| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you 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 <mutex> |
| #include <string> |
| #include <thread> |
| #include <vector> |
| |
| #include <glog/logging.h> |
| #include <gtest/gtest.h> |
| |
| #include "kudu/gutil/atomicops.h" |
| #include "kudu/util/locks.h" |
| #include "kudu/util/monotime.h" |
| #include "kudu/util/rwc_lock.h" |
| #include "kudu/util/test_util.h" |
| |
| namespace kudu { |
| |
| using base::subtle::NoBarrier_Load; |
| using base::subtle::Release_Store; |
| using std::string; |
| using std::thread; |
| using std::vector; |
| |
| class RWCLockTest : public KuduTest {}; |
| |
| // Holds counters of how many threads hold the lock in each of the |
| // provided modes. |
| struct LockHoldersCount { |
| LockHoldersCount() |
| : num_readers(0), |
| num_writers(0), |
| num_committers(0) { |
| } |
| |
| // Check the invariants of the lock counts. |
| void CheckInvariants() { |
| // At no time should we have more than one writer or committer. |
| CHECK_LE(num_writers, 1); |
| CHECK_LE(num_committers, 1); |
| |
| // If we have any readers, then we should not have any committers. |
| if (num_readers > 0) { |
| CHECK_EQ(num_committers, 0); |
| } |
| } |
| |
| void AdjustReaders(int delta) { |
| std::lock_guard<simple_spinlock> l(lock); |
| num_readers += delta; |
| CheckInvariants(); |
| } |
| |
| void AdjustWriters(int delta) { |
| std::lock_guard<simple_spinlock> l(lock); |
| num_writers += delta; |
| CheckInvariants(); |
| } |
| |
| void AdjustCommitters(int delta) { |
| std::lock_guard<simple_spinlock> l(lock); |
| num_committers += delta; |
| CheckInvariants(); |
| } |
| |
| int num_readers; |
| int num_writers; |
| int num_committers; |
| simple_spinlock lock; |
| }; |
| |
| struct SharedState { |
| LockHoldersCount counts; |
| RWCLock rwc_lock; |
| Atomic32 stop; |
| }; |
| |
| void ReaderThread(SharedState* state) { |
| while (!NoBarrier_Load(&state->stop)) { |
| state->rwc_lock.ReadLock(); |
| state->counts.AdjustReaders(1); |
| state->counts.AdjustReaders(-1); |
| state->rwc_lock.ReadUnlock(); |
| } |
| } |
| |
| void WriterThread(SharedState* state) { |
| string local_str; |
| while (!NoBarrier_Load(&state->stop)) { |
| state->rwc_lock.WriteLock(); |
| state->counts.AdjustWriters(1); |
| |
| state->rwc_lock.UpgradeToCommitLock(); |
| state->counts.AdjustWriters(-1); |
| state->counts.AdjustCommitters(1); |
| |
| state->counts.AdjustCommitters(-1); |
| state->rwc_lock.CommitUnlock(); |
| } |
| } |
| |
| |
| TEST_F(RWCLockTest, TestCorrectBehavior) { |
| SharedState state; |
| Release_Store(&state.stop, 0); |
| |
| vector<thread> threads; |
| |
| const int kNumWriters = 5; |
| const int kNumReaders = 5; |
| |
| for (int i = 0; i < kNumWriters; i++) { |
| threads.emplace_back(WriterThread, &state); |
| } |
| for (int i = 0; i < kNumReaders; i++) { |
| threads.emplace_back(ReaderThread, &state); |
| } |
| |
| if (AllowSlowTests()) { |
| SleepFor(MonoDelta::FromSeconds(1)); |
| } else { |
| SleepFor(MonoDelta::FromMilliseconds(100)); |
| } |
| |
| Release_Store(&state.stop, 1); |
| |
| for (thread& t : threads) { |
| t.join(); |
| } |
| } |
| |
| } // namespace kudu |