1 // Copyright 2023 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 //
5 // This is a framework to measure the memory overhead of different containers.
6 // Under the hood, it works by logging allocations and frees using an allocator
7 // hook.
8 //
9 // Since the free callback does not report a size, and the allocator hooks run
10 // in the middle of allocation, the logger simply takes the simplest approach
11 // and logs out the raw data, relying on analyze_containers_memory_usage.py to
12 // turn the raw output into useful numbers.
13 //
14 // The output of consists of m (number of different key/value combinations being
15 // tested) x n (number of different map types being tested) sections:
16 //
17 // <key type 1> -> <value type 1>
18 // ===== <map type 1> =====
19 // iteration 0
20 // alloc <address 1> size <size 1>
21 // iteration 1
22 // alloc <address 2> size <size 2>
23 // free <address 1>
24 // iteration 2
25 // alloc <address 3> size <size 3>
26 // free <address 2>
27 // ...
28 // ...
29 // ...
30 // ===== <map type n>
31 // iteration 0
32 // alloc <address 1000> size <size 1000>
33 // iteration 1
34 // alloc <address 1001> size <size 1001>
35 // free <address 1000>
36 // iteration 2
37 // alloc <address 1002> size <size 1002>
38 // free <address 1001>
39 // ...
40 // ...
41 // ...
42 // <key type m> -> <value type m>
43 // ===== <map type 1> =====
44 // ...
45 // ...
46 // ===== <map type n> =====
47 //
48 // Alternate output strategies are possible, but most of them are worse/more
49 // complex, and do not eliminate the postprocessing step.
50
51 #include <array>
52 #include <atomic>
53 #include <charconv>
54 #include <limits>
55 #include <map>
56 #include <string>
57 #include <unordered_map>
58 #include <utility>
59
60 #include "base/allocator/dispatcher/dispatcher.h"
61 #include "base/containers/flat_map.h"
62 #include "base/logging.h"
63 #include "base/strings/safe_sprintf.h"
64 #include "base/unguessable_token.h"
65 #include "base/values.h"
66 #include "third_party/abseil-cpp/absl/container/btree_map.h"
67 #include "third_party/abseil-cpp/absl/container/flat_hash_map.h"
68 #include "third_party/abseil-cpp/absl/container/node_hash_map.h"
69 #include "third_party/abseil-cpp/absl/types/optional.h"
70
71 namespace {
72
73 std::atomic<bool> log_allocs_and_frees;
74
75 struct AllocationLogger {
76 public:
OnAllocation__anon68df2b7a0111::AllocationLogger77 void OnAllocation(void* address,
78 size_t size,
79 base::allocator::dispatcher::AllocationSubsystem sub_system,
80 const char* type_name) {
81 if (log_allocs_and_frees.load(std::memory_order_acquire)) {
82 char buffer[128];
83 // Assume success; ignore return value.
84 base::strings::SafeSPrintf(buffer, "alloc address %p size %d\n", address,
85 size);
86 RAW_LOG(INFO, buffer);
87 }
88 }
89
OnFree__anon68df2b7a0111::AllocationLogger90 void OnFree(void* address) {
91 if (log_allocs_and_frees.load(std::memory_order_acquire)) {
92 char buffer[128];
93 // Assume success; ignore return value.
94 base::strings::SafeSPrintf(buffer, "freed address %p\n", address);
95 RAW_LOG(INFO, buffer);
96 }
97 }
98
Install__anon68df2b7a0111::AllocationLogger99 static void Install() {
100 static AllocationLogger logger;
101 base::allocator::dispatcher::Dispatcher::GetInstance().InitializeForTesting(
102 &logger);
103 }
104 };
105
106 class ScopedLogAllocAndFree {
107 public:
ScopedLogAllocAndFree()108 ScopedLogAllocAndFree() {
109 log_allocs_and_frees.store(true, std::memory_order_release);
110 }
111
~ScopedLogAllocAndFree()112 ~ScopedLogAllocAndFree() {
113 log_allocs_and_frees.store(false, std::memory_order_release);
114 }
115 };
116
117 // Measures the memory usage for a container with type `Container` from 0 to
118 // 6857 elements, using `inserter` to insert a single element at a time.
119 // `inserter` should be a functor that takes a `Container& container` as its
120 // first parameter and a `size_t current_index` as its second parameter.
121 //
122 // Note that `inserter` can't use `base::FunctionRef` since the inserter is
123 // passed through several layers before actually being instantiated below in
124 // this function.
125 template <typename Container, typename Inserter>
MeasureOneContainer(const Inserter & inserter)126 void MeasureOneContainer(const Inserter& inserter) {
127 char buffer[128];
128
129 RAW_LOG(INFO, "iteration 0");
130 // Record any initial allocations made by an empty container.
131 absl::optional<ScopedLogAllocAndFree> base_size_logger;
132 base_size_logger.emplace();
133 Container c;
134 base_size_logger.reset();
135 // As a hack, also log out sizeof(c) since the initial base size of the
136 // container should be counted too. The exact placeholder used for the address
137 // (in this case "(stack)") isn't important as long as it will not have a
138 // corresponding free line logged for it.
139 base::strings::SafeSPrintf(buffer, "alloc address (stack) size %d",
140 sizeof(c));
141 RAW_LOG(INFO, buffer);
142
143 // Swisstables resizes the backing store around 6858 elements.
