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rocksdb/util/rate_limiter_test.cc

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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "util/rate_limiter.h"
#include <chrono>
#include <cinttypes>
#include <cstdint>
#include <limits>
#include "db/db_test_util.h"
#include "rocksdb/system_clock.h"
#include "test_util/sync_point.h"
#include "test_util/testharness.h"
#include "util/random.h"
namespace ROCKSDB_NAMESPACE {
// TODO(yhchiang): the rate will not be accurate when we run test in parallel.
class RateLimiterTest : public testing::Test {};
TEST_F(RateLimiterTest, OverflowRate) {
GenericRateLimiter limiter(port::kMaxInt64, 1000, 10,
RateLimiter::Mode::kWritesOnly,
SystemClock::Default(), false /* auto_tuned */);
ASSERT_GT(limiter.GetSingleBurstBytes(), 1000000000ll);
}
TEST_F(RateLimiterTest, StartStop) {
std::unique_ptr<RateLimiter> limiter(NewGenericRateLimiter(100, 100, 10));
}
TEST_F(RateLimiterTest, GetTotalBytesThrough) {
std::unique_ptr<RateLimiter> limiter(NewGenericRateLimiter(
20 /* rate_bytes_per_sec */, 1000 * 1000 /* refill_period_us */,
10 /* fairness */));
for (int i = Env::IO_LOW; i <= Env::IO_TOTAL; ++i) {
ASSERT_EQ(limiter->GetTotalBytesThrough(static_cast<Env::IOPriority>(i)),
0);
}
std::int64_t request_byte = 10;
std::int64_t request_byte_sum = 0;
for (int i = Env::IO_LOW; i < Env::IO_TOTAL; ++i) {
limiter->Request(request_byte, static_cast<Env::IOPriority>(i),
nullptr /* stats */, RateLimiter::OpType::kWrite);
request_byte_sum += request_byte;
}
for (int i = Env::IO_LOW; i < Env::IO_TOTAL; ++i) {
EXPECT_EQ(limiter->GetTotalBytesThrough(static_cast<Env::IOPriority>(i)),
request_byte)
<< "Failed to track total_bytes_through_ correctly when IOPriority = "
<< static_cast<Env::IOPriority>(i);
}
EXPECT_EQ(limiter->GetTotalBytesThrough(Env::IO_TOTAL), request_byte_sum)
<< "Failed to track total_bytes_through_ correctly when IOPriority = "
"Env::IO_TOTAL";
}
TEST_F(RateLimiterTest, GetTotalRequests) {
std::unique_ptr<RateLimiter> limiter(NewGenericRateLimiter(
20 /* rate_bytes_per_sec */, 1000 * 1000 /* refill_period_us */,
10 /* fairness */));
for (int i = Env::IO_LOW; i <= Env::IO_TOTAL; ++i) {
ASSERT_EQ(limiter->GetTotalRequests(static_cast<Env::IOPriority>(i)), 0);
}
std::int64_t total_requests_sum = 0;
for (int i = Env::IO_LOW; i < Env::IO_TOTAL; ++i) {
limiter->Request(10, static_cast<Env::IOPriority>(i), nullptr /* stats */,
RateLimiter::OpType::kWrite);
total_requests_sum += 1;
}
for (int i = Env::IO_LOW; i < Env::IO_TOTAL; ++i) {
EXPECT_EQ(limiter->GetTotalRequests(static_cast<Env::IOPriority>(i)), 1)
<< "Failed to track total_requests_ correctly when IOPriority = "
<< static_cast<Env::IOPriority>(i);
}
EXPECT_EQ(limiter->GetTotalRequests(Env::IO_TOTAL), total_requests_sum)
<< "Failed to track total_requests_ correctly when IOPriority = "
"Env::IO_TOTAL";
}
TEST_F(RateLimiterTest, Modes) {
for (auto mode : {RateLimiter::Mode::kWritesOnly,
RateLimiter::Mode::kReadsOnly, RateLimiter::Mode::kAllIo}) {
GenericRateLimiter limiter(2000 /* rate_bytes_per_sec */,
1000 * 1000 /* refill_period_us */,
10 /* fairness */, mode, SystemClock::Default(),
false /* auto_tuned */);
limiter.Request(1000 /* bytes */, Env::IO_HIGH, nullptr /* stats */,
RateLimiter::OpType::kRead);
if (mode == RateLimiter::Mode::kWritesOnly) {
ASSERT_EQ(0, limiter.GetTotalBytesThrough(Env::IO_HIGH));
} else {
ASSERT_EQ(1000, limiter.GetTotalBytesThrough(Env::IO_HIGH));
}
limiter.Request(1000 /* bytes */, Env::IO_HIGH, nullptr /* stats */,
