2 * Copyright 2017 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #include <folly/SmallLocks.h>
19 #include <folly/Random.h>
24 #include <condition_variable>
31 #include <folly/portability/Asm.h>
32 #include <folly/portability/GTest.h>
33 #include <folly/portability/Unistd.h>
35 using folly::MSLGuard;
36 using folly::MicroLock;
37 using folly::MicroSpinLock;
40 #ifdef FOLLY_PICO_SPIN_LOCK_H_
41 using folly::PicoSpinLock;
52 memset(ar, 0, sizeof ar);
56 // Compile time test for packed struct support (requires that both of
57 // these classes are POD).
59 struct ignore1 { MicroSpinLock msl; int16_t foo; } FOLLY_PACK_ATTR;
60 static_assert(sizeof(ignore1) == 3, "Size check failed");
61 static_assert(sizeof(MicroSpinLock) == 1, "Size check failed");
62 #ifdef FOLLY_PICO_SPIN_LOCK_H_
63 struct ignore2 { PicoSpinLock<uint32_t> psl; int16_t foo; } FOLLY_PACK_ATTR;
64 static_assert(sizeof(ignore2) == 6, "Size check failed");
72 auto rng = folly::ThreadLocalPRNG();
73 for (int i = 0; i < max; i++) {
78 for (size_t j = 1; j < sizeof v.ar / sizeof j; ++j) {
79 EXPECT_EQ(first, v.ar[j]);
82 int byte = folly::Random::rand32(rng);
83 memset(v.ar, char(byte), sizeof v.ar);
87 #ifdef FOLLY_PICO_SPIN_LOCK_H_
88 template<class T> struct PslTest {
91 PslTest() { lock.init(); }
94 using UT = typename std::make_unsigned<T>::type;
95 T ourVal = rand() % T(UT(1) << (sizeof(UT) * 8 - 1));
96 for (int i = 0; i < 10000; ++i) {
97 std::lock_guard<PicoSpinLock<T>> guard(lock);
99 for (int n = 0; n < 10; ++n) {
100 folly::asm_volatile_pause();
101 EXPECT_EQ(lock.getData(), ourVal);
111 const int nthrs = 17;
112 std::vector<std::thread> threads;
113 for (int i = 0; i < nthrs; ++i) {
114 threads.push_back(std::thread(&PslTest<T>::doTest, &testObj));
116 for (auto& t : threads) {
128 std::lock_guard<MicroSpinLock> g(lock_);
129 // This bug depends on gcc register allocation and is very sensitive. We
130 // have to use DCHECK instead of EXPECT_*.
131 DCHECK(!lock_.try_lock());
140 TEST(SmallLocks, SpinLockCorrectness) {
141 EXPECT_EQ(sizeof(MicroSpinLock), 1);
143 int nthrs = sysconf(_SC_NPROCESSORS_ONLN) * 2;
144 std::vector<std::thread> threads;
145 for (int i = 0; i < nthrs; ++i) {
146 threads.push_back(std::thread(splock_test));
148 for (auto& t : threads) {
153 #ifdef FOLLY_PICO_SPIN_LOCK_H_
154 TEST(SmallLocks, PicoSpinCorrectness) {
155 doPslTest<int16_t>();
156 doPslTest<uint16_t>();
157 doPslTest<int32_t>();
158 doPslTest<uint32_t>();
159 doPslTest<int64_t>();
160 doPslTest<uint64_t>();
163 TEST(SmallLocks, PicoSpinSigned) {
164 typedef PicoSpinLock<int16_t,0> Lock;
167 EXPECT_EQ(val.getData(), -4);
170 std::lock_guard<Lock> guard(val);
171 EXPECT_EQ(val.getData(), -4);
173 EXPECT_EQ(val.getData(), -8);
175 EXPECT_EQ(val.getData(), -8);
179 TEST(SmallLocks, RegClobber) {
184 #if defined(__SANITIZE_ADDRESS__) && !defined(__clang__) && \
185 (defined(__GNUC__) || defined(__GNUG__))
186 static_assert(sizeof(MicroLock) == 4, "Size check failed");
188 static_assert(sizeof(MicroLock) == 1, "Size check failed");
194 struct SimpleBarrier {
196 SimpleBarrier() : lock_(), cv_(), ready_(false) {}
199 std::unique_lock<std::mutex> lockHeld(lock_);
207 std::unique_lock<std::mutex> lockHeld(lock_);
216 std::condition_variable cv_;
221 TEST(SmallLocks, MicroLock) {
222 volatile uint64_t counters[4] = {0, 0, 0, 0};
223 std::vector<std::thread> threads;
224 static const unsigned nrThreads = 20;
225 static const unsigned iterPerThread = 10000;
226 SimpleBarrier startBarrier;
228 assert(iterPerThread % 4 == 0);
230 // Embed the lock in a larger structure to ensure that we do not
231 // affect bits outside the ones MicroLock is defined to affect.
247 // This thread touches other parts of the host word to show that
248 // MicroLock does not interfere with memory outside of the byte
250 std::thread adjacentMemoryToucher = std::thread([&] {
252 for (unsigned iter = 0; iter < iterPerThread; ++iter) {
261 for (unsigned i = 0; i < nrThreads; ++i) {
262 threads.emplace_back([&] {
264 for (unsigned iter = 0; iter < iterPerThread; ++iter) {
265 unsigned slotNo = iter % 4;
266 x.alock.lock(slotNo);
267 counters[slotNo] += 1;
268 // The occasional sleep makes it more likely that we'll
269 // exercise the futex-wait path inside MicroLock.
270 if (iter % 1000 == 0) {
271 struct timespec ts = {0, 10000};
272 (void)nanosleep(&ts, nullptr);
274 x.alock.unlock(slotNo);
281 for (auto it = threads.begin(); it != threads.end(); ++it) {
285 adjacentMemoryToucher.join();
288 EXPECT_EQ(x.b, (uint8_t)(origB + iterPerThread / 2));
289 EXPECT_EQ(x.d, (uint8_t)(origD + iterPerThread / 2));
290 for (unsigned i = 0; i < 4; ++i) {
291 EXPECT_EQ(counters[i], ((uint64_t)nrThreads * iterPerThread) / 4);
295 TEST(SmallLocks, MicroLockTryLock) {
298 EXPECT_TRUE(lock.try_lock());
299 EXPECT_FALSE(lock.try_lock());