Use a thread for dispatch events

README.md

@@ -84,9 +84,9 @@ follows:
 3. The plugin then sets up a Unix domain socket endpoint to communicate with the
    Wine VST host somewhere in a temporary directory. I chose to use Unix domain
    sockets rather than shared memory to avoid having to do manual
-   synchronization and because it makes it easy to handle different kinds of
-   events asynchronously. Since the Wine VST host can't access the Linux VST
-   host's memory we would have to copy audio buffers in either case.
+   synchronization and because they have very low overhead. Since the Wine VST
+   host can't access the Linux VST host's memory we would have to copy audio
+   buffers in either case.
 4. The plugin launches the Wine VST host in the detected wine prefix, passing
    the name of the `.dll` file it should be loading and the path to the Unix
    domain socket that was just created.

src/plugin/host-bridge.cpp

@@ -95,10 +95,15 @@ HostBridge::HostBridge(audioMasterCallback host_callback)
     plugin.getParameter = getParameter_proxy;
     plugin.processReplacing = process_replacing_proxy;
 
-    // TODO: Replace manual thread creation with an async_read loop
-    // Start accepting host callbacks after we've set up our sockets and basic
-    // `AEffect` struct.
-    removeme = std::thread([&]() { return host_callback_loop(); });
+    // For our communication we use simple threads and blocking operations
+    // instead of asynchronous IO since communication has to be handled in
+    // lockstep anyway
+    host_callback_handler = std::thread([&]() {
+        while (true) {
+            passthrough_event(vst_host_callback, &plugin,
+                              host_callback_function);
+        }
+    });
 
     // Read the plugin's information from the Wine process. This can only be
     // done after we started accepting host callbacks as the plugin might do
@@ -261,15 +266,6 @@ fs::path generate_endpoint_name() {
     return candidate_endpoint;
 }
 
-// TODO: Replace blocking loop with async readers or threads for all of the
-//       sockets. Also extract this functionality somewhere since the host event
-//       callback needs to do exactly the same thing.
-void HostBridge::host_callback_loop() {
-    while (true) {
-        passthrough_event(vst_host_callback, &plugin, host_callback_function);
-    }
-}
-
 /**
  * Locate the wineprefix and set the `WINEPREFIX` environment variable if found.
  * This way it's also possible to run .dll files outside of a wineprefix using

src/plugin/host-bridge.h

@@ -21,7 +21,6 @@
 #include <boost/asio/io_context.hpp>
 #include <boost/asio/local/stream_protocol.hpp>
 #include <boost/process/child.hpp>
-// TODO: Remove
 #include <thread>
 
 /**
@@ -67,9 +66,6 @@ class HostBridge {
     void set_parameter(AEffect* plugin, int32_t index, float value);
     float get_parameter(AEffect* plugin, int32_t index);
 
-    // TODO: Remove debug loop
-    void host_callback_loop();
-
     /**
      * This AEffect struct will be populated using the data passed by the Wine
      * VST host during initialization and then passed as a pointer to the Linux
@@ -96,12 +92,15 @@ class HostBridge {
      */
     boost::asio::local::stream_protocol::socket vst_host_aeffect;
 
+    /**
+     * The thread that handles host callbacks.
+     */
+    std::thread host_callback_handler;
+
     /**
      * The callback function passed by the host to the VST plugin instance.
      */
     audioMasterCallback host_callback_function;
-    // TODO: Remove
-    std::thread removeme;
     /**
      * The Wine process hosting the Windows VST plugin.
      */

src/wine-host/plugin-bridge.cpp

@@ -108,15 +108,19 @@ PluginBridge::PluginBridge(std::string plugin_dll_path,
     // We only needed this little hack during initialization
     current_bridge_isntance = nullptr;
     plugin->ptr1 = this;
+
+    // For our communication we use simple threads and blocking operations
+    // instead of asynchronous IO since communication has to be handled in
+    // lockstep anyway
+    dispatch_handler = std::thread([&]() {
+        while (true) {
+            passthrough_event(host_vst_dispatch, plugin, plugin->dispatcher);
+        }
+    });
 }
 
-// TODO: Replace blocking loop with async readers or threads for all of the
-//       sockets. Also extract this functionality somewhere since the host event
-//       callback needs to do exactly the same thing.
-void PluginBridge::dispatch_loop() {
-    while (true) {
-        passthrough_event(host_vst_dispatch, plugin, plugin->dispatcher);
-    }
+void PluginBridge::wait() {
+    dispatch_handler.join();
 }
 
 intptr_t PluginBridge::host_callback(AEffect* /*plugin*/,

src/wine-host/plugin-bridge.h

@@ -24,6 +24,8 @@
 #include <vestige/aeffect.h>
 #include <windows.h>
 
+#include <thread>
+
 /**
  * This handles the communication between the Linux native VST plugin and the
  * Wine VST host. The functions below should be used as callback functions in an
@@ -45,13 +47,13 @@ class PluginBridge {
      */
     PluginBridge(std::string plugin_dll_path, std::string socket_endpoint_path);
 
+    /**
+     * Block the main thread until the plugin shuts down.
+     */
+    void wait();
+
     intptr_t host_callback(AEffect*, int32_t, int32_t, intptr_t, void*, float);
 
-    // TODO: Remove debug loop
-    void dispatch_loop();
-
-    // TODO: Set up all callback handlers
-
    private:
     /**
      * The shared library handle of the VST plugin. I sadly could not get
@@ -82,4 +84,11 @@ class PluginBridge {
      * pass the Wine plugin's information to the host.
      */
     boost::asio::local::stream_protocol::socket vst_host_aeffect;
+
+    /**
+     * The thread that handles dispatch events from the host.
+     */
+    std::thread dispatch_handler;
+
+    // TODO: Set up all other callback handlers
 };

src/wine-host/vst-host.cpp

@@ -33,10 +33,10 @@ int main(int argc, char* argv[]) {
     const std::string socket_endpoint_path(argv[2]);
 
     try {
-        PluginBridge Pluginbridge(plugin_dll_path, socket_endpoint_path);
+        PluginBridge bridge(plugin_dll_path, socket_endpoint_path);
 
-        // TODO: Remove debug
-        Pluginbridge.dispatch_loop();
+        // Block the main thread until the plugin shuts down
+        bridge.wait();
     } catch (const std::runtime_error& error) {
         std::cerr << "Error while initializing plugin:" << std::endl;
         std::cerr << error.what() << std::endl;