Import LevelDB 1.5, it will be used for the transaction database.

1 files changed, 139 insertions, 0 deletions

diff --git a/src/leveldb/util/histogram.cc b/src/leveldb/util/histogram.cc
new file mode 100644
index 0000000000..bb95f583ea
--- /dev/null
+++ b/src/leveldb/util/histogram.cc
@@ -0,0 +1,139 @@
+// 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);
+}
+
+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