Clean up CodeQL alerts in library and test code

src/main/java/org/apache/datasketches/common/Util.java

@@ -175,22 +175,33 @@ public static byte[] longToBytes(final long v, final byte[] arr) {
 
   /** Byte array conversions *******************/
 
-  static long[] convertToLongArray(final byte[] byteArr, final boolean littleEndian) {
+  /**
+   * Converts a byte array to an array of longs, taking the bytes in groups of 8.
+   *
+   * <p>Each group of 8 bytes becomes one long. If <i>bigEndian</i> is false, the first byte of a group
+   * is the least significant byte of its long (Little-Endian). If true, the first byte of a group is the
+   * most significant byte (Big-Endian).</p>
+   *
+   * <p>If the length of the byte array is not a multiple of 8, the final group has fewer than 8 bytes.
+   * Those bytes are converted in the same byte order and are flush right in the final long; its unused
+   * high-order bytes are zero. For example, the final group {9, 10, 11, 12} becomes
+   * 0x000000000C0B0A09 if Little-Endian and 0x00000000090A0B0C if Big-Endian.</p>
+   *
+   * @param byteArr the given byte array
+   * @param bigEndian if true, the bytes of each group are in Big-Endian order, otherwise Little-Endian.
+   * @return an array of ceiling(byteArr.length / 8) longs.
+   */
+  static long[] convertToLongArray(final byte[] byteArr, final boolean bigEndian) {
     final int len = byteArr.length;
     final long[] longArr = new long[(len / 8) + ((len % 8) != 0 ? 1 : 0)];
     int off = 0;
     int longArrIdx = 0;
     while (off < len) {
-      final int rem = Math.min(len - 1 - off, 7);
+      final int end = Math.min(off + 8, len); //exclusive
       long tgt = 0;
-      if (littleEndian) {
-        for (int j = off + rem, k = 0; j >= off; --j, k++) {
-          tgt |= (byteArr[j] & 0XFFL) << (k * 8);
-        }
-      } else { //BE
-        for (int j = off + rem, k = rem; j >= off; --j, k--) {
-          tgt |= (byteArr[j] & 0XFFL) << (k * 8);
-        }
+      for (int j = off; j < end; j++) {
+        final int shift = bigEndian ? (end - 1 - j) * 8 : (j - off) * 8;
+        tgt |= (byteArr[j] & 0XFFL) << shift;
       }
       off += 8;
       longArr[longArrIdx++] = tgt;

src/main/java/org/apache/datasketches/kll/KllPreambleUtil.java

@@ -139,6 +139,8 @@ final class KllPreambleUtil {
 
   private KllPreambleUtil() {}
 
+  private static final String ITEMS_SERDE_MSG = "SerDe parameter must not be null for ITEMS_SKETCH.";
+
   // Preamble byte addresses
   static final int PREAMBLE_INTS_BYTE_ADR     = 0;
   static final int SER_VER_BYTE_ADR           = 1;
@@ -224,7 +226,7 @@ static String toString(final MemorySegment seg, final SketchType sketchType, fin
   static <T> String toString(final MemorySegment seg, final SketchType sketchType, final boolean includeData,
       final ArrayOfItemsSerDe<T> serDe) {
     if (sketchType == KLL_ITEMS_SKETCH) {
-      Objects.requireNonNull(serDe, "SerDe parameter must not be null for ITEMS_SKETCH.");
+      Objects.requireNonNull(serDe, ITEMS_SERDE_MSG);
     }
     final KllMemorySegmentValidate segVal = new KllMemorySegmentValidate(seg, sketchType, serDe);
     final SketchStructure myStructure = segVal.sketchStructure;
@@ -359,10 +361,11 @@ static <T> String toString(final MemorySegment seg, final SketchType sketchType,
           sb.append(seg.get(JAVA_LONG_UNALIGNED, offsetBytes)).append(LS);
           offsetBytes += typeBytes;
         } else {  //ITEMS_SKETCH
-          sb.append(serDe.deserializeFromMemorySegment(seg, offsetBytes, 1)[0]).append(LS);
-          offsetBytes += serDe.sizeOf(seg, offsetBytes, 1);
-          sb.append(serDe.deserializeFromMemorySegment(seg, offsetBytes, 1)[0]).append(LS);
-          offsetBytes += serDe.sizeOf(seg, offsetBytes, 1);
+          final ArrayOfItemsSerDe<T> itemsSerDe = Objects.requireNonNull(serDe, ITEMS_SERDE_MSG);
+          sb.append(itemsSerDe.deserializeFromMemorySegment(seg, offsetBytes, 1)[0]).append(LS);
+          offsetBytes += itemsSerDe.sizeOf(seg, offsetBytes, 1);
+          sb.append(itemsSerDe.deserializeFromMemorySegment(seg, offsetBytes, 1)[0]).append(LS);
+          offsetBytes += itemsSerDe.sizeOf(seg, offsetBytes, 1);
         }
 
