Minor method renaming that propogated to a lot of places.

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

@@ -421,41 +421,38 @@ public static boolean isPowerOf2(final int v) {
    * Checks the given parameter to make sure it is positive, an integer-power of 2 and greater than
    * zero.
    *
-   * @param v The input argument.
+   * @param powerOf2 The input argument must be a power of 2 and greater than zero.
    * @param argName Used in the thrown exception.
    */
-  public static void checkIfPowerOf2(final int v, final String argName) {
-    if (v > 0 && (v & v - 1) == 0) {
-      return;
-    }
+  public static void checkIfPowerOf2(final int powerOf2, final String argName) {
+    if (powerOf2 > 0 && (powerOf2 & powerOf2 - 1) == 0) { return; }
     throw new SketchesArgumentException("The value of the parameter \"" + argName
-        + "\" must be a positive integer-power of 2" + " and greater than 0: " + v);
+        + "\" must be a positive integer-power of 2" + " and greater than 0: " + powerOf2);
   }
 
   /**
    * Checks the given value if it is a power of 2. If not, it throws an exception.
    * Otherwise, returns the log-base2 of the given value.
-   * @param value must be a power of 2 and greater than zero.
+   * @param powerOf2 must be a power of 2 and greater than zero.
    * @param argName the argument name used in the exception if thrown.
    * @return the log-base2 of the given value
    */
-  public static int toLog2(final int value, final String argName) {
-    checkIfPowerOf2(value, argName);
-    return Integer.numberOfTrailingZeros(value);
+  public static int exactLog2(final int powerOf2, final String argName) {
+    checkIfPowerOf2(powerOf2, argName);
+    return Integer.numberOfTrailingZeros(powerOf2);
   }
 
   /**
    * Gives the log2 of a long that is known to be a power of 2.
    *
-   * @param x number that is greater than zero
+   * @param powerOf2 must be a power of 2 and greater than zero.
    * @return the log2 of a long that is known to be a power of 2.
    */
-  public static int simpleLog2OfLong(final long x) {
-    final int exp = Long.numberOfTrailingZeros(x);
-    if (x != 1L << exp) {
-      throw new SketchesArgumentException("Argument x must be a positive power of 2.");
+  public static int exactLog2OfLong(final long powerOf2) {
+    if (powerOf2 <= 0 || (powerOf2 & (powerOf2 - 1L)) != 0) {
+      throw new SketchesArgumentException("Argument 'powerOf2' must be a positive power of 2.");
     }
-    return exp;
+    return Long.numberOfTrailingZeros(powerOf2);
   }
 
   /**

src/main/java/org/apache/datasketches/frequencies/ItemsSketch.java

@@ -21,7 +21,7 @@
 
 import static org.apache.datasketches.Util.LS;
 import static org.apache.datasketches.Util.isPowerOf2;
-import static org.apache.datasketches.Util.toLog2;
+import static org.apache.datasketches.Util.exactLog2;
 import static org.apache.datasketches.frequencies.PreambleUtil.EMPTY_FLAG_MASK;
 import static org.apache.datasketches.frequencies.PreambleUtil.SER_VER;
 import static org.apache.datasketches.frequencies.PreambleUtil.extractActiveItems;
@@ -188,7 +188,7 @@ public class ItemsSketch<T> {
    * functions of maxMapSize.
    */
   public ItemsSketch(final int maxMapSize) {
-    this(toLog2(maxMapSize, "maxMapSize"), LG_MIN_MAP_SIZE);
+    this(exactLog2(maxMapSize, "maxMapSize"), LG_MIN_MAP_SIZE);
   }
 
   /**

src/main/java/org/apache/datasketches/frequencies/LongsSketch.java

@@ -21,7 +21,7 @@
 
 import static org.apache.datasketches.Util.LS;
 import static org.apache.datasketches.Util.isPowerOf2;
-import static org.apache.datasketches.Util.toLog2;
+import static org.apache.datasketches.Util.exactLog2;
 import static org.apache.datasketches.frequencies.PreambleUtil.EMPTY_FLAG_MASK;
 import static org.apache.datasketches.frequencies.PreambleUtil.SER_VER;
 import static org.apache.datasketches.frequencies.PreambleUtil.extractActiveItems;
@@ -185,7 +185,7 @@ public class LongsSketch {
    * function of maxMapSize.
    */
   public LongsSketch(final int maxMapSize) {
-    this(toLog2(maxMapSize, "maxMapSize"), LG_MIN_MAP_SIZE);
+    this(exactLog2(maxMapSize, "maxMapSize"), LG_MIN_MAP_SIZE);
   }
 
