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authordgrogan@chromium.org <dgrogan@chromium.org@62dab493-f737-651d-591e-8d6aee1b9529>2011-04-19 23:01:25 +0000
committerdgrogan@chromium.org <dgrogan@chromium.org@62dab493-f737-651d-591e-8d6aee1b9529>2011-04-19 23:01:25 +0000
commitb743906eeabc925f3e824d91a9747012bf249e2f (patch)
treee7cb4f854196c43045756469627920e4e7b146c1 /util/histogram.cc
parentb409afe968b6917574ec08e02c4bf6e6f722e3ca (diff)
downloadleveldb-b743906eeabc925f3e824d91a9747012bf249e2f.tar.gz
Revision created by MOE tool push_codebase.
MOE_MIGRATION= git-svn-id: https://leveldb.googlecode.com/svn/trunk@22 62dab493-f737-651d-591e-8d6aee1b9529
Diffstat (limited to 'util/histogram.cc')
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diff --git a/util/histogram.cc b/util/histogram.cc
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-// 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 <math.h>
-#include <stdio.h>
-#include "port/port.h"
-#include "util/histogram.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);
-}
-
-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;
-}
-
-}