You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
272 lines
5.1 KiB
272 lines
5.1 KiB
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style license that can be
|
|
// found in the LICENSE file. See the AUTHORS file for names of contributors.
|
|
|
|
#include "util/histogram.h"
|
|
|
|
#include <math.h>
|
|
#include <stdio.h>
|
|
|
|
#include "port/port.h"
|
|
|
|
namespace leveldb {
|
|
|
|
const double Histogram::kBucketLimit[kNumBuckets] = {
|
|
1,
|
|
2,
|
|
3,
|
|
4,
|
|
5,
|
|
6,
|
|
7,
|
|
8,
|
|
9,
|
|
10,
|
|
12,
|
|
14,
|
|
16,
|
|
18,
|
|
20,
|
|
25,
|
|
30,
|
|
35,
|
|
40,
|
|
45,
|
|
50,
|
|
60,
|
|
70,
|
|
80,
|
|
90,
|
|
100,
|
|
120,
|
|
140,
|
|
160,
|
|
180,
|
|
200,
|
|
250,
|
|
300,
|
|
350,
|
|
400,
|
|
450,
|
|
500,
|
|
600,
|
|
700,
|
|
800,
|
|
900,
|
|
1000,
|
|
1200,
|
|
1400,
|
|
1600,
|
|
1800,
|
|
2000,
|
|
2500,
|
|
3000,
|
|
3500,
|
|
4000,
|
|
4500,
|
|
5000,
|
|
6000,
|
|
7000,
|
|
8000,
|
|
9000,
|
|
10000,
|
|
12000,
|
|
14000,
|
|
16000,
|
|
18000,
|
|
20000,
|
|
25000,
|
|
30000,
|
|
35000,
|
|
40000,
|
|
45000,
|
|
50000,
|
|
60000,
|
|
70000,
|
|
80000,
|
|
90000,
|
|
100000,
|
|
120000,
|
|
140000,
|
|
160000,
|
|
180000,
|
|
200000,
|
|
250000,
|
|
300000,
|
|
350000,
|
|
400000,
|
|
450000,
|
|
500000,
|
|
600000,
|
|
700000,
|
|
800000,
|
|
900000,
|
|
1000000,
|
|
1200000,
|
|
1400000,
|
|
1600000,
|
|
1800000,
|
|
2000000,
|
|
2500000,
|
|
3000000,
|
|
3500000,
|
|
4000000,
|
|
4500000,
|
|
5000000,
|
|
6000000,
|
|
7000000,
|
|
8000000,
|
|
9000000,
|
|
10000000,
|
|
12000000,
|
|
14000000,
|
|
16000000,
|
|
18000000,
|
|
20000000,
|
|
25000000,
|
|
30000000,
|
|
35000000,
|
|
40000000,
|
|
45000000,
|
|
50000000,
|
|
60000000,
|
|
70000000,
|
|
80000000,
|
|
90000000,
|
|
100000000,
|
|
120000000,
|
|
140000000,
|
|
160000000,
|
|
180000000,
|
|
200000000,
|
|
250000000,
|
|
300000000,
|
|
350000000,
|
|
400000000,
|
|
450000000,
|
|
500000000,
|
|
600000000,
|
|
700000000,
|
|
800000000,
|
|
900000000,
|
|
1000000000,
|
|
1200000000,
|
|
1400000000,
|
|
1600000000,
|
|
1800000000,
|
|
2000000000,
|
|
2500000000.0,
|
|
3000000000.0,
|
|
3500000000.0,
|
|
4000000000.0,
|
|
4500000000.0,
|
|
5000000000.0,
|
|
6000000000.0,
|
|
7000000000.0,
|
|
8000000000.0,
|
|
9000000000.0,
|
|
1e200,
|
|
};
|
|
|
|
void Histogram::Clear() {
|
|
min_ = kBucketLimit[kNumBuckets - 1];
|
|
max_ = 0;
|
|
num_ = 0;
|
|
sum_ = 0;
|
|
sum_squares_ = 0;
|
|
for (int i = 0; i < kNumBuckets; i++) {
|
|
buckets_[i] = 0;
|
|
}
|
|
}
|
|
|
|
void Histogram::Add(double value) {
|
|
// Linear search is fast enough for our usage in db_bench
|
|
int b = 0;
|
|
while (b < kNumBuckets - 1 && kBucketLimit[b] <= value) {
