1 /*
 2  * Copyright (c) 2018, 2019, Red Hat, Inc. All rights reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.
 8  *
 9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
14  *
15  * You should have received a copy of the GNU General Public License version
16  * 2 along with this work; if not, write to the Free Software Foundation,
17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20  * or visit www.oracle.com if you need additional information or have any
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24 
25 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHNUMBERSEQ_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHNUMBERSEQ_HPP
27 
28 #include "utilities/numberSeq.hpp"
29 
30 // HDR sequence stores the low-resolution high-dynamic-range values.
31 // It does so by maintaining the double array, where first array defines
32 // the magnitude of the value being stored, and the second array maintains
33 // the low resolution histogram within that magnitude. For example, storing
34 // 4.352819 * 10^3 increments the bucket _hdr[3][435]. This allows for
35 // memory efficient storage of huge amount of samples.
36 //
37 // Accepts positive numbers only.
38 class HdrSeq: public NumberSeq {
39 private:
40   enum PrivateConstants {
41     ValBuckets = 512,
42     MagBuckets = 24,
43     MagMinimum = -12
44   };
45   int** _hdr;
46 
47 public:
48   HdrSeq();
49   ~HdrSeq();
50 
51   virtual void add(double val);
52   double percentile(double level) const;
53 
54   // Merge this HdrSeq into hdr2, optionally clearing this HdrSeq
55   void merge(HdrSeq& hdr2, bool clear_this = true);
56 };
57 
58 // Binary magnitude sequence stores the power-of-two histogram.
59 // It has very low memory requirements, and is thread-safe. When accuracy
60 // is not needed, it is preferred over HdrSeq.
61 class BinaryMagnitudeSeq : public CHeapObj<mtGC> {
62 private:
63   size_t  _sum;
64   size_t* _mags;
65 
66 public:
67   BinaryMagnitudeSeq();
68   ~BinaryMagnitudeSeq();
69 
70   void add(size_t val);
71   size_t num() const;
72   size_t level(int level) const;
73   size_t sum() const;
74   int min_level() const;
75   int max_level() const;
76   void clear();
77 };
78 
79 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHNUMBERSEQ_HPP