mutilate/HistogramSampler.h
Jacob Leverich 386320d266 Initial check-in.
This is extracted from another git repo.  This is the first release, and
the prior commit history is not terribly interesting, so I'm not going
to bother using filter-branch to try to cleanly isolate the history for
this tool.

Cheers.
2012-08-23 14:30:32 -07:00

93 lines
1.7 KiB
C++

/* -*- c++ -*- */
#ifndef HISTOGRAMSAMPLER_H
#define HISTOGRAMSAMPLER_H
#include <inttypes.h>
#include <assert.h>
#include <vector>
#include "Operation.h"
// parameters: # of bins, range? size of bins?
class HistogramSampler {
public:
std::vector<uint64_t> bins;
int width;
double overflow_sum;
HistogramSampler() = delete;
HistogramSampler(int _bins, int _width) : overflow_sum(0.0) {
assert(_bins > 0 && _width > 0);
bins.resize(_bins + 1, 0);
width = _width;
}
void sample(const Operation &op) {
sample(op.time());
}
void sample(double s) {
assert(s >= 0);
size_t bin = s / width;
if (bin >= bins.size()) {
bin = bins.size() - 1;
overflow_sum += s;
}
bins[bin]++;
}
double average() {
uint64_t count = total();
double sum = 0.0;
for (size_t i = 0; i < bins.size() - 1; i++) {
sum += bins[i] * (i*width + (i+1)*width) / 2;
}
sum += overflow_sum;
return sum / count;
}
double get_nth(double nth) {
uint64_t count = total();
uint64_t n = 0;
double target = count * nth/100;
for (size_t i = 0; i < bins.size(); i++) {
n += bins[i];
if (n > target) { // The nth is inside bins[i].
double left = target - (n - bins[i]);
return i*width + left / bins[i] * width;
}
}
return bins.size() * width;
}
uint64_t total() {
uint64_t sum = 0.0;
for (auto i: bins) sum += i;
return sum;
}
void accumulate(const HistogramSampler &h) {
assert(width == h.width && bins.size() == h.bins.size());
for (size_t i = 0; i < bins.size(); i++) bins[i] += h.bins[i];
overflow_sum += h.overflow_sum;
}
};
#endif // HISTOGRAMSAMPLER_H