[rrd4j] Reliably get the latest value, if the filter end date is set …

…to "now" (#16059)

Signed-off-by: Kai Kreuzer <[email protected]>

bundles/org.openhab.persistence.rrd4j/src/main/java/org/openhab/persistence/rrd4j/internal/RRD4jPersistenceService.java

@@ -15,6 +15,7 @@
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.time.Duration;
 import java.time.Instant;
 import java.time.ZoneId;
 import java.time.ZonedDateTime;
@@ -444,15 +445,13 @@ public Iterable<HistoricItem> query(FilterCriteria filter) {
 
         try {
             if (filterBeginDate == null) {
-                // as rrd goes back for years and gets more and more
-                // inaccurate, we only support descending order
-                // and a single return value
-                // if there is no begin date is given - this case is
-                // required specifically for the historicState()
-                // query, which we want to support
+                // as rrd goes back for years and gets more and more inaccurate, we only support descending order
+                // and a single return value if no begin date is given - this case is required specifically for the
+                // historicState() query, which we want to support
                 if (filter.getOrdering() == Ordering.DESCENDING && filter.getPageSize() == 1
                         && filter.getPageNumber() == 0) {
-                    if (filterEndDate == null) {
+                    if (filterEndDate == null || Duration.between(filterEndDate, ZonedDateTime.now()).getSeconds() < db
+                            .getRrdDef().getStep()) {
                         // we are asked only for the most recent value!
                         double lastValue = db.getLastDatasourceValue(DATASOURCE_STATE);
                         if (!Double.isNaN(lastValue)) {