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- /*
- * Copyright 2011-present Facebook, Inc.
- *
- * 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
- *
- * http://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 <folly/synchronization/SmallLocks.h>
- #include <cassert>
- #include <condition_variable>
- #include <cstdio>
- #include <mutex>
- #include <string>
- #include <thread>
- #include <vector>
- #include <glog/logging.h>
- #include <folly/Random.h>
- #include <folly/portability/Asm.h>
- #include <folly/portability/GTest.h>
- #include <folly/portability/PThread.h>
- #include <folly/portability/Unistd.h>
- using folly::MicroLock;
- using folly::MicroSpinLock;
- using folly::MSLGuard;
- using std::string;
- #ifdef FOLLY_PICO_SPIN_LOCK_H_
- using folly::PicoSpinLock;
- #endif
- namespace {
- struct LockedVal {
- int ar[1024];
- MicroSpinLock lock;
- LockedVal() {
- lock.init();
- memset(ar, 0, sizeof ar);
- }
- };
- // Compile time test for packed struct support (requires that both of
- // these classes are POD).
- FOLLY_PACK_PUSH
- struct ignore1 {
- MicroSpinLock msl;
- int16_t foo;
- } FOLLY_PACK_ATTR;
- static_assert(sizeof(ignore1) == 3, "Size check failed");
- static_assert(sizeof(MicroSpinLock) == 1, "Size check failed");
- #ifdef FOLLY_PICO_SPIN_LOCK_H_
- struct ignore2 {
- PicoSpinLock<uint32_t> psl;
- int16_t foo;
- } FOLLY_PACK_ATTR;
- static_assert(sizeof(ignore2) == 6, "Size check failed");
- #endif
- FOLLY_PACK_POP
- LockedVal v;
- void splock_test() {
- const int max = 1000;
- auto rng = folly::ThreadLocalPRNG();
- for (int i = 0; i < max; i++) {
- folly::asm_volatile_pause();
- MSLGuard g(v.lock);
- int first = v.ar[0];
- for (size_t j = 1; j < sizeof v.ar / sizeof j; ++j) {
- EXPECT_EQ(first, v.ar[j]);
- }
- int byte = folly::Random::rand32(rng);
- memset(v.ar, char(byte), sizeof v.ar);
- }
- }
- #ifdef FOLLY_PICO_SPIN_LOCK_H_
- template <class T>
- struct PslTest {
- PicoSpinLock<T> lock;
- PslTest() {
- lock.init();
- }
- void doTest() {
- using UT = typename std::make_unsigned<T>::type;
- T ourVal = rand() % T(UT(1) << (sizeof(UT) * 8 - 1));
- for (int i = 0; i < 100; ++i) {
- std::lock_guard<PicoSpinLock<T>> guard(lock);
- lock.setData(ourVal);
- for (int n = 0; n < 10; ++n) {
- folly::asm_volatile_pause();
- EXPECT_EQ(lock.getData(), ourVal);
- }
- }
- }
- };
- template <class T>
- void doPslTest() {
- PslTest<T> testObj;
- const int nthrs = 17;
- std::vector<std::thread> threads;
- for (int i = 0; i < nthrs; ++i) {
- threads.push_back(std::thread(&PslTest<T>::doTest, &testObj));
- }
- for (auto& t : threads) {
- t.join();
- }
- }
- #endif
- struct TestClobber {
- TestClobber() {
- lock_.init();
- }
- void go() {
- std::lock_guard<MicroSpinLock> g(lock_);
- // This bug depends on gcc register allocation and is very sensitive. We
- // have to use DCHECK instead of EXPECT_*.
