Made detection of BigEndian consistent throughout.

Added finals (automatic) where possible.

Added parentheses (automatic) to reduce ambiguity

Fixed some missing license headers.

Author: leerho

pom.xml

@@ -96,10 +96,9 @@ under the License.
     <!-- System-wide properties -->
     <maven.version>3.9.10</maven.version>
     <java.version>24</java.version>
-    <jvm-arguments>-Xmx10g -Duser.language=en -Duser.country=US -Dfile.encoding=UTF-8</jvm-arguments>
+    <jvm-arguments>-Xmx4g -Duser.language=en -Duser.country=US -Dfile.encoding=UTF-8</jvm-arguments>
     <maven.compiler.source>${java.version}</maven.compiler.source>
     <maven.compiler.target>${java.version}</maven.compiler.target>
-    <argLine>${jvm-arguments}</argLine>
     <charset.encoding>UTF-8</charset.encoding>
     <project.build.sourceEncoding>${charset.encoding}</project.build.sourceEncoding>
     <project.build.resourceEncoding>${charset.encoding}</project.build.resourceEncoding>
@@ -159,7 +158,7 @@ under the License.
           <version>${maven-compiler-plugin.version}</version>
           <configuration>
             <compilerArgs>
-              <arg>${jvm-arguments}</arg>
+              <arg></arg>
             </compilerArgs>
           </configuration>
         </plugin>

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

@@ -0,0 +1,35 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.datasketches.common;
+
+/**
+ * The DataSketches Library is not supported on Big Endian machines.
+ */
+public class BigEndianNativeOrderNotSupportedException extends SketchesException {
+  private static final long serialVersionUID = 1L;
+
+  /**
+   * Constructs a new runtime exception with the message:
+   * "The DataSketches Library is not supported on Big Endian machines."
+   */
+  public BigEndianNativeOrderNotSupportedException() {
+    super("The DataSketches Library is not supported on Big Endian machines.");
+  }
+}

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

@@ -19,6 +19,7 @@
 
 package org.apache.datasketches.common;
 
+import java.nio.ByteOrder;
 import java.util.HashMap;
 import java.util.Locale;
 import java.util.Map;
@@ -165,19 +166,22 @@ public enum Family {
 
   private static final Map<Integer, Family> lookupID = new HashMap<>();
   private static final Map<String, Family> lookupFamName = new HashMap<>();
-  private int id_;
-  private String famName_;
-  private int minPreLongs_;
-  private int maxPreLongs_;
+  private final int id_;
+  private final String famName_;
+  private final int minPreLongs_;
+  private final int maxPreLongs_;
 
   static {
     for (final Family f : values()) {
       lookupID.put(f.getID(), f);
       lookupFamName.put(f.getFamilyName().toUpperCase(Locale.US), f);
     }
+    if (ByteOrder.nativeOrder() != ByteOrder.LITTLE_ENDIAN) {
+      throw new BigEndianNativeOrderNotSupportedException();
+    }
   }
 
-  private Family(final int id, final String famName, final int minPreLongs, final int maxPreLongs) {
+  Family(final int id, final String famName, final int minPreLongs, final int maxPreLongs) {
     id_ = id;
     famName_ = famName.toUpperCase(Locale.US);
     minPreLongs_ = minPreLongs;

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

@@ -28,6 +28,7 @@
 import static org.apache.datasketches.hash.MurmurHash3.hash;
 
 import java.lang.foreign.MemorySegment;
+import java.nio.ByteOrder;
 import java.util.Comparator;
 
 /**
@@ -38,6 +39,12 @@
 @SuppressWarnings("unchecked")
 public final class Util {
 
+  static {
+    if (ByteOrder.nativeOrder() != ByteOrder.LITTLE_ENDIAN) {
+      throw new BigEndianNativeOrderNotSupportedException();
+    }
+  }
+
   /**
    * The java line separator character as a String.
    */
@@ -812,7 +819,7 @@ public static <T> Object maxT(final Object item1, final Object item2, final Comp
   }
 
   /**
-   * Is item1 Less-Than item2
+   * Is item1 Less-Than item2?
    * @param <T> the type
    * @param item1 item one
    * @param item2 item two
@@ -824,7 +831,7 @@ public static <T> boolean lt(final Object item1, final Object item2, final Compa
   }
 
