[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_client/src/main/native/include/HALSimWS.h

@@ -0,0 +1,75 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 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 <WSProviderContainer.h>
+#include <WSProvider_SimDevice.h>
+#include <wpi/uv/Async.h>
+#include <wpi/uv/Loop.h>
+#include <wpi/uv/Tcp.h>
+#include <wpi/uv/Timer.h>
+
+namespace wpi {
+class json;
+}  // namespace wpi
+
+namespace wpilibws {
+
+class HALSimWSClientConnection;
+
+class HALSimWS : public std::enable_shared_from_this<HALSimWS> {
+ public:
+  using LoopFunc = std::function<void(void)>;
+  using UvExecFunc = wpi::uv::Async<LoopFunc>;
+
+  HALSimWS(wpi::uv::Loop& loop, ProviderContainer& providers,
+           HALSimWSProviderSimDevices& simDevicesProvider);
+  HALSimWS(const HALSimWS&) = delete;
+  HALSimWS& operator=(const HALSimWS&) = delete;
+
+  bool Initialize();
+  void Start();
+
+  bool RegisterWebsocket(std::shared_ptr<HALSimBaseWebSocketConnection> hws);
+  void CloseWebsocket(std::shared_ptr<HALSimBaseWebSocketConnection> hws);
+
+  void OnNetValueChanged(const wpi::json& msg);
+
+  wpi::StringRef GetTargetHost() const { return m_host; }
+  wpi::StringRef GetTargetUri() const { return m_uri; }
+  int GetTargetPort() const { return m_port; }
+  wpi::uv::Loop& GetLoop() { return m_loop; }
+
+  UvExecFunc& GetExec() { return *m_exec; }
+
+ private:
+  void AttemptConnect();
+
+  bool m_tcp_connected = false;
+  std::shared_ptr<wpi::uv::Timer> m_connect_timer;
+  int m_connect_attempts = 0;
+
+  std::weak_ptr<HALSimBaseWebSocketConnection> m_hws;
+
+  wpi::uv::Loop& m_loop;
+  std::shared_ptr<wpi::uv::Tcp> m_tcp_client;
+  std::shared_ptr<UvExecFunc> m_exec;
+
+  ProviderContainer& m_providers;
+  HALSimWSProviderSimDevices& m_simDevicesProvider;
+
+  std::string m_host;
+  std::string m_uri;
+  int m_port;
+};
+
+}  // namespace wpilibws

simulation/halsim_ws_client/src/main/native/include/HALSimWSClient.h

@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) 2020 FIRST. All Rights Reserved.                             */
+/* 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.                                                               */
@@ -8,67 +8,27 @@
 #pragma once
 
 #include <memory>
-#include <string>
 
 #include <WSProviderContainer.h>
 #include <WSProvider_SimDevice.h>
-#include <wpi/json.h>
-#include <wpi/uv/AsyncFunction.h>
-#include <wpi/uv/Loop.h>
-#include <wpi/uv/Tcp.h>
-#include <wpi/uv/Timer.h>
+#include <wpi/EventLoopRunner.h>
+
+#include "HALSimWS.h"
 
 namespace wpilibws {
 
-class HALSimWSClientConnection;
-
-class HALSimWS {
+class HALSimWSClient {
  public:
-  static std::shared_ptr<HALSimWS> GetInstance() { return g_instance; }
-  static void SetInstance(std::shared_ptr<HALSimWS> inst) { g_instance = inst; }
-
-  explicit HALSimWS(ProviderContainer& providers,
-                    HALSimWSProviderSimDevices& simDevicesProvider)
-      : m_providers(providers), m_simDevicesProvider(simDevicesProvider) {}
-  HALSimWS(const HALSimWS&) = delete;
-  HALSimWS& operator=(const HALSimWS&) = delete;
+  HALSimWSClient() = default;
+  HALSimWSClient(const HALSimWSClient&) = delete;
+  HALSimWSClient& operator=(const HALSimWSClient&) = 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);
-
-  void OnNetValueChanged(const wpi::json& msg);
-
-  std::string GetTargetHost() const { return m_host; }
-  std::string GetTargetUri() const { return m_uri; }
-  int GetTargetPort() { return m_port; }
-  std::shared_ptr<wpi::uv::Loop> GetLoop() { return m_loop; }
-
- private:
-  static std::shared_ptr<HALSimWS> g_instance;
-
-  void MainLoop();
-
-  void AttemptConnect();
-
-  bool m_tcp_connected = false;
-  std::shared_ptr<wpi::uv::Timer> m_connect_timer;
-  int m_connect_attempts = 0;
-
-  std::weak_ptr<HALSimBaseWebSocketConnection> m_hws;
-
-  ProviderContainer& m_providers;
-  HALSimWSProviderSimDevices& m_simDevicesProvider;
-
-  std::shared_ptr<wpi::uv::Loop> m_loop;
-  std::shared_ptr<wpi::uv::Tcp> m_tcp_client;
-
-  std::string m_host;
-  std::string m_uri;
-  int m_port;
+  ProviderContainer providers;
+  HALSimWSProviderSimDevices simDevices{providers};
+  wpi::EventLoopRunner runner;
+  std::shared_ptr<HALSimWS> simws;
 };
 
 }  // namespace wpilibws

simulation/halsim_ws_client/src/main/native/include/HALSimWSClientConnection.h

@@ -8,15 +8,20 @@
 #pragma once
 
 #include <memory>
+#include <utility>
 
 #include <HALSimBaseWebSocketConnection.h>
 #include <wpi/WebSocket.h>
-#include <wpi/json.h>
 #include <wpi/mutex.h>
-#include <wpi/uv/AsyncFunction.h>
 #include <wpi/uv/Buffer.h>
 #include <wpi/uv/Stream.h>
 
+#include "HALSimWS.h"
+
+namespace wpi {
+class json;
+}  // namespace wpi
+
 namespace wpilibws {
 
 class HALSimWS;
@@ -25,25 +30,24 @@ class HALSimWSClientConnection
     : public HALSimBaseWebSocketConnection,
       public std::enable_shared_from_this<HALSimWSClientConnection> {
  public:
-  using BufferPool = wpi::uv::SimpleBufferPool<4>;
-  using LoopFunc = std::function<void(void)>;
-  using UvExecFunc = wpi::uv::AsyncFunction<void(LoopFunc)>;
-
-  explicit HALSimWSClientConnection(std::shared_ptr<wpi::uv::Stream> stream)
-      : m_stream(stream) {}
+  explicit HALSimWSClientConnection(std::shared_ptr<HALSimWS> client,
+                                    std::shared_ptr<wpi::uv::Stream> stream)
+      : m_client(std::move(client)),
+        m_stream(std::move(stream)),
+        m_buffers(128) {}
 
  public:
   void OnSimValueChanged(const wpi::json& msg) override;
   void Initialize();
 
  private:
+  std::shared_ptr<HALSimWS> m_client;
   std::shared_ptr<wpi::uv::Stream> m_stream;
 
   bool m_ws_connected = false;
   wpi::WebSocket* m_websocket = nullptr;
 
-  std::shared_ptr<UvExecFunc> m_exec;
-  std::unique_ptr<BufferPool> m_buffers;
+  wpi::uv::SimpleBufferPool<4> m_buffers;
   std::mutex m_buffers_mutex;
 };