Added lookahead scheduler.

Most scheduler now use estimated finish time instead of predicted execution time.

src/scheduling/AbstractScheduler.cpp

@@ -67,6 +67,7 @@ void SchedulerBase::notifyWEPUpdate(wep::WorkflowExecutionPlan& wep, std::set<we
 
 bool SchedulerBase::executeSchedulingDecision(WepMapEntry& wepe, std::shared_ptr<SchedulingDecision> sd, std::unique_lock<std::mutex>& schedulerLock) noexcept {
 	wepe.decisions.insert(sd);
+	scheduledTasks[sd->resource].push_back(sd);
 	schedulerLock.unlock();
 	sd->activityInstance->setSchedulingDecision(sd);
 	if (sd->activityInstance->activityType() == wfs::ActivityType::Atomic) {
@@ -92,6 +93,13 @@ void SchedulerBase::notifySchedulingDecisionStatusUpdate(std::shared_ptr<Schedul
 		std::unique_lock<std::mutex> objLock(schedulerMutex);
 		auto wepe = wepMap.find(sd->wep);
 		if (wepe != wepMap.end()) {
+			auto& innerMap = scheduledTasks[sd->resource];
+			for (auto i = innerMap.begin(); i != innerMap.end(); i++) {
+				if (*i == sd) {
+					innerMap.erase(i);
+					break;
+				}
+			}
 			_notifySchedulingDecisionStatusUpdate(wepe->second, sd, objLock);
 			// Notify enactment engine
 			auto ee = wepe->second.engine;
@@ -102,6 +110,36 @@ void SchedulerBase::notifySchedulingDecisionStatusUpdate(std::shared_ptr<Schedul
 	}
 }
 
+double SchedulerBase::_getResourceEstimatedAvailableTime(resource::ComputingResource* resource) {
+	if (resource->getFreeSlotCount() > 0) {
+		return 0.0;
+	} else {
+		// Calculating the estimated available time for resources with more than 1 slot is not trivial
+		// Here we are employing a heuristic that partitions the scheduled tasks into chunks the size of the maximal slot count,
+		// takes the minimum time of each chunk and adds them together.
+		unsigned i = 0;
+		double eat = 0;
+		double minTime = -1;
+		auto& tasks = scheduledTasks[resource];
+		for (auto t : tasks) {
+			i++;
+			if (minTime < 0) {
+				minTime = t->getPrediction().getExecutionTime().getValue();
+			} else {
+				if (i > resource->getMaxSlotCount()) {
+					eat += minTime;
+					i = 0;
+					minTime = t->getPrediction().getExecutionTime().getValue();
+				} else {
+					if (t->getPrediction().getExecutionTime().getValue() < minTime) {
+						minTime = t->getPrediction().getExecutionTime().getValue();
+					}
+				}
+			}
+		}
+		return eat;
+	}
+}
 
 } /* namespace scheduling */
 } /* namespace wfr */