   /**
-   * Is item1 Less-Than-Or-Equal-To item2
+   * Is item1 Less-Than-Or-Equal-To item2?
    * @param <T> the type
    * @param item1 item one
    * @param item2 item two

src/main/java/org/apache/datasketches/cpc/PreambleUtil.java

@@ -31,7 +31,6 @@
 import static org.apache.datasketches.cpc.RuntimeAsserts.rtAssertEquals;
 
 import java.lang.foreign.MemorySegment;
-import java.nio.ByteOrder;
 import java.util.Objects;
 
 import org.apache.datasketches.common.Family;
@@ -142,12 +141,6 @@ final class PreambleUtil {
 
   private PreambleUtil() {}
 
-  static {
-    if (ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN) {
-      throw new SketchesStateException("This sketch will not work on Big Endian CPUs.");
-    }
-  }
-
   private static final String fmt = "%10d%10x";
 
   /**
@@ -156,7 +149,7 @@ private PreambleUtil() {}
   static final byte SER_VER = 1;
 
   //Flag bit masks, Byte 5
-  static final int BIG_ENDIAN_FLAG_MASK     = 1; //Reserved.
+  static final int RESERVED_FLAG_MASK       = 1; //Reserved.
   static final int COMPRESSED_FLAG_MASK     = 2;
   static final int HIP_FLAG_MASK            = 4;
   static final int SUP_VAL_FLAG_MASK        = 8; //num Suprising Values > 0
@@ -584,7 +577,6 @@ static String toString(final MemorySegment seg, final boolean detail) {
 
     //Flags of the Flags byte
     final String flagsStr = zeroPad(Integer.toBinaryString(flags), 8) + ", " + (flags);
-    final boolean bigEndian = (flags & BIG_ENDIAN_FLAG_MASK) > 0;
     final boolean compressed = (flags & COMPRESSED_FLAG_MASK) > 0;
     final boolean hasHip = (flags & HIP_FLAG_MASK) > 0;
     final boolean hasSV = (flags & SUP_VAL_FLAG_MASK) > 0;
@@ -593,8 +585,6 @@ static String toString(final MemorySegment seg, final boolean detail) {
     final int formatOrdinal = (flags >>> 2) & 0x7;
     final Format format = Format.ordinalToFormat(formatOrdinal);
 
-    final String nativeOrderStr = ByteOrder.nativeOrder().toString();
-
     long numCoupons = 0;
     long numSv = 0;
     long winOffset = 0;
@@ -616,8 +606,6 @@ static String toString(final MemorySegment seg, final boolean detail) {
     sb.append("Byte 3: lgK                     : ").append(lgK).append(LS);
     sb.append("Byte 4: First Interesting Col   : ").append(fiCol).append(LS);
     sb.append("Byte 5: Flags                   : ").append(flagsStr).append(LS);
-    sb.append("  BIG_ENDIAN_STORAGE            : ").append(bigEndian).append(LS);
-    sb.append("  (Native Byte Order)           : ").append(nativeOrderStr).append(LS);
     sb.append("  Compressed                    : ").append(compressed).append(LS);
     sb.append("  Has HIP                       : ").append(hasHip).append(LS);
     sb.append("  Has Surprising Values         : ").append(hasSV).append(LS);

src/main/java/org/apache/datasketches/hll/PreambleUtil.java

@@ -32,7 +32,6 @@
 import static org.apache.datasketches.hll.HllUtil.RESIZE_NUMER;
 
 import java.lang.foreign.MemorySegment;
-import java.nio.ByteOrder;
 
 import org.apache.datasketches.common.Family;
 
@@ -133,7 +132,7 @@ private PreambleUtil() {}
   static int HLL_BYTE_ARR_START             = 40;
 
   //Flag bit masks
-  static final int BIG_ENDIAN_FLAG_MASK     = 1; //Set but not read. Reserved.
+  static final int RESERVED_FLAG_MASK       = 1; //Set to 0 but not read.
   static final int READ_ONLY_FLAG_MASK      = 2; //Set but not read. Reserved.
   static final int EMPTY_FLAG_MASK          = 4;
   static final int COMPACT_FLAG_MASK        = 8;
@@ -150,8 +149,6 @@ private PreambleUtil() {}
   static final int LIST_PREINTS             = 2;
   static final int HASH_SET_PREINTS         = 3;
   static final int HLL_PREINTS              = 10;
-  static final boolean NATIVE_ORDER_IS_BIG_ENDIAN  =
-      (ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN);
 