RateLimiter::OpType::kWrite);
if (mode == RateLimiter::Mode::kAllIo) {
ASSERT_EQ(2000, limiter.GetTotalBytesThrough(Env::IO_HIGH));
} else {
ASSERT_EQ(1000, limiter.GetTotalBytesThrough(Env::IO_HIGH));
}
}
}
TEST_F(RateLimiterTest, GeneratePriorityIterationOrder) {
std::unique_ptr<RateLimiter> limiter(NewGenericRateLimiter(
20 /* rate_bytes_per_sec */, 1000 * 1000 /* refill_period_us */,
10 /* fairness */));
bool possible_random_one_in_fairness_results_for_high_mid_pri[4][2] = {
{false, false}, {false, true}, {true, false}, {true, true}};
std::vector<Env::IOPriority> possible_priority_iteration_orders[4] = {
{Env::IO_USER, Env::IO_HIGH, Env::IO_MID, Env::IO_LOW},
{Env::IO_USER, Env::IO_HIGH, Env::IO_LOW, Env::IO_MID},
{Env::IO_USER, Env::IO_MID, Env::IO_LOW, Env::IO_HIGH},
{Env::IO_USER, Env::IO_LOW, Env::IO_MID, Env::IO_HIGH}};
for (int i = 0; i < 4; ++i) {
SyncPoint::GetInstance()->SetCallBack(
"GenericRateLimiter::GeneratePriorityIterationOrder::"
"PostRandomOneInFairnessForHighPri",
[&](void* arg) {
bool* high_pri_iterated_after_mid_low_pri = (bool*)arg;
*high_pri_iterated_after_mid_low_pri =
possible_random_one_in_fairness_results_for_high_mid_pri[i][0];
});
SyncPoint::GetInstance()->SetCallBack(
"GenericRateLimiter::GeneratePriorityIterationOrder::"
"PostRandomOneInFairnessForMidPri",
[&](void* arg) {
bool* mid_pri_itereated_after_low_pri = (bool*)arg;
*mid_pri_itereated_after_low_pri =
possible_random_one_in_fairness_results_for_high_mid_pri[i][1];
});
SyncPoint::GetInstance()->SetCallBack(
"GenericRateLimiter::GeneratePriorityIterationOrder::"
"PreReturnPriIterationOrder",
[&](void* arg) {
std::vector<Env::IOPriority>* pri_iteration_order =
(std::vector<Env::IOPriority>*)arg;
EXPECT_EQ(*pri_iteration_order, possible_priority_iteration_orders[i])
<< "Failed to generate priority iteration order correctly when "
"high_pri_iterated_after_mid_low_pri = "
<< possible_random_one_in_fairness_results_for_high_mid_pri[i][0]
<< ", mid_pri_itereated_after_low_pri = "
<< possible_random_one_in_fairness_results_for_high_mid_pri[i][1]
<< std::endl;
});
SyncPoint::GetInstance()->EnableProcessing();
limiter->Request(20 /* request max bytes to drain so that refill and order
generation will be triggered every time
GenericRateLimiter::Request() is called */
,
Env::IO_USER, nullptr /* stats */,
RateLimiter::OpType::kWrite);
}
SyncPoint::GetInstance()->DisableProcessing();
SyncPoint::GetInstance()->ClearCallBack(
"GenericRateLimiter::GeneratePriorityIterationOrder::"
"PreReturnPriIterationOrder");
SyncPoint::GetInstance()->ClearCallBack(
"GenericRateLimiter::GeneratePriorityIterationOrder::"
"PostRandomOneInFairnessForMidPri");
SyncPoint::GetInstance()->ClearCallBack(
"GenericRateLimiter::GeneratePriorityIterationOrder::"
"PostRandomOneInFairnessForHighPri");
}
TEST_F(RateLimiterTest, Rate) {
auto* env = Env::Default();
struct Arg {
Arg(int32_t _target_rate, int _burst)
: limiter(NewGenericRateLimiter(_target_rate /* rate_bytes_per_sec */,
100 * 1000 /* refill_period_us */,
10 /* fairness */)),
request_size(_target_rate /
10 /* refill period here is 1/10 second */),
burst(_burst) {}
std::unique_ptr<RateLimiter> limiter;
int32_t request_size;
int burst;
};
auto writer = [](void* p) {
const auto& thread_clock = SystemClock::Default();
auto* arg = static_cast<Arg*>(p);
// Test for 2 seconds
auto until = thread_clock->NowMicros() + 2 * 1000000;
Random r((uint32_t)(thread_clock->NowNanos() %
std::numeric_limits<uint32_t>::max()));
while (thread_clock->NowMicros() < until) {
