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: libcpp-has-no-threads
10 // UNSUPPORTED: c++03, c++11
11 
12 // shared_timed_mutex was introduced in macosx10.12
13 // UNSUPPORTED: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11}}
14 
15 // TODO(ldionne): This test fails on Ubuntu Focal on our CI nodes (and only there), in 32 bit mode.
16 // UNSUPPORTED: linux && 32bits-on-64bits
17 
18 // <shared_mutex>
19 
20 // class shared_timed_mutex;
21 
22 // void lock_shared();
23 
24 #include <thread>
25 
26 #include <atomic>
27 #include <cassert>
28 #include <cstdlib>
29 #include <shared_mutex>
30 #include <vector>
31 
32 #include "make_test_thread.h"
33 #include "test_macros.h"
34 
35 std::shared_timed_mutex m;
36 
37 typedef std::chrono::system_clock Clock;
38 typedef Clock::time_point time_point;
39 typedef Clock::duration duration;
40 typedef std::chrono::milliseconds ms;
41 typedef std::chrono::nanoseconds ns;
42 
43 std::atomic<unsigned> countDown;
44 time_point readerStart; // Protected by the above mutex 'm'
45 time_point writerStart; // Protected by the above mutex 'm'
46 
47 ms WaitTime = ms(250);
48 
49 void readerMustWait() {
50   --countDown;
51   m.lock_shared();
52   time_point t1 = Clock::now();
53   time_point t0 = readerStart;
54   m.unlock_shared();
55   assert(t0.time_since_epoch() > ms(0));
56   assert(t1 - t0 >= WaitTime);
57 }
58 
59 void reader() {
60   --countDown;
61   m.lock_shared();
62   m.unlock_shared();
63 }
64 
65 void writerMustWait() {
66   --countDown;
67   m.lock();
68   time_point t1 = Clock::now();
69   time_point t0 = writerStart;
70   m.unlock();
71   assert(t0.time_since_epoch() > ms(0));
72   assert(t1 - t0 >= WaitTime);
73 }
74 
75 int main(int, char**)
76 {
77   int threads = 5;
78 
79   countDown.store(threads);
80   m.lock();
81   std::vector<std::thread> v;
82   for (int i = 0; i < threads; ++i)
83     v.push_back(support::make_test_thread(readerMustWait));
84   while (countDown > 0)
85     std::this_thread::yield();
86   readerStart = Clock::now();
87   std::this_thread::sleep_for(WaitTime);
88   m.unlock();
89   for (auto& t : v)
90     t.join();
91 
92   countDown.store(threads + 1);
93   m.lock_shared();
94   for (auto& t : v)
95     t = support::make_test_thread(reader);
96   std::thread q = support::make_test_thread(writerMustWait);
97   while (countDown > 0)
98     std::this_thread::yield();
99   writerStart = Clock::now();
100   std::this_thread::sleep_for(WaitTime);
101   m.unlock_shared();
102   for (auto& t : v)
103     t.join();
104   q.join();
105 
106   return 0;
107 }
108