libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.sharedtimedmutex.requirements/thread.sharedtimedmutex.class/try_lock_shared.pass.cpp

   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 // <shared_mutex>
  13
  14 // class shared_timed_mutex;
  15
  16 // bool try_lock_shared();
  17
  18 #include <shared_mutex>
  19 #include <cassert>
  20 #include <thread>
  21 #include <vector>
  22
  23 #include "make_test_thread.h"
  24
  25 int main(int, char**) {
  26   // Try to lock-shared a mutex that is not locked yet. This should succeed.
  27   {
  28     std::shared_timed_mutex m;
  29     std::vector<std::thread> threads;
  30     for (int i = 0; i != 5; ++i) {
  31       threads.push_back(support::make_test_thread([&] {
  32         bool succeeded = m.try_lock_shared();
  33         assert(succeeded);
  34         m.unlock_shared();
  35       }));
  36     }
  37
  38     for (auto& t : threads)
  39       t.join();
  40   }
  41
  42   // Try to lock-shared a mutex that is already exclusively locked. This should fail.
  43   {
  44     std::shared_timed_mutex m;
  45     m.lock();
  46
  47     std::vector<std::thread> threads;
  48     for (int i = 0; i != 5; ++i) {
  49       threads.push_back(support::make_test_thread([&] {
  50         bool succeeded = m.try_lock_shared();
  51         assert(!succeeded);
  52       }));
  53     }
  54
  55     for (auto& t : threads)
  56       t.join();
  57
  58     m.unlock();
  59   }
  60
  61   // Try to lock-shared a mutex that is already lock-shared. This should succeed.
  62   {
  63     std::shared_timed_mutex m;
  64     m.lock_shared();
  65     std::vector<std::thread> threads;
  66     for (int i = 0; i != 5; ++i) {
  67       threads.push_back(support::make_test_thread([&] {
  68         bool succeeded = m.try_lock_shared();
  69         assert(succeeded);
  70         m.unlock_shared();
  71       }));
  72     }
  73     m.unlock_shared();
  74
  75     for (auto& t : threads)
  76       t.join();
  77   }
  78
  79   return 0;
  80 }