2 * Copyright 2016 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 i = 1; i < sizeof v.ar / sizeof i; ++i) {
79 EXPECT_EQ(first, v.ar[i]);
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 T ourVal = rand() % (T(1) << (sizeof(T) * 8 - 1));
95 for (int i = 0; i < 10000; ++i) {
96 std::lock_guard<PicoSpinLock<T>> guard(lock);
98 for (int n = 0; n < 10; ++n) {
99 folly::asm_volatile_pause();
100 EXPECT_EQ(lock.getData(), ourVal);
110 const int nthrs = 17;
111 std::vector<std::thread> threads;
112 for (int i = 0; i < nthrs; ++i) {
113 threads.push_back(std::thread(&PslTest<T>::doTest, &testObj));
115 for (auto& t : threads) {
127 std::lock_guard<MicroSpinLock> g(lock_);
128 // This bug depends on gcc register allocation and is very sensitive. We
129 // have to use DCHECK instead of EXPECT_*.
130 DCHECK(!lock_.try_lock());
139 TEST(SmallLocks, SpinLockCorrectness) {
140 EXPECT_EQ(sizeof(MicroSpinLock), 1);
142 int nthrs = sysconf(_SC_NPROCESSORS_ONLN) * 2;
143 std::vector<std::thread> threads;
144 for (int i = 0; i < nthrs; ++i) {
145 threads.push_back(std::thread(splock_test));
147 for (auto& t : threads) {
152 #ifdef FOLLY_PICO_SPIN_LOCK_H_
153 TEST(SmallLocks, PicoSpinCorrectness) {
154 doPslTest<int16_t>();
155 doPslTest<uint16_t>();
156 doPslTest<int32_t>();
157 doPslTest<uint32_t>();
158 doPslTest<int64_t>();
159 doPslTest<uint64_t>();
162 TEST(SmallLocks, PicoSpinSigned) {
163 typedef PicoSpinLock<int16_t,0> Lock;
166 EXPECT_EQ(val.getData(), -4);
169 std::lock_guard<Lock> guard(val);
170 EXPECT_EQ(val.getData(), -4);
172 EXPECT_EQ(val.getData(), -8);
174 EXPECT_EQ(val.getData(), -8);
178 TEST(SmallLocks, RegClobber) {
183 #if defined(__SANITIZE_ADDRESS__) && !defined(__clang__) && \
184 (defined(__GNUC__) || defined(__GNUG__))
185 static_assert(sizeof(MicroLock) == 4, "Size check failed");
187 static_assert(sizeof(MicroLock) == 1, "Size check failed");
193 struct SimpleBarrier {
195 SimpleBarrier() : lock_(), cv_(), ready_(false) {}
198 std::unique_lock<std::mutex> lockHeld(lock_);
206 std::unique_lock<std::mutex> lockHeld(lock_);
215 std::condition_variable cv_;
220 TEST(SmallLocks, MicroLock) {
221 volatile uint64_t counters[4] = {0, 0, 0, 0};
222 std::vector<std::thread> threads;
223 static const unsigned nrThreads = 20;
224 static const unsigned iterPerThread = 10000;
225 SimpleBarrier startBarrier;
227 assert(iterPerThread % 4 == 0);
229 // Embed the lock in a larger structure to ensure that we do not
230 // affect bits outside the ones MicroLock is defined to affect.
246 // This thread touches other parts of the host word to show that
247 // MicroLock does not interfere with memory outside of the byte
249 std::thread adjacentMemoryToucher = std::thread([&] {
251 for (unsigned iter = 0; iter < iterPerThread; ++iter) {
260 for (unsigned i = 0; i < nrThreads; ++i) {
261 threads.emplace_back([&] {
263 for (unsigned iter = 0; iter < iterPerThread; ++iter) {
264 unsigned slotNo = iter % 4;
265 x.alock.lock(slotNo);
266 counters[slotNo] += 1;
267 // The occasional sleep makes it more likely that we'll
268 // exercise the futex-wait path inside MicroLock.
269 if (iter % 1000 == 0) {
270 struct timespec ts = {0, 10000};
271 (void)nanosleep(&ts, nullptr);
273 x.alock.unlock(slotNo);
280 for (auto it = threads.begin(); it != threads.end(); ++it) {
284 adjacentMemoryToucher.join();
287 EXPECT_EQ(x.b, (uint8_t)(origB + iterPerThread / 2));
288 EXPECT_EQ(x.d, (uint8_t)(origD + iterPerThread / 2));
289 for (unsigned i = 0; i < 4; ++i) {
290 EXPECT_EQ(counters[i], ((uint64_t)nrThreads * iterPerThread) / 4);
294 TEST(SmallLocks, MicroLockTryLock) {
297 EXPECT_TRUE(lock.try_lock());
298 EXPECT_FALSE(lock.try_lock());