StatHist.h

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/*
 * Copyright (C) 1996-2025 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */
 
#ifndef SQUID_SRC_STATHIST_H
#define SQUID_SRC_STATHIST_H
 
/* for StoreEntry */
#include "Store.h"
 
typedef double hbase_f(double);
 
typedef void StatHistBinDumper(StoreEntry *, int idx, double val, double size, int count);
 
class StatHist
{
public:
    StatHist() = default;
    StatHist(const StatHist &);
    ~StatHist() {
        xfree(bins); // can handle case of bins being nullptr
        capacity_ = 0;  // mark as destructed, may be needed for troubleshooting
    }
 
    typedef uint64_t bins_type;
 
    StatHist &operator=(const StatHist &);
 
    double deltaPctile(const StatHist &B, double pctile) const;
 
    double val(unsigned int bin) const;
 
    void count(double val);
 
    void dump(StoreEntry *sentry, StatHistBinDumper * bd) const;
 
    void logInit(unsigned int capacity, double min, double max);
 
    void enumInit(unsigned int last_enum);
 
    StatHist &operator += (const StatHist &B);
 
protected:
    void init(unsigned int capacity, hbase_f * val_in, hbase_f * val_out, double min, double max);
 
    unsigned int findBin(double v);
 
    bins_type *bins = nullptr;
    unsigned int capacity_ = 0;
 
    double min_ = 0.0;
 
    double max_ = 0.0;
 
    double scale_ = 1.0;
    hbase_f *val_in = nullptr;        /* e.g., log() for log-based histogram */
    hbase_f *val_out = nullptr;       /* e.g., exp() for log based histogram */
};
 
double statHistDeltaMedian(const StatHist & A, const StatHist & B);
double statHistDeltaPctile(const StatHist & A, const StatHist & B, double pctile);
StatHistBinDumper statHistEnumDumper;
StatHistBinDumper statHistIntDumper;
 
inline StatHist&
StatHist::operator =(const StatHist & src)
{
    if (this==&src) //handle self-assignment
        return *this;
    if (capacity_ != src.capacity_) {
        xfree(bins); // xfree can handle NULL pointers, no need to check
        capacity_=src.capacity_;
        bins = static_cast<bins_type *>(xcalloc(src.capacity_, sizeof(bins_type)));
    }
    min_=src.min_;
    max_=src.max_;
    scale_=src.scale_;
    val_in=src.val_in;
    val_out=src.val_out;
    if (bins)
        memcpy(bins,src.bins,capacity_*sizeof(*bins));
    return *this;
}
 
#endif /* SQUID_SRC_STATHIST_H */