| 1 | //===----------------------------------------------------------------------===// |
|---|---|
| 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | // |
| 9 | // UNSUPPORTED: no-threads |
| 10 | // UNSUPPORTED: c++03, c++11 |
| 11 | |
| 12 | // <shared_mutex> |
| 13 | |
| 14 | // class shared_timed_mutex; |
| 15 | |
| 16 | #include <shared_mutex> |
| 17 | |
| 18 | #include <atomic> |
| 19 | #include <chrono> |
| 20 | #include <thread> |
| 21 | #include <cstdlib> |
| 22 | #include <cassert> |
| 23 | |
| 24 | #include "make_test_thread.h" |
| 25 | #include "test_macros.h" |
| 26 | |
| 27 | std::shared_timed_mutex m; |
| 28 | |
| 29 | const int total_readers = 2; |
| 30 | std::atomic<int> readers_started(0); |
| 31 | std::atomic<int> readers_finished(0); |
| 32 | |
| 33 | // Wait for the readers to start then try and acquire the write lock. |
| 34 | void writer_one() { |
| 35 | while (readers_started != total_readers) {} |
| 36 | bool b = m.try_lock_for(rtime: std::chrono::milliseconds(500)); |
| 37 | assert(b == false); |
| 38 | } |
| 39 | |
| 40 | void blocked_reader() { |
| 41 | ++readers_started; |
| 42 | // Wait until writer_one is waiting for the write lock. |
| 43 | while (m.try_lock_shared()) { |
| 44 | m.unlock_shared(); |
| 45 | } |
| 46 | // Attempt to get the read lock. writer_one should be blocking us because |
| 47 | // writer_one is blocked by main. |
| 48 | m.lock_shared(); |
| 49 | ++readers_finished; |
| 50 | m.unlock_shared(); |
| 51 | } |
| 52 | |
| 53 | int main(int, char**) |
| 54 | { |
| 55 | typedef std::chrono::steady_clock Clock; |
| 56 | |
| 57 | m.lock_shared(); |
| 58 | std::thread t1 = support::make_test_thread(writer_one); |
| 59 | // create some readers |
| 60 | std::thread t2 = support::make_test_thread(blocked_reader); |
| 61 | std::thread t3 = support::make_test_thread(blocked_reader); |
| 62 | // Kill the test after 10 seconds if it hasn't completed. |
| 63 | auto end_point = Clock::now() + std::chrono::seconds(10); |
| 64 | while (readers_finished != total_readers && Clock::now() < end_point) { |
| 65 | std::this_thread::sleep_for(rtime: std::chrono::seconds(1)); |
| 66 | } |
| 67 | assert(readers_finished == total_readers); |
| 68 | m.unlock_shared(); |
| 69 | t1.join(); |
| 70 | t2.join(); |
| 71 | t3.join(); |
| 72 | |
| 73 | return 0; |
| 74 | } |
| 75 |