   /**

src/main/java/org/apache/datasketches/frequencies/ReversePurgeItemHashMap.java

@@ -20,7 +20,7 @@
 package org.apache.datasketches.frequencies;
 
 import static org.apache.datasketches.Util.LS;
-import static org.apache.datasketches.Util.toLog2;
+import static org.apache.datasketches.Util.exactLog2;
 import static org.apache.datasketches.frequencies.Util.hash;
 
 import java.lang.reflect.Array;
@@ -59,7 +59,7 @@ class ReversePurgeItemHashMap<T> {
    * The hash table will be expected to store LOAD_FACTOR * mapSize (key, value) pairs.
    */
   ReversePurgeItemHashMap(final int mapSize) {
-    lgLength = toLog2(mapSize, "mapSize");
+    lgLength = exactLog2(mapSize, "mapSize");
     this.loadThreshold = (int) (mapSize * LOAD_FACTOR);
     this.keys = new Object[mapSize];
     this.values = new long[mapSize];

src/main/java/org/apache/datasketches/frequencies/ReversePurgeLongHashMap.java

@@ -20,7 +20,7 @@
 package org.apache.datasketches.frequencies;
 
 import static org.apache.datasketches.Util.LS;
-import static org.apache.datasketches.Util.toLog2;
+import static org.apache.datasketches.Util.exactLog2;
 import static org.apache.datasketches.frequencies.Util.hash;
 
 import org.apache.datasketches.QuickSelect;
@@ -56,7 +56,7 @@ class ReversePurgeLongHashMap {
    * The hash table will be expected to store LOAD_FACTOR * mapSize (key, value) pairs.
    */
   ReversePurgeLongHashMap(final int mapSize) {
-    lgLength = toLog2(mapSize, "mapSize");
+    lgLength = exactLog2(mapSize, "mapSize");
     loadThreshold = (int) (mapSize * LOAD_FACTOR);
     keys = new long[mapSize];
     values = new long[mapSize];

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

@@ -20,7 +20,7 @@
 package org.apache.datasketches.hll;
 
 import static org.apache.datasketches.Util.ceilingPowerOf2;
-import static org.apache.datasketches.Util.simpleLog2OfLong;
+import static org.apache.datasketches.Util.exactLog2OfLong;
 import static org.apache.datasketches.Util.zeroPad;
 import static org.apache.datasketches.hll.HllUtil.LG_AUX_ARR_INTS;
 import static org.apache.datasketches.hll.HllUtil.LG_INIT_SET_SIZE;
@@ -463,10 +463,10 @@ static int computeLgArr(final Memory mem, final int count, final int lgConfigK)
     int ceilPwr2 = ceilingPowerOf2(count);
     if ((RESIZE_DENOM * count) > (RESIZE_NUMER * ceilPwr2)) { ceilPwr2 <<= 1; }
     if (curMode == CurMode.SET) {
-      return Math.max(LG_INIT_SET_SIZE, simpleLog2OfLong(ceilPwr2));
+      return Math.max(LG_INIT_SET_SIZE, exactLog2OfLong(ceilPwr2));
     }
     //only used for HLL4
-    return Math.max(LG_AUX_ARR_INTS[lgConfigK], simpleLog2OfLong(ceilPwr2));
+    return Math.max(LG_AUX_ARR_INTS[lgConfigK], exactLog2OfLong(ceilPwr2));
   }
 
 }

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

@@ -91,7 +91,7 @@ private ReservoirItemsSketch(final int k, final ResizeFactor rf) {
 
     itemsSeen_ = 0;
 
-    final int ceilingLgK = Util.toLog2(Util.ceilingPowerOf2(reservoirSize_), "ReservoirItemsSketch");
+    final int ceilingLgK = Util.exactLog2(Util.ceilingPowerOf2(reservoirSize_), "ReservoirItemsSketch");
     final int initialLgSize =
             SamplingUtil.startingSubMultiple(ceilingLgK, rf_.lg(), MIN_LG_ARR_ITEMS);
 
@@ -249,8 +249,8 @@ public static <T> ReservoirItemsSketch<T> heapify(final Memory srcMem,
     if (itemsSeen < k) {
       // under-full so determine size to allocate, using ceilingLog2(totalSeen) as minimum
       // casts to int are safe since under-full
-      final int ceilingLgK = Util.toLog2(Util.ceilingPowerOf2(k), "heapify");
-      final int minLgSize = Util.toLog2(Util.ceilingPowerOf2((int) itemsSeen), "heapify");
+      final int ceilingLgK = Util.exactLog2(Util.ceilingPowerOf2(k), "heapify");
+      final int minLgSize = Util.exactLog2(Util.ceilingPowerOf2((int) itemsSeen), "heapify");
       final int initialLgSize = SamplingUtil.startingSubMultiple(ceilingLgK, rf.lg(),
               Math.max(minLgSize, MIN_LG_ARR_ITEMS));
 