         sb.append("RETAINED DATA").append(LS);
@@ -383,9 +386,10 @@ static <T> String toString(final MemorySegment seg, final SketchType sketchType,
             offsetBytes += typeBytes;
           }
         } else { //ITEMS_SKETCH
-          final T[] itemsArr = serDe.deserializeFromMemorySegment(seg, offsetBytes, retainedItems);
+          final ArrayOfItemsSerDe<T> itemsSerDe = Objects.requireNonNull(serDe, ITEMS_SERDE_MSG);
+          final T[] itemsArr = itemsSerDe.deserializeFromMemorySegment(seg, offsetBytes, retainedItems);
           for (int i = 0; i < itemsArr.length; i++) {
-            sb.append(i + ", " + serDe.toString(itemsArr[i])).append(LS);
+            sb.append(i + ", " + itemsSerDe.toString(itemsArr[i])).append(LS);
           }
         }
 
@@ -399,7 +403,8 @@ static <T> String toString(final MemorySegment seg, final SketchType sketchType,
           } else if (sketchType == KLL_LONGS_SKETCH) {
             sb.append(seg.get(JAVA_LONG_UNALIGNED, DATA_START_ADR_SINGLE_ITEM)).append(LS);
           } else { //ITEMS_SKETCH
-            sb.append(serDe.deserializeFromMemorySegment(seg, DATA_START_ADR_SINGLE_ITEM, 1)[0]).append(LS);
+            final ArrayOfItemsSerDe<T> itemsSerDe = Objects.requireNonNull(serDe, ITEMS_SERDE_MSG);
+            sb.append(itemsSerDe.deserializeFromMemorySegment(seg, DATA_START_ADR_SINGLE_ITEM, 1)[0]).append(LS);
           }
 
       } else { //COMPACT_EMPTY

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

@@ -288,8 +288,8 @@ public String toString() {
   // gadgetBytes will be null only if gadget_ == null AND empty == true
   public byte[] toByteArray(final ArrayOfItemsSerDe<T> serDe, final Class<?> clazz) {
     final int preLongs, outBytes;
-    final boolean empty = gadget_ == null;
-    final byte[] gadgetBytes = (gadget_ != null ? gadget_.toByteArray(serDe, clazz) : null);
+    final byte[] gadgetBytes = (gadget_ == null) ? null : gadget_.toByteArray(serDe, clazz);
+    final boolean empty = gadgetBytes == null;
 
     if (empty) {
       preLongs = Family.RESERVOIR_UNION.getMinPreLongs();

