Merge 75e5d7f3ef into 10557d7ffe

src/java/org/apache/cassandra/service/StorageService.java

@@ -3518,14 +3518,21 @@ public class StorageService extends NotificationBroadcasterSupport implements IE
         long totalRowCountEstimate = cfs.estimatedKeysForRange(range);
 
         // splitCount should be much smaller than number of key samples, to avoid huge sampling error
-        int minSamplesPerSplit = 4;
-        int maxSplitCount = keys.size() / minSamplesPerSplit + 1;
-        int splitCount = Math.max(1, Math.min(maxSplitCount, (int)(totalRowCountEstimate / keysPerSplit)));
+        int splitCount = calculateSplitCount(keysPerSplit, totalRowCountEstimate, keys.size());
 
         List<Token> tokens = keysToTokens(range, keys);
         return getSplits(tokens, splitCount, cfs);
     }
 
+    static int calculateSplitCount(int keysPerSplit, long totalRowCountEstimate, int numberOfKeys)
+    {
+        int minSamplesPerSplit = 4;
+        long maxSplitCount = numberOfKeys / minSamplesPerSplit + 1;
+        long splitCount = totalRowCountEstimate / keysPerSplit;
+        int splitCountWithLimit = (int) Math.min(maxSplitCount, splitCount);
+        return Math.max(1, splitCountWithLimit);
+    }
+
     private List<Pair<Range<Token>, Long>> getSplits(List<Token> tokens, int splitCount, ColumnFamilyStore cfs)
     {
         double step = (double) (tokens.size() - 1) / splitCount;

test/unit/org/apache/cassandra/service/StorageServiceTest.java

@@ -295,4 +295,46 @@ public class StorageServiceTest extends TestBaseImpl
             assertEquals("Cannot specify tokens without keyspace.", ex.getMessage());
         }
     }
+
+    @Test
+    public void calculateSplitCount_SmallRowCount_NotLimited()
+    {
+        int result = StorageService.calculateSplitCount(2, 8, 40);
+        assertEquals(4, result);
+    }
+
+    @Test
+    public void calculateSplitCount_ZeroRowCount_ReturnsMinimumOfOne()
+    {
+        int result = StorageService.calculateSplitCount(1, 0, 40);
+        assertEquals(1, result);
+    }
+
+    @Test
+    public void calculateSplitCount_ForLargeRowCount_LimitsResult()
+    {
+        int result = StorageService.calculateSplitCount(2, 100, 40);
+        assertEquals(11, result);
+    }
+
+    @Test
+    public void calculateSplitCount_ForMaxIntegerRowCount_LimitsResult()
+    {
+        int result = StorageService.calculateSplitCount(1, Integer.MAX_VALUE, 4);
+        assertEquals(2, result);
+    }
+
+    @Test
+    public void calculateSplitCount_ForOverflowingRowCount_LimitsResult()
+    {
+        int result = StorageService.calculateSplitCount(1, Integer.MAX_VALUE + 1L, 4);
+        assertEquals(2, result);
+    }
+
+    @Test
+    public void calculateSplitCount_ForMaxLongRowCount_LimitsResult()
+    {
+        int result = StorageService.calculateSplitCount(1, Long.MAX_VALUE, 4);
+        assertEquals(2, result);
+    }
 }