Merge pull request #724 from Fengzdadi/issue-721-varopt-rweight-validation

[Sampling] Validate VarOpt totalRWeight during heapify

Author: leerho

src/main/java/org/apache/datasketches/sampling/VarOptItemsSketch.java

@@ -331,6 +331,11 @@ public static <T> VarOptItemsSketch<T> heapify(final MemorySegment srcSeg,
     if (numPreLongs == Family.VAROPT.getMaxPreLongs()) {
       if (rCount > 0) {
         totalRWeight = extractTotalRWeight(srcSeg);
+        if (Double.isNaN(totalRWeight) || (totalRWeight <= 0.0)) {
+          throw new SketchesArgumentException("Possible Corruption: deserializing in full mode "
+                  + "but invalid R region weight. Found r = " + rCount
+                  + ", R region weight = " + totalRWeight);
+        }
       } else {
         throw new SketchesArgumentException(
                 "Possible Corruption: "

src/test/java/org/apache/datasketches/sampling/VarOptItemsSketchTest.java

@@ -288,6 +288,42 @@ public void checkCorruptSerializedWeight() {
     }
   }
 
+  @Test
+  public void checkCorruptSerializedRWeightNaN() {
+    final int k = 32;
+    final VarOptItemsSketch<Long> sketch = getUnweightedLongsVIS(k, k + 1);
+    final byte[] bytes = sketch.toByteArray(new ArrayOfLongsSerDe());
+    final MemorySegment seg = MemorySegment.ofArray(bytes);
+    assertEquals(PreambleUtil.extractPreLongs(seg), Family.VAROPT.getMaxPreLongs());
+
+    PreambleUtil.insertTotalRWeight(seg, Double.NaN);
+
+    try {
+      VarOptItemsSketch.heapify(seg, new ArrayOfLongsSerDe());
+      fail();
+    } catch (final SketchesArgumentException e) {
+      assertTrue(e.getMessage().contains("invalid R region weight"));
+    }
+  }
+
+  @Test
+  public void checkCorruptSerializedRWeightZero() {
+    final int k = 32;
+    final VarOptItemsSketch<Long> sketch = getUnweightedLongsVIS(k, k + 1);
+    final byte[] bytes = sketch.toByteArray(new ArrayOfLongsSerDe());
+    final MemorySegment seg = MemorySegment.ofArray(bytes);
+    assertEquals(PreambleUtil.extractPreLongs(seg), Family.VAROPT.getMaxPreLongs());
+
+    PreambleUtil.insertTotalRWeight(seg, 0.0);
+
+    try {
+      VarOptItemsSketch.heapify(seg, new ArrayOfLongsSerDe());
+      fail();
+    } catch (final SketchesArgumentException e) {
+      assertTrue(e.getMessage().contains("invalid R region weight"));
+    }
+  }
+
   @Test
   public void checkCumulativeWeight() {
     final int k = 256;