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

@@ -241,8 +241,8 @@ public String toString() {
   // gadgetBytes will be null only if gadget_ == null AND empty == true
   public byte[] toByteArray() {
     final int preLongs, outBytes;
-    final boolean empty = gadget_ == null;
-    final byte[] gadgetBytes = (gadget_ != null ? gadget_.toByteArray() : null);
+    final byte[] gadgetBytes = (gadget_ == null) ? null : gadget_.toByteArray();
+    final boolean empty = gadgetBytes == null;
 
     if (empty) {
       preLongs = Family.RESERVOIR_UNION.getMinPreLongs();

src/test/java/org/apache/datasketches/common/UtilTest.java

@@ -58,6 +58,9 @@
 import static org.testng.Assert.assertTrue;
 import static org.testng.Assert.fail;
 
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+
 import org.testng.Assert;
 import org.testng.annotations.Test;
 
@@ -431,22 +434,39 @@ public void checkExactLog2OfIntWithArg() {
   static void checkConvertToLongArray() {
     final byte[] arr = {1,2,3,4,5,6,7,8,9,10,11,12};
 
+    //Little-Endian; the 4-byte tail is flush right
     long[] out = convertToLongArray(arr, false);
+    assertEquals(out.length, 2);
     String s = zeroPad(Long.toHexString(out[0]), 16);
     assertEquals(s, "0807060504030201");
     s = zeroPad(Long.toHexString(out[1]), 16);
     assertEquals(s, "000000000c0b0a09");
 
+    //Big-Endian; the 4-byte tail is flush right
     out = convertToLongArray(arr, true);
+    assertEquals(out.length, 2);
     s = zeroPad(Long.toHexString(out[0]), 16);
     assertEquals(s, "0102030405060708");
     s = zeroPad(Long.toHexString(out[1]), 16);
     assertEquals(s, "00000000090a0b0c");
+
+    //full groups agree with ByteBuffer in both byte orders
+    final byte[] arr16 = new byte[16];
+    for (int i = 0; i < 16; i++) { arr16[i] = (byte) (0xF0 + i); } //high bit set, to check sign handling
+    for (final boolean bigEndian : new boolean[] {false, true}) {
+      final ByteBuffer bb = ByteBuffer.wrap(arr16).order(bigEndian ? ByteOrder.BIG_ENDIAN : ByteOrder.LITTLE_ENDIAN);
+      out = convertToLongArray(arr16, bigEndian);
+      assertEquals(out.length, 2);
+      assertEquals(out[0], bb.getLong(0));
+      assertEquals(out[1], bb.getLong(8));
+    }
+
+    assertEquals(convertToLongArray(new byte[0], true).length, 0);
   }
 
   @Test
   static void checkCeilingMultiple2expK() {
-    final long n = (1 << 36) - 1L;
+    final long n = (1L << 36) - 1L;
     final int k = 6;
     final long v = ceilingMultiple2expK(n, k);
     final long v2 = (long)Math.ceil(n / (double)(1 << k));

src/test/java/org/apache/datasketches/common/positional/PositionalSegmentTest.java

@@ -40,10 +40,10 @@ public void checkBytes() {
     final MemorySegment seg = MemorySegment.ofArray(new byte[n * Byte.BYTES]);
     final PositionalSegment posSeg = PositionalSegment.wrap(seg);
     for (int i = 0; i < (n/2); i++) { posSeg.setByte((byte)i); }
-    for (int i = n/2; i < n; i++) { posSeg.setByte(i * Byte.BYTES, (byte)i); }
+    for (int i = n/2; i < n; i++) { posSeg.setByte((long) i * Byte.BYTES, (byte)i); }
     posSeg.resetPosition();
     for (int i = 0; i < n; i++) {
-      final byte v1 = posSeg.getByte(i * Byte.BYTES);
+      final byte v1 = posSeg.getByte((long) i * Byte.BYTES);
       final byte v2 = posSeg.getByte();
       assertEquals(v1, v2);
       assertEquals(v2, i);
@@ -57,7 +57,7 @@ public void checkBytes() {
 
     final MemorySegment seg2 = posSeg.getMemorySegment();
     for (int i = 0; i < n; i++) {
-      assertEquals(seg2.get(JAVA_BYTE, i * Byte.BYTES), (byte)i);
+      assertEquals(seg2.get(JAVA_BYTE, (long) i * Byte.BYTES), (byte)i);
     }
   }
 
