// 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 "absl/container/internal/hashtablez_sampler.h"
#include <atomic>
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <limits>
#include <random>
#include <vector>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "absl/profiling/internal/sample_recorder.h"
#include "absl/synchronization/blocking_counter.h"
#include "absl/synchronization/internal/thread_pool.h"
#include "absl/synchronization/mutex.h"
#include "absl/synchronization/notification.h"
#include "absl/time/clock.h"
#include "absl/time/time.h"
#ifdef ABSL_INTERNAL_HAVE_SSE2
constexpr int kProbeLength = 16;
#else
constexpr int kProbeLength = 8;
#endif
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace container_internal {
#if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
class HashtablezInfoHandlePeer {
public:
static HashtablezInfo* GetInfo(HashtablezInfoHandle* h) { return h->info_; }
};
#else
class HashtablezInfoHandlePeer {
public:
static HashtablezInfo* GetInfo(HashtablezInfoHandle*) { return nullptr; }
};
#endif // defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
namespace {
using ::absl::synchronization_internal::ThreadPool;
using ::testing::IsEmpty;
using ::testing::UnorderedElementsAre;
std::vector<size_t> GetSizes(HashtablezSampler* s) {
std::vector<size_t> res;
s->Iterate([&](const HashtablezInfo& info) {
res.push_back(info.size.load(std::memory_order_acquire));
});
return res;
}
HashtablezInfo* Register(HashtablezSampler* s, size_t size) {
const int64_t test_stride = 123;
const size_t test_element_size = 17;
const size_t test_key_size = 3;
const size_t test_value_size = 5;
auto* info =
s->Register(test_stride, test_element_size, /*key_size=*/test_key_size,
/*value_size=*/test_value_size, /*soo_capacity=*/0);
assert(info != nullptr);
info->size.store(size);
return info;
}
TEST(HashtablezInfoTest, PrepareForSampling) {
absl::Time test_start = absl::Now();
const int64_t test_stride = 123;
const size_t test_element_size = 17;
const size_t test_key_size = 15;
const size_t test_value_size = 13;
HashtablezInfo info;
absl::MutexLock l(&info.init_mu);
info.PrepareForSampling(test_stride, test_element_size,
/*key_size=*/test_key_size,
/*value_size=*/test_value_size,
/*soo_capacity_value=*/1);
EXPECT_EQ(info.capacity.load(), 0);
EXPECT_EQ(info.size.load(), 0);
EXPECT_EQ(info.num_erases.load(), 0);
EXPECT_EQ(info.num_rehashes.load(), 0);
EXPECT_EQ(info.max_probe_length.load(), 0);
EXPECT_EQ(info.total_probe_length.load(), 0);
EXPECT_EQ(info.hashes_bitwise_or.load(), 0);
EXPECT_EQ(info.hashes_bitwise_and.load(), ~size_t{});
EXPECT_EQ(info.hashes_bitwise_xor.load(), 0);
EXPECT_EQ(info.max_reserve.load(), 0);
EXPECT_GE(info.create_time, test_start);
EXPECT_EQ(info.weight, test_stride);
EXPECT_EQ(info.inline_element_size, test_element_size);
EXPECT_EQ(info.key_size, test_key_size);
EXPECT_EQ(info.value_size, test_value_size);
EXPECT_EQ(info.soo_capacity, 1);
info.capacity.store(1, std::memory_order_relaxed);
info.size.store(1, std::memory_order_relaxed);
info.num_erases.store(1, std::memory_order_relaxed);
info.max_probe_length.store(1, std::memory_order_relaxed);
info.total_probe_length.store(1, std::memory_order_relaxed);
info.hashes_bitwise_or.store(1, std::memory_order_relaxed);
info.hashes_bitwise_and.store(1, std::memory_order_relaxed);
info.hashes_bitwise_xor.store(1, std::memory_order_relaxed);
info.max_reserve.store(1, std::memory_order_relaxed);
info.create_time = test_start - absl::Hours(20);
info.PrepareForSampling(test_stride * 2, test_element_size,
/*key_size=*/test_key_size,
/*value_size=*/test_value_size,
/*soo_capacity_value=*/0);
EXPECT_EQ(info.capacity.load(), 0);
EXPECT_EQ(info.size.load(), 0);
EXPECT_EQ(info.num_erases.load(), 0);
EXPECT_EQ(info.num_rehashes.load(), 0);
EXPECT_EQ(info.max_probe_length.load(), 0);
EXPECT_EQ(info.total_probe_length.load(), 0);
