[sim] WebSockets: don't override HAL_Main

Also clean up some other implementation aspects for cleaner shutdown and
reduce peak memory allocation.

simulation/halsim_ws_server/src/main/native/include/HALSimHttpConnection.h

@@ -9,35 +9,31 @@
 
 #include <cinttypes>
 #include <memory>
-#include <string>
-#include <vector>
+#include <utility>
 
 #include <HALSimBaseWebSocketConnection.h>
 #include <wpi/HttpWebSocketServerConnection.h>
-#include <wpi/json.h>
 #include <wpi/mutex.h>
 #include <wpi/uv/AsyncFunction.h>
 #include <wpi/uv/Buffer.h>
 
-namespace wpilibws {
+#include "HALSimWeb.h"
 
-class HALSimWeb;
+namespace wpi {
+class json;
+}  // namespace wpi
+
+namespace wpilibws {
 
 class HALSimHttpConnection
     : public wpi::HttpWebSocketServerConnection<HALSimHttpConnection>,
       public HALSimBaseWebSocketConnection {
  public:
-  using BufferPool = wpi::uv::SimpleBufferPool<4>;
-
-  using LoopFunc = std::function<void(void)>;
-  using UvExecFunc = wpi::uv::AsyncFunction<void(LoopFunc)>;
-
-  explicit HALSimHttpConnection(std::shared_ptr<wpi::uv::Stream> stream,
-                                wpi::StringRef webroot_sys,
-                                wpi::StringRef webroot_user)
+  HALSimHttpConnection(std::shared_ptr<HALSimWeb> server,
+                       std::shared_ptr<wpi::uv::Stream> stream)
       : wpi::HttpWebSocketServerConnection<HALSimHttpConnection>(stream, {}),
-        m_webroot_sys(webroot_sys),
-        m_webroot_user(webroot_user) {}
+        m_server(std::move(server)),
+        m_buffers(128) {}
 
  public:
   // callable from any thread
@@ -56,18 +52,13 @@ class HALSimHttpConnection
   void Log(int code);
 
  private:
-  // Absolute paths of folders to retrieve data from
-  // -> /
-  std::string m_webroot_sys;
-  // -> /user
-  std::string m_webroot_user;
+  std::shared_ptr<HALSimWeb> m_server;
 
   // is the websocket connected?
   bool m_isWsConnected = false;
 
   // these are only valid if the websocket is connected
-  std::shared_ptr<UvExecFunc> m_exec;
-  std::unique_ptr<BufferPool> m_buffers;
+  wpi::uv::SimpleBufferPool<4> m_buffers;
   std::mutex m_buffers_mutex;
 };
 

simulation/halsim_ws_server/src/main/native/include/HALSimWSServer.h

@@ -8,74 +8,27 @@
 #pragma once
 
 #include <memory>
-#include <string>
 
-#include <WSBaseProvider.h>
 #include <WSProviderContainer.h>
 #include <WSProvider_SimDevice.h>
-#include <wpi/StringMap.h>
-#include <wpi/json.h>
-#include <wpi/mutex.h>
-#include <wpi/uv/AsyncFunction.h>
-#include <wpi/uv/Buffer.h>
-#include <wpi/uv/Loop.h>
-#include <wpi/uv/Tcp.h>
+#include <wpi/EventLoopRunner.h>
+
+#include "HALSimWeb.h"
 
 namespace wpilibws {
 
-class HALSimHttpConnection;
-
-class HALSimWeb {
+class HALSimWSServer {
  public:
-  static std::shared_ptr<HALSimWeb> GetInstance() { return g_instance; }
-  static void SetInstance(std::shared_ptr<HALSimWeb> inst) {
-    g_instance = inst;
-  }
-
-  explicit HALSimWeb(ProviderContainer& providers,
-                     HALSimWSProviderSimDevices& simDevicesProvider)
-      : m_providers(providers), m_simDevicesProvider(simDevicesProvider) {}
-
-  HALSimWeb(const HALSimWeb&) = delete;
-  HALSimWeb& operator=(const HALSimWeb&) = delete;
+  HALSimWSServer() = default;
+  HALSimWSServer(const HALSimWSServer&) = delete;
+  HALSimWSServer& operator=(const HALSimWSServer&) = delete;
 
   bool Initialize();
-  static void Main(void*);
-  static void Exit(void*);
 