@@ -67,10 +67,10 @@ public void checkChars() {
     final MemorySegment seg = MemorySegment.ofArray(new byte[n * Character.BYTES]);
     final PositionalSegment posSeg = PositionalSegment.wrap(seg);
     for (int i = 0; i < (n/2); i++) { posSeg.setChar((char)i); }
-    for (int i = n/2; i < n; i++) { posSeg.setChar(i * Character.BYTES, (char)i); }
+    for (int i = n/2; i < n; i++) { posSeg.setChar((long) i * Character.BYTES, (char)i); }
     posSeg.resetPosition();
     for (int i = 0; i < n; i++) {
-      final int v1 = posSeg.getChar(i *Character.BYTES);
+      final int v1 = posSeg.getChar((long) i * Character.BYTES);
       final int v2 = posSeg.getChar();
       assertEquals(v1, v2);
       assertEquals(v2, i);
@@ -84,7 +84,7 @@ public void checkChars() {
 
     final MemorySegment seg2 = posSeg.getMemorySegment();
     for (int i = 0; i < n; i++) {
-      assertEquals(seg2.get(JAVA_CHAR_UNALIGNED, i * Character.BYTES), (char)i);
+      assertEquals(seg2.get(JAVA_CHAR_UNALIGNED, (long) i * Character.BYTES), (char)i);
     }
   }
 
@@ -94,10 +94,10 @@ public void checkShorts() {
     final MemorySegment seg = MemorySegment.ofArray(new byte[n * Short.BYTES]);
     final PositionalSegment posSeg = PositionalSegment.wrap(seg);
     for (int i = 0; i < (n/2); i++) { posSeg.setShort((short)i); }
-    for (int i = n/2; i < n; i++) { posSeg.setShort(i * Short.BYTES, (short)i); }
+    for (int i = n/2; i < n; i++) { posSeg.setShort((long) i * Short.BYTES, (short)i); }
     posSeg.resetPosition();
     for (int i = 0; i < n; i++) {
-      final int v1 = posSeg.getShort(i *Short.BYTES);
+      final int v1 = posSeg.getShort((long) i * Short.BYTES);
       final int v2 = posSeg.getShort();
       assertEquals(v1, v2);
       assertEquals(v2, i);
@@ -111,7 +111,7 @@ public void checkShorts() {
 
     final MemorySegment seg2 = posSeg.getMemorySegment();
     for (int i = 0; i < n; i++) {
-      assertEquals(seg2.get(JAVA_SHORT_UNALIGNED, i * Short.BYTES), (short)i);
+      assertEquals(seg2.get(JAVA_SHORT_UNALIGNED, (long) i * Short.BYTES), (short)i);
     }
   }
 
@@ -121,10 +121,10 @@ public void checkInts() {
     final MemorySegment seg = MemorySegment.ofArray(new byte[n * Integer.BYTES]);
     final PositionalSegment posSeg = PositionalSegment.wrap(seg);
     for (int i = 0; i < (n/2); i++) { posSeg.setInt((int)i); }
-    for (int i = n/2; i < n; i++) { posSeg.setInt(i * Integer.BYTES, (int)i); }
+    for (int i = n/2; i < n; i++) { posSeg.setInt((long) i * Integer.BYTES, (int)i); }
     posSeg.resetPosition();
     for (int i = 0; i < n; i++) {
-      final int v1 = posSeg.getInt(i * Integer.BYTES);
+      final int v1 = posSeg.getInt((long) i * Integer.BYTES);
       final int v2 = posSeg.getInt();
       assertEquals(v1, v2);
       assertEquals(v2, i);
@@ -138,7 +138,7 @@ public void checkInts() {
 
     final MemorySegment seg2 = posSeg.getMemorySegment();
     for (int i = 0; i < n; i++) {
-      assertEquals(seg2.get(JAVA_INT_UNALIGNED, i * Integer.BYTES), (int)i);
+      assertEquals(seg2.get(JAVA_INT_UNALIGNED, (long) i * Integer.BYTES), (int)i);
     }
   }
 
