observer: fix that some backends would be in inconsistent observer state when no notify_in_constructor

Author: jcelerier

include/libremidi/backends/alsa_raw/observer.hpp

@@ -54,8 +54,7 @@ class observer_impl_base
 #endif
 
     // Set-up initial state
-    if (configuration.notify_in_constructor)
-      this->check_devices();
+    this->check_devices(configuration.notify_in_constructor);
 
 #if LIBREMIDI_HAS_UDEV
     // Start thread
@@ -139,7 +138,7 @@ class observer_impl_base
           this->m_timer_fd.cancel();
         m_fds[2].revents = 0;
 
-        check_devices();
+        check_devices(true);
       }
     }
   }
@@ -185,7 +184,7 @@ class observer_impl_base
          .type = type}};
   }
 
-  void check_devices()
+  void check_devices(bool notify)
   {
     Enumerator new_devs{*this};
 
@@ -203,18 +202,6 @@ class observer_impl_base
       }
     }
 
-    for (auto& in_next : new_devs.inputs)
-    {
-      if (auto it = std::find(m_current_inputs.begin(), m_current_inputs.end(), in_next);
-          it == m_current_inputs.end())
-      {
-        if (auto& cb = this->configuration.input_added)
-        {
-          cb(to_port_info<true>(in_next));
-        }
-      }
-    }
-
     for (auto& out_prev : m_current_outputs)
     {
       if (auto it = std::find(new_devs.outputs.begin(), new_devs.outputs.end(), out_prev);
@@ -227,14 +214,29 @@ class observer_impl_base
       }
     }
 
-    for (auto& out_next : new_devs.outputs)
+    if (notify)
     {
-      if (auto it = std::find(m_current_outputs.begin(), m_current_outputs.end(), out_next);
-          it == m_current_outputs.end())
+      if (auto& cb = this->configuration.input_added)
+      {
+        for (auto& in_next : new_devs.inputs)
+        {
+          if (auto it = std::find(m_current_inputs.begin(), m_current_inputs.end(), in_next);
+              it == m_current_inputs.end())
+          {
+            cb(to_port_info<true>(in_next));
+          }
+        }
+      }
+
+      if (auto& cb = this->configuration.output_added)
       {
-        if (auto& cb = this->configuration.output_added)
+        for (auto& out_next : new_devs.outputs)
         {
-          cb(to_port_info<false>(out_next));
+          if (auto it = std::find(m_current_outputs.begin(), m_current_outputs.end(), out_next);
+              it == m_current_outputs.end())
+          {
+            cb(to_port_info<false>(out_next));
+          }
         }
       }
     }

include/libremidi/backends/alsa_seq/observer.hpp

@@ -65,8 +65,7 @@ class observer_impl
       return;
 
     // Init with the existing ports
-    if (configuration.notify_in_constructor)
-      init_all_ports();
+    init_all_ports();
 
     // Create the port to listen on the server events
     {
@@ -222,7 +221,7 @@ class observer_impl
         snd, this->seq, [this](snd_seq_client_info_t& client, snd_seq_port_info_t& port) {
       int clt = snd.seq.client_info_get_client(&client);
       int pt = snd.seq.port_info_get_port(&port);
-      register_port(clt, pt);
+      register_port(clt, pt, configuration.notify_in_constructor);
     });
   }
 
@@ -262,7 +261,7 @@ class observer_impl
     return ret;
   }
 
-  void register_port(int client, int port)
+  void register_port(int client, int port, bool notify)
   {
     auto pp = get_info(client, port);
     if (!pp)
@@ -272,14 +271,17 @@ class observer_impl
       return;
 
     m_knownClients[{p.client, p.port}] = p;
-    if (p.is_input && configuration.input_added)
+    if (notify)
     {
-      configuration.input_added(to_port_info<true>(p));
-    }
+      if (p.is_input && configuration.input_added)
+      {
+        configuration.input_added(to_port_info<true>(p));
+      }
 
-    if (p.is_output && configuration.output_added)
-    {
-      configuration.output_added(to_port_info<false>(p));
+      if (p.is_output && configuration.output_added)
+      {
+        configuration.output_added(to_port_info<false>(p));
+      }
     }
   }
 
@@ -330,7 +332,7 @@ class observer_impl
       }
 #endif
       case SND_SEQ_EVENT_PORT_START: {
-        this->register_port(ev.data.addr.client, ev.data.addr.port);
+        this->register_port(ev.data.addr.client, ev.data.addr.port, true);
         break;
       }
       case SND_SEQ_EVENT_PORT_EXIT: {

include/libremidi/backends/emscripten/observer.cpp

@@ -19,8 +19,7 @@ LIBREMIDI_INLINE observer_emscripten::observer_emscripten(
   // Trigger an initial notification
   webmidi.load_current_infos();
 
-  if (configuration.notify_in_constructor)
-    update(webmidi.inputs(), webmidi.outputs());
+  update(webmidi.inputs(), webmidi.outputs(), configuration.notify_in_constructor);
 }
 
 LIBREMIDI_INLINE observer_emscripten::~observer_emscripten()
@@ -83,7 +82,7 @@ std::vector<libremidi::output_port> observer_emscripten::get_output_ports() cons
 
 LIBREMIDI_INLINE void observer_emscripten::update(
     const std::vector<observer_emscripten::device>& current_inputs,
-    const std::vector<observer_emscripten::device>& current_outputs)
+    const std::vector<observer_emscripten::device>& current_outputs, bool notify)
 {
   // WebMIDI never remove inputs, it just marks them as disconnected.
   // At least in known browsers...
@@ -93,13 +92,15 @@ LIBREMIDI_INLINE void observer_emscripten::update(
   for (std::size_t i = m_known_inputs.size(); i < current_inputs.size(); i++)
   {
     m_known_inputs.push_back(current_inputs[i]);
-    configuration.input_added(to_port_info<true>(i, m_known_inputs[i]));
+    if (notify)
+      configuration.input_added(to_port_info<true>(i, m_known_inputs[i]));
   }
 
   for (std::size_t i = m_known_outputs.size(); i < current_outputs.size(); i++)
   {
     m_known_outputs.push_back(current_outputs[i]);
-    configuration.output_added(to_port_info<false>(i, m_known_outputs[i]));
+    if (notify)
+      configuration.output_added(to_port_info<false>(i, m_known_outputs[i]));
   }
 }
 }

include/libremidi/backends/emscripten/observer.hpp

@@ -22,8 +22,9 @@ class observer_emscripten final : public observer_api
       observer_configuration&& conf, emscripten_observer_configuration&& apiconf);
   ~observer_emscripten();
 
-  void
-  update(const std::vector<device>& current_inputs, const std::vector<device>& current_outputs);
+  void update(
+      const std::vector<device>& current_inputs, const std::vector<device>& current_outputs,
+      bool notify);
 
   libremidi::API get_current_api() const noexcept override;