From dee86c0f52ea411e7bd8e2fcc058e3d979574fba Mon Sep 17 00:00:00 2001
From: Tuukka Lehtonen <tuukka.lehtonen@semantum.fi>
Date: Thu, 30 Apr 2020 00:55:09 +0300
Subject: [PATCH] Fixed CSVFormatter mind floating point inaccuracy when
 resampling

These changes prevent the resampling export mode from dropping samples
that have timestamps closer than 1e-13 sec to the last exported sample
time stamp.

gitlab #529

(cherry picked from commit 4a7923add5be874cc352faf9afd0f627794de32e)
---
 .../simantics/history/csv/CSVFormatter.java   | 49 +++++++++++++++++--
 1 file changed, 45 insertions(+), 4 deletions(-)

diff --git a/bundles/org.simantics.history/src/org/simantics/history/csv/CSVFormatter.java b/bundles/org.simantics.history/src/org/simantics/history/csv/CSVFormatter.java
index 6cc7a2a6f..b04e0dd37 100644
--- a/bundles/org.simantics.history/src/org/simantics/history/csv/CSVFormatter.java
+++ b/bundles/org.simantics.history/src/org/simantics/history/csv/CSVFormatter.java
@@ -38,6 +38,23 @@ import org.simantics.history.util.ValueBand;
  */
 public class CSVFormatter {
 
+	/**
+	 * This is the tolerance used to decide whether or not the last data point of
+	 * the exported items is included in the exported material or not. If
+	 * <code>0 <= (t - t(lastDataPoint) < {@value #RESAMPLING_END_TIMESTAMP_INCLUSION_TOLERANCE}</code>
+	 * is true, then the last exported data point will be
+	 * <code>lastDataPoint</code>, with timestamp <code>t(lastDataPoint)</code> even
+	 * if <code>t > t(lastDataPoint)</code>.
+	 * 
+	 * <p>
+	 * This works around problems where floating point inaccuracy causes a data
+	 * point to be left out from the the export when it would be fair for the user
+	 * to expect the data to be exported would contain a point with time stamp
+	 * <code>9.999999999999996</code> when sampling with time-step <code>1.0</code>
+	 * starting from time <code>0.0</code>.
+	 */
+	private static final double RESAMPLING_END_TIMESTAMP_INCLUSION_TOLERANCE = 1e-13;
+
 	List<Item> items = new ArrayList<Item>();
 	double from = -Double.MAX_VALUE;
 	double end  =  Double.MAX_VALUE;
@@ -329,6 +346,13 @@ public class CSVFormatter {
 			BigDecimal bigTime = new BigDecimal(String.valueOf(time));
 			BigDecimal bigTimeStep = new BigDecimal(String.valueOf(timeStep));
 
+			// Loop kill-switch for the case where timeStep > 0
+			boolean breakAfterNextWrite = false;
+
+//			System.out.println("time:     " + time);
+//			System.out.println("timeStep: " + timeStep);
+//			System.out.println("_end:     " + Double.toString(_end));
+
 			for (Item i : items) i.iter.gotoTime(time);
 			do {
 				if ( monitor!=null && monitor.isCanceled() ) return;
@@ -394,10 +418,26 @@ public class CSVFormatter {
 
 				sb.append( lineFeed );
 
-	            // Read next values, and the following times
-	            if ( timeStep>0.0 ) {
-	            	bigTime = bigTime.add(bigTimeStep);
-	            	time = bigTime.doubleValue();
+				if (breakAfterNextWrite)
+					break;
+
+				// Read next values, and the following times
+				if ( timeStep>0.0 ) {
+					bigTime = bigTime.add(bigTimeStep);
+					time = bigTime.doubleValue();
+
+					// gitlab #529: prevent last data point from getting dropped
+					// due to small imprecisions in re-sampling mode.
+					double diff = time - _end;
+					if (diff > 0 && diff <= RESAMPLING_END_TIMESTAMP_INCLUSION_TOLERANCE) {
+						time = _end;
+						breakAfterNextWrite = true;
+						// Take floating point inaccuracy into account when re-sampling
+						// to prevent the last data point from being left out if there
+						// is small-enough imprecision in the last data point time stamp
+						// to be considered negligible compared to expected stepped time.
+					}
+
 	            } else {
 	            	// Get smallest end time that is larger than current time
 	            	Double nextTime = null;
@@ -420,6 +460,7 @@ public class CSVFormatter {
             		if(contains(i, time)) hasMore = true;
             	}
             	
+            	//System.out.println("hasMore @ " + time + " (" + bigTime + ") = " + hasMore);
             	if(!hasMore) break;
             	
 	        } while (time<=_end);
-- 
2.47.1