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-exceptions
10 // UNSUPPORTED: libcpp-has-no-threads
11 
12 // <condition_variable>
13 
14 // class condition_variable_any;
15 
16 // RUN: %{build}
17 // RUN: %{run} 1
18 // RUN: %{run} 2
19 // RUN: %{run} 3
20 // RUN: %{run} 4
21 // RUN: %{run} 5
22 // RUN: %{run} 6
23 
24 // -----------------------------------------------------------------------------
25 // Overview
26 //   Check that std::terminate is called if wait(...) fails to meet its post
27 //   conditions. This can happen when reacquiring the mutex throws
28 //   an exception.
29 //
30 //  The following methods are tested within this file
31 //   1.  void wait(Lock& lock);
32 //   2.  void wait(Lock& lock, Pred);
33 //   3.  void wait_for(Lock& lock, Duration);
34 //   4.  void wait_for(Lock& lock, Duration, Pred);
35 //   5.  void wait_until(Lock& lock, TimePoint);
36 //   6.  void wait_until(Lock& lock, TimePoint, Pred);
37 //
38 // Plan
39 //   1 Create a mutex type, 'ThrowingMutex', that throws when the lock is acquired
40 //     for the *second* time.
41 //
42 //   2 Replace the terminate handler with one that exits with a '0' exit code.
43 //
44 //   3 Create a 'condition_variable_any' object 'cv' and a 'ThrowingMutex'
45 //     object 'm' and lock 'm'.
46 //
47 //   4 Start a thread 'T2' that will notify 'cv' once 'm' has been unlocked.
48 //
49 //   5 From the main thread call the specified wait method on 'cv' with 'm'.
50 //     When 'T2' notifies 'cv' and the wait method attempts to re-lock
51 //    'm' an exception will be thrown from 'm.lock()'.
52 //
53 //   6 Check that control flow does not return from the wait method and that
54 //     terminate is called (If the program exits with a 0 exit code we know
55 //     that terminate has been called)
56 
57 
58 #include <condition_variable>
59 #include <atomic>
60 #include <thread>
61 #include <chrono>
62 #include <string>
63 #include <cstdlib>
64 #include <cassert>
65 
66 void my_terminate() {
67   std::_Exit(0); // Use _Exit to prevent cleanup from taking place.
68 }
69 
70 // The predicate used in the cv.wait calls.
71 bool pred = false;
72 bool pred_function() {
73   return pred == true;
74 }
75 
76 class ThrowingMutex
77 {
78   std::atomic_bool locked;
79   unsigned state = 0;
80   ThrowingMutex(const ThrowingMutex&) = delete;
81   ThrowingMutex& operator=(const ThrowingMutex&) = delete;
82 public:
83   ThrowingMutex() {
84     locked = false;
85   }
86   ~ThrowingMutex() = default;
87 
88   void lock() {
89     locked = true;
90     if (++state == 2) {
91       assert(pred); // Check that we actually waited until we were signaled.
92       throw 1;  // this throw should end up calling terminate()
93     }
94   }
95 
96   void unlock() { locked = false; }
97   bool isLocked() const { return locked == true; }
98 };
99 
100 ThrowingMutex mut;
101 std::condition_variable_any cv;
102 
103 void signal_me() {
104   while (mut.isLocked()) {} // wait until T1 releases mut inside the cv.wait call.
105   pred = true;
106   cv.notify_one();
107 }
108 
109 typedef std::chrono::system_clock Clock;
110 typedef std::chrono::milliseconds MS;
111 
112 int main(int argc, char **argv) {
113   assert(argc == 2);
114   int id = std::stoi(argv[1]);
115   assert(id >= 1 && id <= 6);
116   std::set_terminate(my_terminate); // set terminate after std::stoi because it can throw.
117   MS wait(250);
118   try {
119     mut.lock();
120     assert(pred == false);
121     std::thread(signal_me).detach();
122     switch (id) {
123       case 1: cv.wait(mut); break;
124       case 2: cv.wait(mut, pred_function); break;
125       case 3: cv.wait_for(mut, wait); break;
126       case 4: cv.wait_for(mut, wait, pred_function); break;
127       case 5: cv.wait_until(mut, Clock::now() + wait); break;
128       case 6: cv.wait_until(mut, Clock::now() + wait, pred_function); break;
129       default: assert(false);
130     }
131   } catch (...) {}
132   assert(false);
133 
134   return 0;
135 }
136