have a source-wide initialize called on experiment start

src/PowerDataSource.h

@@ -42,6 +42,10 @@ class PowerDataSource
 		return std::make_pair(sample.timestamp, strlen);
 	}
 
+	// Called once per data source which have open counters, at start of each experiment (after counter creation)
+	static void initializeExperiment()
+	{ }
+
 private:
 	PowerDataSourceDetail *m_detail;
 };

src/Registry.cpp

@@ -3,6 +3,7 @@
 #include <algorithm>
 #include <map>
 #include <utility>
+#include <set>
 
 static std::map<std::string,Registry::SourceInfo> s_sources;
 static std::map<std::string,std::pair<std::string,std::string>> s_aliases;
@@ -69,9 +70,21 @@ PowerDataSourcePtr Registry::openCounter(const std::string & name)
 
 	PowerDataSourcePtr dataSource = s_sources[sourceName].openCounter(counterName);
 	dataSource->setName(name);
+	s_sources[sourceName].has_at_least_one_open_counter = true;
+
 	return dataSource;
 }
 
+void Registry::callInitializeExperimentsOnOpenSources()
+{
+	for (auto & name_si: s_sources) {
+		if (name_si.second.has_at_least_one_open_counter) {
+			name_si.second.has_at_least_one_open_counter = false;
+			name_si.second.initializeExperiment();
+		}
+	}
+}
+
 bool Registry::isAvailable(const std::string & sourceName, const std::string & counterName)
 {
 	if (s_sources.find(sourceName) == s_sources.end())

src/Registry.h

@@ -16,11 +16,14 @@ class Registry
 
 		// Postpone registration to Registry::setup
 		std::function<void(SourceInfo & si)> setup;
+		std::function<void()> initializeExperiment;
 
 		bool available() const
 		{
 			return !availableCounters.empty();
 		}
+
+		bool has_at_least_one_open_counter;
 	};
 
 	static void setup();
@@ -30,11 +33,13 @@ class Registry
 	{
 		SourceInfo sourceInfo;
 
+		sourceInfo.has_at_least_one_open_counter = false;
 		sourceInfo.setup = [](SourceInfo & si){
 			si.availableCounters = DataSourceT::detectAvailableCounters();
 			for (const auto & alias: DataSourceT::possibleAliases()) {
 				registerAlias(alias.first, DataSourceT::sourceName(), alias.second);
 			}
+			si.initializeExperiment = [](){ DataSourceT::initializeExperiment(); };
 		};
 
 		sourceInfo.openCounter = [](const std::string & counterName){
@@ -48,6 +53,8 @@ class Registry
 	static std::vector<std::pair<std::string,std::string>> availableAliases();
 	static PowerDataSourcePtr openCounter(const std::string & name);
 
+	static void callInitializeExperimentsOnOpenSources();
+
 private:
 	static int registerSource(const std::string & sourceName, const SourceInfo & sourceInfo);
 	static bool isAvailable(const std::string & sourceName, const std::string & counterName);

src/Sampler.cpp

@@ -62,6 +62,8 @@ Sampler::Sampler(std::chrono::milliseconds interval, const std::vector<std::stri
 	m_detail->worker = std::thread([=]{ run(
 		settings::continuous_print_flag ? cptick : atick
 	); });
+
+	Registry::callInitializeExperimentsOnOpenSources();
 }
 
 Sampler::~Sampler()

src/data_sources/AppleM.cpp

@@ -151,17 +151,16 @@ class M1nPointSharedDetail
 
 	std::map<std::string, IOReportChannelRef> counter_to_channel;
 
-	// I hate this function. It should only be called once per experiment run or for the entire progam
-	// PinPoint should be adapted to call a source-class-wide "start now, for real" function on registered sources
-	void update_subscriptions()
+	void initializeExperiment()
 	{
 		CFMutableDictionaryRef _sub_chans;
 		active_subscription = cf_shared(IOReportCreateSubscription(NULL, desired_channels.get(), &_sub_chans, 0, 0));
 		if (!active_subscription) {
 			throw std::runtime_error("Cannot create IOReport subscription");
 		}
 		subscribed_channels = cf_shared(_sub_chans);
-		initialize_experiment();
+
+		initial_samples = _pull_raw_samples();
 	}
 
 	void read_and_update_all_open_sources()
@@ -198,11 +197,6 @@ class M1nPointSharedDetail
 		}
 		return res;
 	}
-
-	void initialize_experiment()
-	{
-		initial_samples = _pull_raw_samples();
-	}
 };
 
 static M1nPointSharedDetail m1npoint;
@@ -237,7 +231,6 @@ AppleM::AppleM(const std::string & key) :
 
 	m_detail->last_value_key = IOReportChannelGetChannelID(channel);
 	m1npoint.last_values[m_detail->last_value_key] = AppleMDetail::kOutdated;
-	m1npoint.update_subscriptions();
 }
 
 EnergySample AppleM::read_energy()
@@ -284,6 +277,11 @@ Aliases AppleM::possibleAliases()
 	return Aliases();
 }
 
+void AppleM::initializeExperiment()
+{
+	m1npoint.initializeExperiment();
+}
+
 PINPOINT_REGISTER_DATA_SOURCE(AppleM)
 
 #endif

src/data_sources/AppleM.h

@@ -22,6 +22,8 @@ class AppleM: public EnergyDataSource
 
 	virtual ~AppleM();
 
+	static void initializeExperiment();
+
 private:
 	AppleM(const std::string & key);