Adjust seen_samples for dejittering when flushing samples from an inlet, i.e. not pulling them (#117)

Author: tstenner

src/stream_inlet_impl.h

@@ -305,7 +305,11 @@ class stream_inlet_impl {
 	std::size_t samples_available() { return data_receiver_.samples_available(); }
 
 	/// Flush the queue, return the number of dropped samples
-	uint32_t flush() { return data_receiver_.flush(); }
+	uint32_t flush() {
+		int nskipped = data_receiver_.flush();
+		postprocessor_.skip_samples(nskipped);
+		return nskipped;
+	}
 
 	/** Query whether the clock was potentially reset since the last call to was_clock_reset().
 	 *

src/time_postprocessor.cpp

@@ -45,6 +45,11 @@ double time_postprocessor::process_timestamp(double value) {
 		return process_internal(value);
 }
 
+void time_postprocessor::skip_samples(uint32_t skipped_samples) {
+	if (options_ & proc_dejitter && dejitter.smoothing_applicable())
+		dejitter.samples_since_t0_ += skipped_samples;
+}
+
 double time_postprocessor::process_internal(double value) {
 	// --- clock synchronization ---
 	if (options_ & proc_clocksync) {

src/time_postprocessor.h

@@ -61,6 +61,9 @@ class time_postprocessor {
 	/// Override the half-time (forget factor) of the time-stamp smoothing.
 	void smoothing_halftime(float value) { halftime_ = value; }
 
+	/// Inform the post processor some samples were skipped
+	void skip_samples(uint32_t skipped_samples);
+
 private:
 	/// Internal function to process a time stamp.
 	double process_internal(double value);

testing/test_ext_DataType.cpp

@@ -3,6 +3,7 @@
 #include <catch2/catch.hpp>
 #include <cstdint>
 #include <lsl_cpp.h>
+#include <thread>
 
 TEMPLATE_TEST_CASE(
 	"datatransfer", "[datatransfer][basic]", char, int16_t, int32_t, int64_t, float, double) {
@@ -69,3 +70,35 @@ TEST_CASE("TypeConversion", "[datatransfer][types][basic]") {
 		CHECK(result == val);
 	}
 }
+
+TEST_CASE("Flush", "[datatransfer][basic]") {
+	Streampair sp{create_streampair(
+		lsl::stream_info("FlushTest", "flush", 1, 1, lsl::cf_double64, "FlushTest"))};
+	sp.in_.set_postprocessing(lsl::post_dejitter);
+
+	const int n=20;
+
+	std::thread pusher([&](){
+		double data = lsl::local_clock();
+		for(int i=0; i<n; ++i) {
+			sp.out_.push_sample(&data, data, true);
+			std::this_thread::sleep_for(std::chrono::milliseconds(100));
+			data+=.1;
+		}
+	});
+
+	double data_in, ts_in;
+	ts_in = sp.in_.pull_sample(&data_in, 1.);
+	REQUIRE(ts_in == Approx(data_in));
+	std::this_thread::sleep_for(std::chrono::milliseconds(700));
+	int pulled = sp.in_.flush() + 1;
+
+	for(; pulled < n; ++pulled) {
+		INFO(pulled);
+		ts_in = sp.in_.pull_sample(&data_in, 1.);
+		REQUIRE(ts_in == Approx(data_in));
+	}
+
+	pusher.join();
+	//sp.in_.set_postprocessing(lsl::post_none);
+}