summaryrefslogtreecommitdiff
path: root/absl/container/sample_element_size_test.cc
diff options
context:
space:
mode:
Diffstat (limited to 'absl/container/sample_element_size_test.cc')
-rw-r--r--absl/container/sample_element_size_test.cc114
1 files changed, 114 insertions, 0 deletions
diff --git a/absl/container/sample_element_size_test.cc b/absl/container/sample_element_size_test.cc
new file mode 100644
index 00000000..b23626b4
--- /dev/null
+++ b/absl/container/sample_element_size_test.cc
@@ -0,0 +1,114 @@
+// Copyright 2018 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/container/flat_hash_map.h"
+#include "absl/container/flat_hash_set.h"
+#include "absl/container/node_hash_map.h"
+#include "absl/container/node_hash_set.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace container_internal {
+namespace {
+
+#if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
+// Create some tables of type `Table`, then look at all the new
+// `HashtablezInfo`s to make sure that the `inline_element_size ==
+// expected_element_size`. The `inline_element_size` is the amount of memory
+// allocated for each slot of a hash table, that is `sizeof(slot_type)`. Add
+// the new `HashtablezInfo`s to `preexisting_info`. Store all the new tables
+// into `tables`.
+template <class Table>
+void TestInlineElementSize(
+ HashtablezSampler& sampler,
+ // clang-tidy gives a false positive on this declaration. This unordered
+ // set cannot be flat_hash_set, however, since that would introduce a mutex
+ // deadlock.
+ std::unordered_set<const HashtablezInfo*>& preexisting_info, // NOLINT
+ std::vector<Table>& tables, const typename Table::value_type& elt,
+ size_t expected_element_size) {
+ for (int i = 0; i < 10; ++i) {
+ // We create a new table and must store it somewhere so that when we store
+ // a pointer to the resulting `HashtablezInfo` into `preexisting_info`
+ // that we aren't storing a dangling pointer.
+ tables.emplace_back();
+ // We must insert an element to get a hashtablez to instantiate.
+ tables.back().insert(elt);
+ }
+ size_t new_count = 0;
+ sampler.Iterate([&](const HashtablezInfo& info) {
+ if (preexisting_info.insert(&info).second) {
+ EXPECT_EQ(info.inline_element_size, expected_element_size);
+ ++new_count;
+ }
+ });
+ // Make sure we actually did get a new hashtablez.
+ EXPECT_GT(new_count, 0);
+}
+
+struct bigstruct {
+ char a[1000];
+ friend bool operator==(const bigstruct& x, const bigstruct& y) {
+ return memcmp(x.a, y.a, sizeof(x.a)) == 0;
+ }
+ template <typename H>
+ friend H AbslHashValue(H h, const bigstruct& c) {
+ return H::combine_contiguous(std::move(h), c.a, sizeof(c.a));
+ }
+};
+#endif
+
+TEST(FlatHashMap, SampleElementSize) {
+#if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
+ // Enable sampling even if the prod default is off.
+ SetHashtablezEnabled(true);
+ SetHashtablezSampleParameter(1);
+
+ auto& sampler = GlobalHashtablezSampler();
+ std::vector<flat_hash_map<int, bigstruct>> flat_map_tables;
+ std::vector<flat_hash_set<bigstruct>> flat_set_tables;
+ std::vector<node_hash_map<int, bigstruct>> node_map_tables;
+ std::vector<node_hash_set<bigstruct>> node_set_tables;
+
+ // It takes thousands of new tables after changing the sampling parameters
+ // before you actually get some instrumentation. And if you must actually
+ // put something into those tables.
+ for (int i = 0; i < 10000; ++i) {
+ flat_map_tables.emplace_back();
+ flat_map_tables.back()[i] = bigstruct{};
+ }
+
+ // clang-tidy gives a false positive on this declaration. This unordered set
+ // cannot be a flat_hash_set, however, since that would introduce a mutex
+ // deadlock.
+ std::unordered_set<const HashtablezInfo*> preexisting_info; // NOLINT
+ sampler.Iterate(
+ [&](const HashtablezInfo& info) { preexisting_info.insert(&info); });
+ TestInlineElementSize(sampler, preexisting_info, flat_map_tables,
+ {0, bigstruct{}}, sizeof(int) + sizeof(bigstruct));
+ TestInlineElementSize(sampler, preexisting_info, node_map_tables,
+ {0, bigstruct{}}, sizeof(void*));
+ TestInlineElementSize(sampler, preexisting_info, flat_set_tables, //
+ bigstruct{}, sizeof(bigstruct));
+ TestInlineElementSize(sampler, preexisting_info, node_set_tables, //
+ bigstruct{}, sizeof(void*));
+#endif
+}
+
+} // namespace
+} // namespace container_internal
+ABSL_NAMESPACE_END
+} // namespace absl