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#pragma once
#include <util/generic/bitops.h>
#include <cmath>
#include "percentile_base.h"
namespace NMonitoring {
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Percentile tracker for monitoring
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
template <size_t BASE_BITS, size_t EXP_BITS, size_t FRAME_COUNT>
struct TPercentileTrackerLg : public TPercentileBase {
static constexpr size_t BUCKET_COUNT = size_t(1) << EXP_BITS;
static constexpr size_t BUCKET_SIZE = size_t(1) << BASE_BITS;
static constexpr size_t ITEMS_COUNT = BUCKET_COUNT * BUCKET_SIZE;
static constexpr size_t TRACKER_LIMIT = BUCKET_SIZE * ((size_t(1) << BUCKET_COUNT) - 1)
- (size_t(1) << (BUCKET_COUNT - 1));
static constexpr size_t MAX_GRANULARITY = size_t(1) << (BUCKET_COUNT - 1);
size_t Borders[BUCKET_COUNT];
std::atomic<size_t> Items[ITEMS_COUNT];
size_t Frame[FRAME_COUNT][ITEMS_COUNT];
size_t CurrentFrame;
TPercentileTrackerLg()
: CurrentFrame(0)
{
Borders[0] = 0;
for (size_t i = 1; i < BUCKET_COUNT; ++i) {
Borders[i] = Borders[i-1] + (BUCKET_SIZE << (i - 1));
}
for (size_t i = 0; i < ITEMS_COUNT; ++i) {
Items[i].store(0);
}
for (size_t frame = 0; frame < FRAME_COUNT; ++frame) {
for (size_t bucket = 0; bucket < ITEMS_COUNT; ++bucket) {
Frame[frame][bucket] = 0;
}
}
}
size_t inline BucketIdxIf(size_t value) {
static_assert(BASE_BITS == 5, "if-based bucket calculation cannot be used if BASE_BITS != 5");
size_t bucket_idx;
if (value < 8160) {
if (value < 480) {
if (value < 96) {
if (value < 32) {
bucket_idx = 0;
} else {
bucket_idx = 1;
}
} else {
if (value < 224) {
bucket_idx = 2;
} else {
bucket_idx = 3;
}
}
} else {
if (value < 2016) {
if (value < 992) {
bucket_idx = 4;
} else {
bucket_idx = 5;
}
} else {
if (value < 4064) {
bucket_idx = 6;
} else {
bucket_idx = 7;
}
}
}
} else {
if (value < 131040) {
if (value < 32736) {
if (value < 16352) {
bucket_idx = 8;
} else {
bucket_idx = 9;
}
} else {
if (value < 65504) {
bucket_idx = 10;
} else {
bucket_idx = 11;
}
}
} else {
if (value < 524256) {
if (value < 262112) {
bucket_idx = 12;
} else {
bucket_idx = 13;
}
} else {
if (value < 1048544) {
bucket_idx = 14;
} else {
bucket_idx = 15;
}
}
}
}
return Min(bucket_idx, BUCKET_COUNT - 1);
}
size_t inline BucketIdxBinarySearch(size_t value) {
size_t l = 0;
size_t r = BUCKET_COUNT;
while (l < r - 1) {
size_t mid = (l + r) / 2;
if (value < Borders[mid]) {
r = mid;
} else {
l = mid;
}
}
return l;
}
size_t inline BucketIdxMostSignificantBit(size_t value) {
size_t bucket_idx = MostSignificantBit(value + BUCKET_SIZE) - BASE_BITS;
return Min(bucket_idx, BUCKET_COUNT - 1);
}
void Increment(size_t value) {
size_t bucket_idx = BucketIdxMostSignificantBit(value);
size_t inside_bucket_idx = (value - Borders[bucket_idx] + (1 << bucket_idx) - 1) >> bucket_idx;
size_t idx = bucket_idx * BUCKET_SIZE + inside_bucket_idx;
Items[Min(idx, ITEMS_COUNT - 1)].fetch_add(1, std::memory_order_relaxed);
}
// Needed only for tests
size_t GetPercentile(float threshold) {
std::array<size_t, ITEMS_COUNT> totals;
size_t total = 0;
for (size_t i = 0; i < ITEMS_COUNT; ++i) {
total += Items[i].load();
totals[i] = total;
}
size_t item_threshold = std::llround(threshold * (float)total);
item_threshold = Min(item_threshold, total);
auto it = LowerBound(totals.begin(), totals.end(), item_threshold);
size_t index = it - totals.begin();
size_t bucket_idx = index / BUCKET_SIZE;
return Borders[bucket_idx] + ((index % BUCKET_SIZE) << bucket_idx);
}
// shift frame (call periodically)
void Update() {
std::array<size_t, ITEMS_COUNT> totals;
size_t total = 0;
for (size_t i = 0; i < ITEMS_COUNT; ++i) {
size_t item = Items[i].load(std::memory_order_relaxed);
size_t prevItem = Frame[CurrentFrame][i];
Frame[CurrentFrame][i] = item;
total += item - prevItem;
totals[i] = total;
}
for (size_t i = 0; i < Percentiles.size(); ++i) {
TPercentile &percentile = Percentiles[i];
size_t threshold = std::llround(percentile.first * (float)total);
threshold = Min(threshold, total);
auto it = LowerBound(totals.begin(), totals.end(), threshold);
size_t index = it - totals.begin();
size_t bucket_idx = index / BUCKET_SIZE;
(*percentile.second) = Borders[bucket_idx] + ((index % BUCKET_SIZE) << bucket_idx);
}
CurrentFrame = (CurrentFrame + 1) % FRAME_COUNT;
}
};
} // NMonitoring
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