8298138: Shenandoah: HdrSeq asserts "sub-bucket index (512) overflow for value ( 1.00)"

Reviewed-by: rkennke, shade

Author: Y. Srinivas Ramakrishna

src/hotspot/share/gc/shenandoah/shenandoahNumberSeq.cpp

@@ -56,7 +56,7 @@ void HdrSeq::add(double val) {
   int mag;
   if (v > 0) {
     mag = 0;
-    while (v > 1) {
+    while (v >= 1) {
       mag++;
       v /= 10;
     }
@@ -71,7 +71,7 @@ void HdrSeq::add(double val) {
   int bucket = -MagMinimum + mag;
   int sub_bucket = (int) (v * ValBuckets);
 
-  // Defensively saturate for product bits:
+  // Defensively saturate for product bits
   if (bucket < 0) {
     assert (false, "bucket index (%d) underflow for value (%8.2f)", bucket, val);
     bucket = 0;

src/hotspot/share/gc/shenandoah/shenandoahNumberSeq.hpp

@@ -55,7 +55,7 @@ class HdrSeq: public NumberSeq {
 // Binary magnitude sequence stores the power-of-two histogram.
 // It has very low memory requirements, and is thread-safe. When accuracy
 // is not needed, it is preferred over HdrSeq.
-class BinaryMagnitudeSeq {
+class BinaryMagnitudeSeq : public CHeapObj<mtGC> {
 private:
   size_t  _sum;
   size_t* _mags;

test/hotspot/gtest/gc/shenandoah/test_shenandoahNumberSeq.cpp

@@ -0,0 +1,74 @@
+/*
+ * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+ * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "gc/shenandoah/shenandoahNumberSeq.hpp"
+#include <iostream>
+#include "unittest.hpp"
+#include "utilities/ostream.hpp"
+
+class ShenandoahNumberSeqTest: public ::testing::Test {
+ protected:
+  HdrSeq seq;
+};
+
+class BasicShenandoahNumberSeqTest: public ShenandoahNumberSeqTest {
+ protected:
+  const double err = 0.5;
+  BasicShenandoahNumberSeqTest() {
+    seq.add(0);
+    seq.add(1);
+    seq.add(10);
+    for (int i = 0; i < 7; i++) {
+      seq.add(100);
+    }
+    std::cout << " p0 = " << seq.percentile(0);
+    std::cout << " p10 = " << seq.percentile(10);
+    std::cout << " p20 = " << seq.percentile(20);
+    std::cout << " p30 = " << seq.percentile(30);
+    std::cout << " p50 = " << seq.percentile(50);
+    std::cout << " p80 = " << seq.percentile(80);
+    std::cout << " p90 = " << seq.percentile(90);
+    std::cout << " p100 = " << seq.percentile(100);
+  }
+};
+
+TEST_VM_F(BasicShenandoahNumberSeqTest, maximum_test) {
+  EXPECT_EQ(seq.maximum(), 100);
+}
+
+TEST_VM_F(BasicShenandoahNumberSeqTest, minimum_test) {
+  EXPECT_EQ(0, seq.percentile(0));
+}
+
+TEST_VM_F(BasicShenandoahNumberSeqTest, percentile_test) {
+  EXPECT_NEAR(0, seq.percentile(10), err);
+  EXPECT_NEAR(1, seq.percentile(20), err);
+  EXPECT_NEAR(10, seq.percentile(30), err);
+  EXPECT_NEAR(100, seq.percentile(40), err);
+  EXPECT_NEAR(100, seq.percentile(50), err);
+  EXPECT_NEAR(100, seq.percentile(75), err);
+  EXPECT_NEAR(100, seq.percentile(90), err);
+  EXPECT_NEAR(100, seq.percentile(100), err);
+}