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      1 //===----------------------------------------------------------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is dual licensed under the MIT and the University of Illinois Open
      6 // Source Licenses. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // UNSUPPORTED: libcpp-has-no-threads
     11 // UNSUPPORTED: c++98, c++03, c++11
     12 
     13 // <shared_mutex>
     14 
     15 // template <class Mutex> class shared_lock;
     16 
     17 // bool try_lock();
     18 
     19 #include <shared_mutex>
     20 #include <cassert>
     21 
     22 #include "test_macros.h"
     23 
     24 bool try_lock_called = false;
     25 
     26 struct mutex
     27 {
     28     bool try_lock_shared()
     29     {
     30         try_lock_called = !try_lock_called;
     31         return try_lock_called;
     32     }
     33     void unlock_shared() {}
     34 };
     35 
     36 mutex m;
     37 
     38 int main()
     39 {
     40     std::shared_lock<mutex> lk(m, std::defer_lock);
     41     assert(lk.try_lock() == true);
     42     assert(try_lock_called == true);
     43     assert(lk.owns_lock() == true);
     44 #ifndef TEST_HAS_NO_EXCEPTIONS
     45     try
     46     {
     47         lk.try_lock();
     48         assert(false);
     49     }
     50     catch (std::system_error& e)
     51     {
     52         assert(e.code().value() == EDEADLK);
     53     }
     54 #endif
     55     lk.unlock();
     56     assert(lk.try_lock() == false);
     57     assert(try_lock_called == false);
     58     assert(lk.owns_lock() == false);
     59     lk.release();
     60 #ifndef TEST_HAS_NO_EXCEPTIONS
     61     try
     62     {
     63         lk.try_lock();
     64         assert(false);
     65     }
     66     catch (std::system_error& e)
     67     {
     68         assert(e.code().value() == EPERM);
     69     }
     70 #endif
     71 }
     72