Add boilerplate for CLAP sockets

src/common/communication/clap.h

@@ -0,0 +1,285 @@
+// yabridge: a Wine plugin bridge
+// Copyright (C) 2020-2022 Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+#pragma once
+
+#include <future>
+#include <variant>
+
+#include "../logging/clap.h"
+#include "../serialization/clap.h"
+#include "common.h"
+
+/**
+ * Manages all the sockets used for communicating between the plugin and the
+ * Wine host when hosting a CLAP plugin.
+ *
+ * On the plugin side this class should be initialized with `listen` set to
+ * `true` before launching the Wine plugin host. This will start listening on
+ * the sockets, and the call to `connect()` will then accept any incoming
+ * connections.
+ *
+ * We'll have a host -> plugin connection for sending control messages (which is
+ * just a made up term to more easily differentiate between the two directions),
+ * and a plugin -> host connection to allow the plugin to make callbacks. Both
+ * of these connections are capable of spawning additional sockets and threads
+ * as needed.
+ *
+ * Every plugin instance gets a dedicated audio thread socket so they can be
+ * addressed concurrently.
+ *
+ * @tparam Thread The thread implementation to use. On the Linux side this
+ *   should be `std::jthread` and on the Wine side this should be `Win32Thread`.
+ */
+template <typename Thread>
+class ClapSockets final : public Sockets {
+   public:
+    /**
+     * Sets up the sockets using the specified base directory. The sockets won't
+     * be active until `connect()` gets called.
+     *
+     * @param io_context The IO context the sockets should be bound to. Relevant
+     *   when doing asynchronous operations.
+     * @param endpoint_base_dir The base directory that will be used for the
+     *   Unix domain sockets.
+     * @param listen If `true`, start listening on the sockets. Incoming
+     *   connections will be accepted when `connect()` gets called. This should
+     *   be set to `true` on the plugin side, and `false` on the Wine host side.
+     *
+     * @see ClapSockets::connect
+     */
+    ClapSockets(asio::io_context& io_context,
+                const ghc::filesystem::path& endpoint_base_dir,
+                bool listen)
+        : Sockets(endpoint_base_dir),
+          host_plugin_control_(
+              io_context,
+              (base_dir_ / "host_plugin_control.sock").string(),
+              listen),
+          plugin_host_callback_(
+              io_context,
+              (base_dir_ / "plugin_host_callback.sock").string(),
+              listen),
+          io_context_(io_context) {}
+
+    // NOLINTNEXTLINE(clang-analyzer-optin.cplusplus.VirtualCall)
+    ~ClapSockets() noexcept override { close(); }
+
+    void connect() override {
+        host_plugin_control_.connect();
+        plugin_host_callback_.connect();
+    }
+
+    void close() override {
+        // Manually close all sockets so we break out of any blocking operations
+        // that may still be active
+        host_plugin_control_.close();
+        plugin_host_callback_.close();
+
+        // This map should be empty at this point, but who knows
+        std::lock_guard lock(audio_thread_sockets_mutex_);
+        for (auto& [instance_id, socket] : audio_thread_sockets_) {
+            socket.close();
+        }
+    }
+
+    /**
+     * Connect to the dedicated audio thread socket socket for a plugin
+     * instance. This should be called on the plugin side after instantiating
+     * the plugin.
+     *
+     * @param instance_id The object instance identifier of the socket.
+     */
+    void add_audio_thread_and_connect(size_t instance_id) {
+        std::lock_guard lock(audio_thread_sockets_mutex_);
+        audio_thread_sockets_.try_emplace(
+            instance_id, io_context_,
+            (base_dir_ / ("host_plugin_audio_thread_" +
+                          std::to_string(instance_id) + ".sock"))
+                .string(),
+            false);
+
+        audio_thread_sockets_.at(instance_id).connect();
+    }
+
+    /**
+     * Create and listen on a dedicated audio thread socket for a plugin object
+     * instance. The calling thread will block until the socket has been closed.
+     * This should be called from the Wine plugin host side after instantiating
+     * the plugin.
+     *
+     * @param instance_id The object instance identifier of the socket.
+     * @param socket_listening_latch A promise we'll set a value for once the
+     *   socket is being listened on so we can wait for it. Otherwise it can be
+     *   that the native plugin already tries to connect to the socket before
+     *   Wine plugin host is even listening on it.
+     * @param cb An overloaded function that can take every type `T` in the
+     *   `ClapAudioThreadControlRequest` variant and then returns `T::Response`.
+     *
+     * @tparam F A function type in the form of `T::Response(T)` for every `T`
+     *   in `ClapAudioThreadControlRequest::Payload`.
+     */
+    template <typename F>
+    void add_audio_thread_and_listen(size_t instance_id,
+                                     std::promise<void>& socket_listening_latch,
+                                     F&& callback) {
+        {
+            std::lock_guard lock(audio_thread_sockets_mutex_);
+            audio_thread_sockets_.try_emplace(
+                instance_id, io_context_,
+                (base_dir_ / ("host_plugin_audio_thread_" +
+                              std::to_string(instance_id) + ".sock"))
+                    .string(),
+                true);
+        }
+
+        socket_listening_latch.set_value();
+        audio_thread_sockets_.at(instance_id).connect();
+
+        // This `true` indicates that we want to reuse our serialization and
+        // receiving buffers for all calls. This slightly reduces the amount of
+        // allocations in the audio processing loop.
