Switch interval validation to accept DateHistogramInterval

Author: gmarouli

server/src/main/java/org/elasticsearch/action/downsample/DownsampleConfig.java

@@ -144,25 +144,28 @@ public DownsampleConfig(final StreamInput in) throws IOException {
      * - The target interval needs to be a multiple of the source interval
      * throws an IllegalArgumentException to signal that the target interval is not acceptable
      */
-    public static void validateSourceAndTargetIntervals(DownsampleConfig source, DownsampleConfig target) {
-        long sourceMillis = source.fixedInterval.estimateMillis();
-        long targetMillis = target.fixedInterval.estimateMillis();
+    public static void validateSourceAndTargetIntervals(
+        DateHistogramInterval sourceFxedInterval,
+        DateHistogramInterval targetFixedInterval
+    ) {
+        long sourceMillis = sourceFxedInterval.estimateMillis();
+        long targetMillis = targetFixedInterval.estimateMillis();
         if (sourceMillis >= targetMillis) {
             // Downsampling interval must be greater than source interval
             throw new IllegalArgumentException(
                 "Downsampling interval ["
-                    + target.fixedInterval
+                    + targetFixedInterval
                     + "] must be greater than the source index interval ["
-                    + source.fixedInterval
+                    + sourceFxedInterval
                     + "]."
             );
         } else if (targetMillis % sourceMillis != 0) {
             // Downsampling interval must be a multiple of the source interval
             throw new IllegalArgumentException(
                 "Downsampling interval ["
-                    + target.fixedInterval
+                    + targetFixedInterval
                     + "] must be a multiple of the source index interval ["
-                    + source.fixedInterval
+                    + sourceFxedInterval
                     + "]."
             );
         }

x-pack/plugin/downsample/src/main/java/org/elasticsearch/xpack/downsample/TransportDownsampleAction.java

@@ -863,15 +863,16 @@ private static void validateDownsamplingConfiguration(
 
         Map<String, String> meta = timestampFieldType.meta();
         if (meta.isEmpty() == false) {
-            String interval = meta.get(config.getIntervalType());
-            DownsampleConfig.SamplingMethod sourceSamplingMethod = DownsampleConfig.SamplingMethod.fromIndexMetadata(sourceIndexMetadata);
-            if (interval != null) {
+            String sourceInterval = meta.get(config.getIntervalType());
+            if (sourceInterval != null) {
                 try {
-                    DownsampleConfig sourceConfig = new DownsampleConfig(new DateHistogramInterval(interval), sourceSamplingMethod);
-                    DownsampleConfig.validateSourceAndTargetIntervals(sourceConfig, config);
+                    DownsampleConfig.validateSourceAndTargetIntervals(new DateHistogramInterval(sourceInterval), config.getFixedInterval());
                 } catch (IllegalArgumentException exception) {
                     e.addValidationError("Source index is a downsampled index. " + exception.getMessage());
                 }
+                DownsampleConfig.SamplingMethod sourceSamplingMethod = DownsampleConfig.SamplingMethod.fromIndexMetadata(
+                    sourceIndexMetadata
+                );
                 if (Objects.equals(sourceSamplingMethod, config.getSamplingMethodOrDefault()) == false) {
                     e.addValidationError(
                         "Source index is a downsampled index. Downsampling method ["