DA: delayed start feature

- Using the "delay" parameter, analyzers can be started in a delayed way
- Useful to let sensor caches fill and prevent errors being thrown

src/analytics/README.md

@@ -158,6 +158,7 @@ file. The following is instead a list of configuration parameters that are avail
 |:----- |:----------- |
 | default | Name of the template that must be used to configure this analyzer.
 | interval | Specifies how often the analyzer will be invoked to perform computations, and thus the sampling interval of its output sensors. Only used for analyzers in _streaming_ mode.
+| delay | Delay in milliseconds to be applied to the start of the analyzer. This parameter only applies to streaming analyzers. It can be used to allow for input sensor caches to be populated before the analyzer is started.
 | minValues |   Minimum number of readings that need to be stored in output sensors before these are pushed as MQTT messages. Only used for analyzers in _streaming_ mode.
 | mqttPart |    Part of the MQTT topic associated to this analyzer. Only used when the Unit system is not employed (see this [section](#mqttTopics)).
 | sync | If set to _true_, computation will be performed at time intervals synchronized with sensor readings.

src/analytics/includes/AnalyzerConfiguratorTemplate.h

@@ -308,6 +308,8 @@ protected:
                 an.setMqttPart(val.second.data());
             } else if (boost::iequals(val.first, "sync")) {
                 an.setSync(val.second.data() == "true");
+            } else if (boost::iequals(val.first, "delay")) {
+                an.setDelayInterval(stoull(val.second.data()) / 1000);
             } else if (boost::iequals(val.first, "duplicate")) {
                 an.setDuplicate(val.second.data() == "true");
             } else if (boost::iequals(val.first, "streaming")) {

src/analytics/includes/AnalyzerInterface.h

@@ -53,6 +53,7 @@ public:
             _interval(1000),
             _cacheInterval(900000),
             _cacheSize(1),
+            _delayInterval(0),
             _pendingTasks(0),
             _onDemandLock(false),
             _timer(nullptr) {}
@@ -73,6 +74,7 @@ public:
             _interval(other._interval),
             _cacheInterval(other._cacheInterval),
             _cacheSize(other._cacheSize),
+            _delayInterval(other._delayInterval),
             _pendingTasks(0),
             _onDemandLock(false),
             _timer(nullptr) {}
@@ -98,6 +100,7 @@ public:
         _interval = other._interval;
         _cacheInterval = other._cacheInterval;
         _cacheSize = other._cacheSize;
+        _delayInterval = other._delayInterval;
         _pendingTasks.store(0);
         _onDemandLock.store(false);
         _timer = nullptr;
@@ -200,6 +203,7 @@ public:
     unsigned			getMinValues()	const	{ return _minValues; }
     unsigned			getInterval()	const	{ return _interval; }
     unsigned			getCacheSize()	const	{ return _cacheSize; }
+    unsigned            getDelayInterval() const { return _delayInterval; }
     int                 getUnitID()     const   { return _unitID; }
 
     // Setter methods
@@ -213,6 +217,7 @@ public:
     void setMinValues(unsigned minValues)			{ _minValues = minValues; }
     void setInterval(unsigned interval)				{ _interval = interval; }
     void setCacheInterval(unsigned cacheInterval)	{ _cacheInterval = cacheInterval; }
+    void setDelayInterval(unsigned delayInterval)	{ _delayInterval = delayInterval; }
     virtual vector<UnitPtr>& getUnits()             = 0;
 
 protected:
@@ -263,6 +268,8 @@ protected:
     unsigned int _cacheInterval;
     // Real size of the cache, as determined from cacheInterval
     unsigned int _cacheSize;
+    // Time in seconds to wait for before starting computation
+    unsigned int _delayInterval;
     // Number of pending ASIO tasks
     atomic_uint _pendingTasks;
     // Lock used to serialize access to the ondemand functionality

src/analytics/includes/AnalyzerTemplate.h

@@ -166,7 +166,10 @@ public:
         _keepRunning = 1;
         _pendingTasks++;
         _timer->async_wait(bind(&AnalyzerTemplate<S>::computeAsync, this));
-        LOG(info) << "Analyzer " << _name << " started.";
+        if(_delayInterval == 0)
+            LOG(info) << "Analyzer " << _name << " started.";
+        else
+            LOG(info) << "Analyzer " << _name << " will be started after a delay of " << _delayInterval << " seconds.";
     }
 
     /**
@@ -360,6 +363,13 @@ protected:
     *
     */
     virtual void computeAsync() override {
+        // Sleeping until we are allowed to start
+        if(_delayInterval > 0) {
+            sleep(_delayInterval);
+            _delayInterval = 0;
+            LOG(info) << "Analyzer " + _name + ": starting computation after delayed start!";
+        }
+
         try {
             if (_duplicate && _unitID >= 0)
                 compute(_unitID);