@@ -335,7 +335,7 @@ public void update(final T item) {
    * Resets this sketch to the empty state, but retains the original value of k.
    */
   public void reset() {
-    final int ceilingLgK = Util.toLog2(Util.ceilingPowerOf2(reservoirSize_), "ReservoirItemsSketch");
+    final int ceilingLgK = Util.exactLog2(Util.ceilingPowerOf2(reservoirSize_), "ReservoirItemsSketch");
     final int initialLgSize =
             SamplingUtil.startingSubMultiple(ceilingLgK, rf_.lg(), MIN_LG_ARR_ITEMS);
 

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

@@ -92,7 +92,7 @@ private ReservoirLongsSketch(final int k, final ResizeFactor rf) {
 
     itemsSeen_ = 0;
 
-    final int ceilingLgK = Util.toLog2(Util.ceilingPowerOf2(reservoirSize_), "ReservoirLongsSketch");
+    final int ceilingLgK = Util.exactLog2(Util.ceilingPowerOf2(reservoirSize_), "ReservoirLongsSketch");
     final int initialLgSize =
             SamplingUtil.startingSubMultiple(ceilingLgK, rf_.lg(), MIN_LG_ARR_LONGS);
 
@@ -229,8 +229,8 @@ public static ReservoirLongsSketch heapify(final Memory srcMem) {
     if (itemsSeen < k) {
       // under-full so determine size to allocate, using ceilingLog2(totalSeen) as minimum
       // casts to int are safe since under-full
-      final int ceilingLgK = Util.toLog2(Util.ceilingPowerOf2(k), "heapify");
-      final int minLgSize = Util.toLog2(Util.ceilingPowerOf2((int) itemsSeen), "heapify");
+      final int ceilingLgK = Util.exactLog2(Util.ceilingPowerOf2(k), "heapify");
+      final int minLgSize = Util.exactLog2(Util.ceilingPowerOf2((int) itemsSeen), "heapify");
       final int initialLgSize = SamplingUtil.startingSubMultiple(ceilingLgK, rf.lg(),
               Math.max(minLgSize, MIN_LG_ARR_LONGS));
 
@@ -334,7 +334,7 @@ public void update(final long item) {
    * Resets this sketch to the empty state, but retains the original value of k.
    */
   public void reset() {
-    final int ceilingLgK = Util.toLog2(Util.ceilingPowerOf2(reservoirSize_),
+    final int ceilingLgK = Util.exactLog2(Util.ceilingPowerOf2(reservoirSize_),
             "ReservoirLongsSketch");
     final int initialLgSize =
             SamplingUtil.startingSubMultiple(ceilingLgK, rf_.lg(), MIN_LG_ARR_LONGS);

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

@@ -76,7 +76,7 @@ public static short computeSize(final int k) {
               + "less than " + MAX_ABS_VALUE + ", found: " + k);
     }
 
-    final int p = Util.toLog2(Util.floorPowerOf2(k), "computeSize: p");
+    final int p = Util.exactLog2(Util.floorPowerOf2(k), "computeSize: p");
 
     // because of floor() + 1 below, need to check power of 2 here
     if (Util.isPowerOf2(k)) {

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

@@ -136,7 +136,7 @@ private VarOptItemsSketch(final int k, final ResizeFactor rf) {
     totalWtR_ = 0;
     numMarksInH_ = 0;
 
-    final int ceilingLgK = Util.toLog2(Util.ceilingPowerOf2(k_), "VarOptItemsSketch");
+    final int ceilingLgK = Util.exactLog2(Util.ceilingPowerOf2(k_), "VarOptItemsSketch");
     final int initialLgSize =
             SamplingUtil.startingSubMultiple(ceilingLgK, rf_.lg(), MIN_LG_ARR_ITEMS);
 
@@ -347,8 +347,8 @@ public static <T> VarOptItemsSketch<T> heapify(final Memory srcMem,
 
     if (rCount == 0) {
       // Not in sampling mode, so determine size to allocate, using ceilingLog2(hCount) as minimum
-      final int ceilingLgK = Util.toLog2(Util.ceilingPowerOf2(k), "heapify");
-      final int minLgSize = Util.toLog2(Util.ceilingPowerOf2(hCount), "heapify");
+      final int ceilingLgK = Util.exactLog2(Util.ceilingPowerOf2(k), "heapify");
+      final int minLgSize = Util.exactLog2(Util.ceilingPowerOf2(hCount), "heapify");
       final int initialLgSize = SamplingUtil.startingSubMultiple(ceilingLgK, rf.lg(),
               Math.max(minLgSize, MIN_LG_ARR_ITEMS));
 