- DCHECK(!lock_.try_lock());
- }
- private:
- MicroSpinLock lock_;
- };
- } // namespace
- TEST(SmallLocks, SpinLockCorrectness) {
- EXPECT_EQ(sizeof(MicroSpinLock), 1);
- int nthrs = sysconf(_SC_NPROCESSORS_ONLN) * 2;
- std::vector<std::thread> threads;
- for (int i = 0; i < nthrs; ++i) {
- threads.push_back(std::thread(splock_test));
- }
- for (auto& t : threads) {
- t.join();
- }
- }
- #ifdef FOLLY_PICO_SPIN_LOCK_H_
- TEST(SmallLocks, PicoSpinCorrectness) {
- doPslTest<int16_t>();
- doPslTest<uint16_t>();
- doPslTest<int32_t>();
- doPslTest<uint32_t>();
- doPslTest<int64_t>();
- doPslTest<uint64_t>();
- }
- TEST(SmallLocks, PicoSpinSigned) {
- typedef PicoSpinLock<int16_t, 0> Lock;
- Lock val;
- val.init(-4);
- EXPECT_EQ(val.getData(), -4);
- {
- std::lock_guard<Lock> guard(val);
- EXPECT_EQ(val.getData(), -4);
- val.setData(-8);
- EXPECT_EQ(val.getData(), -8);
- }
- EXPECT_EQ(val.getData(), -8);
- }
- #endif
- TEST(SmallLocks, RegClobber) {
- TestClobber().go();
- }
- FOLLY_PACK_PUSH
- #if defined(__SANITIZE_ADDRESS__) && !defined(__clang__) && \
- (defined(__GNUC__) || defined(__GNUG__))
- static_assert(sizeof(MicroLock) == 4, "Size check failed");
- #else
- static_assert(sizeof(MicroLock) == 1, "Size check failed");
- #endif
- FOLLY_PACK_POP
- namespace {
- struct SimpleBarrier {
- SimpleBarrier() : lock_(), cv_(), ready_(false) {}
- void wait() {
- std::unique_lock<std::mutex> lockHeld(lock_);
- while (!ready_) {
- cv_.wait(lockHeld);
- }
- }
- void run() {
- {
- std::unique_lock<std::mutex> lockHeld(lock_);
- ready_ = true;
- }
- cv_.notify_all();
- }
- private:
- std::mutex lock_;
- std::condition_variable cv_;
- bool ready_;
- };
- } // namespace
- TEST(SmallLocks, MicroLock) {
- volatile uint64_t counters[4] = {0, 0, 0, 0};
- std::vector<std::thread> threads;
- static const unsigned nrThreads = 20;
- static const unsigned iterPerThread = 10000;
- SimpleBarrier startBarrier;
- assert(iterPerThread % 4 == 0);
- // Embed the lock in a larger structure to ensure that we do not
- // affect bits outside the ones MicroLock is defined to affect.
- struct {
- uint8_t a;
- std::atomic<uint8_t> b;
- MicroLock alock;
- std::atomic<uint8_t> d;
- } x;
- uint8_t origB = 'b';
- uint8_t origD = 'd';
- x.a = 'a';
- x.b = origB;
- x.alock.init();
- x.d = origD;
- // This thread touches other parts of the host word to show that
- // MicroLock does not interfere with memory outside of the byte
- // it owns.
- std::thread adjacentMemoryToucher = std::thread([&] {
- startBarrier.wait();
- for (unsigned iter = 0; iter < iterPerThread; ++iter) {
- if (iter % 2) {
- x.b++;
- } else {
- x.d++;
- }
- }
- });
- for (unsigned i = 0; i < nrThreads; ++i) {
- threads.emplace_back([&] {
- startBarrier.wait();
- for (unsigned iter = 0; iter < iterPerThread; ++iter) {
- unsigned slotNo = iter % 4;
- x.alock.lock(slotNo);
- counters[slotNo] += 1;
- // The occasional sleep makes it more likely that we'll
- // exercise the futex-wait path inside MicroLock.
- if (iter % 1000 == 0) {
- struct timespec ts = {0, 10000};
- (void)nanosleep(&ts, nullptr);
- }
- x.alock.unlock(slotNo);
- }
- });
- }
- startBarrier.run();
- for (auto it = threads.begin(); it != threads.end(); ++it) {
- it->join();
- }
- adjacentMemoryToucher.join();
- EXPECT_EQ(x.a, 'a');
- EXPECT_EQ(x.b, (uint8_t)(origB + iterPerThread / 2));
- EXPECT_EQ(x.d, (uint8_t)(origD + iterPerThread / 2));
- for (unsigned i = 0; i < 4; ++i) {
- EXPECT_EQ(counters[i], ((uint64_t)nrThreads * iterPerThread) / 4);
- }
- }
- TEST(SmallLocks, MicroLockTryLock) {
- MicroLock lock;
- lock.init();
- EXPECT_TRUE(lock.try_lock());
- EXPECT_FALSE(lock.try_lock());
- lock.unlock();
- }
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