EXPECT_EQ(info.hashes_bitwise_or.load(), 0);
EXPECT_EQ(info.hashes_bitwise_and.load(), ~size_t{});
EXPECT_EQ(info.hashes_bitwise_xor.load(), 0);
EXPECT_EQ(info.max_reserve.load(), 0);
EXPECT_EQ(info.weight, 2 * test_stride);
EXPECT_EQ(info.inline_element_size, test_element_size);
EXPECT_EQ(info.key_size, test_key_size);
EXPECT_EQ(info.value_size, test_value_size);
EXPECT_GE(info.create_time, test_start);
EXPECT_EQ(info.soo_capacity, 0);
}
TEST(HashtablezInfoTest, RecordStorageChanged) {
HashtablezInfo info;
absl::MutexLock l(&info.init_mu);
const int64_t test_stride = 21;
const size_t test_element_size = 19;
const size_t test_key_size = 17;
const size_t test_value_size = 15;
info.PrepareForSampling(test_stride, test_element_size,
/*key_size=*/test_key_size,
/*value_size=*/test_value_size,
/*soo_capacity_value=*/0);
RecordStorageChangedSlow(&info, 17, 47);
EXPECT_EQ(info.size.load(), 17);
EXPECT_EQ(info.capacity.load(), 47);
RecordStorageChangedSlow(&info, 20, 20);
EXPECT_EQ(info.size.load(), 20);
EXPECT_EQ(info.capacity.load(), 20);
}
TEST(HashtablezInfoTest, RecordInsert) {
HashtablezInfo info;
absl::MutexLock l(&info.init_mu);
const int64_t test_stride = 25;
const size_t test_element_size = 23;
const size_t test_key_size = 21;
const size_t test_value_size = 19;
info.PrepareForSampling(test_stride, test_element_size,
/*key_size=*/test_key_size,
/*value_size=*/test_value_size,
/*soo_capacity_value=*/0);
EXPECT_EQ(info.max_probe_length.load(), 0);
RecordInsertSlow(&info, 0x0000FF00, 6 * kProbeLength);
EXPECT_EQ(info.max_probe_length.load(), 6);
EXPECT_EQ(info.hashes_bitwise_and.load(), 0x0000FF00);
EXPECT_EQ(info.hashes_bitwise_or.load(), 0x0000FF00);
EXPECT_EQ(info.hashes_bitwise_xor.load(), 0x0000FF00);
RecordInsertSlow(&info, 0x000FF000, 4 * kProbeLength);
EXPECT_EQ(info.max_probe_length.load(), 6);
EXPECT_EQ(info.hashes_bitwise_and.load(), 0x0000F000);
EXPECT_EQ(info.hashes_bitwise_or.load(), 0x000FFF00);
EXPECT_EQ(info.hashes_bitwise_xor.load(), 0x000F0F00);
RecordInsertSlow(&info, 0x00FF0000, 12 * kProbeLength);
EXPECT_EQ(info.max_probe_length.load(), 12);
EXPECT_EQ(info.hashes_bitwise_and.load(), 0x00000000);
EXPECT_EQ(info.hashes_bitwise_or.load(), 0x00FFFF00);
EXPECT_EQ(info.hashes_bitwise_xor.load(), 0x00F00F00);
}
TEST(HashtablezInfoTest, RecordErase) {
const int64_t test_stride = 31;
const size_t test_element_size = 29;
const size_t test_key_size = 27;
const size_t test_value_size = 25;
HashtablezInfo info;
absl::MutexLock l(&info.init_mu);
info.PrepareForSampling(test_stride, test_element_size,
/*key_size=*/test_key_size,
/*value_size=*/test_value_size,
/*soo_capacity_value=*/1);
EXPECT_EQ(info.num_erases.load(), 0);
EXPECT_EQ(info.size.load(), 0);
RecordInsertSlow(&info, 0x0000FF00, 6 * kProbeLength);
EXPECT_EQ(info.size.load(), 1);
RecordEraseSlow(&info);
EXPECT_EQ(info.size.load(), 0);
EXPECT_EQ(info.num_erases.load(), 1);
EXPECT_EQ(info.inline_element_size, test_element_size);
EXPECT_EQ(info.key_size, test_key_size);
EXPECT_EQ(info.value_size, test_value_size);
EXPECT_EQ(info.soo_capacity, 1);
}
TEST(HashtablezInfoTest, RecordRehash) {
const int64_t test_stride = 33;
const size_t test_element_size = 31;
const size_t test_key_size = 29;
const size_t test_value_size = 27;
HashtablezInfo info;
absl::MutexLock l(&info.init_mu);
info.PrepareForSampling(test_stride, test_element_size,
/*key_size=*/test_key_size,
/*value_size=*/test_value_size,
/*soo_capacity_value=*/0);
RecordInsertSlow(&info, 0x1, 0);
RecordInsertSlow(&info, 0x2, kProbeLength);
RecordInsertSlow(&info, 0x4, kProbeLength);
RecordInsertSlow(&info, 0x8, 2 * kProbeLength);
EXPECT_EQ(info.size.load(), 4);
EXPECT_EQ(info.total_probe_length.load(), 4);
RecordEraseSlow(&info);
RecordEraseSlow(&info);
EXPECT_EQ(info.size.load(), 2);
EXPECT_EQ(info.total_probe_length.load(), 4);
EXPECT_EQ(info.num_erases.load(), 2);
