From 7306809991fe3949a3845d6a83394824a2e88c49 Mon Sep 17 00:00:00 2001
From: Robbert van der Helm <mail@robbertvanderhelm.nl>
Date: Sat, 19 Dec 2020 22:17:10 +0100
Subject: [PATCH] Drop IPlugView pointer when host drops proxy

---
 src/common/logging/vst3.cpp                      |  9 +++++++++
 src/common/logging/vst3.h                        |  1 +
 src/common/serialization/vst3.h                  |  3 ++-
 src/common/serialization/vst3/plug-view-proxy.h  | 16 ++++++++++++++++
 .../bridges/vst3-impls/plug-view-proxy.cpp       |  9 ++++-----
 src/wine-host/bridges/vst3.cpp                   |  8 ++++++++
 6 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/src/common/logging/vst3.cpp b/src/common/logging/vst3.cpp
index 541373a1..6a173766 100644
--- a/src/common/logging/vst3.cpp
+++ b/src/common/logging/vst3.cpp
@@ -35,6 +35,15 @@ void Vst3Logger::log_unknown_interface(
     }
 }
 
+bool Vst3Logger::log_request(bool is_host_vst,
+                             const Vst3PlugViewProxy::Destruct& request) {
+    return log_request_base(is_host_vst, [&](auto& message) {
+        // We don't know what class this instance was originally instantiated
+        // as, but it also doesn't really matter
+        message << request.owner_instance_id << ": IPlugView::~IPlugView()";
+    });
+}
+
 bool Vst3Logger::log_request(bool is_host_vst,
                              const Vst3PluginProxy::Construct& request) {
     return log_request_base(is_host_vst, [&](auto& message) {
diff --git a/src/common/logging/vst3.h b/src/common/logging/vst3.h
index de5a73d5..3e02db4f 100644
--- a/src/common/logging/vst3.h
+++ b/src/common/logging/vst3.h
@@ -59,6 +59,7 @@ class Vst3Logger {
     // `log_request()` call returned `true`. This way we can filter out the
     // log message for the response together with the request.
 
+    bool log_request(bool is_host_vst, const Vst3PlugViewProxy::Destruct&);
     bool log_request(bool is_host_vst, const Vst3PluginProxy::Construct&);
     bool log_request(bool is_host_vst, const Vst3PluginProxy::Destruct&);
     bool log_request(bool is_host_vst, const Vst3PluginProxy::SetState&);
diff --git a/src/common/serialization/vst3.h b/src/common/serialization/vst3.h
index 2b1d554d..f870e2ed 100644
--- a/src/common/serialization/vst3.h
+++ b/src/common/serialization/vst3.h
@@ -59,7 +59,8 @@ struct WantsConfiguration {
  * encodes the information we request or the operation we want to perform. A
  * request of type `ControlRequest(T)` should send back a `T::Response`.
  */
-using ControlRequest = std::variant<Vst3PluginProxy::Construct,
+using ControlRequest = std::variant<Vst3PlugViewProxy::Destruct,
+                                    Vst3PluginProxy::Construct,
                                     Vst3PluginProxy::Destruct,
                                     Vst3PluginProxy::SetState,
                                     Vst3PluginProxy::GetState,
diff --git a/src/common/serialization/vst3/plug-view-proxy.h b/src/common/serialization/vst3/plug-view-proxy.h
index c8d50d4c..4a04bc4c 100644
--- a/src/common/serialization/vst3/plug-view-proxy.h
+++ b/src/common/serialization/vst3/plug-view-proxy.h
@@ -72,6 +72,22 @@ class Vst3PlugViewProxy : public YaPlugView {
      */
     Vst3PlugViewProxy(const ConstructArgs&& args);
 
+    /**
+     * Message to request the Wine plugin host to destroy the `IPlugView*`
+     * returned by the object with the given instance ID. Sent from the
+     * destructor of `Vst3PlugViewProxyImpl`.
+     */
+    struct Destruct {
+        using Response = Ack;
+
+        native_size_t owner_instance_id;
+
+        template <typename S>
+        void serialize(S& s) {
+            s.value8b(owner_instance_id);
+        }
+    };
+
     /**
      * @remark The plugin side implementation should send a control message to
      *   clean up the instance on the Wine side in its destructor.
diff --git a/src/plugin/bridges/vst3-impls/plug-view-proxy.cpp b/src/plugin/bridges/vst3-impls/plug-view-proxy.cpp
index 0ab49fa0..808f84f2 100644
--- a/src/plugin/bridges/vst3-impls/plug-view-proxy.cpp
+++ b/src/plugin/bridges/vst3-impls/plug-view-proxy.cpp
@@ -22,11 +22,10 @@ Vst3PlugViewProxyImpl::Vst3PlugViewProxyImpl(
     : Vst3PlugViewProxy(std::move(args)), bridge(bridge) {}
 
 Vst3PlugViewProxyImpl::~Vst3PlugViewProxyImpl() {
-    // TODO: Implement this:
-    // // Also drop the plug view smart pointer on the Wine side when this gets
-    // // dropped
-    // bridge.send_message(
-    //     Vst3PlugViewProxy::Destruct{.instance_id = instance_id()});
+    // Also drop the plug view smart pointer on the Wine side when this gets
+    // dropped
+    bridge.send_message(
+        Vst3PlugViewProxy::Destruct{.owner_instance_id = owner_instance_id()});
 }
 
 tresult PLUGIN_API
diff --git a/src/wine-host/bridges/vst3.cpp b/src/wine-host/bridges/vst3.cpp
index a0ce3426..f4ca651f 100644
--- a/src/wine-host/bridges/vst3.cpp
+++ b/src/wine-host/bridges/vst3.cpp
@@ -67,6 +67,14 @@ void Vst3Bridge::run() {
     sockets.host_vst_control.receive_messages(
         std::nullopt,
         overload{
+            [&](const Vst3PlugViewProxy::Destruct& request)
+                -> Vst3PlugViewProxy::Destruct::Response {
+                // When the pointer gets dropped by the host, we want to drop it
+                // here as well
+                object_instances[request.owner_instance_id].plug_view.reset();
+
+                return Ack{};
+            },
             [&](const Vst3PluginProxy::Construct& request)
                 -> Vst3PluginProxy::Construct::Response {
                 Steinberg::TUID cid;