chore: initial commit

rediska/frontend/RequestManager.hpp

@@ -0,0 +1,52 @@
+#pragma once
+
+#include <grpcpp/grpcpp.h>
+#include <grpcpp/support/async_stream.h>
+#include <memory>
+#include <optional>
+#include "rediska/common/QueueMessage.hpp"
+
+// One global context kept alive as long as the server lives.
+inline grpc::ServerContext& GlobalServerContext() {
+    static grpc::ServerContext ctx;
+    return ctx;
+}
+
+// The thing recieved from the completion queue in case of a request.
+struct BaseRequestManager {
+    virtual void ListenForOne(grpc::ServerCompletionQueue& cq) = 0;
+    virtual std::optional<QueueMessage> ConsumeMessage() = 0;
+    virtual ~BaseRequestManager() = default;
+};
+
+// This is basically storage for an incoming request.
+template <typename Derived, typename RequestT, typename ResponderT, typename ServiceT, auto RequestMethod>
+class RequestManager : public BaseRequestManager {
+protected:
+    RequestT request;
+    std::unique_ptr<ResponderT> responder;
+    ServiceT& service;
+
+    std::unique_ptr<grpc::internal::ServerAsyncStreamingInterface> TakeResponder() {
+        return std::unique_ptr<grpc::internal::ServerAsyncStreamingInterface>(std::move(responder));
+    }
+
+public:
+    explicit RequestManager(ServiceT& svc) : service(svc) { }
+
+    // Sets up listening for a new request.
+    // You must ensure this object lives until the request is consumed, or grpc will be unhappy.
+    // The tag you recieve from the queue is a EventVariant* that you must take ownership of.
+    void ListenForOne(grpc::ServerCompletionQueue& cq) override {
+        request = RequestT{};
+        // FIXME: just leak this stupid shit for now idk how to fix I'm done with this stupid language
+        auto* ctx = new grpc::ServerContext();
+        responder = std::make_unique<ResponderT>(ctx);
+        (service.*RequestMethod)(ctx, &request, responder.get(), &cq, &cq, std::make_unique<EventVariant>(RequestEvent{*this}).release());
+    }
+
+    std::optional<QueueMessage> ConsumeMessage() override {
+        QueueMessage msg = static_cast<Derived*>(this)->BuildMessage();
+        return msg;
+    }
+};