Templatize percentile_filter.h and move it to base/analytics.

webrtc/base/analytics/percentile_filter.h

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include "webrtc/modules/video_coding/percentile_filter.h"
+#ifndef WEBRTC_BASE_ANALYTICS_PERCENTILE_FILTER_H_
+#define WEBRTC_BASE_ANALYTICS_PERCENTILE_FILTER_H_
+
+#include <stdint.h>

[magjed_webrtc, 2016/11/30 14:22:43]

this include looks unused

[terelius, 2016/11/30 14:32:16]

It is included for int64_t percentile_index_;

 
 #include <iterator>
+#include <set>
 
 #include "webrtc/base/checks.h"
 
 namespace webrtc {
 
-PercentileFilter::PercentileFilter(float percentile)
+// Class to efficiently get the percentile value from a group of observations.
+// The percentile is the value below which a given percentage of the
+// observations fall.
+template <typename T>
+class PercentileFilter {
+ public:
+  // Construct filter. |percentile| should be between 0 and 1.
+  explicit PercentileFilter(float percentile);
+
+  // Insert one observation. The complexity of this operation is logarithmic in
+  // the size of the container.
+  void Insert(const T& value);
+
+  // Remove one observation. The complexity of this operation is logarithmic in
+  // the size of the container.
+  void Erase(const T& value);
+
+  // Get the percentile value. The complexity of this operation is constant.
+  T GetPercentileValue() const;
+
+ private:
+  // Update iterator and index to point at target percentile value.
+  void UpdatePercentileIterator();
+
+  const float percentile_;
+  std::multiset<T> set_;
+  // Maintain iterator and index of current target percentile value.
+  typename std::multiset<T>::iterator percentile_it_;
+  int64_t percentile_index_;
+};
+
+template <typename T>
+PercentileFilter<T>::PercentileFilter(float percentile)
     : percentile_(percentile),
       percentile_it_(set_.begin()),
       percentile_index_(0) {
   RTC_CHECK_GE(percentile, 0.0f);
   RTC_CHECK_LE(percentile, 1.0f);
 }
 
-void PercentileFilter::Insert(const int64_t& value) {
+template <typename T>
+void PercentileFilter<T>::Insert(const T& value) {
   // Insert element at the upper bound.
   set_.insert(value);
   if (set_.size() == 1u) {
     // First element inserted - initialize percentile iterator and index.
     percentile_it_ = set_.begin();
     percentile_index_ = 0;
   } else if (value < *percentile_it_) {
     // If new element is before us, increment |percentile_index_|.
     ++percentile_index_;
   }
   UpdatePercentileIterator();
 }
 
-void PercentileFilter::Erase(const int64_t& value) {
-  std::multiset<int64_t>::const_iterator it = set_.lower_bound(value);
+template <typename T>
+void PercentileFilter<T>::Erase(const T& value) {
+  typename std::multiset<T>::const_iterator it = set_.lower_bound(value);
   // Ignore erase operation if the element is not present in the current set.
   if (it == set_.end() || *it != value)
     return;
   if (it == percentile_it_) {
-    // If same iterator, update to the following element. Index is not affected.
+    // If same iterator, update to the following element. Index is not
+    // affected.
     percentile_it_ = set_.erase(it);
   } else {
     set_.erase(it);
     // If erased element was before us, decrement |percentile_index_|.
     if (value <= *percentile_it_)
       --percentile_index_;
   }
   UpdatePercentileIterator();
 }
 
-void PercentileFilter::UpdatePercentileIterator() {
+template <typename T>
+void PercentileFilter<T>::UpdatePercentileIterator() {
   if (set_.empty())
     return;
   const int64_t index = static_cast<int64_t>(percentile_ * (set_.size() - 1));
   std::advance(percentile_it_, index - percentile_index_);
   percentile_index_ = index;
 }
 
-int64_t PercentileFilter::GetPercentileValue() const {
+template <typename T>
+T PercentileFilter<T>::GetPercentileValue() const {
   return set_.empty() ? 0 : *percentile_it_;
 }
 
 }  // namespace webrtc
+
+#endif  // WEBRTC_BASE_ANALYTICS_PERCENTILE_FILTER_H_