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 #include <algorithm>
10 #include <random>
11 
12 #ifndef _LIBCPP_HAS_NO_THREADS
13 #  include <mutex>
14 #  if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
15 #    pragma comment(lib, "pthread")
16 #  endif
17 #endif
18 
19 _LIBCPP_BEGIN_NAMESPACE_STD
20 
21 #ifndef _LIBCPP_HAS_NO_THREADS
22 static constinit __libcpp_mutex_t __rs_mut = _LIBCPP_MUTEX_INITIALIZER;
23 #endif
24 unsigned __rs_default::__c_ = 0;
25 
26 __rs_default::__rs_default() {
27 #ifndef _LIBCPP_HAS_NO_THREADS
28   __libcpp_mutex_lock(&__rs_mut);
29 #endif
30   __c_ = 1;
31 }
32 
33 __rs_default::__rs_default(const __rs_default&) { ++__c_; }
34 
35 __rs_default::~__rs_default() {
36 #ifndef _LIBCPP_HAS_NO_THREADS
37   if (--__c_ == 0)
38     __libcpp_mutex_unlock(&__rs_mut);
39 #else
40   --__c_;
41 #endif
42 }
43 
44 __rs_default::result_type __rs_default::operator()() {
45   static mt19937 __rs_g;
46   return __rs_g();
47 }
48 
49 __rs_default __rs_get() { return __rs_default(); }
50 
51 _LIBCPP_END_NAMESPACE_STD
52