+        audio_thread_sockets_.at(instance_id)
+            .template receive_messages<true>(std::nullopt,
+                                             std::forward<F>(callback));
+    }
+
+    /**
+     * If `instance_id` is in `audio_thread_sockets_`, then close its socket and
+     * remove it from the map. This is called when handling
+     * `clap_plugin::destroy` on both the plugin and the Wine sides.
+     *
+     * @param instance_id The object instance identifier of the socket.
+     *
+     * @return Whether the socket was closed and removed. Returns false if it
+     *   wasn't in the map.
+     */
+    bool remove_audio_thread(size_t instance_id) {
+        std::lock_guard lock(audio_thread_sockets_mutex_);
+        if (audio_thread_sockets_.contains(instance_id)) {
+            audio_thread_sockets_.at(instance_id).close();
+            audio_thread_sockets_.erase(instance_id);
+
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    /**
+     * Send a message from the native plugin to the Wine plugin host to handle
+     * an audio thread function call. Since those functions are called from a
+     * hot loop we want every instance to have a dedicated socket and thread for
+     * handling those. These calls also always reuse buffers to minimize
+     * allocations.
+     *
+     * @tparam T Some object in the `ClapAudioThreadControlRequest` variant. All
+     *   of these objects need to have an `instance_id` field.
+     */
+    template <typename T>
+    typename T::Response send_audio_thread_message(
+        const T& object,
+        std::optional<std::pair<ClapLogger&, bool>> logging) {
+        typename T::Response response_object;
+        return receive_audio_thread_message_into(object, response_object,
+                                                 object.instance_id, logging);
+    }
+
+    /**
+     * Overload for use with `MessageReference<T>`, since we cannot
+     * directly get the instance ID there.
+     */
+    template <typename T>
+    typename T::Response send_audio_thread_message(
+        const MessageReference<T>& object_ref,
+        std::optional<std::pair<ClapLogger&, bool>> logging) {
+        typename T::Response response_object;
+        return receive_audio_thread_message_into(
+            object_ref, response_object, object_ref.get().instance_id, logging);
+    }
+
+    /**
+     * Alternative to `send_audio_thread_message()` for use with
+     * `MessageReference<T>`, where we also want deserialize into an existing
+     * object to prevent allocations. Used during audio processing.
+     *
+     * TODO: Think of a better name for this
+     */
+    template <typename T>
+    typename T::Response& receive_audio_thread_message_into(
+        const MessageReference<T>& request_ref,
+        typename T::Response& response_ref,
+        std::optional<std::pair<ClapLogger&, bool>> logging) {
+        return receive_audio_thread_message_into(
+            request_ref, response_ref, request_ref.get().instance_id, logging);
+    }
+
+    /**
+     * For sending messages from the host to the plugin. After we have a better
+     * idea of what our communication model looks like we'll probably want to
+     * provide an abstraction similar to `Vst2EventHandler`. This only handles
+     * main thread function calls. Audio thread calls are done using a dedicated
+     * socket per plugin instance.
+     *
+     * This will be listened on by the Wine plugin host when it calls
+     * `receive_multi()`.
+     */
+    TypedMessageHandler<Thread, ClapLogger, ClapMainThreadControlRequest>
+        host_plugin_control_;
+
+    /**
+     * For sending callbacks from the plugin back to the host.
+     */
+    TypedMessageHandler<Thread, ClapLogger, ClapMainThreadCallbackRequest>
+        plugin_host_callback_;
+
+   private:
+    /**
+     * The actual implementation for `send_audio_thread_message` and
+     * `receive_audio_thread_message_into`. Here we keep a thread local
+     * static variable for our buffers sending.
+     */
+    template <typename T>
+    typename T::Response& receive_audio_thread_message_into(
+        const T& object,
+        typename T::Response& response_object,
+        size_t instance_id,
+        std::optional<std::pair<ClapLogger&, bool>> logging) {
+        thread_local SerializationBuffer<256> audio_thread_buffer{};
+
+        return audio_thread_sockets_.at(instance_id)
+            .receive_into(object, response_object, logging,
+                          audio_thread_buffer);
+    }
+
+    asio::io_context& io_context_;
+
+    /**
+     * Every plugin instance gets a dedicated audio thread socket. These
+     * functions are always called in a hot loop, so there should not be any
+     * waiting or additional thread or socket creation happening there.
+     *
+     * TODO: All plugin instances have a socket for re-entrant audio thread
+     *       function calls. This is probably not needed. It's probably useful
+     *       to investgate why this socket was added back to the VST3 audio
+     *       threads.
+     */
+    std::unordered_map<
+        size_t,
+        TypedMessageHandler<Thread, ClapLogger, ClapAudioThreadControlRequest>>
+        audio_thread_sockets_;
+    std::mutex audio_thread_sockets_mutex_;
+};