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 // dylib support for shared_mutex was added in macosx10.12
13 // XFAIL: 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 timed_mutex;
21 
22 // template <class Rep, class Period>
23 //   shared_lock(mutex_type& m, const chrono::duration<Rep, Period>& rel_time);
24 
25 #include <thread>
26 
27 #include <atomic>
28 #include <cassert>
29 #include <cstdlib>
30 #include <shared_mutex>
31 #include <vector>
32 
33 #include "make_test_thread.h"
34 #include "test_macros.h"
35 
36 std::shared_timed_mutex m;
37 
38 typedef std::chrono::steady_clock Clock;
39 typedef Clock::time_point time_point;
40 typedef Clock::duration duration;
41 typedef std::chrono::milliseconds ms;
42 typedef std::chrono::nanoseconds ns;
43 
44 ms LongTime = ms(5000);
45 ms ShortTime = ms(50);
46 
47 static const unsigned Threads = 5;
48 
49 std::atomic<unsigned> CountDown(Threads);
50 
51 void f1()
52 {
53   // Preemptive scheduling means that one cannot make assumptions about when
54   // code executes and therefore we cannot assume anthing about when the mutex
55   // starts waiting relative to code in the main thread. We can however prove
56   // that a timeout occured and that implies that this code is waiting.
57   // See f2() below.
58   //
59   // Nevertheless, we should at least try to ensure that the mutex waits and
60   // therefore we use an atomic variable to signal to the main thread that this
61   // code is just a few instructions away from waiting.
62   --CountDown;
63   std::shared_lock<std::shared_timed_mutex> lk(m, LongTime);
64   assert(lk.owns_lock() == true);
65 }
66 
67 void f2()
68 {
69   time_point t0 = Clock::now();
70   std::shared_lock<std::shared_timed_mutex> lk(m, ShortTime);
71   time_point t1 = Clock::now();
72   assert(lk.owns_lock() == false);
73   assert(t1 - t0 >= ShortTime);
74 }
75 
76 int main(int, char**)
77 {
78   {
79     m.lock();
80     std::vector<std::thread> v;
81     for (unsigned i = 0; i < Threads; ++i)
82       v.push_back(support::make_test_thread(f1));
83     while (CountDown > 0)
84       std::this_thread::yield();
85     // Give one more chance for threads to block and wait for the mutex.
86     std::this_thread::yield();
87     std::this_thread::sleep_for(ShortTime);
88     m.unlock();
89     for (auto& t : v)
90       t.join();
91   }
92   {
93     m.lock();
94     std::vector<std::thread> v;
95     for (unsigned i = 0; i < Threads; ++i)
96       v.push_back(support::make_test_thread(f2));
97     for (auto& t : v)
98       t.join();
99     m.unlock();
100   }
101 
102   return 0;
103 }
104