histogram.h

// histogram.h

#ifndef UTIL_HISTOGRAM_HEADER
#define UTIL_HISTOGRAM_HEADER

#include "../pch.h"

#include <string>

namespace mongo {

    using std::string;

    class Histogram {
    public:
        struct Options {
            boost::uint32_t numBuckets;
            boost::uint32_t bucketSize;
            boost::uint32_t initialValue;

            // use exponential buckets?
            bool            exponential;

            Options()
                : numBuckets(0)
                , bucketSize(0)
                , initialValue(0)
                , exponential(false) {}
        };
        explicit Histogram( const Options& opts );
        ~Histogram();

        void insert( boost::uint32_t element );

        string toHTML() const;

        // testing interface below -- consider it private

        boost::uint64_t getCount( boost::uint32_t bucket ) const;

        boost::uint32_t getBoundary( boost::uint32_t bucket ) const;

        boost::uint32_t getBucketsNum() const;

    private:
        boost::uint32_t _findBucket( boost::uint32_t element ) const;

        boost::uint32_t  _initialValue;  // no value lower than it is recorded
        boost::uint32_t  _numBuckets;    // total buckets in the histogram

        // all below owned here
        boost::uint32_t* _boundaries;    // maximum element of each bucket
        boost::uint64_t* _buckets;       // current count of each bucket

        Histogram( const Histogram& );
        Histogram& operator=( const Histogram& );
    };

}  // namespace mongo

#endif  //  UTIL_HISTOGRAM_HEADER

---