@@ -474,7 +474,7 @@ public void update(final T item, final double weight) {
    * Resets this sketch to the empty state, but retains the original value of k.
    */
   public void reset() {
-    final int ceilingLgK = Util.toLog2(Util.ceilingPowerOf2(k_), "VarOptItemsSketch");
+    final int ceilingLgK = Util.exactLog2(Util.ceilingPowerOf2(k_), "VarOptItemsSketch");
     final int initialLgSize =
             SamplingUtil.startingSubMultiple(ceilingLgK, rf_.lg(), MIN_LG_ARR_ITEMS);
 

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

@@ -24,7 +24,7 @@
 import static org.apache.datasketches.Util.REBUILD_THRESHOLD;
 import static org.apache.datasketches.Util.checkSeedHashes;
 import static org.apache.datasketches.Util.computeSeedHash;
-import static org.apache.datasketches.Util.simpleLog2OfLong;
+import static org.apache.datasketches.Util.exactLog2OfLong;
 
 import java.util.Arrays;
 
@@ -184,7 +184,7 @@ private static long[] getResultHashArr( //returns a new array
     final long[] tmpHashArrA = new long[countA];
 
     //search for non matches and build temp arrays
-    final int lgHTBLen = simpleLog2OfLong(hashTableB.length);
+    final int lgHTBLen = exactLog2OfLong(hashTableB.length);
     int nonMatches = 0;
     for (int i = 0; i < countA; i++) {
       final long hash = hashArrA[i];

src/main/java/org/apache/datasketches/tuple/AnotB.java

@@ -23,7 +23,7 @@
 import static org.apache.datasketches.HashOperations.convertToHashTable;
 import static org.apache.datasketches.HashOperations.hashSearch;
 import static org.apache.datasketches.Util.REBUILD_THRESHOLD;
-import static org.apache.datasketches.Util.simpleLog2OfLong;
+import static org.apache.datasketches.Util.exactLog2OfLong;
 
 import java.lang.reflect.Method;
 import java.util.Arrays;
@@ -522,7 +522,7 @@ private static <S extends Summary> DataArrays<S> getCopyOfResultArraysTuple(
     final S[] tmpSummaryArrA = Util.newSummaryArray(summaryArrA, countA);
 
     //search for non matches and build temp arrays
-    final int lgHTBLen = simpleLog2OfLong(hashTableB.length);
+    final int lgHTBLen = exactLog2OfLong(hashTableB.length);
     int nonMatches = 0;
     for (int i = 0; i < countA; i++) {
       final long hash = hashArrA[i];
@@ -568,7 +568,7 @@ private static <S extends Summary> DataArrays<S> getCopyOfResultArraysTheta(
     final S[] tmpSummaryArrA = Util.newSummaryArray(summaryArrA, countA);
 
     //search for non matches and build temp arrays
-    final int lgHTBLen = simpleLog2OfLong(hashTableB.length);
+    final int lgHTBLen = exactLog2OfLong(hashTableB.length);
     int nonMatches = 0;
     for (int i = 0; i < countA; i++) {
       final long hash = hashArrA[i];

src/main/java/org/apache/datasketches/tuple/QuickSelectSketch.java

@@ -23,7 +23,7 @@
 import static org.apache.datasketches.Util.REBUILD_THRESHOLD;
 import static org.apache.datasketches.Util.RESIZE_THRESHOLD;
 import static org.apache.datasketches.Util.ceilingPowerOf2;
-import static org.apache.datasketches.Util.simpleLog2OfLong;
+import static org.apache.datasketches.Util.exactLog2OfLong;
 
 import java.lang.reflect.Array;
 import java.nio.ByteOrder;
@@ -261,7 +261,7 @@ public int getNominalEntries() {
    * @return log_base2 of Nominal Entries
    */
   public int getLgK() {
-    return simpleLog2OfLong(nomEntries_);
+    return exactLog2OfLong(nomEntries_);
   }
 
   /**

src/main/java/org/apache/datasketches/tuple/arrayofdoubles/ArrayOfDoublesAnotBImpl.java

@@ -25,7 +25,7 @@
 import static org.apache.datasketches.HashOperations.count;
 import static org.apache.datasketches.HashOperations.hashSearch;
 import static org.apache.datasketches.Util.REBUILD_THRESHOLD;
-import static org.apache.datasketches.Util.simpleLog2OfLong;
+import static org.apache.datasketches.Util.exactLog2OfLong;
 
 import java.util.Arrays;
 
@@ -174,7 +174,7 @@ private static DataArrays getResultArrays(
     double[] tmpValuesArrA = new double[countA * numValues];
 
     //search for non matches and build temp arrays
-    final int lgHTBLen = simpleLog2OfLong(hashTableB.length);
+    final int lgHTBLen = exactLog2OfLong(hashTableB.length);
     int nonMatches = 0;
     for (int i = 0; i < countA; i++) {
       final long hash = hashArrA[i];