Sync MDP: implement MemoryDumpProvider

base/trace_event/memory_usage_estimators.h

+// Copyright 2016 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 BASE_TRACE_EVENT_MEMORY_USAGE_ESTIMATORS_H_
+#define BASE_TRACE_EVENT_MEMORY_USAGE_ESTIMATORS_H_
+
+#include <memory>
+#include <set>
+#include <string>
+#include <type_traits>
+#include <unordered_map>
+#include <vector>
+
+#include "base/strings/string16.h"
+
+namespace base {
+namespace trace_event {
+
+inline size_t EstimateMemoryUsage(const std::string& string) {
+#if defined(__GLIBCXX__) && _GLIBCXX_USE_CXX11_ABI == 0
+  // libstdc++ with COW std::string - each string allocates a header
+  // (see std::basic_string::_Rep_base). We don't take into account
+  // number of references, but we do handle 'empty string' case.
+  struct _Rep_base {
+    std::basic_string::size_type length;
+    std::basic_string::size_type capacity;
+    int refcount;
+  };
+  static const char* empty_cstr = nullptr;
+  if (!empty_cstr) empty_cstr = std::string().c_str();
+  return (string.c_str() == empty_cstr) ?
+      0 :
+      sizeof(_Rep_base) + (string.capacity() + 1);
+#else
+  const char* cstr = string.c_str();
+  const char* inline_cstr = reinterpret_cast<const char*>(&string);
+  if (cstr >= inline_cstr && cstr < inline_cstr + sizeof(string)) {
+    // Inline string
+    return 0;
+  }
+  return string.capacity();
+#endif
+}
+
+// TODO(dskiba): EstimateMemoryUsage(std::basic_string<T>)
+inline size_t EstimateMemoryUsage(const base::string16& string) {
+#if defined(__GLIBCXX__) && _GLIBCXX_USE_CXX11_ABI == 0
+  // See comment in EstimateMemoryUsage(std::string).
+  static const char16* empty_cstr = nullptr;
+  if (!empty_cstr) empty_cstr = base::string16().c_str();
+  return (string.c_str() == empty_cstr) ?
+      0 :
+      3 * sizeof(size_t) + (string.capacity() + 1) * sizeof(char16);
+#else
+  const char* cstr = reinterpret_cast<const char*>(string.c_str());
+  const char* inline_cstr = reinterpret_cast<const char*>(&string);
+  if (cstr >= inline_cstr && cstr < inline_cstr + sizeof(string)) {
+    // Inline string
+    return 0;
+  }
+  return string.capacity() * sizeof(char16);
+#endif
+}
+
+template <class T>
+typename std::enable_if<
+    std::is_arithmetic<T>::value || std::is_enum<T>::value,
+    size_t>::type
+EstimateMemoryUsage(T) { return 0; }
+
+template <class T>
+auto EstimateMemoryUsage(const T& object) ->
+    decltype(object.EstimateMemoryUsage()) {
+  static_assert(std::is_same<decltype(object.EstimateMemoryUsage()),
+                             size_t>::value,
+                "EstimateMemoryUsage() must return size_t");
+  return object.EstimateMemoryUsage();
+}
+
+// Any template that recursively calls EstimateMemoryUsage() should be
+// declared here first.
+
+template <class T>
+size_t EstimateMemoryUsage(const std::unique_ptr<T>& ptr);
+
+template <class F, class S>
+size_t EstimateMemoryUsage(const std::pair<F, S>& pair);
+
+template <class T, size_t N>
+size_t EstimateMemoryUsage(T (&array)[N]);
+
+template <class T, class A>
+size_t EstimateMemoryUsage(const std::vector<T, A>& vector);
+
+template <class T, class C, class A>
+size_t EstimateMemoryUsage(const std::set<T, C, A>& set);
+
+template <class K, class V, class H, class KE, class A>
+size_t EstimateMemoryUsage(
+    const std::unordered_map<K, V, H, KE, A>& map);
+
+// Definitions
+
+template <class T>
+size_t InternalEstimateItemMemoryUsage(T* pointer) {
+  // By default pointers treated as not owning
+  return 0;
+}
+
+template <class T>
+size_t InternalEstimateItemMemoryUsage(const T& value) {
+  return EstimateMemoryUsage(value);
+}
+
+template <class T>
+size_t EstimateMemoryUsage(const std::unique_ptr<T>& ptr) {
+  return ptr ? (sizeof(T) + EstimateMemoryUsage(*ptr)) : 0;
+}
+
+template <class F, class S>
+size_t EstimateMemoryUsage(const std::pair<F, S>& pair) {
+  return EstimateMemoryUsage(pair.first) +
+         EstimateMemoryUsage(pair.second);
+}
+
+template <class T, size_t N>
+size_t EstimateMemoryUsage(T (&array)[N]) {
+  size_t memory_usage = 0;
+  for (const auto& item: array) {
+    memory_usage += EstimateMemoryUsage(item);
+  }
+  return memory_usage;
+}
+
+template <class T, class A>
+size_t EstimateMemoryUsage(const std::vector<T, A>& vector) {
+  size_t memory_usage = vector.capacity() * sizeof(T);
+  for (const auto& element: vector) {
+    memory_usage += EstimateMemoryUsage(element);
+  }
+  return memory_usage;
+}
+
+template <class T, class C, class A>
+size_t EstimateMemoryUsage(const std::set<T, C, A>& set) {
+  // TODO(dskiba): revisit, likely not accurate enough
+  size_t memory_usage = set.size() * sizeof(T);
+  for (const auto& element: set) {
+    memory_usage += EstimateMemoryUsage(element);
+  }
+  return memory_usage;
+}
+
+template <class K, class V, class H, class KE, class A>
+size_t InternalEstimateShallowMemoryUsage(
+    const std::unordered_map<K, V, H, KE, A>& map) {
+  struct Node {
+    typename std::unordered_map<K, V, H, KE, A>::value_type value;
+    Node* next;
+    Node* prev;
+  };
+  using Bucket = Node*;
+  return map.bucket_count() * sizeof(Bucket) + map.size() * sizeof(Node);
+}
+
+template <class K, class V, class H, class KE, class A>
+size_t EstimateMemoryUsage(
+    const std::unordered_map<K, V, H, KE, A>& map) {
+  size_t memory_usage = InternalEstimateShallowMemoryUsage(map);
+  for (const auto& item: map) {
+    memory_usage += InternalEstimateItemMemoryUsage(item.first) +
+                    InternalEstimateItemMemoryUsage(item.second);
+  }
+  return memory_usage;
+}
+
+template <class K, class V, class H, class KE, class A, class Estimator>
+size_t EstimateMemoryUsage(
+    const std::unordered_map<K, V, H, KE, A>& map,
+    Estimator estimator) {
+  size_t memory_usage = InternalEstimateShallowMemoryUsage(map);
+  for (const auto& item: map) {
+    memory_usage += estimator(item.first) +
+                    estimator(item.second);
+  }
+  return memory_usage;
+}
+
+}  // namespace trace_event
+}  // namespace base
+
+#endif  // BASE_TRACE_EVENT_MEMORY_USAGE_ESTIMATORS_H_