RecordRehashSlow(&info, 3 * kProbeLength);
EXPECT_EQ(info.size.load(), 2);
EXPECT_EQ(info.total_probe_length.load(), 3);
EXPECT_EQ(info.num_erases.load(), 0);
EXPECT_EQ(info.num_rehashes.load(), 1);
EXPECT_EQ(info.inline_element_size, test_element_size);
EXPECT_EQ(info.key_size, test_key_size);
EXPECT_EQ(info.value_size, test_value_size);
EXPECT_EQ(info.soo_capacity, 0);
}
TEST(HashtablezInfoTest, RecordReservation) {
HashtablezInfo info;
absl::MutexLock l(&info.init_mu);
const int64_t test_stride = 35;
const size_t test_element_size = 33;
const size_t test_key_size = 31;
const size_t test_value_size = 29;
info.PrepareForSampling(test_stride, test_element_size,
/*key_size=*/test_key_size,
/*value_size=*/test_value_size,
/*soo_capacity_value=*/0);
RecordReservationSlow(&info, 3);
EXPECT_EQ(info.max_reserve.load(), 3);
RecordReservationSlow(&info, 2);
// High watermark does not change
EXPECT_EQ(info.max_reserve.load(), 3);
RecordReservationSlow(&info, 10);
// High watermark does change
EXPECT_EQ(info.max_reserve.load(), 10);
}
#if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
TEST(HashtablezSamplerTest, SmallSampleParameter) {
const size_t test_element_size = 31;
const size_t test_key_size = 33;
const size_t test_value_size = 35;
SetHashtablezEnabled(true);
SetHashtablezSampleParameter(100);
for (int i = 0; i < 1000; ++i) {
SamplingState next_sample = {0, 0};
HashtablezInfo* sample =
SampleSlow(next_sample, test_element_size,
/*key_size=*/test_key_size, /*value_size=*/test_value_size,
/*soo_capacity=*/0);
EXPECT_GT(next_sample.next_sample, 0);
EXPECT_EQ(next_sample.next_sample, next_sample.sample_stride);
EXPECT_NE(sample, nullptr);
UnsampleSlow(sample);
}
}
TEST(HashtablezSamplerTest, LargeSampleParameter) {
const size_t test_element_size = 31;
const size_t test_key_size = 33;
const size_t test_value_size = 35;
SetHashtablezEnabled(true);
SetHashtablezSampleParameter(std::numeric_limits<int32_t>::max());
for (int i = 0; i < 1000; ++i) {
SamplingState next_sample = {0, 0};
HashtablezInfo* sample =
SampleSlow(next_sample, test_element_size,
/*key_size=*/test_key_size, /*value_size=*/test_value_size,
/*soo_capacity=*/0);
EXPECT_GT(next_sample.next_sample, 0);
EXPECT_EQ(next_sample.next_sample, next_sample.sample_stride);
EXPECT_NE(sample, nullptr);
UnsampleSlow(sample);
}
}
TEST(HashtablezSamplerTest, Sample) {
const size_t test_element_size = 31;
const size_t test_key_size = 33;
const size_t test_value_size = 35;
SetHashtablezEnabled(true);
SetHashtablezSampleParameter(100);
int64_t num_sampled = 0;
int64_t total = 0;
double sample_rate = 0.0;
for (int i = 0; i < 1000000; ++i) {
HashtablezInfoHandle h =
Sample(test_element_size,
/*key_size=*/test_key_size, /*value_size=*/test_value_size,
/*soo_capacity=*/0);
++total;
if (h.IsSampled()) {
++num_sampled;
}
sample_rate = static_cast<double>(num_sampled) / total;
if (0.005 < sample_rate && sample_rate < 0.015) break;
}
EXPECT_NEAR(sample_rate, 0.01, 0.005);
}
TEST(HashtablezSamplerTest, Handle) {
auto& sampler = GlobalHashtablezSampler();
const int64_t test_stride = 41;
const size_t test_element_size = 39;
const size_t test_key_size = 37;
const size_t test_value_size = 35;
HashtablezInfoHandle h(sampler.Register(test_stride, test_element_size,
/*key_size=*/test_key_size,
/*value_size=*/test_value_size,
/*soo_capacity=*/0));
auto* info = HashtablezInfoHandlePeer::GetInfo(&h);
info->hashes_bitwise_and.store(0x12345678, std::memory_order_relaxed);
bool found = false;
sampler.Iterate([&](const HashtablezInfo& h) {
if (&h == info) {
EXPECT_EQ(h.weight, test_stride);
EXPECT_EQ(h.hashes_bitwise_and.load(), 0x12345678);
found = true;
}
});
EXPECT_TRUE(found);
h.Unregister();
h = HashtablezInfoHandle();
found = false;
sampler.Iterate([&](const HashtablezInfo& h) {
if (&h == info) {
// this will only happen if some other thread has resurrected the info
// the old handle was using.
