[sim] Add WebSocket extension (client/server) (#2589)

This allows access to HAL-level simulation data via a WebSocket connection.

The server additionally serves local files.

The following environment variables can be used for configuration:
HALSIMWS_USERROOT (server) - local directory to use for file serving for /user/ URIs, defaults to ./sim/user
HALSIMWS_SYSROOT (server) - local directory to use for file serving for all other URIs, defaults to ./sim
HALSIMWS_URI (client or server) - WebSocket URI, defaults to /wpilibws
HALSIMWS_PORT (client or server) - port number, defaults to 8080
HALSIMWS_HOST (client) - host to connect to, defaults to localhost

Co-authored-by: Zhiquan Yeo <zyeo8@bloomberg.net>
Co-authored-by: Peter Johnson <johnson.peter@gmail.com>
Co-authored-by: jpokornyiii <jpokornyiii@gmail.com>

simulation/halsim_ws_server/src/test/native/cpp/main.cpp

@@ -0,0 +1,155 @@
+/*----------------------------------------------------------------------------*/
+/* 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include <hal/HALBase.h>
+#include <hal/Main.h>
+#include <hal/simulation/DIOData.h>
+#include <wpi/raw_ostream.h>
+#include <wpi/uv/Loop.h>
+
+#include "HALSimWSServer.h"
+#include "WebServerClientTest.h"
+#include "gtest/gtest.h"
+
+using namespace wpilibws;
+
+extern "C" int HALSIM_InitExtension(
+    void);  // from simulation/halsim_ws_server/src/main/native/cpp/main.cpp
+
+const int POLLING_SPEED = 10;  // 10 ms polling
+
+class WebServerIntegrationTest : public ::testing::Test {
+ public:
+  WebServerIntegrationTest() {
+    const int MAX_TEST_TIME = 1000;  // 1 second
+
+    // Initialize HAL layer including webserver
+    HALSIM_InitExtension();
+
+    // Create and initialize client
+    m_webserver_client =
+        std::shared_ptr<WebServerClientTest>((new WebServerClientTest()));
+    WebServerClientTest::SetInstance(m_webserver_client);
+    auto webserver = HALSimWeb::GetInstance();
+    auto loop = webserver->GetLoop();
+    m_webserver_client->Initialize(loop);
+
+    // Create failover timer to prevent running forever
+    m_failoverTimer = wpi::uv::Timer::Create(loop);
+    m_failoverTimer->timeout.connect([loop] { loop->Stop(); });
+    m_failoverTimer->Start(uv::Timer::Time(MAX_TEST_TIME));
+  }
+
+  ~WebServerIntegrationTest() {
+    // Exit HAL layer which exits webserver
+    HAL_ExitMain();
+    HALSimWeb::Exit(nullptr);
+
+    // Exit client
+    m_webserver_client->Exit();
+    WebServerClientTest::SetInstance(nullptr);
+
+    // Unreference timers from loop
+    m_failoverTimer->Unreference();
+  }
+
+  bool IsConnectedClientWS() { return m_webserver_client->IsConnectedWS(); }
+  void TerminateOnNextMessage(bool flag) {
+    m_webserver_client->SetTerminateFlag(flag);
+  }
+
+ private:
+  std::shared_ptr<WebServerClientTest> m_webserver_client;
+  std::shared_ptr<wpi::uv::Timer> m_failoverTimer;
+};
+
+TEST_F(WebServerIntegrationTest, DigitalOutput) {
+  // Create expected results
+  const bool EXPECTED_VALUE = false;
+  const int PIN = 0;
+
+  // Attach timer to loop for test function
+  auto ws = HALSimWeb::GetInstance();
+  auto loop = ws->GetLoop();
+  auto timer = wpi::uv::Timer::Create(loop);
+  timer->timeout.connect([&] {
+    if (IsConnectedClientWS()) {
+      wpi::outs() << "***** Setting DIO value for pin " << PIN << " to "
+                  << (EXPECTED_VALUE ? "true" : "false") << "\n";
+      HALSIM_SetDIOValue(PIN, EXPECTED_VALUE);
+      TerminateOnNextMessage(true);
+    } else {
+      // Recheck in POLLING_SPEED ms
+      timer->Start(uv::Timer::Time(POLLING_SPEED));
+    }
+  });
+  timer->Start(uv::Timer::Time(POLLING_SPEED));
+
+  HAL_RunMain();
+  timer->Unreference();
+
+  // Get values from JSON message
+  std::string test_type;
+  std::string test_device;
+  bool test_value = true;  // Default value from HAL initialization
+  try {
+    auto& msg = WebServerClientTest::GetInstance()->GetLastMessage();
+    test_type = msg.at("type").get_ref<const std::string&>();
+    test_device = msg.at("device").get_ref<const std::string&>();
+    auto& data = msg.at("data");
+    wpi::json::const_iterator it = data.find("<>value");
+    if (it != data.end()) {
+      test_value = it.value();
+    }
+  } catch (wpi::json::exception& e) {
+    wpi::errs() << "Error with incoming message: " << e.what() << "\n";
+  }
+
+  // Compare results
+  EXPECT_EQ("DIO", test_type);
+  EXPECT_EQ(std::to_string(PIN), test_device);
+  EXPECT_EQ(EXPECTED_VALUE, test_value);
+}
+
+TEST_F(WebServerIntegrationTest, DigitalInput) {
+  // Create expected results
+  const bool EXPECTED_VALUE = false;
+  const int PIN = 0;
+
+  // Attach timer to loop for test function
+  auto ws = HALSimWeb::GetInstance();
+  auto loop = ws->GetLoop();
+  auto timer = wpi::uv::Timer::Create(loop);
+  timer->timeout.connect([&] {
+    if (IsConnectedClientWS()) {
+      wpi::json msg = {{"type", "DIO"},
+                       {"device", std::to_string(PIN)},
+                       {"data", {{"<>value", EXPECTED_VALUE}}}};
+      wpi::outs() << "***** Input JSON: " << msg.dump() << "\n";
+      WebServerClientTest::GetInstance()->SendMessage(msg);
+      loop->Stop();
+    } else {
+      // Recheck in POLLING_SPEED ms
+      timer->Start(uv::Timer::Time(POLLING_SPEED));
+    }
+  });
+  timer->Start(uv::Timer::Time(POLLING_SPEED));
+
+  HAL_RunMain();
+  timer->Unreference();
+
+  // Compare results
+  bool test_value = HALSIM_GetDIOValue(PIN);
+  EXPECT_EQ(EXPECTED_VALUE, test_value);
+}
+
+int main(int argc, char* argv[]) {
+  ::testing::InitGoogleTest(&argc, argv);
+  HAL_Initialize(500, 0);
+  int ret = RUN_ALL_TESTS();
+  return ret;
+}