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++98, c++03, c++11
11 
12 // shared_timed_mutex was introduced in macosx10.12
13 // UNSUPPORTED: with_system_cxx_lib=macosx10.11
14 // UNSUPPORTED: with_system_cxx_lib=macosx10.10
15 // UNSUPPORTED: with_system_cxx_lib=macosx10.9
16 
17 // <shared_mutex>
18 
19 // class shared_timed_mutex;
20 
21 // void lock_shared();
22 
23 #include <shared_mutex>
24 #include <thread>
25 #include <vector>
26 #include <cstdlib>
27 #include <cassert>
28 
29 #include "test_macros.h"
30 
31 std::shared_timed_mutex m;
32 
33 typedef std::chrono::system_clock Clock;
34 typedef Clock::time_point time_point;
35 typedef Clock::duration duration;
36 typedef std::chrono::milliseconds ms;
37 typedef std::chrono::nanoseconds ns;
38 
39 std::atomic<unsigned> countDown;
40 time_point readerStart; // Protected by the above mutex 'm'
41 time_point writerStart; // Protected by the above mutex 'm'
42 
43 ms WaitTime = ms(250);
44 
45 void readerMustWait() {
46   --countDown;
47   m.lock_shared();
48   time_point t1 = Clock::now();
49   time_point t0 = readerStart;
50   m.unlock_shared();
51   assert(t0.time_since_epoch() > ms(0));
52   assert(t1 - t0 >= WaitTime);
53 }
54 
55 void reader() {
56   --countDown;
57   m.lock_shared();
58   m.unlock_shared();
59 }
60 
61 void writerMustWait() {
62   --countDown;
63   m.lock();
64   time_point t1 = Clock::now();
65   time_point t0 = writerStart;
66   m.unlock();
67   assert(t0.time_since_epoch() > ms(0));
68   assert(t1 - t0 >= WaitTime);
69 }
70 
71 int main(int, char**)
72 {
73   int threads = 5;
74 
75   countDown.store(threads);
76   m.lock();
77   std::vector<std::thread> v;
78   for (int i = 0; i < threads; ++i)
79     v.push_back(std::thread(readerMustWait));
80   while (countDown > 0)
81     std::this_thread::yield();
82   readerStart = Clock::now();
83   std::this_thread::sleep_for(WaitTime);
84   m.unlock();
85   for (auto& t : v)
86     t.join();
87 
88   countDown.store(threads + 1);
89   m.lock_shared();
90   for (auto& t : v)
91     t = std::thread(reader);
92   std::thread q(writerMustWait);
93   while (countDown > 0)
94     std::this_thread::yield();
95   writerStart = Clock::now();
96   std::this_thread::sleep_for(WaitTime);
97   m.unlock_shared();
98   for (auto& t : v)
99     t.join();
100   q.join();
101 
102   return 0;
103 }
104