for (int i = 0; i < static_cast<int>(r.Skewed(arg->burst * 2) + 1); ++i) {
arg->limiter->Request(r.Uniform(arg->request_size - 1) + 1,
Env::IO_USER, nullptr /* stats */,
RateLimiter::OpType::kWrite);
}
for (int i = 0; i < static_cast<int>(r.Skewed(arg->burst) + 1); ++i) {
arg->limiter->Request(r.Uniform(arg->request_size - 1) + 1,
Env::IO_HIGH, nullptr /* stats */,
RateLimiter::OpType::kWrite);
}
for (int i = 0; i < static_cast<int>(r.Skewed(arg->burst / 2 + 1) + 1);
++i) {
arg->limiter->Request(r.Uniform(arg->request_size - 1) + 1, Env::IO_MID,
nullptr /* stats */, RateLimiter::OpType::kWrite);
}
arg->limiter->Request(r.Uniform(arg->request_size - 1) + 1, Env::IO_LOW,
nullptr /* stats */, RateLimiter::OpType::kWrite);
}
};
int samples = 0;
int samples_at_minimum = 0;
for (int i = 1; i <= 16; i *= 2) {
int32_t target = i * 1024 * 10;
Arg arg(target, i / 4 + 1);
int64_t old_total_bytes_through = 0;
for (int iter = 1; iter <= 2; ++iter) {
// second iteration changes the target dynamically
if (iter == 2) {
target *= 2;
arg.limiter->SetBytesPerSecond(target);
}
auto start = env->NowMicros();
for (int t = 0; t < i; ++t) {
env->StartThread(writer, &arg);
}
env->WaitForJoin();
auto elapsed = env->NowMicros() - start;
double rate =
(arg.limiter->GetTotalBytesThrough() - old_total_bytes_through) *
1000000.0 / elapsed;
old_total_bytes_through = arg.limiter->GetTotalBytesThrough();
fprintf(stderr,
"request size [1 - %" PRIi32 "], limit %" PRIi32
" KB/sec, actual rate: %lf KB/sec, elapsed %.2lf seconds\n",
arg.request_size - 1, target / 1024, rate / 1024,
elapsed / 1000000.0);
++samples;
if (rate / target >= 0.80) {
++samples_at_minimum;
}
ASSERT_LE(rate / target, 1.25);
}
}
// This can fail in heavily loaded CI environments
bool skip_minimum_rate_check =
#if (defined(TRAVIS) || defined(CIRCLECI)) && defined(OS_MACOSX)
true;
#else
getenv("SANDCASTLE");
#endif
if (skip_minimum_rate_check) {
fprintf(stderr, "Skipped minimum rate check (%d / %d passed)\n",
samples_at_minimum, samples);
} else {
ASSERT_EQ(samples_at_minimum, samples);
}
}
TEST_F(RateLimiterTest, LimitChangeTest) {
// starvation test when limit changes to a smaller value
int64_t refill_period = 1000 * 1000;
auto* env = Env::Default();
ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->EnableProcessing();
struct Arg {
Arg(int32_t _request_size, Env::IOPriority _pri,
std::shared_ptr<RateLimiter> _limiter)
: request_size(_request_size), pri(_pri), limiter(_limiter) {}
int32_t request_size;
Env::IOPriority pri;
std::shared_ptr<RateLimiter> limiter;
};
auto writer = [](void* p) {
auto* arg = static_cast<Arg*>(p);
arg->limiter->Request(arg->request_size, arg->pri, nullptr /* stats */,
RateLimiter::OpType::kWrite);
};
for (uint32_t i = 1; i <= 16; i <<= 1) {
int32_t target = i * 1024 * 10;
// refill per second
for (int iter = 0; iter < 2; iter++) {
std::shared_ptr<RateLimiter> limiter =
std::make_shared<GenericRateLimiter>(
target, refill_period, 10, RateLimiter::Mode::kWritesOnly,
SystemClock::Default(), false /* auto_tuned */);
ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->LoadDependency(
{{"GenericRateLimiter::Request",
"RateLimiterTest::LimitChangeTest:changeLimitStart"},
{"RateLimiterTest::LimitChangeTest:changeLimitEnd",
"GenericRateLimiter::RefillBytesAndGrantRequests"}});
Arg arg(target, Env::IO_HIGH, limiter);
// The idea behind is to start a request first, then before it refills,
// update limit to a different value (2X/0.5X). No starvation should
// be guaranteed under any situation
// TODO(lightmark): more test cases are welcome.
