rocksdb/util/statistics.cc

#include "leveldb/statistics.h"
#include <cstdio>

namespace leveldb {

namespace {
// a buffer size used for temp string buffers
const int kBufferSize = 200;

std::string HistogramToString (
    Statistics* dbstats,
    const Histograms& histogram_type,
    const std::string& name) {

  char buffer[kBufferSize];
  HistogramData histogramData;
  dbstats->histogramData(histogram_type, &histogramData);
  snprintf(
      buffer,
      kBufferSize,
      "%s statistics Percentiles :=> 50 : %f 95 : %f 99 : %f\n",
      name.c_str(),
      histogramData.median,
      histogramData.percentile95,
      histogramData.percentile99
  );
  return std::string(buffer);
};

std::string TickerToString (
    Statistics* dbstats,
    const Tickers& ticker,
    const std::string& name) {

  char buffer[kBufferSize];
  snprintf(buffer, kBufferSize, "%s COUNT : %ld\n",
            name.c_str(), dbstats->getTickerCount(ticker));
  return std::string(buffer);
};
} // namespace

std::string Statistics::ToString() {
  std::string res;
  res.reserve(20000);
  for (const auto& t : TickersNameMap) {
    res.append(TickerToString(this, t.first, t.second));
  }
  for (const auto& h : HistogramsNameMap) {
    res.append(HistogramToString(this, h.first, h.second));
  }
  res.shrink_to_fit();
  return res;
}

} // namespace leveldb