144 for (size_t i = 1; i <= 6857; ++i) {
145 base::strings::SafeSPrintf(buffer, "iteration %d", i);
146 RAW_LOG(INFO, buffer);
147 inserter(c, i);
148 }
149 }
150
151 // Measures the memory usage for all the container types under test. `inserter`
152 // is used to insert a single element at a time into the tested container.
153 template <typename K, typename V, typename Inserter>
Measure(const Inserter & inserter)154 void Measure(const Inserter& inserter) {
155 using Hasher = std::conditional_t<std::is_same_v<base::UnguessableToken, K>,
156 base::UnguessableTokenHash, std::hash<K>>;
157
158 RAW_LOG(INFO, "===== base::flat_map =====");
159 MeasureOneContainer<base::flat_map<K, V>>(inserter);
160 RAW_LOG(INFO, "===== std::map =====");
161 MeasureOneContainer<std::map<K, V>>(inserter);
162 RAW_LOG(INFO, "===== std::unordered_map =====");
163 MeasureOneContainer<std::unordered_map<K, V, Hasher>>(inserter);
164 RAW_LOG(INFO, "===== absl::btree_map =====");
165 MeasureOneContainer<absl::btree_map<K, V>>(inserter);
166 RAW_LOG(INFO, "===== absl::flat_hash_map =====");
167 MeasureOneContainer<absl::flat_hash_map<K, V, Hasher>>(inserter);
168 RAW_LOG(INFO, "===== absl::node_hash_map =====");
169 MeasureOneContainer<absl::node_hash_map<K, V, Hasher>>(inserter);
170 }
171
172 } // namespace
173
main()174 int main() {
175 AllocationLogger::Install();
176
177 RAW_LOG(INFO, "int -> int");
178 Measure<int, int>([](auto& container, size_t i) {
179 ScopedLogAllocAndFree scoped_logging;
180 container.insert({i, 0});
181 });
182 RAW_LOG(INFO, "int -> void*");
183 Measure<int, void*>([](auto& container, size_t i) {
184 ScopedLogAllocAndFree scoped_logging;
185 container.insert({i, nullptr});
186 });
187 RAW_LOG(INFO, "int -> std::string");
188 Measure<int, std::string>([](auto& container, size_t i) {
189 ScopedLogAllocAndFree scoped_logging;
190 container.insert({i, ""});
191 });
192 RAW_LOG(INFO, "size_t -> int");
193 Measure<size_t, int>([](auto& container, size_t i) {
194 ScopedLogAllocAndFree scoped_logging;
195 container.insert({i, 0});
196 });
197 RAW_LOG(INFO, "size_t -> void*");
198 Measure<size_t, void*>([](auto& container, size_t i) {
199 ScopedLogAllocAndFree scoped_logging;
200 container.insert({i, nullptr});
201 });
202 RAW_LOG(INFO, "size_t -> std::string");
203 Measure<size_t, std::string>([](auto& container, size_t i) {
204 ScopedLogAllocAndFree scoped_logging;
205 container.insert({i, ""});
206 });
207 RAW_LOG(INFO, "std::string -> std::string");
208 Measure<std::string, std::string>([](auto& container, size_t i) {
209 std::string key;
210 key.resize(std::numeric_limits<size_t>::digits10 + 1);
211 auto result = std::to_chars(&key.front(), &key.back(), i);
212 key.resize(result.ptr - &key.front());
213 ScopedLogAllocAndFree scoped_logging;
214 container.insert({key, ""});
215 });
216 RAW_LOG(INFO, "base::UnguessableToken -> void*");
217 Measure<base::UnguessableToken, void*>([](auto& container, size_t i) {
218 auto token = base::UnguessableToken::Create();
219 ScopedLogAllocAndFree scoped_logging;
220 container.insert({token, nullptr});
221 });
222 RAW_LOG(INFO, "base::UnguessableToken -> base::Value");
223 Measure<base::UnguessableToken, base::Value>([](auto& container, size_t i) {
224 auto token = base::UnguessableToken::Create();
225 base::Value value;
226 ScopedLogAllocAndFree scoped_logging;
227 container.insert({token, std::move(value)});
228 });
229 RAW_LOG(INFO, "base::UnguessableToken -> std::array<std::string, 4>");
230 Measure<base::UnguessableToken, std::array<std::string, 4>>(
231 [](auto& container, size_t i) {
232 auto token = base::UnguessableToken::Create();
233 ScopedLogAllocAndFree scoped_logging;
234 container.insert({token, {}});
235 });
236 RAW_LOG(INFO, "base::UnguessableToken -> std::array<std::string, 8>");
237 Measure<base::UnguessableToken, std::array<std::string, 8>>(
238 [](auto& container, size_t i) {
239 auto token = base::UnguessableToken::Create();
240 ScopedLogAllocAndFree scoped_logging;
241 container.insert({token, {}});
242 });
243 RAW_LOG(INFO, "base::UnguessableToken -> std::array<std::string, 16>");
244 Measure<base::UnguessableToken, std::array<std::string, 16>>(
245 [](auto& container, size_t i) {
246 auto token = base::UnguessableToken::Create();
247 ScopedLogAllocAndFree scoped_logging;
248 container.insert({token, {}});
249 });
250
251 return 0;
252 }
253