[Software][Cyclope controller] Added a watchdog timer that needs to b…

…e cleared repeatedly by the opened web page to avoid stopping the robot.

This watchdog triggers when the web server connection is lost and immediately stops the robot.

Software/cyclope/package/cyclope-controller/src/Sources/WebServer.cpp

@@ -4,11 +4,14 @@
  */
 #include <ArtificialIntelligenceProgramManager.hpp>
 #include <Adc.hpp>
+#include <cerrno>
 #include <cstring>
+#include <Lidar.hpp>
 #include <Light.hpp>
 #include <Log.hpp>
 #include <microhttpd.h>
 #include <Motor.hpp>
+#include <signal.h>
 #include <stdexcept>
 #include <unordered_map>
 #include <WebPageExecuteProgram.hpp>
@@ -20,15 +23,20 @@
 
 namespace WebServer
 {
+	/** The watchdog will fire if it is not cleared for this amount of time. */
+	constexpr unsigned int WATCHDOG_TIMEOUT_SECONDS = 3;
+	/** The watchdog is cleared at this rate, granting that it will never fire. */
+	constexpr unsigned int WATCHDOG_CLEAR_PERIOD = 1;
+
 	/** All available commands the user can send. */
 	typedef enum
 	{
 		WEB_SERVER_COMMUNICATION_PROTOCOL_COMMAND_SET_MOTION,
 		WEB_SERVER_COMMUNICATION_PROTOCOL_COMMAND_GET_BATTERY_VOLTAGE,
 		WEB_SERVER_COMMUNICATION_PROTOCOL_COMMAND_SET_LIGHT_ENABLED,
 		WEB_SERVER_COMMUNICATION_PROTOCOL_COMMAND_STOP_CURRENT_AI_PROGRAM,
-		WEB_SERVER_COMMUNICATION_PROTOCOL_COMMAND_SET_STREAMING_CAMERA_ENABLED,
-		WEB_SERVER_COMMUNICATION_PROTOCOL_COMMANDS_COUNT
+		WEB_SERVER_COMMUNICATION_PROTOCOL_COMMAND_CLEAR_WATCHDOG,
+		WEB_SERVER_COMMUNICATION_PROTOCOL_COMMAND_SET_STREAMING_CAMERA_ENABLED
 	} WebServerCommunicationProtocolCommand;
 
 	/** The server handle. */
@@ -92,7 +100,8 @@ namespace WebServer
 			"				COMMUNICATION_PROTOCOL_COMMAND_SET_MOTION: '0',\n"
 			"				COMMUNICATION_PROTOCOL_COMMAND_GET_BATTERY_VOLTAGE: '1',\n"
 			"				COMMUNICATION_PROTOCOL_COMMAND_SET_LIGHT_ENABLED: '2',\n"
-			"				COMMUNICATION_PROTOCOL_COMMAND_STOP_CURRENT_AI_PROGRAM: '3'\n"
+			"				COMMUNICATION_PROTOCOL_COMMAND_STOP_CURRENT_AI_PROGRAM: '3',\n"
+			"				COMMUNICATION_PROTOCOL_COMMAND_CLEAR_WATCHDOG: '4'\n"
 			"			}\n"
 			"\n"
 			"			const RobotMotion =\n"
@@ -122,6 +131,13 @@ namespace WebServer
 			"				userInterfaceControl = document.getElementById(htmlElementId);\n"
 			"				userInterfaceControl.innerHTML = text;\n"
 			"			}\n"
+			"\n"
+			"			function feedWatchdog()\n"
+			"			{\n"
+			"				command = CommunicationProtocol.COMMUNICATION_PROTOCOL_COMMAND_CLEAR_WATCHDOG;\n"
+			"				communicationProtocolSendCommand(command);\n"
+			"			}\n"
+			"			setInterval(feedWatchdog, " + std::to_string(WATCHDOG_CLEAR_PERIOD * 1000) + ");\n"
 			"		</script>\n";
 	}
 
@@ -232,6 +248,10 @@ namespace WebServer
 				ArtificialIntelligenceProgramManager::stopRunningProgram();
 				break;
 
+			case WEB_SERVER_COMMUNICATION_PROTOCOL_COMMAND_CLEAR_WATCHDOG:
+				alarm(WATCHDOG_TIMEOUT_SECONDS); // Reset the watchdog
+				break;
+
 			default:
 				LOG(LOG_ERR, "Unknown command '%c'.", pointerStringCommand[0]);
 				return -1;
@@ -394,8 +414,36 @@ namespace WebServer
 		return returnValue;
 	}
 
+	/** Called when the watchdog fires. */
+	static void _watchogSignalHandler(int)
+	{
+		LOG(LOG_WARNING, "The watchdog fired, stopping the robot.");
+
+		// Stop the currently running AI program (if any)
+		ArtificialIntelligenceProgramManager::stopRunningProgram();
+
+		// Stop the robot to be sure
+		Motor::setRobotMotion(Motor::ROBOT_MOTION_STOP);
+		Lidar::setEnabled(false);
+		Light::setEnabled(false);
+
+		// Stop the watchdog to avoid it retrigger itself continuously
+		int result = alarm(0);
+		if (result < 0) LOG(LOG_ERR, "Failed to disable the watchdog (%s).", strerror(errno));
+	}
+
 	int initialize()
 	{
+		// Create the event handler that will be called if the watchdog fires
+		struct sigaction signalAction{};
+		signalAction.sa_handler = _watchogSignalHandler;
+		int result = sigaction(SIGALRM, &signalAction, nullptr);
+		if (result < 0)
+		{
+			LOG(LOG_ERR, "Error : failed to install the SIGALRM handler (%s).", strerror(errno));
+			return -1;
+		}
+
 		// Start the web server daemon and configure it to accept connections from any IP
 		_pointerServerHandle = MHD_start_daemon(MHD_USE_THREAD_PER_CONNECTION, 80, NULL, NULL, _accessHandlerCallback, NULL, MHD_OPTION_END);
 		if (_pointerServerHandle == NULL)