@@ -149,10 +149,10 @@ public void checkLongs() {
     final MemorySegment seg = MemorySegment.ofArray(new byte[n * Long.BYTES]);
     final PositionalSegment posSeg = PositionalSegment.wrap(seg);
     for (int i = 0; i < (n/2); i++) { posSeg.setLong(i); }
-    for (int i = n/2; i < n; i++) { posSeg.setLong(i * Long.BYTES, i); }
+    for (int i = n/2; i < n; i++) { posSeg.setLong((long) i * Long.BYTES, i); }
     posSeg.resetPosition();
     for (int i = 0; i < n; i++) {
-      final long v1 = posSeg.getLong(i * Long.BYTES);
+      final long v1 = posSeg.getLong((long) i * Long.BYTES);
       final long v2 = posSeg.getLong();
       assertEquals(v1, v2);
       assertEquals(v2, i);
@@ -166,7 +166,7 @@ public void checkLongs() {
 
     final MemorySegment seg2 = posSeg.getMemorySegment();
     for (int i = 0; i < n; i++) {
-      assertEquals(seg2.get(JAVA_LONG_UNALIGNED, i * Long.BYTES), i);
+      assertEquals(seg2.get(JAVA_LONG_UNALIGNED, (long) i * Long.BYTES), i);
     }
   }
 
@@ -176,10 +176,10 @@ public void checkFloats() {
     final MemorySegment seg = MemorySegment.ofArray(new byte[n * Float.BYTES]);
     final PositionalSegment posSeg = PositionalSegment.wrap(seg);
     for (int i = 0; i < (n/2); i++) { posSeg.setFloat(i); }
-    for (int i = n/2; i < n; i++) { posSeg.setFloat(i * Float.BYTES, i); }
+    for (int i = n/2; i < n; i++) { posSeg.setFloat((long) i * Float.BYTES, i); }
     posSeg.resetPosition();
     for (int i = 0; i < n; i++) {
-      final float v1 = posSeg.getFloat(i * Float.BYTES);
+      final float v1 = posSeg.getFloat((long) i * Float.BYTES);
       final float v2 = posSeg.getFloat();
       assertEquals(v1, v2);
       assertEquals(v2, i);
@@ -193,7 +193,7 @@ public void checkFloats() {
 
     final MemorySegment seg2 = posSeg.getMemorySegment();
     for (int i = 0; i < n; i++) {
-      assertEquals(seg2.get(JAVA_FLOAT_UNALIGNED, i * Float.BYTES), i);
+      assertEquals(seg2.get(JAVA_FLOAT_UNALIGNED, (long) i * Float.BYTES), i);
     }
   }
 
@@ -203,10 +203,10 @@ public void checkDoubles() {
     final MemorySegment seg = MemorySegment.ofArray(new byte[n * Double.BYTES]);
     final PositionalSegment posSeg = PositionalSegment.wrap(seg);
     for (int i = 0; i < (n/2); i++) { posSeg.setDouble(i); }
-    for (int i = n/2; i < n; i++) { posSeg.setDouble(i * Double.BYTES, i); }
+    for (int i = n/2; i < n; i++) { posSeg.setDouble((long) i * Double.BYTES, i); }
     posSeg.resetPosition();
     for (int i = 0; i < n; i++) {
-      final double v1 = posSeg.getDouble(i * Double.BYTES);
+      final double v1 = posSeg.getDouble((long) i * Double.BYTES);
       final double v2 = posSeg.getDouble();
       assertEquals(v1, v2);
       assertEquals(v2, i);
@@ -220,7 +220,7 @@ public void checkDoubles() {
 