-  bool RegisterWebsocket(std::shared_ptr<HALSimBaseWebSocketConnection> hws);
-  void CloseWebsocket(std::shared_ptr<HALSimBaseWebSocketConnection> hws);
-
-  // network -> sim
-  void OnNetValueChanged(const wpi::json& msg);
-
-  std::string GetServerUri() const { return m_uri; }
-  int GetServerPort() { return m_port; }
-  std::shared_ptr<wpi::uv::Loop> GetLoop() { return m_loop; }
-
- private:
-  static std::shared_ptr<HALSimWeb> g_instance;
-
-  void MainLoop();
-
-  // connected http connection that contains active websocket
-  std::weak_ptr<HALSimBaseWebSocketConnection> m_hws;
-
-  // list of providers
-  ProviderContainer& m_providers;
-  HALSimWSProviderSimDevices& m_simDevicesProvider;
-
-  std::shared_ptr<wpi::uv::Loop> m_loop;
-  std::shared_ptr<wpi::uv::Tcp> m_server;
-
-  // Absolute paths of folders to retrieve data from
-  // -> /
-  std::string m_webroot_sys;
-  // -> /user
-  std::string m_webroot_user;
-
-  std::string m_uri;
-  int m_port;
+  ProviderContainer providers;
+  HALSimWSProviderSimDevices simDevices{providers};
+  wpi::EventLoopRunner runner;
+  std::shared_ptr<HALSimWeb> simWeb;
 };
 
 }  // namespace wpilibws

simulation/halsim_ws_server/src/main/native/include/HALSimWeb.h

@@ -0,0 +1,78 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <functional>
+#include <memory>
+#include <string>
+
+#include <WSBaseProvider.h>
+#include <WSProviderContainer.h>
+#include <WSProvider_SimDevice.h>
+#include <wpi/StringRef.h>
+#include <wpi/uv/Async.h>
+#include <wpi/uv/Loop.h>
+#include <wpi/uv/Tcp.h>
+
+namespace wpi {
+class json;
+}  // namespace wpi
+
+namespace wpilibws {
+
+class HALSimWeb : public std::enable_shared_from_this<HALSimWeb> {
+ public:
+  using LoopFunc = std::function<void(void)>;
+  using UvExecFunc = wpi::uv::Async<LoopFunc>;
+
+  HALSimWeb(wpi::uv::Loop& loop, ProviderContainer& providers,
+            HALSimWSProviderSimDevices& simDevicesProvider);
+
+  HALSimWeb(const HALSimWeb&) = delete;
+  HALSimWeb& operator=(const HALSimWeb&) = delete;
+
+  bool Initialize();
+  void Start();
+
+  bool RegisterWebsocket(std::shared_ptr<HALSimBaseWebSocketConnection> hws);
+  void CloseWebsocket(std::shared_ptr<HALSimBaseWebSocketConnection> hws);
+
+  // network -> sim
+  void OnNetValueChanged(const wpi::json& msg);
+
+  wpi::StringRef GetWebrootSys() const { return m_webroot_sys; }
+  wpi::StringRef GetWebrootUser() const { return m_webroot_user; }
+  wpi::StringRef GetServerUri() const { return m_uri; }
+  int GetServerPort() const { return m_port; }
+  wpi::uv::Loop& GetLoop() { return m_loop; }
+
+  UvExecFunc& GetExec() { return *m_exec; }
+
+ private:
+  // connected http connection that contains active websocket
+  std::weak_ptr<HALSimBaseWebSocketConnection> m_hws;
+
+  wpi::uv::Loop& m_loop;
+  std::shared_ptr<wpi::uv::Tcp> m_server;
+  std::shared_ptr<UvExecFunc> m_exec;
+
+  // list of providers
+  ProviderContainer& m_providers;
+  HALSimWSProviderSimDevices& m_simDevicesProvider;
+
+  // Absolute paths of folders to retrieve data from
+  // -> /
+  std::string m_webroot_sys;
+  // -> /user
+  std::string m_webroot_user;
+
+  std::string m_uri;
+  int m_port;
+};
+
+}  // namespace wpilibws