libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.sharedtimedmutex.requirements/thread.sharedtimedmutex.class/try_lock.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();
  17
  18 #include <shared_mutex>
  19 #include <atomic>
  20 #include <cassert>
  21 #include <chrono>
  22 #include <thread>
  23
  24 #include "make_test_thread.h"
  25
  26 int main(int, char**) {
  27   // Try to exclusive-lock a mutex that is not locked yet. This should succeed.
  28   {
  29     std::shared_timed_mutex m;
  30     bool succeeded = m.try_lock();
  31     assert(succeeded);
  32     m.unlock();
  33   }
  34
  35   // Try to exclusive-lock a mutex that is already locked exclusively. This should fail.
  36   {
  37     std::shared_timed_mutex m;
  38     m.lock();
  39
  40     std::thread t = support::make_test_thread([&] {
  41       bool succeeded = m.try_lock();
  42       assert(!succeeded);
  43     });
  44     t.join();
  45
  46     m.unlock();
  47   }
  48
  49   // Try to exclusive-lock a mutex that is already share-locked. This should fail.
  50   {
  51     std::shared_timed_mutex m;
  52     m.lock_shared();
  53
  54     std::thread t = support::make_test_thread([&] {
  55       bool succeeded = m.try_lock();
  56       assert(!succeeded);
  57     });
  58     t.join();
  59
  60     m.unlock_shared();
  61   }
  62
  63   return 0;
  64 }