Move event subscription from protocol_peer to protocol.

Author: evoskuil

include/bitcoin/node/protocols/protocol.hpp

@@ -31,6 +31,11 @@ namespace libbitcoin {
 namespace node {
 
 /// Abstract base for node protocols, thread safe.
+/// This node::protocol is not derived from network::protocol, but given the
+/// channel constructor parameter is derived from network::channel, the strand
+/// is accessible despite lack of bind/post/parallel templates access. This
+/// allows event subscription by derived protocols without the need to derive
+/// from protocol_peer (which would prevent derivation from service protocols).
 class BCN_API protocol
 {
 protected:
@@ -42,8 +47,7 @@ class BCN_API protocol
     // reinterpret_pointer_cast because channel is abstract.
     inline protocol(const auto& session,
         const network::channel::ptr& channel) NOEXCEPT
-      : channel_(std::reinterpret_pointer_cast<node::channel>(channel)),
-        session_(session)
+      : channel_(channel), session_(session)
     {
     }
 
@@ -63,12 +67,35 @@ class BCN_API protocol
     /// The candidate|confirmed chain is current.
     virtual bool is_current(bool confirmed) const NOEXCEPT;
 
+    /// Events subscription.
+    /// -----------------------------------------------------------------------
+
+    /// Subscribe to chaser events (max one active per protocol).
+    virtual void subscribe_events(event_notifier&& handler) NOEXCEPT;
+
+    /// Override to handle subscription completion (stranded).
+    virtual void subscribed(const code& ec, object_key key) NOEXCEPT;
+
+    /// Unsubscribe from chaser events.
+    /// Subscribing protocol must invoke from overridden stopping().
+    virtual void unsubscribe_events() NOEXCEPT;
+
+    /// Get the subscription key (for notify_one).
+    virtual object_key events_key() const NOEXCEPT;
+
 private:
+    void handle_subscribed(const code& ec, object_key key) NOEXCEPT;
+    void handle_subscribe(const code& ec, object_key key,
+        const event_completer& complete) NOEXCEPT;
+
     // This channel requires stranded calls, base is thread safe.
-    const node::channel::ptr channel_;
+    const network::channel::ptr channel_;
 
     // This is thread safe.
     const node::session::ptr session_;
+
+    // This is protected by singular subscription.
+    object_key key_{};
 };
 
 } // namespace node

include/bitcoin/node/protocols/protocol_peer.hpp

@@ -102,35 +102,12 @@ class BCN_API protocol_peer
     virtual void notify_one(object_key key, const code& ec, chase event_,
         event_value value) const NOEXCEPT;
 
-    /// Events subscription.
-    /// -----------------------------------------------------------------------
-
-    /// Subscribe to chaser events (max one active per protocol).
-    virtual void subscribe_events(event_notifier&& handler) NOEXCEPT;
-
-    /// Override to handle subscription completion (stranded).
-    virtual void subscribed(const code& ec, object_key key) NOEXCEPT;
-
-    /// Unsubscribe from chaser events.
-    /// Subscribing protocol must invoke from overridden stopping().
-    virtual void unsubscribe_events() NOEXCEPT;
-
-    /// Get the subscription key (for notify_one).
-    virtual object_key events_key() const NOEXCEPT;
-
 private:
-    void handle_subscribed(const code& ec, object_key key) NOEXCEPT;
-    void handle_subscribe(const code& ec, object_key key,
-        const event_completer& complete) NOEXCEPT;
-
     // This derived channel requires stranded calls, base is thread safe.
     const node::channel_peer::ptr channel_;
 
     // This is thread safe.
     const node::session::ptr session_;
-
-    // This is protected by singular subscription.
-    object_key key_{};
 };
 
 } // namespace node

src/protocols/protocol.cpp

@@ -24,6 +24,10 @@
 namespace libbitcoin {
 namespace node {
 
+#define CLASS protocol
+
+using namespace std::placeholders;
+
 // Properties.
 // ----------------------------------------------------------------------------
 
@@ -62,5 +66,71 @@ bool protocol::is_current(bool confirmed) const NOEXCEPT
     return session_->is_current(confirmed);
 }
 