|
|
b++;
|
|
}
|
|
buckets_[b] += 1.0;
|
|
if (min_ > value) min_ = value;
|
|
if (max_ < value) max_ = value;
|
|
num_++;
|
|
sum_ += value;
|
|
sum_squares_ += (value * value);
|
|
}
|
|
|
|
void Histogram::Merge(const Histogram& other) {
|
|
if (other.min_ < min_) min_ = other.min_;
|
|
if (other.max_ > max_) max_ = other.max_;
|
|
num_ += other.num_;
|
|
sum_ += other.sum_;
|
|
sum_squares_ += other.sum_squares_;
|
|
for (int b = 0; b < kNumBuckets; b++) {
|
|
buckets_[b] += other.buckets_[b];
|
|
}
|
|
}
|
|
|
|
double Histogram::Median() const { return Percentile(50.0); }
|
|
|
|
double Histogram::Percentile(double p) const {
|
|
double threshold = num_ * (p / 100.0);
|
|
double sum = 0;
|
|
for (int b = 0; b < kNumBuckets; b++) {
|
|
sum += buckets_[b];
|
|
if (sum >= threshold) {
|
|
// Scale linearly within this bucket
|
|
double left_point = (b == 0) ? 0 : kBucketLimit[b - 1];
|
|
double right_point = kBucketLimit[b];
|
|
double left_sum = sum - buckets_[b];
|
|
double right_sum = sum;
|
|
double pos = (threshold - left_sum) / (right_sum - left_sum);
|
|
double r = left_point + (right_point - left_point) * pos;
|
|
if (r < min_) r = min_;
|
|
if (r > max_) r = max_;
|
|
return r;
|
|
}
|
|
}
|
|
return max_;
|
|
}
|
|
|
|
double Histogram::Average() const {
|
|
if (num_ == 0.0) return 0;
|
|
return sum_ / num_;
|
|
}
|
|
|
|
double Histogram::StandardDeviation() const {
|
|
if (num_ == 0.0) return 0;
|
|
double variance = (sum_squares_ * num_ - sum_ * sum_) / (num_ * num_);
|
|
return sqrt(variance);
|
|
}
|
|
|
|
std::string Histogram::ToString() const {
|
|
std::string r;
|
|
char buf[200];
|
|
snprintf(buf, sizeof(buf), "Count: %.0f Average: %.4f StdDev: %.2f\n", num_,
|
|
Average(), StandardDeviation());
|
|
r.append(buf);
|
|
snprintf(buf, sizeof(buf), "Min: %.4f Median: %.4f Max: %.4f\n",
|
|
(num_ == 0.0 ? 0.0 : min_), Median(), max_);
|
|
r.append(buf);
|
|
r.append("------------------------------------------------------\n");
|
|
const double mult = 100.0 / num_;
|
|
double sum = 0;
|
|
for (int b = 0; b < kNumBuckets; b++) {
|
|
if (buckets_[b] <= 0.0) continue;
|
|
sum += buckets_[b];
|
|
snprintf(buf, sizeof(buf), "[ %7.0f, %7.0f ) %7.0f %7.3f%% %7.3f%% ",
|
|
((b == 0) ? 0.0 : kBucketLimit[b - 1]), // left
|
|
kBucketLimit[b], // right
|
|
buckets_[b], // count
|
|
mult * buckets_[b], // percentage
|
|
mult * sum); // cumulative percentage
|
|
r.append(buf);
|
|
|
|
// Add hash marks based on percentage; 20 marks for 100%.
|
|
int marks = static_cast<int>(20 * (buckets_[b] / num_) + 0.5);
|
|
r.append(marks, '#');
|
|
r.push_back('\n');
|
|
}
|
|
return r;
|
|
}
|
|
|
|
} // namespace leveldb
|