[tracing] Implement composable memory usage estimators.

base/trace_event/estimate_memory_usage_unittest.cc

+// 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.
+
+#include "base/trace_event/estimate_memory_usage.h"
+
+#include <stdlib.h>
+
+#include "base/memory/ptr_util.h"
+#include "base/strings/string16.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace trace_event {
+
+namespace {
+
+// Test class with predictable memory usage.
+class Data {
+ public:
+  explicit Data(size_t size = 17): size_(size) {
+  }
+
+  size_t size() const { return size_; }
+
+  size_t EstimateMemoryUsage() const {
+    return size_;
+  }
+
+  bool operator < (const Data& other) const {
+    return size_ < other.size_;
+  }
+  bool operator == (const Data& other) const {
+    return size_ == other.size_;
+  }
+
+  struct Hasher {
+    size_t operator () (const Data& data) const {
+      return data.size();
+    }
+  };
+
+ private:
+  size_t size_;
+};
+
+}  // namespace
+
+TEST(EstimateMemoryUsageTest, String) {
+  std::string string(777, 'a');
+  EXPECT_EQ(string.capacity() + 1, EstimateMemoryUsage(string));
+}
+
+TEST(EstimateMemoryUsageTest, String16) {
+  string16 string(777, 'a');
+  EXPECT_EQ(sizeof(char16) * (string.capacity() + 1),
+            EstimateMemoryUsage(string));
+}
+
+TEST(EstimateMemoryUsageTest, Arrays) {
+  // std::array
+  {
+    std::array<Data, 10> array;
+    EXPECT_EQ(170u, EstimateMemoryUsage(array));
+  }
+
+  // T[N]
+  {
+    Data array[10];
+    EXPECT_EQ(170u, EstimateMemoryUsage(array));
+  }
+
+  // C array
+  {
+    struct Item {
+      char payload[10];
+    };
+    Item* array = new Item[7];
+    EXPECT_EQ(70u, EstimateMemoryUsage(array, 7));
+    delete[] array;
+  }
+}
+
+TEST(EstimateMemoryUsageTest, UniquePtr) {
+  // Empty
+  {
+    std::unique_ptr<Data> ptr;
+    EXPECT_EQ(0u, EstimateMemoryUsage(ptr));
+  }
+
+  // Not empty
+  {
+    std::unique_ptr<Data> ptr(new Data());
+    EXPECT_EQ(25u, EstimateMemoryUsage(ptr));
+  }
+
+  // With a pointer
+  {
+    std::unique_ptr<Data*> ptr(new Data*());
+    EXPECT_EQ(8u, EstimateMemoryUsage(ptr));

[Primiano Tucci (use gerrit), 2016/11/08 14:09:16]

s/8u/sizeof(void*)/ ?

+  }
+
+  // With an array
+  {
+    struct Item {
+      int payload[10];

[Primiano Tucci (use gerrit), 2016/11/08 14:09:16]

s/int/uint32_t/ to keep it a bit more readable

+    };
+    std::unique_ptr<Item[]> ptr(new Item[7]);
+    EXPECT_EQ(280u, EstimateMemoryUsage(ptr, 7));
+  }
+}
+
+TEST(EstimateMemoryUsageTest, Vector) {
+  {
+    std::vector<Data> vector;
+    for (int i = 0; i != 1000; ++i) {
+      vector.push_back(Data(i));
+    }
+    EXPECT_EQ(507692u, EstimateMemoryUsage(vector));
+  }
+
+  // Capacity
+  {
+    struct POD {
+      short data;
+    };
+    std::vector<POD> vector;
+    vector.reserve(1000);
+    EXPECT_EQ(2000u, EstimateMemoryUsage(vector));
+  }
+}
+
+TEST(EstimateMemoryUsageTest, List) {
+  struct POD {
+    short data;
+  };
+  std::list<POD> list;
+  for (int i = 0; i != 1000; ++i) {
+    list.push_back(POD());
+  }
+  EXPECT_EQ(24000u, EstimateMemoryUsage(list));
+}
+
+TEST(EstimateMemoryUsageTest, Set) {
+  std::set<std::pair<int, Data>> set;
+  for (int i = 0; i != 1000; ++i) {
+    set.insert({i, Data(i)});
+  }
+  EXPECT_EQ(547500u, EstimateMemoryUsage(set));
+}
+
+TEST(EstimateMemoryUsageTest, MultiSet) {
+  std::multiset<bool> set;
+  for (int i = 0; i != 1000; ++i) {
+    set.insert((i & 1) != 0);
+  }
+  EXPECT_EQ(32000u, EstimateMemoryUsage(set));
+}
+
+TEST(EstimateMemoryUsageTest, Map) {
+  std::map<Data, int> map;
+  for (int i = 0; i != 1000; ++i) {
+    map.insert({Data(i), i});
+  }
+  EXPECT_EQ(547500u, EstimateMemoryUsage(map));
+}
+
+TEST(EstimateMemoryUsageTest, MultiMap) {
+  std::multimap<char, Data> map;
+  for (int i = 0; i != 1000; ++i) {
+    map.insert({static_cast<char>(i), Data(i)});
+  }
+  EXPECT_EQ(547500u, EstimateMemoryUsage(map));
+}
+
+TEST(EstimateMemoryUsageTest, UnorderedSet) {
+  std::unordered_set<Data, Data::Hasher> set;
+  for (int i = 0; i != 1000; ++i) {
+    set.insert(Data(i));
+  }
+  EXPECT_EQ(537428u, EstimateMemoryUsage(set));
+}
+
+TEST(EstimateMemoryUsageTest, UnorderedMultiSet) {
+  std::unordered_multiset<short> set;
+  for (int i = 0; i != 1000; ++i) {
+    set.insert(static_cast<short>(i));
+  }
+  EXPECT_EQ(37928u, EstimateMemoryUsage(set));
+}
+
+TEST(EstimateMemoryUsageTest, UnorderedMap) {
+  std::unordered_map<Data, void*, Data::Hasher> map;
+  for (int i = 0; i != 1000; ++i) {
+    map.insert({Data(i), reinterpret_cast<void*>(i)});
+  }
+  EXPECT_EQ(545428u, EstimateMemoryUsage(map));
+}
+
+TEST(EstimateMemoryUsageTest, UnorderedMultiMap) {
+  std::unordered_multimap<char, short> map;
+  for (int i = 0; i != 1000; ++i) {
+    map.insert({static_cast<char>(i), 777});
+  }
+  EXPECT_EQ(37928u, EstimateMemoryUsage(map));
+}
+
+}  // namespace trace_event
+}  // namespace base