Add one stage pipeline to /ok

src/http_handler.hpp

@@ -1,10 +1,14 @@
 #pragma once
 
+#include "ThreadPipeline.h"
 #include "connection.hpp"
 #include "connection_handler.hpp"
+#include "perfetto_categories.hpp"
+#include "server.hpp"
 #include <llhttp.h>
 #include <memory>
 #include <string_view>
+#include <thread>
 
 /**
  * HTTP routes supported by WeaselDB server.
@@ -57,8 +61,34 @@ struct HttpConnectionState {
  * Supports the WeaselDB REST API endpoints with enum-based routing.
  */
 class HttpHandler : public ConnectionHandler {
+  ThreadPipeline<std::unique_ptr<Connection>> ok_pipeline{10, {1}};
+  std::thread ok_thread{[this]() {
+    pthread_setname_np(pthread_self(), "stage-0");
+    for (;;) {
+      auto guard = ok_pipeline.acquire(0, 0);
+      for (auto &c : guard.batch) {
+        if (!c) {
+          return;
+        }
+        auto *state = static_cast<HttpConnectionState *>(c->user_data);
+        TRACE_EVENT("http", "pipeline thread",
+                    perfetto::Flow::Global(state->request_id));
+        Server::releaseBackToServer(std::move(c));
+      }
+    }
+  }};
+
 public:
   HttpHandler() = default;
+  ~HttpHandler() {
+    {
+      auto guard = ok_pipeline.push(1, true);
+      for (auto &c : guard.batch) {
+        c = {};
+      }
+    }
+    ok_thread.join();
+  }
 
   void on_connection_established(Connection &conn) override;
   void on_connection_closed(Connection &conn) override;