if (h.hashes_bitwise_and.load() == 0x12345678) {
found = true;
}
}
});
EXPECT_FALSE(found);
}
#endif
TEST(HashtablezSamplerTest, Registration) {
HashtablezSampler sampler;
auto* info1 = Register(&sampler, 1);
EXPECT_THAT(GetSizes(&sampler), UnorderedElementsAre(1));
auto* info2 = Register(&sampler, 2);
EXPECT_THAT(GetSizes(&sampler), UnorderedElementsAre(1, 2));
info1->size.store(3);
EXPECT_THAT(GetSizes(&sampler), UnorderedElementsAre(3, 2));
sampler.Unregister(info1);
sampler.Unregister(info2);
}
TEST(HashtablezSamplerTest, Unregistration) {
HashtablezSampler sampler;
std::vector<HashtablezInfo*> infos;
for (size_t i = 0; i < 3; ++i) {
infos.push_back(Register(&sampler, i));
}
EXPECT_THAT(GetSizes(&sampler), UnorderedElementsAre(0, 1, 2));
sampler.Unregister(infos[1]);
EXPECT_THAT(GetSizes(&sampler), UnorderedElementsAre(0, 2));
infos.push_back(Register(&sampler, 3));
infos.push_back(Register(&sampler, 4));
EXPECT_THAT(GetSizes(&sampler), UnorderedElementsAre(0, 2, 3, 4));
sampler.Unregister(infos[3]);
EXPECT_THAT(GetSizes(&sampler), UnorderedElementsAre(0, 2, 4));
sampler.Unregister(infos[0]);
sampler.Unregister(infos[2]);
sampler.Unregister(infos[4]);
EXPECT_THAT(GetSizes(&sampler), IsEmpty());
}
TEST(HashtablezSamplerTest, MultiThreaded) {
HashtablezSampler sampler;
Notification stop;
ThreadPool pool(10);
for (int i = 0; i < 10; ++i) {
const int64_t sampling_stride = 11 + i % 3;
const size_t elt_size = 10 + i % 2;
const size_t key_size = 12 + i % 4;
const size_t value_size = 13 + i % 5;
pool.Schedule([&sampler, &stop, sampling_stride, elt_size, key_size,
value_size]() {
std::random_device rd;
std::mt19937 gen(rd());
std::vector<HashtablezInfo*> infoz;
while (!stop.HasBeenNotified()) {
if (infoz.empty()) {
infoz.push_back(sampler.Register(sampling_stride, elt_size,
/*key_size=*/key_size,
/*value_size=*/value_size,
/*soo_capacity=*/0));
}
switch (std::uniform_int_distribution<>(0, 2)(gen)) {
case 0: {
infoz.push_back(sampler.Register(sampling_stride, elt_size,
/*key_size=*/key_size,
/*value_size=*/value_size,
/*soo_capacity=*/0));
break;
}
case 1: {
size_t p =
std::uniform_int_distribution<>(0, infoz.size() - 1)(gen);
HashtablezInfo* info = infoz[p];
infoz[p] = infoz.back();
infoz.pop_back();
EXPECT_EQ(info->weight, sampling_stride);
sampler.Unregister(info);
break;
}
case 2: {
absl::Duration oldest = absl::ZeroDuration();
sampler.Iterate([&](const HashtablezInfo& info) {
oldest = std::max(oldest, absl::Now() - info.create_time);
});
ASSERT_GE(oldest, absl::ZeroDuration());
break;
}
}
}
});
}
// The threads will hammer away. Give it a little bit of time for tsan to
// spot errors.
absl::SleepFor(absl::Seconds(3));
stop.Notify();
}
TEST(HashtablezSamplerTest, Callback) {
HashtablezSampler sampler;
auto* info1 = Register(&sampler, 1);
auto* info2 = Register(&sampler, 2);
static const HashtablezInfo* expected;
auto callback = [](const HashtablezInfo& info) {
// We can't use `info` outside of this callback because the object will be
// disposed as soon as we return from here.
EXPECT_EQ(&info, expected);
};
// Set the callback.
EXPECT_EQ(sampler.SetDisposeCallback(callback), nullptr);
expected = info1;
sampler.Unregister(info1);
// Unset the callback.
EXPECT_EQ(callback, sampler.SetDisposeCallback(nullptr));
expected = nullptr; // no more calls.
sampler.Unregister(info2);
}
} // namespace
} // namespace container_internal
ABSL_NAMESPACE_END
} // namespace absl
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