+// Events subscription.
+// ----------------------------------------------------------------------------
+
+void protocol::subscribe_events(event_notifier&& handler) NOEXCEPT
+{
+    // This is a shared instance multiply-derived from network::protocol.
+    const auto self = dynamic_cast<network::protocol&>(*this)
+        .shared_from_sibling<node::protocol, network::protocol>();
+
+    event_completer completer = std::bind(&protocol::handle_subscribed, self,
+        _1, _2);
+
+    session_->subscribe_events(std::move(handler),
+        std::bind(&protocol::handle_subscribe,
+            self, _1, _2, std::move(completer)));
+}
+
+// private
+void protocol::handle_subscribe(const code& ec, object_key key,
+    const event_completer& complete) NOEXCEPT
+{
+    // The key member is protected by one event subscription per protocol.
+    BC_ASSERT_MSG(is_zero(key_), "unsafe access");
+
+    // Protocol stop is thread safe.
+    if (ec)
+    {
+        channel_->stop(ec);
+        return;
+    }
+
+    key_ = key;
+    complete(ec, key_);
+}
+
+void protocol::handle_subscribed(const code& ec, object_key key) NOEXCEPT
+{
+    // This is a shared instance multiply-derived from network::protocol.
+    const auto self = dynamic_cast<network::protocol&>(*this)
+        .shared_from_sibling<node::protocol, network::protocol>();
+
+    boost::asio::post(channel_->strand(),
+        std::bind(&protocol::subscribed, self, ec, key));
+}
+
+void protocol::subscribed(const code& ec, object_key) NOEXCEPT
+{
+    BC_ASSERT(channel_->stranded());
+
+    // Unsubscriber race is ok.
+    if (channel_->stopped() || ec)
+        unsubscribe_events();
+}
+
+// As this has no completion handler resubscription is not allowed.
+void protocol::unsubscribe_events() NOEXCEPT
+{
+    session_->unsubscribe_events(key_);
+    key_ = {};
+}
+
+object_key protocol::events_key() const NOEXCEPT
+{
+    return key_;
+}
+
 } // namespace node
 } // namespace libbitcoin

src/protocols/protocol_peer.cpp

@@ -23,11 +23,8 @@
 namespace libbitcoin {
 namespace node {
 
-#define CLASS protocol_peer
-
 using namespace system;
 using namespace network;
-using namespace std::placeholders;
 
 // Organizers.
 // ----------------------------------------------------------------------------
@@ -62,7 +59,7 @@ void protocol_peer::performance(uint64_t speed,
     network::result_handler&& handler) const NOEXCEPT
 {
     // Passed protocol->session->full_node->check_chaser.post->do_update.
-    session_->performance(key_, speed, std::move(handler));
+    session_->performance(events_key(), speed, std::move(handler));
 }
 
 code protocol_peer::fault(const code& ec) NOEXCEPT
@@ -103,59 +100,5 @@ void protocol_peer::notify_one(object_key key, const code& ec, chase event_,
     session_->notify_one(key, ec, event_, value);
 }
 
-// Events subscription.
-// ----------------------------------------------------------------------------
-
-void protocol_peer::subscribe_events(event_notifier&& handler) NOEXCEPT
-{
-    event_completer completer = BIND(handle_subscribed, _1, _2);
-    session_->subscribe_events(std::move(handler),
-        BIND(handle_subscribe, _1, _2, std::move(completer)));
-}
-
-// private
-void protocol_peer::handle_subscribe(const code& ec, object_key key,
-    const event_completer& complete) NOEXCEPT
-{
-    // The key member is protected by one event subscription per protocol.
-    BC_ASSERT_MSG(is_zero(key_), "unsafe access");
-
-    // Protocol stop is thread safe.
-    if (ec)
-    {
-        stop(ec);
-        return;
-    }
-
-    key_ = key;
-    complete(ec, key_);
-}
-
-void protocol_peer::handle_subscribed(const code& ec, object_key key) NOEXCEPT
-{
-    POST(subscribed, ec, key);
-}
-
-void protocol_peer::subscribed(const code& ec, object_key) NOEXCEPT
-{
-    BC_ASSERT(stranded());
-
-    // Unsubscriber race is ok.
-    if (stopped(ec))
-        unsubscribe_events();
-}
-
-// As this has no completion handler resubscription is not allowed.
-void protocol_peer::unsubscribe_events() NOEXCEPT
-{
-    session_->unsubscribe_events(key_);
-    key_ = {};
-}
-
-object_key protocol_peer::events_key() const NOEXCEPT
-{
-    return key_;
-}
-
 } // namespace node
 } // namespace libbitcoin