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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
* Ceph - scalable distributed file system
*
* This is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1, as published by the Free Software
* Foundation. See file COPYING.
* Copyright 2013 Inktank
*/
#ifndef HISTOGRAM_H_
#define HISTOGRAM_H_
/**
* power of 2 histogram
*/
struct pow2_hist_t { //
/**
* histogram
*
* bin size is 2^index
* value is count of elements that are <= the current bin but > the previous bin.
*/
vector<int32_t> h;
private:
/// expand to at least another's size
void _expand_to(unsigned s) {
if (s > h.size())
h.resize(s, 0);
}
/// drop useless trailing 0's
void _contract() {
unsigned p = h.size();
while (p > 0 && h[p-1] == 0)
--p;
h.resize(p);
}
public:
void clear() {
h.clear();
}
void set(int bin, int32_t v) {
_expand_to(bin + 1);
h[bin] = v;
_contract();
}
void add(const pow2_hist_t& o) {
_expand_to(o.h.size());
for (unsigned p = 0; p < o.h.size(); ++p)
h[p] += o.h[p];
_contract();
}
void sub(const pow2_hist_t& o) {
_expand_to(o.h.size());
for (unsigned p = 0; p < o.h.size(); ++p)
h[p] -= o.h[p];
_contract();
}
int32_t upper_bound() const {
return 1 << h.size();
}
void dump(Formatter *f) const;
void encode(bufferlist &bl) const;
void decode(bufferlist::iterator &bl);
static void generate_test_instances(std::list<pow2_hist_t*>& o);
};
WRITE_CLASS_ENCODER(pow2_hist_t)
#endif /* HISTOGRAM_H_ */
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