Merge pull request #584 from apache/quotient-filter

Reverted double laod factor to float and corrected builder tests

src/main/java/org/apache/datasketches/filters/quotientfilter/QuotientFilter.java

@@ -32,11 +32,11 @@
 
 public class QuotientFilter extends Filter {
 
-  public static final double DEFAULT_LOAD_FACTOR = 0.8;
+  public static final float DEFAULT_LOAD_FACTOR = 0.8f;
 
   int lgQ_;
   int numFingerprintBits_;
-  double loadFactor_;
+  float loadFactor_;
   int numEntries_;
   int numExpansions_;
   BitArray bitArray_;
@@ -51,7 +51,7 @@ public QuotientFilter(final int lgQ, final int numFingerprintBits) {
     this(lgQ, numFingerprintBits, DEFAULT_LOAD_FACTOR);
   }
 
-  public QuotientFilter(final int lgQ, final int numFingerprintBits, final double loadFactor) {
+  public QuotientFilter(final int lgQ, final int numFingerprintBits, final float loadFactor) {
     lgQ_ = lgQ;
     numFingerprintBits_ = numFingerprintBits;
     loadFactor_ = loadFactor;
@@ -149,7 +149,7 @@ public int getLgQ() {
     return lgQ_;
   }
 
-  public double getLoadFactor() {
+  public float getLoadFactor() {
     return loadFactor_;
   }
 

src/main/java/org/apache/datasketches/filters/quotientfilter/QuotientFilterBuilder.java

@@ -59,7 +59,7 @@ public static byte suggestFingerprintLength(double targetFalsePositiveProb) {
      * @param maxDistinctItems The maximum number of distinct items that can be inserted into the filter.
      * @return The log-base-2 of the number of slots in the filter.
      */
-    public static byte suggestLgNumSlots(long maxDistinctItems, double loadFactor) {
+    public static byte suggestLgNumSlots(long maxDistinctItems, float loadFactor) {
         if (maxDistinctItems <= 0) {
             throw new SketchesArgumentException("maxDistinctItems must be strictly positive");
         }
@@ -82,7 +82,7 @@ public static byte suggestLgNumSlots(long maxDistinctItems) {
     @param lgNumSlots The log-base-2 of the number of slots in the filter
     @return The maximum number of items that can be inserted into the filter
      */
-    public static long suggestMaxNumItemsFromNumSlots(int lgNumSlots, double loadFactor) {
+    public static long suggestMaxNumItemsFromNumSlots(int lgNumSlots, float loadFactor) {
         if (lgNumSlots <= 0) {
             throw new SketchesArgumentException("lgNumSlots must be at least 1.");
         } else if (lgNumSlots >= 31) {
@@ -107,7 +107,7 @@ public static long suggestMaxNumItemsFromNumSlots(byte lgNumSlots) {
      * @return A QFPair object containing the suggested number of slots (lgNumSlots) and the suggested fingerprint length.
      * @throws SketchesArgumentException if the input parameters are not valid.
      */
-    public static QFPair suggestParamsFromMaxDistinctsFPP(long maxDistinctItems, double loadFactor, double targetFalsePositiveProb) {
+    public static QFPair suggestParamsFromMaxDistinctsFPP(long maxDistinctItems, float loadFactor, double targetFalsePositiveProb) {
         validateAccuracyInputs(maxDistinctItems, loadFactor, targetFalsePositiveProb);
         byte lgNumSlots = suggestLgNumSlots(maxDistinctItems, loadFactor);
         byte fingerprintLength = suggestFingerprintLength(targetFalsePositiveProb);
@@ -118,7 +118,7 @@ public static QFPair suggestParamsFromMaxDistinctsFPP(long maxDistinctItems, dou
         return suggestParamsFromMaxDistinctsFPP(maxDistinctItems, DEFAULT_LOAD_FACTOR, targetFalsePositiveProb);
     }
 
-    private static void validateAccuracyInputs(final long maxDistinctItems, final double loadFactor, final double targetFalsePositiveProb) {
+    private static void validateAccuracyInputs(final long maxDistinctItems, final float loadFactor, final double targetFalsePositiveProb) {
         if (maxDistinctItems <= 0) {
             throw new SketchesArgumentException("maxDistinctItems must be strictly positive");
         }

src/test/java/org/apache/datasketches/filters/quotientfilter/QuotientFilterBuilderTest.java