   static String toString(final byte[] byteArr) {
     final MemorySegment seg = MemorySegment.ofArray(byteArr);
@@ -168,8 +165,6 @@ static String toString(final MemorySegment seg) {
     final int flags = seg.get(JAVA_BYTE, FLAGS_BYTE);
     //Flags
     final String flagsStr = zeroPad(Integer.toBinaryString(flags), 8) + ", " + (flags);
-    final boolean bigEndian = (flags & BIG_ENDIAN_FLAG_MASK) > 0;
-    final String nativeOrder = ByteOrder.nativeOrder().toString();
     final boolean compact = (flags & COMPACT_FLAG_MASK) > 0;
     final boolean oooFlag = (flags & OUT_OF_ORDER_FLAG_MASK) > 0;
     final boolean readOnly = (flags & READ_ONLY_FLAG_MASK) > 0;
@@ -219,8 +214,6 @@ else if (curMode == CurMode.HLL) {
     }
     //expand byte 5: Flags
     sb.append("Byte 5: Flags:                : ").append(flagsStr).append(LS);
-    sb.append("  BIG_ENDIAN_STORAGE          : ").append(bigEndian).append(LS);
-    sb.append("  (Native Byte Order)         : ").append(nativeOrder).append(LS);
     sb.append("  READ_ONLY                   : ").append(readOnly).append(LS);
     sb.append("  EMPTY                       : ").append(empty).append(LS);
     sb.append("  COMPACT                     : ").append(compact).append(LS);
@@ -286,8 +279,7 @@ static void insertLgK(final MemorySegment wseg, final int lgK) {
   }
 
   static int extractLgArr(final MemorySegment seg) {
-    final int lgArr = seg.get(JAVA_BYTE, LG_ARR_BYTE) & 0XFF;
-    return lgArr;
+    return seg.get(JAVA_BYTE, LG_ARR_BYTE) & 0XFF;
   }
 
   static void insertLgArr(final MemorySegment wseg, final int lgArr) {

src/main/java/org/apache/datasketches/quantiles/PreambleUtil.java

@@ -28,7 +28,6 @@
 import static org.apache.datasketches.quantiles.ClassicUtil.computeRetainedItems;
 
 import java.lang.foreign.MemorySegment;
-import java.nio.ByteOrder;
 
 //@formatter:off
 
@@ -92,15 +91,12 @@ private PreambleUtil() {}
   static final int COMBINED_BUFFER            = 32; //to 39 (Only for DoublesSketch)
 
   // flag bit masks
-  static final int BIG_ENDIAN_FLAG_MASK       = 1;
+  static final int RESERVED_FLAG_MASK         = 1;
   static final int READ_ONLY_FLAG_MASK        = 2;
   static final int EMPTY_FLAG_MASK            = 4;
   static final int COMPACT_FLAG_MASK          = 8;
   static final int ORDERED_FLAG_MASK          = 16;
 
-  static final boolean NATIVE_ORDER_IS_BIG_ENDIAN  =
-      (ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN);
-
   /**
    * Default K for about 1.7% normalized rank accuracy
    */
@@ -143,8 +139,6 @@ private static String memorySegmentToString(final MemorySegment srcSeg, final bo
     final int familyID = extractFamilyID(srcSeg);
     final String famName = idToFamily(familyID).toString();
     final int flags = extractFlags(srcSeg);
-    final boolean bigEndian = (flags & BIG_ENDIAN_FLAG_MASK) > 0;
-    final String nativeOrder = ByteOrder.nativeOrder().toString();
     final boolean readOnly  = (flags & READ_ONLY_FLAG_MASK) > 0;
     final boolean empty = (flags & EMPTY_FLAG_MASK) > 0;
     final boolean compact = (flags & COMPACT_FLAG_MASK) > 0;
@@ -166,8 +160,7 @@ private static String memorySegmentToString(final MemorySegment srcSeg, final bo
     sb.append("Byte  1: Serialization Version: ").append(serVer).append(LS);
     sb.append("Byte  2: Family               : ").append(famName).append(LS);
     sb.append("Byte  3: Flags Field          : ").append(String.format("%02o", flags)).append(LS);
-    sb.append("  BIG ENDIAN                  : ").append(bigEndian).append(LS);
-    sb.append("  (Native Byte Order)         : ").append(nativeOrder).append(LS);
+    sb.append("  RESERVED                    : ").append(LS);
     sb.append("  READ ONLY                   : ").append(readOnly).append(LS);
     sb.append("  EMPTY                       : ").append(empty).append(LS);
     sb.append("  COMPACT                     : ").append(compact).append(LS);

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

@@ -28,7 +28,6 @@
 import static org.apache.datasketches.common.Util.zeroPad;
 
 import java.lang.foreign.MemorySegment;
-import java.nio.ByteOrder;
 import java.util.Locale;
 
 import org.apache.datasketches.common.Family;
@@ -210,8 +209,6 @@ private PreambleUtil() {}
   static final int EBPPS_RHO_DOUBLE      = 32;
 