env->StartThread(writer, &arg);
int32_t new_limit = (target << 1) >> (iter << 1);
TEST_SYNC_POINT("RateLimiterTest::LimitChangeTest:changeLimitStart");
arg.limiter->SetBytesPerSecond(new_limit);
TEST_SYNC_POINT("RateLimiterTest::LimitChangeTest:changeLimitEnd");
env->WaitForJoin();
fprintf(stderr,
"[COMPLETE] request size %" PRIi32 " KB, new limit %" PRIi32
"KB/sec, refill period %" PRIi64 " ms\n",
target / 1024, new_limit / 1024, refill_period / 1000);
}
}
}
TEST_F(RateLimiterTest, AutoTuneIncreaseWhenFull) {
const std::chrono::seconds kTimePerRefill(1);
const int kRefillsPerTune = 100; // needs to match util/rate_limiter.cc
SpecialEnv special_env(Env::Default(), /*time_elapse_only_sleep*/ true);
auto stats = CreateDBStatistics();
std::unique_ptr<RateLimiter> rate_limiter(new GenericRateLimiter(
1000 /* rate_bytes_per_sec */,
std::chrono::microseconds(kTimePerRefill).count(), 10 /* fairness */,
RateLimiter::Mode::kWritesOnly, special_env.GetSystemClock(),
true /* auto_tuned */));
// Rate limiter uses `CondVar::TimedWait()`, which does not have access to the
// `Env` to advance its time according to the fake wait duration. The
// workaround is to install a callback that advance the `Env`'s mock time.
ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
"GenericRateLimiter::Request:PostTimedWait", [&](void* arg) {
int64_t time_waited_us = *static_cast<int64_t*>(arg);
special_env.SleepForMicroseconds(static_cast<int>(time_waited_us));
});
ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->EnableProcessing();
// verify rate limit increases after a sequence of periods where rate limiter
// is always drained
int64_t orig_bytes_per_sec = rate_limiter->GetSingleBurstBytes();
rate_limiter->Request(orig_bytes_per_sec, Env::IO_HIGH, stats.get(),
RateLimiter::OpType::kWrite);
while (std::chrono::microseconds(special_env.NowMicros()) <=
kRefillsPerTune * kTimePerRefill) {
rate_limiter->Request(orig_bytes_per_sec, Env::IO_HIGH, stats.get(),
RateLimiter::OpType::kWrite);
}
int64_t new_bytes_per_sec = rate_limiter->GetSingleBurstBytes();
ASSERT_GT(new_bytes_per_sec, orig_bytes_per_sec);
ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->DisableProcessing();
// decreases after a sequence of periods where rate limiter is not drained
orig_bytes_per_sec = new_bytes_per_sec;
special_env.SleepForMicroseconds(static_cast<int>(
kRefillsPerTune * std::chrono::microseconds(kTimePerRefill).count()));
// make a request so tuner can be triggered
rate_limiter->Request(1 /* bytes */, Env::IO_HIGH, stats.get(),
RateLimiter::OpType::kWrite);
new_bytes_per_sec = rate_limiter->GetSingleBurstBytes();
ASSERT_LT(new_bytes_per_sec, orig_bytes_per_sec);
}
} // namespace ROCKSDB_NAMESPACE
int main(int argc, char** argv) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
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