components/metrics: Add runtime memory leak detector

third_party/tcmalloc/chromium/src/ranked_list.h

+// Copyright (c) 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef _RANKED_LIST_H_
+#define _RANKED_LIST_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/custom_allocator.h"
+#include "base/stl_allocator.h"
+#include "leak_detector_value_type.h"
+
+// RankedList lets you add entries and automatically sorts them internally, so
+// they can be accessed in sorted order. The entries are stored as a vector
+// array.
+
+namespace leak_detector {
+
+class RankedList {
+ public:
+  using ValueType = LeakDetectorValueType;
+
+  // A single entry in the RankedList. The RankedList sorts entries by |count|.
+  struct Entry {
+    int count;
+    ValueType value;
+  };
+
+  RankedList(size_t max_size) : max_size_(max_size) {
+    entries_.reserve(max_size + 1);
+  }
+  ~RankedList() {}
+
+  // Access individual element. Does not do boundary checking.
+  const Entry& entry(int index) const {
+    return entries_[index];
+  }
+  size_t size() const {
+    return entries_.size();
+  }
+
+  // Add a new value-count pair to the list. Does not check for existing entries
+  // with the same value.
+  void Add(const ValueType& value, int count);
+
+ private:
+  // Returns the position to insert a new value. Returns -1 if it cannot be
+  // inserted.
+  int GetInsertionIndex(int count) const;
+
+  // Max and min counts.
+  const int max_count() const {
+    return entries_.empty() ? 0 : entries_[0].count;
+  }
+  const int min_count() const {
+    return entries_.empty() ? 0 : entries_[size() - 1].count;
+  }
+
+  // Max number of items in the list.
+  size_t max_size_;
+
+  // Points to the array of entries.
+  std::vector<Entry, STL_Allocator<Entry, CustomAllocator>> entries_;
+};
+
+}  // namespace leak_detector
+
+#endif  // _RANKED_LIST_H_