   // flag bit masks
-  //static final int BIG_ENDIAN_FLAG_MASK = 1;
-  //static final int READ_ONLY_FLAG_MASK  = 2;
   static final int EMPTY_FLAG_MASK      = 4;
   static final int HAS_PARTIAL_ITEM_MASK = 8; // EBPPS only
   static final int GADGET_FLAG_MASK     = 128;
@@ -221,9 +218,6 @@ private PreambleUtil() {}
   static final int VAROPT_SER_VER       = 2;
   static final int EBPPS_SER_VER        = 1;
 
-  static final boolean NATIVE_ORDER_IS_BIG_ENDIAN  =
-      (ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN);
-
   // STRINGS
 
   /**
@@ -274,8 +268,6 @@ private static String sketchPreambleToString(final MemorySegment seg,
     // Flags
     final int flags = extractFlags(seg);
     final String flagsStr = zeroPad(Integer.toBinaryString(flags), 8) + ", " + (flags);
-    //final boolean bigEndian = (flags & BIG_ENDIAN_FLAG_MASK) > 0;
-    //final String nativeOrder = ByteOrder.nativeOrder().toString();
     //final boolean readOnly = (flags & READ_ONLY_FLAG_MASK) > 0;
     final boolean isEmpty = (flags & EMPTY_FLAG_MASK) > 0;
     final boolean isGadget = (flags & GADGET_FLAG_MASK) > 0;
@@ -304,8 +296,6 @@ private static String sketchPreambleToString(final MemorySegment seg,
       .append("Byte  1: Serialization Version: ").append(serVer).append(LS)
       .append("Byte  2: Family               : ").append(family.toString()).append(LS)
       .append("Byte  3: Flags Field          : ").append(flagsStr).append(LS)
-      //.append("  BIG_ENDIAN_STORAGE          : ").append(bigEndian).append(LS)
-      //.append("  (Native Byte Order)         : ").append(nativeOrder).append(LS)
       //.append("  READ_ONLY                   : ").append(readOnly).append(LS)
       .append("  EMPTY                       : ").append(isEmpty).append(LS);
     if (family == Family.VAROPT) {
@@ -344,8 +334,6 @@ private static String unionPreambleToString(final MemorySegment seg,
     // Flags
     final int flags = extractFlags(seg);
     final String flagsStr = zeroPad(Integer.toBinaryString(flags), 8) + ", " + (flags);
-    //final boolean bigEndian = (flags & BIG_ENDIAN_FLAG_MASK) > 0;
-    //final String nativeOrder = ByteOrder.nativeOrder().toString();
     //final boolean readOnly = (flags & READ_ONLY_FLAG_MASK) > 0;
     final boolean isEmpty = (flags & EMPTY_FLAG_MASK) > 0;
 
@@ -366,8 +354,6 @@ private static String unionPreambleToString(final MemorySegment seg,
             + "Byte  1: Serialization Version    : " + serVer + LS
             + "Byte  2: Family                   : " + family.toString() + LS
             + "Byte  3: Flags Field              : " + flagsStr + LS
-            //+ "  BIG_ENDIAN_STORAGE              : " + bigEndian + LS
-            //+ "  (Native Byte Order)             : " + nativeOrder + LS
             //+ "  READ_ONLY                       : " + readOnly + LS
             + "  EMPTY                           : " + isEmpty + LS
             + "Bytes  4-7: Max Sketch Size (maxK): " + k + LS

src/main/java/org/apache/datasketches/theta/DirectQuickSelectSketch.java

@@ -151,7 +151,6 @@ private DirectQuickSelectSketch(
     insertFamilyID(dstSeg, family.getID());                //byte 2
     insertLgNomLongs(dstSeg, lgNomLongs);                  //byte 3
     insertLgArrLongs(dstSeg, lgArrLongs);                  //byte 4
-    //flags: bigEndian = readOnly = compact = ordered = false; empty = true : 00100 = 4
     insertFlags(dstSeg, EMPTY_FLAG_MASK);                  //byte 5
     insertSeedHash(dstSeg, Util.computeSeedHash(seed));    //bytes 6,7
     insertCurCount(dstSeg, 0);                             //bytes 8-11
@@ -250,7 +249,6 @@ public void reset() {
     final int preambleLongs = wseg_.get(JAVA_BYTE, PREAMBLE_LONGS_BYTE) & 0X3F;
     final int preBytes = preambleLongs << 3;
     wseg_.asSlice(preBytes, arrLongs * 8L).fill((byte)0);
-    //flags: bigEndian = readOnly = compact = ordered = false; empty = true.
     wseg_.set(JAVA_BYTE, FLAGS_BYTE, (byte) EMPTY_FLAG_MASK);
     wseg_.set(JAVA_INT_UNALIGNED, RETAINED_ENTRIES_INT, 0);
     final float p = wseg_.get(JAVA_FLOAT_UNALIGNED, P_FLOAT);