move(msg_data));
-#ifdef SALTICIDAE_MSG_STAT
-    conn.nsent++;
-    sent_by_opcode.add(msg);
-#endif
-}
-
 template<typename O, O _, O __>
 template<typename MsgType>
-void PeerNetwork<O, _, __>::send_msg(const MsgType &msg, const Peer *peer) {
+void PeerNetwork<O, _, __>::_send_msg(const MsgType &msg, const Peer *peer) {
     if (peer->connected)
         MsgNet::send_msg(msg, *(peer->conn));
     else
@@ -607,6 +691,7 @@ void PeerNetwork<O, _, __>::send_msg(const MsgType &msg, const Peer *peer) {
 template<typename O, O _, O __>
 template<typename MsgType>
 void PeerNetwork<O, _, __>::send_msg(const MsgType &msg, const NetAddr &addr) {
+    mutex_lg_t _pn_lg(pn_mlock);
     auto it = id2peer.find(addr);
     if (it == id2peer.end())
     {
@@ -614,48 +699,11 @@ void PeerNetwork<O, _, __>::send_msg(const MsgType &msg, const NetAddr &addr) {
                             std::string(addr).c_str());
         throw PeerNetworkError("peer does not exist");
     }
-    send_msg(msg, it->second.get());
-}
-
-template<typename O, O _, O __>
-void PeerNetwork<O, _, __>::Peer::reset_ping_timer() {
-    assert(ev_ping_timer);
-    ev_ping_timer.del();
-    ev_ping_timer.add_with_timeout(
-        gen_rand_timeout(conn->get_net()->ping_period));
-}
-
-template<typename O, O _, O __>
-void PeerNetwork<O, _, __>::reset_conn_timeout(Conn &conn) {
-    assert(conn.ev_timeout);
-    conn.ev_timeout.del();
-    conn.ev_timeout.add_with_timeout(conn_timeout);
-    SALTICIDAE_LOG_INFO("reset timeout %.2f", conn_timeout);
-}
-
-template<typename O, O _, O __>
-void PeerNetwork<O, _, __>::Peer::send_ping() {
-    auto pn = conn->get_net();
-    ping_timer_ok = false;
-    pong_msg_ok = false;
-    pn->reset_conn_timeout(*conn);
-    pn->send_msg(MsgPing(pn->listen_port), this);
-}
-
-template<typename O, O _, O __>
-void PeerNetwork<O, _, __>::Peer::ping_timer(evutil_socket_t, short) {
-    ping_timer_ok = true;
-    if (pong_msg_ok)
-    {
-        reset_ping_timer();
-        send_ping();
-    }
-}
-
-template<typename O, O _, O __>
-const std::vector<NetAddr> &PeerNetwork<O, _, __>::all_peers() const {
-    return peer_list;
+    auto p = it->second.get();
+    mutex_lg_t _p_lg(p->mlock);
+    _send_msg(msg, p);
 }
+/* end: functions invoked by the user loop */
 
 template<typename OpcodeType>
 void ClientNetwork<OpcodeType>::Conn::on_setup() {
diff --git a/include/salticidae/type.h b/include/salticidae/type.h
index c454265..68deeb0 100644
--- a/include/salticidae/type.h
+++ b/include/salticidae/type.h
@@ -33,6 +33,7 @@
 #include <cstdio>
 #include <ios>
 #include <functional>
+#include <mutex>
 
 namespace salticidae {
 
@@ -40,6 +41,8 @@ const auto _1 = std::placeholders::_1;
 const auto _2 = std::placeholders::_2;
 
 using bytearray_t = std::vector<uint8_t>;
+using mutex_lg_t = std::lock_guard<std::mutex>;
+using mutex_ul_t = std::unique_lock<std::mutex>;
 
 template<typename T> T htole(T) = delete;
 template<> inline uint16_t htole<uint16_t>(uint16_t x) { return htole16(x); }