[GitHub] [iotdb] ZhanGHanG9991 commented on a diff in pull request #6928: [IOTDB-4073] Add SessionTimeWindowAccessStrategy in UDF

[GitBox <gi...@apache.org>]

ZhanGHanG9991 commented on code in PR #6928:
URL: https://github.com/apache/iotdb/pull/6928#discussion_r945428308


##########
server/src/main/java/org/apache/iotdb/db/mpp/transformation/dag/intermediate/SingleInputColumnMultiReferenceIntermediateLayer.java:
##########
@@ -542,4 +543,120 @@ public RowWindow currentWindow() {
       }
     };
   }
+
+  @Override
+  protected LayerRowWindowReader constructRowSessionTimeWindowReader(
+      SessionTimeWindowAccessStrategy strategy, float memoryBudgetInMB) {
+    final long displayWindowBegin = strategy.getDisplayWindowBegin();
+    final long displayWindowEnd = strategy.getDisplayWindowEnd();
+    final long sessionTimeGap = strategy.getSessionTimeGap();
+
+    final SafetyPile safetyPile = safetyLine.addSafetyPile();
+    final ElasticSerializableTVListBackedSingleColumnWindow window =
+        new ElasticSerializableTVListBackedSingleColumnWindow(tvList);
+
+    return new LayerRowWindowReader() {
+
+      private boolean isFirstIteration = true;
+      private boolean hasAtLeastOneRow = false;
+
+      private long nextWindowTimeBegin = displayWindowBegin;
+      private long nextWindowTimeEnd = 0;
+      private int nextIndexBegin = 0;
+      private int nextIndexEnd = 1;
+
+      @Override
+      public YieldableState yield() throws IOException, QueryProcessException {
+        if (isFirstIteration) {
+          if (tvList.size() == 0) {
+            final YieldableState yieldableState =
+                LayerCacheUtils.yieldPoint(
+                    parentLayerPointReaderDataType, parentLayerPointReader, tvList);
+            if (yieldableState != YieldableState.YIELDABLE) {
+              return yieldableState;
+            }
+          }
+          nextWindowTimeBegin = Math.max(displayWindowBegin, tvList.getTime(0));
+          hasAtLeastOneRow = tvList.size() != 0;
+          isFirstIteration = false;
+        }
+
+        if (!hasAtLeastOneRow || displayWindowEnd <= nextWindowTimeBegin) {
+          return YieldableState.NOT_YIELDABLE_NO_MORE_DATA;
+        }
+
+        while (tvList.getTime(tvList.size() - 1) < displayWindowEnd) {

Review Comment:
   The if statement below while loop has break. We needn't store all data.



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