From 784f6c75bf8d878b395b8eb7b5e92fa24d9b32ba Mon Sep 17 00:00:00 2001
From: Soeren Apel <soeren@apelpie.net>
Date: Mon, 12 Mar 2018 15:58:06 +0100
Subject: [PATCH] SignalBase: Speed up conversion and prevent leaving samples
 unconverted

Unconverted samples can happen due to a race condition: being notified
of new samples coming in is ignored when the thread is already executing.
If these notifications however were the last ones sent out because the
segment was completed right after, the currently ongoing conversion
will finish but not be restarted with the final sample range.

With this patch, this is prevented.
---
 pv/data/signalbase.cpp | 47 ++++++++++++++++++++++++++++++++++--------
 pv/data/signalbase.hpp |  2 ++
 2 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/pv/data/signalbase.cpp b/pv/data/signalbase.cpp
index 7746ab4..54063b1 100644
--- a/pv/data/signalbase.cpp
+++ b/pv/data/signalbase.cpp
@@ -439,14 +439,9 @@ bool SignalBase::conversion_is_a2l() const
 		(conversion_type_ == A2LConversionBySchmittTrigger)));
 }
 
-void SignalBase::convert_single_segment(AnalogSegment *asegment, LogicSegment *lsegment)
+void SignalBase::convert_single_segment_range(AnalogSegment *asegment,
+	LogicSegment *lsegment, uint64_t start_sample, uint64_t end_sample)
 {
-	uint64_t start_sample, end_sample;
-	start_sample = end_sample = 0;
-
-	start_sample = lsegment->get_sample_count();
-	end_sample = asegment->get_sample_count();
-
 	if (end_sample > start_sample) {
 		tie(min_value_, max_value_) = asegment->get_min_max();
 
@@ -541,6 +536,38 @@ void SignalBase::convert_single_segment(AnalogSegment *asegment, LogicSegment *l
 	}
 }
 
+void SignalBase::convert_single_segment(AnalogSegment *asegment, LogicSegment *lsegment)
+{
+	uint64_t start_sample, end_sample, old_end_sample;
+	start_sample = end_sample = 0;
+	bool complete_state, old_complete_state;
+
+	start_sample = lsegment->get_sample_count();
+	end_sample = asegment->get_sample_count();
+	complete_state = asegment->is_complete();
+
+	// Don't do anything if the segment is still being filled and the sample count is too small
+	if ((!complete_state) && (end_sample - start_sample < ConversionBlockSize))
+		return;
+
+	do {
+		convert_single_segment_range(asegment, lsegment, start_sample, end_sample);
+
+		old_end_sample = end_sample;
+		old_complete_state = complete_state;
+
+		start_sample = lsegment->get_sample_count();
+		end_sample = asegment->get_sample_count();
+		complete_state = asegment->is_complete();
+
+		// If the segment has been incomplete when we were called and has been
+		// completed in the meanwhile, we convert the remaining samples as well.
+		// Also, if a sufficient number of samples was added in the meanwhile,
+		// we do another round of sample conversion.
+	} while ((complete_state != old_complete_state) ||
+		(end_sample - old_end_sample >= ConversionBlockSize));
+}
+
 void SignalBase::conversion_thread_proc()
 {
 	shared_ptr<Analog> analog_data;
@@ -582,7 +609,9 @@ void SignalBase::conversion_thread_proc()
 	do {
 		convert_single_segment(asegment, lsegment);
 
-		if (analog_data->analog_segments().size() > logic_data->logic_segments().size()) {
+		// Only advance to next segment if the current input segment is complete
+		if (asegment->is_complete() &&
+			analog_data->analog_segments().size() > logic_data->logic_segments().size()) {
 			// There are more segments to process
 			segment_id++;
 
@@ -600,7 +629,7 @@ void SignalBase::conversion_thread_proc()
 
 			lsegment = logic_data->logic_segments().back().get();
 		} else {
-			// No more segments to process, wait for data or interrupt
+			// No more samples/segments to process, wait for data or interrupt
 			if (!conversion_interrupt_) {
 				unique_lock<mutex> input_lock(conversion_input_mutex_);
 				conversion_input_cond_.wait(input_lock);
diff --git a/pv/data/signalbase.hpp b/pv/data/signalbase.hpp
index 47c593f..efe4a54 100644
--- a/pv/data/signalbase.hpp
+++ b/pv/data/signalbase.hpp
@@ -280,6 +280,8 @@ private:
 	uint8_t convert_a2l_schmitt_trigger(float lo_thr, float hi_thr,
 		float value, uint8_t &state);
 
+	void convert_single_segment_range(AnalogSegment *asegment,
+		LogicSegment *lsegment, uint64_t start_sample, uint64_t end_sample);
 	void convert_single_segment(pv::data::AnalogSegment *asegment,
 		pv::data::LogicSegment *lsegment);
 	void conversion_thread_proc();
-- 
2.30.2