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 // dylib support for shared_mutex was added in macosx10.12
13 // XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11}}
14
15 // <shared_mutex>
16
17 // class timed_mutex;
18
19 // template <class Rep, class Period>
20 // shared_lock(mutex_type& m, const chrono::duration<Rep, Period>& rel_time);
21
22 #include <thread>
23
24 #include <atomic>
25 #include <cassert>
26 #include <cstdlib>
27 #include <shared_mutex>
28 #include <vector>
29
30 #include "make_test_thread.h"
31 #include "test_macros.h"
32
33 std::shared_timed_mutex m;
34
35 typedef std::chrono::steady_clock Clock;
36 typedef Clock::time_point time_point;
37 typedef Clock::duration duration;
38 typedef std::chrono::milliseconds ms;
39 typedef std::chrono::nanoseconds ns;
40
41 ms LongTime = ms(5000);
42 ms ShortTime = ms(50);
43
44 static const unsigned Threads = 5;
45
46 std::atomic<unsigned> CountDown(Threads);
47
f1()48 void f1()
49 {
50 // Preemptive scheduling means that one cannot make assumptions about when
51 // code executes and therefore we cannot assume anthing about when the mutex
52 // starts waiting relative to code in the main thread. We can however prove
53 // that a timeout occured and that implies that this code is waiting.
54 // See f2() below.
55 //
56 // Nevertheless, we should at least try to ensure that the mutex waits and
57 // therefore we use an atomic variable to signal to the main thread that this
58 // code is just a few instructions away from waiting.
59 --CountDown;
60 std::shared_lock<std::shared_timed_mutex> lk(m, LongTime);
61 assert(lk.owns_lock() == true);
62 }
63
f2()64 void f2()
65 {
66 time_point t0 = Clock::now();
67 std::shared_lock<std::shared_timed_mutex> lk(m, ShortTime);
68 time_point t1 = Clock::now();
69 assert(lk.owns_lock() == false);
70 assert(t1 - t0 >= ShortTime);
71 }
72
main(int,char **)73 int main(int, char**)
74 {
75 {
76 m.lock();
77 std::vector<std::thread> v;
78 for (unsigned i = 0; i < Threads; ++i)
79 v.push_back(support::make_test_thread(f1));
80 while (CountDown > 0)
81 std::this_thread::yield();
82 // Give one more chance for threads to block and wait for the mutex.
83 std::this_thread::yield();
84 std::this_thread::sleep_for(ShortTime);
85 m.unlock();
86 for (auto& t : v)
87 t.join();
88 }
89 {
90 m.lock();
91 std::vector<std::thread> v;
92 for (unsigned i = 0; i < Threads; ++i)
93 v.push_back(support::make_test_thread(f2));
94 for (auto& t : v)
95 t.join();
96 m.unlock();
97 }
98
99 return 0;
100 }
101