Device: Allow the suppression of disconnects from extensions

device/device.cpp

@@ -240,13 +240,13 @@ bool Device::open() {
 		while(!stopHeartbeatThread) {
 			// Wait for 110ms for a possible heartbeat
 			std::this_thread::sleep_for(std::chrono::milliseconds(110));
-			if(!receivedMessage) {
+			if(!receivedMessage && !heartbeatSuppressed()) {
 				// No heartbeat received, request a status
 				com->sendCommand(Command::RequestStatusUpdate);
 				// The response should come back quickly if the com is quiet
 				std::this_thread::sleep_for(std::chrono::milliseconds(10));
 				// Check if we got a message, and if not, if settings are being applied
-				if(!receivedMessage && !settings->applyingSettings) {
+				if(!receivedMessage && !heartbeatSuppressed()) {
 					if(!stopHeartbeatThread && !isDisconnected())
 						report(APIEvent::Type::DeviceDisconnected, APIEvent::Severity::Error);
 					break;
@@ -630,6 +630,11 @@ optional<double> Device::getAnalogIO(IO type, size_t number /* = 1 */) {
 	return nullopt;
 }
 
+Lifetime Device::suppressDisconnects() {
+	heartbeatSuppressedByUser++;
+	return Lifetime([this] { heartbeatSuppressedByUser--; });
+}
+
 void Device::addExtension(std::shared_ptr<DeviceExtension>&& extension) {
 	std::lock_guard<std::mutex> lk(extensionsLock);
 	extensions.push_back(extension);

include/icsneo/api/lifetime.h

@@ -0,0 +1,34 @@
+#ifndef __ICSNEO_LIFETIME_H_
+#define __ICSNEO_LIFETIME_H_
+
+#include <functional>
+
+namespace icsneo {
+
+class Lifetime {
+public:
+	Lifetime() = default;
+	Lifetime(std::function<void(void)> onDeath) : fnOnDeath(onDeath) {}
+	~Lifetime() {
+		if(fnOnDeath)
+			fnOnDeath();
+	}
+
+	// Disallow copies so the fnOnDeath only happens once
+	Lifetime(const Lifetime&) = delete;
+	Lifetime& operator=(const Lifetime&) = delete;
+
+	// Explicitly allow moves
+	Lifetime(Lifetime&& moved) { *this = std::move(moved); }
+	Lifetime& operator=(Lifetime&& rhs) {
+		fnOnDeath = std::move(rhs.fnOnDeath);
+		rhs.fnOnDeath = std::function<void(void)>();
+		return *this;
+	}
+private:
+	std::function<void(void)> fnOnDeath;
+};
+
+}
+
+#endif

include/icsneo/device/device.h

@@ -9,6 +9,7 @@
 #include <cstring>
 #include <atomic>
 #include "icsneo/api/eventmanager.h"
+#include "icsneo/api/lifetime.h"
 #include "icsneo/device/neodevice.h"
 #include "icsneo/device/idevicesettings.h"
 #include "icsneo/device/nullsettings.h"
@@ -24,6 +25,7 @@
 #include "icsneo/communication/message/flexray/control/flexraycontrolmessage.h"
 #include "icsneo/third-party/concurrentqueue/concurrentqueue.h"
 #include "icsneo/platform/optional.h"
+#include "icsneo/platform/nodiscard.h"
 
 namespace icsneo {
 
@@ -155,6 +157,12 @@ public:
 
 	virtual std::vector<std::shared_ptr<FlexRay::Controller>> getFlexRayControllers() const { return {}; }
 
+	/**
+	 * For use by extensions only.
+	 */
+	NODISCARD("If the Lifetime is not held, disconnects will be immediately unsuppressed")
+	Lifetime suppressDisconnects();
+
 	const device_eventhandler_t& getEventHandler() const { return report; }
 
 	std::shared_ptr<Communication> com;
@@ -275,6 +283,10 @@ private:
 	std::vector<Network> supportedTXNetworks;
 	std::vector<Network> supportedRXNetworks;
 	
+	// Use heartbeatSuppressed instead when reading
+	std::atomic<int> heartbeatSuppressedByUser{0};
+	bool heartbeatSuppressed() const { return heartbeatSuppressedByUser > 0 || (settings && settings->applyingSettings); }
+
 	void handleNeoVIMessage(std::shared_ptr<CANMessage> message);
 	
 	enum class LEDState : uint8_t {

include/icsneo/platform/nodiscard.h

@@ -0,0 +1,15 @@
+#ifndef __ICSNEO_NODISCARD_H_
+#define __ICSNEO_NODISCARD_H_
+
+/**
+ * Allow the use of the nodiscard attribute where it is supported.
+ */
+#if __cplusplus > 201703L // C++20 and above
+#define NODISCARD(str) [[nodiscard(str)]]
+#elif __cplusplus > 201402L // C++17 and above
+#define NODISCARD(str) [[nodiscard]]
+#else
+#define NODISCARD(str)
+#endif
+
+#endif