HBASE-23245 : MutableHistogram constructor changes and provide HistogramImpl maxExpected as long (#787)

Signed-off-by: Andrew Purtell <apurtell@apache.org>
Signed-off-by: Xu Cang <xucang@apache.org> 
Signed-off-by: Guangxu Cheng <gxcheng@apache.org>

Author: virajjasani

hbase-hadoop2-compat/src/main/java/org/apache/hadoop/metrics2/lib/MutableHistogram.java

@@ -42,10 +42,6 @@ public MutableHistogram(MetricsInfo info) {
   }
 
   public MutableHistogram(String name, String description) {
-    this(name, description, Integer.MAX_VALUE << 2);
-  }
-
-  protected MutableHistogram(String name, String description, long maxExpected) {
     this.name = StringUtils.capitalize(name);
     this.desc = StringUtils.uncapitalize(description);
     this.histogram = new HistogramImpl();

hbase-hadoop2-compat/src/main/java/org/apache/hadoop/metrics2/lib/MutableRangeHistogram.java

@@ -36,11 +36,7 @@ public MutableRangeHistogram(MetricsInfo info) {
   }
 
   public MutableRangeHistogram(String name, String description) {
-    this(name, description, Integer.MAX_VALUE << 2);
-  }
-
-  public MutableRangeHistogram(String name, String description, long expectedMax) {
-    super(name, description, expectedMax);
+    super(name, description);
   }
 
   /**

hbase-hadoop2-compat/src/main/java/org/apache/hadoop/metrics2/lib/MutableSizeHistogram.java

@@ -26,6 +26,7 @@
  */
 @InterfaceAudience.Private
 public class MutableSizeHistogram extends MutableRangeHistogram {
+
   private final static String RANGE_TYPE = "SizeRangeCount";
   private final static long[] RANGES = {10,100,1000,10000,100000,1000000,10000000,100000000};
 
@@ -34,11 +35,7 @@ public MutableSizeHistogram(MetricsInfo info) {
   }
 
   public MutableSizeHistogram(String name, String description) {
-    this(name, description, RANGES[RANGES.length-2]);
-  }
-
-  public MutableSizeHistogram(String name, String description, long expectedMax) {
-    super(name, description, expectedMax);
+    super(name, description);
   }
 
   @Override

hbase-hadoop2-compat/src/main/java/org/apache/hadoop/metrics2/lib/MutableTimeHistogram.java

@@ -35,11 +35,7 @@ public MutableTimeHistogram(MetricsInfo info) {
   }
 
   public MutableTimeHistogram(String name, String description) {
-    this(name, description, RANGES[RANGES.length - 2]);
-  }
-
-  public MutableTimeHistogram(String name, String description, long expectedMax) {
-    super(name, description, expectedMax);
+    super(name, description);
   }
 
   @Override

hbase-metrics/src/main/java/org/apache/hadoop/hbase/metrics/impl/HistogramImpl.java

@@ -36,7 +36,7 @@ public class HistogramImpl implements Histogram {
   private final CounterImpl counter;
 
   public HistogramImpl() {
-    this(Integer.MAX_VALUE << 2);
+    this((long) Integer.MAX_VALUE << 2);
   }
 
   public HistogramImpl(long maxExpected) {

hbase-metrics/src/test/java/org/apache/hadoop/hbase/metrics/impl/TestHistogramImpl.java

@@ -63,19 +63,19 @@ public void testSnapshot() {
     Snapshot snapshot = histogram.snapshot();
 
     assertEquals(100, snapshot.getCount());
-    assertEquals(50, snapshot.getMedian());
+    assertEquals(49, snapshot.getMedian());
     assertEquals(49, snapshot.getMean());
     assertEquals(0, snapshot.getMin());
     assertEquals(99, snapshot.getMax());
-    assertEquals(25, snapshot.get25thPercentile());
-    assertEquals(75, snapshot.get75thPercentile());
-    assertEquals(90, snapshot.get90thPercentile());
-    assertEquals(95, snapshot.get95thPercentile());
-    assertEquals(98, snapshot.get98thPercentile());
-    assertEquals(99, snapshot.get99thPercentile());
-    assertEquals(99, snapshot.get999thPercentile());
+    assertEquals(24, snapshot.get25thPercentile());
+    assertEquals(74, snapshot.get75thPercentile());
+    assertEquals(89, snapshot.get90thPercentile());
+    assertEquals(94, snapshot.get95thPercentile());
+    assertEquals(97, snapshot.get98thPercentile());
+    assertEquals(98, snapshot.get99thPercentile());
+    assertEquals(98, snapshot.get999thPercentile());
 
-    assertEquals(51, snapshot.getCountAtOrBelow(50));
+    assertEquals(100, snapshot.getCountAtOrBelow(50));
 
     // check that histogram is reset.
     assertEquals(100, histogram.getCount()); // count does not reset
@@ -98,5 +98,23 @@ public void testSnapshot() {
     assertEquals(198, snapshot.get98thPercentile());
     assertEquals(199, snapshot.get99thPercentile());
     assertEquals(199, snapshot.get999thPercentile());
+
+    IntStream.range(500, 1000).forEach(histogram::update);
+
+    snapshot = histogram.snapshot();
+
+    assertEquals(500, snapshot.getCount());
+    assertEquals(749, snapshot.getMedian());
+    assertEquals(749, snapshot.getMean());
+    assertEquals(500, snapshot.getMin());
+    assertEquals(999, snapshot.getMax());
+    assertEquals(624, snapshot.get25thPercentile());
+    assertEquals(874, snapshot.get75thPercentile());
+    assertEquals(949, snapshot.get90thPercentile());
+    assertEquals(974, snapshot.get95thPercentile());
+    assertEquals(989, snapshot.get98thPercentile());
+    assertEquals(994, snapshot.get99thPercentile());
+    assertEquals(998, snapshot.get999thPercentile());
+
   }
 }