     final MemorySegment seg2 = posSeg.getMemorySegment();
     for (int i = 0; i < n; i++) {
-      assertEquals(seg2.get(JAVA_DOUBLE_UNALIGNED, i * Double.BYTES), i);
+      assertEquals(seg2.get(JAVA_DOUBLE_UNALIGNED, (long) i * Double.BYTES), i);
     }
   }
 

src/test/java/org/apache/datasketches/cpc/CpcWrapperTest.java

@@ -41,9 +41,9 @@ public void check() {
     final CpcSketch sk1 = new CpcSketch(lgK);
     final CpcSketch sk2 = new CpcSketch(lgK);
     final CpcSketch skD = new CpcSketch(lgK);
-    final double dEst = skD.getEstimate();
-    final double dlb = skD.getLowerBound(2);
-    final double dub = skD.getUpperBound(2);
+    assertEquals(skD.getEstimate(), 0.0);
+    assertEquals(skD.getLowerBound(2), 0.0);
+    assertEquals(skD.getUpperBound(2), 0.0);
 
     final int n = 100000;
     for (int i = 0; i < n; i++) {
@@ -56,9 +56,9 @@ public void check() {
 
     final CpcUnion union = new CpcUnion(lgK);
     final CpcSketch result = union.getResult();
-    final double uEst = result.getEstimate();
-    final double ulb = result.getLowerBound(2);
-    final double uub = result.getUpperBound(2);
+    assertEquals(result.getEstimate(), 0.0);
+    assertEquals(result.getLowerBound(2), 0.0);
+    assertEquals(result.getUpperBound(2), 0.0);
     union.update(sk1);
     union.update(sk2);
     final CpcSketch merged = union.getResult();
@@ -90,7 +90,7 @@ public void checkIsCompressed() {
     final byte[] byteArr = sk.toByteArray();
     byteArr[5] &= (byte) -3;
     try {
-      final CpcWrapper wrapper = new CpcWrapper(MemorySegment.ofArray(byteArr));
+      new CpcWrapper(MemorySegment.ofArray(byteArr));
       fail();
     } catch (final AssertionError e) {}
   }

src/test/java/org/apache/datasketches/hll/HllSketchTest.java

@@ -268,13 +268,13 @@ private static void checkSerSizes(final int lgConfigK, final TgtHllType tgtHllTy
   @Test
   public void checkConfigKLimits() {
     try {
-      final HllSketch sk = new HllSketch(HllUtil.MIN_LOG_K - 1);
+      new HllSketch(HllUtil.MIN_LOG_K - 1);
       fail();
     } catch (final SketchesArgumentException e) {
       //expected
     }
     try {
-      final HllSketch sk = new HllSketch(HllUtil.MAX_LOG_K + 1);
+      new HllSketch(HllUtil.MAX_LOG_K + 1);
       fail();
     } catch (final SketchesArgumentException e) {
       //expected
@@ -303,7 +303,7 @@ public void checkMemorySegmentNotLargeEnough() {
     final int bytes = getMaxUpdatableSerializationBytes(8, TgtHllType.HLL_8);
     final MemorySegment wseg = MemorySegment.ofArray(new byte[bytes -1]);
     try {
-      final HllSketch sk = new HllSketch(8, TgtHllType.HLL_8, wseg);
+      new HllSketch(8, TgtHllType.HLL_8, wseg);
       fail();
     } catch (final SketchesArgumentException e) {
       //OK
@@ -415,7 +415,7 @@ public void checkWritableWrapOfCompact() {
     final HllSketch sk = new HllSketch();
     final byte[] byteArr = sk.toCompactByteArray();
     final MemorySegment wseg = MemorySegment.ofArray(byteArr);
-    final HllSketch sk2 = HllSketch.writableWrap(wseg);
+    HllSketch.writableWrap(wseg);
   }
 
   @SuppressWarnings("unused")