Changes to message cap feature

- Setting a maxMsgNum of -1 will result in the minimum possible value
(slightly above the predicted message rate) being picked as a cap
- Added some logging to make the feature more verbose

src/Configuration.cpp

@@ -106,7 +106,7 @@ bool Configuration::readGlobal() {
 		}else if (boost::iequals(global.first, "threads")) {
 			_global.threads = stoi(global.second.data());
 		} else if (boost::iequals(global.first, "maxMsgNum")) {
-			_global.maxMsgNum = stoull(global.second.data());
+			_global.maxMsgNum = stoi(global.second.data());
 		} else if (boost::iequals(global.first, "daemonize")) {
 			if (global.second.data() == "true") {
 				_global.daemonize = 1;

src/Configuration.h

@@ -25,7 +25,7 @@ typedef struct {
 	std::string brokerHost;
 	std::string hierarchy;
 	uint32_t threads;
-	unsigned int maxMsgNum;
+	int maxMsgNum;
 	boost::log::trivial::severity_level logLevelFile;
 	boost::log::trivial::severity_level logLevelCmd;
 	pluginSettings_t pluginSettings;

src/MQTTPusher.cpp

@@ -14,7 +14,7 @@
 #define LOGM(sev) LOG(sev) << "Mosquitto: "
 
 MQTTPusher::MQTTPusher(int brokerPort, const std::string& brokerHost, const std::string& sensorPattern, int qosLevel,
-					   pluginVector_t& plugins, an_pluginVector_t& aPlugins, unsigned int maxNumberOfMessages, unsigned int maxInflightMsgNum, unsigned int maxQueuedMsgNum) :
+					   pluginVector_t& plugins, an_pluginVector_t& aPlugins, int maxNumberOfMessages, unsigned int maxInflightMsgNum, unsigned int maxQueuedMsgNum) :
 		_qosLevel(qosLevel),
 		_brokerPort(brokerPort),
 		_brokerHost(brokerHost),
@@ -23,7 +23,7 @@ MQTTPusher::MQTTPusher(int brokerPort, const std::string& brokerHost, const std:
 		_analyticsPlugins(aPlugins),
 		_connected(false),
 		_keepRunning(true),
-		_overrideMsgCap(true),
+		_msgCap(DISABLED),
 		_doHalt(false),
 		_halted(false),
 		_maxNumberOfMessages(maxNumberOfMessages),
@@ -116,7 +116,7 @@ void MQTTPusher::push() {
                     for (const auto &g : p.configurator->getSensorGroups()) {
                         for (const auto &s : g->getSensors()) {
                             if (s->getSizeOfReadingQueue() >= g->getMinValues()) {
-                                if (_overrideMsgCap || totalCount < _maxNumberOfMessages) {
+                                if (_msgCap == DISABLED || totalCount < _maxNumberOfMessages) {
                                     if (sendReadings(*s, reads, totalCount) > 0) {
                                         break;
                                     }
@@ -136,7 +136,7 @@ void MQTTPusher::push() {
                         for (const auto &u : a->getUnits()) {
                             for (const auto &s : u->getBaseOutputs()) {
                                 if (s->getSizeOfReadingQueue() >= a->getMinValues()) {
-                                    if (_overrideMsgCap || totalCount < _maxNumberOfMessages) {
+                                    if (_msgCap == DISABLED || totalCount < _maxNumberOfMessages) {
                                         if (sendReadings(*s, reads, totalCount) > 0) {
                                             break;
                                         }
@@ -250,7 +250,17 @@ void MQTTPusher::computeMsgRate() {
 			for(const auto& u : a->getUnits())
 				msgRate += u->getBaseOutputs().size() * ( 1000 / a->getInterval() ) / a->getMinValues();
 	// The formula below assumes the pusher's sleep time is 1 sec; if not, change accordingly
-	_overrideMsgCap = _maxNumberOfMessages == 0 || msgRate > _maxNumberOfMessages;
-	if( _overrideMsgCap && _maxNumberOfMessages != 0 )
-		LOGM(warning) << "Cannot enforce max rate of " << _maxNumberOfMessages << " msg/s lower than actual " << msgRate << " msg/s!";
+	if(_maxNumberOfMessages >= 0 && _msgCap != MINIMUM) {
+		_msgCap = _maxNumberOfMessages == 0 || msgRate > _maxNumberOfMessages ? DISABLED : ENABLED;
+		if (_msgCap == DISABLED && _maxNumberOfMessages > 0)
+			LOGM(warning) << "Cannot enforce max rate of " << _maxNumberOfMessages << " msg/s lower than actual " << msgRate << " msg/s!";
+		else if(_maxNumberOfMessages > 0)
+			LOGM(info) << "Enforcing message cap of " << _maxNumberOfMessages << " msg/s against actual " << msgRate << " msg/s.";
+		else
+			LOGM(info) << "No message cap enforced. Predicted message rate is " << msgRate << " msg/s.";
+	} else {
+		_msgCap = MINIMUM;
+		_maxNumberOfMessages = msgRate + 10;
+		LOGM(info) << "Enforcing message cap of " << _maxNumberOfMessages << " msg/s against actual " << msgRate << " msg/s.";
+	}
 }

src/MQTTPusher.h

@@ -17,13 +17,15 @@
 #include "analytics/AnalyticsManager.h"
 #include <map>
 
+enum msgCap_t {DISABLED = 1, ENABLED = 2, MINIMUM = 3};
+
 /**
  * Class responsible for collecting values from the sensors and pushing them to the database.
  */
 class MQTTPusher {
 public:
 	MQTTPusher(int brokerPort, const std::string& brokerHost, const std::string& sensorPattern, int qosLevel,
-			   pluginVector_t& plugins, an_pluginVector_t& aPlugins, unsigned int maxNumberOfMessages, unsigned int maxInflightMsgNum, unsigned int maxQueuedMsgNum);
+			   pluginVector_t& plugins, an_pluginVector_t& aPlugins, int maxNumberOfMessages, unsigned int maxInflightMsgNum, unsigned int maxQueuedMsgNum);
 	virtual ~MQTTPusher();
 
 	void push();
@@ -63,10 +65,10 @@ private:
 	struct mosquitto* _mosq;
 	bool _connected;
 	bool _keepRunning;
-	bool _overrideMsgCap;
+	msgCap_t _msgCap;
 	bool _doHalt;
 	bool _halted;
-	unsigned int _maxNumberOfMessages;
+	int _maxNumberOfMessages;
 	unsigned int _maxInflightMsgNum;
 	unsigned int _maxQueuedMsgNum;