@@ -46,9 +46,9 @@ public static void testSuggestLgNumSlots(){
         QuotientFilterBuilder qfb = new QuotientFilterBuilder();
 
         // invalid number of items
-        assertThrows(SketchesArgumentException.class, () -> QuotientFilterBuilder.suggestLgNumSlots(0,0.9));
-        assertThrows(SketchesArgumentException.class, () -> QuotientFilterBuilder.suggestLgNumSlots(-1, 0.9));
-        assertThrows(SketchesArgumentException.class, () -> QuotientFilterBuilder.suggestLgNumSlots(5000000000L, 0.9));
+        assertThrows(SketchesArgumentException.class, () -> QuotientFilterBuilder.suggestLgNumSlots(0,0.9f));
+        assertThrows(SketchesArgumentException.class, () -> QuotientFilterBuilder.suggestLgNumSlots(-1, 0.9f));
+        assertThrows(SketchesArgumentException.class, () -> QuotientFilterBuilder.suggestLgNumSlots(5000000000L, 0.9f));
         assertThrows(SketchesArgumentException.class, () -> QuotientFilterBuilder.suggestLgNumSlots(0));
         assertThrows(SketchesArgumentException.class, () -> QuotientFilterBuilder.suggestLgNumSlots(-1));
         assertThrows(SketchesArgumentException.class, () -> QuotientFilterBuilder.suggestLgNumSlots(5000000000L));
@@ -58,7 +58,7 @@ public static void testSuggestLgNumSlots(){
 
         for (int i = 0; i < numItems.length; i++) {
             long num = numItems[i];
-            byte result = qfb.suggestLgNumSlots(num, 0.9);
+            byte result = qfb.suggestLgNumSlots(num, 0.9f);
             assertEquals(result, results[i]);
             result = qfb.suggestLgNumSlots(num);
             assertEquals(result, results[i]);
@@ -74,14 +74,17 @@ public static void testSuggestMaxNumItems(){
         assertThrows(SketchesArgumentException.class, () -> QuotientFilterBuilder.suggestMaxNumItemsFromNumSlots((byte)0));
         assertThrows(SketchesArgumentException.class, () -> QuotientFilterBuilder.suggestMaxNumItemsFromNumSlots((byte)32));
 
-
         int[] lgNumSlots = {1, 2, 3, 6, 10, 15, 25, 30,};
-        long[] results_ninety_pc = {1, 3, 7, 57, 921, 29491, 30198988, 966367641} ;
-        long[] results_eighty_pc = {1, 3, 6, 51, 819, 26214, 26843545, 858993459} ;
+        long[] results_ninety_pc = {1, 3, 7, 57, 922, 29504, 30212096, 966787072} ;
+        long[] results_eighty_pc = {1, 3, 6, 51, 820, 26240, 26869760, 859832320} ;
+
+        // load capacities arbitrarily chosen using powers of two for exact arithmetic
+        float ninety_pc_appx = 922f / 1024f; // ≈ 0.9
+        float eighty_pc_appx = 820f / 1024f; // ≈ 0.8
 
         for (int i = 0; i < lgNumSlots.length; i++) {
-            long result_ninety = qfb.suggestMaxNumItemsFromNumSlots(lgNumSlots[i], 0.9);
-            long result_eighty = qfb.suggestMaxNumItemsFromNumSlots(lgNumSlots[i], 0.8);
+            long result_ninety = qfb.suggestMaxNumItemsFromNumSlots(lgNumSlots[i], ninety_pc_appx);
+            long result_eighty = qfb.suggestMaxNumItemsFromNumSlots(lgNumSlots[i], eighty_pc_appx);
             assertEquals(result_ninety, results_ninety_pc[i]);
             assertEquals(result_eighty, results_eighty_pc[i]);
         }
@@ -109,7 +112,7 @@ public static void testSuggestParamsFromMaxDistinctsFPP(){
         byte[] expected_fingerprintLength = {34, 7, 24} ;
 
         for (int i = 0; i < numItems.length; i++) {
-            QuotientFilterBuilder.QFPair pair = qfb.suggestParamsFromMaxDistinctsFPP(numItems[i], 0.9, fpp[i]);
+            QuotientFilterBuilder.QFPair pair = qfb.suggestParamsFromMaxDistinctsFPP(numItems[i], 0.9f, fpp[i]);
             lgNumSlots = pair.lgNumSlots;
             fingerprintLength = pair.fingerprintLength;
             assertEquals(expected_lgNumSlotsNinety[i], lgNumSlots);