libcxx/src/tzdb_list.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 // For information see https://libcxx.llvm.org/DesignDocs/TimeZone.html
  10
  11 #include <chrono>
  12
  13 #include <__mutex/unique_lock.h>
  14 #include <forward_list>
  15
  16 // When threads are not available the locking is not required.
  17 #ifndef _LIBCPP_HAS_NO_THREADS
  18 #  include <shared_mutex>
  19 #endif
  20
  21 _LIBCPP_BEGIN_NAMESPACE_STD
  22
  23 namespace chrono {
  24
  25 //===----------------------------------------------------------------------===//
  26 //                          Private API
  27 //===----------------------------------------------------------------------===//
  28
  29 class tzdb_list::__impl {
  30 public:
  31   explicit __impl(tzdb&& __tzdb) { __tzdb_.push_front(std::move(__tzdb)); }
  32
  33   using const_iterator = tzdb_list::const_iterator;
  34
  35   const tzdb& front() const noexcept {
  36 #ifndef _LIBCPP_HAS_NO_THREADS
  37     shared_lock __lock{__mutex_};
  38 #endif
  39     return __tzdb_.front();
  40   }
  41
  42   const_iterator erase_after(const_iterator __p) {
  43 #ifndef _LIBCPP_HAS_NO_THREADS
  44     unique_lock __lock{__mutex_};
  45 #endif
  46     return __tzdb_.erase_after(__p);
  47   }
  48
  49   tzdb& __emplace_front(tzdb&& __tzdb) {
  50 #ifndef _LIBCPP_HAS_NO_THREADS
  51     unique_lock __lock{__mutex_};
  52 #endif
  53     return __tzdb_.emplace_front(std::move(__tzdb));
  54   }
  55
  56   const_iterator begin() const noexcept {
  57 #ifndef _LIBCPP_HAS_NO_THREADS
  58     shared_lock __lock{__mutex_};
  59 #endif
  60     return __tzdb_.begin();
  61   }
  62   const_iterator end() const noexcept {
  63     //  forward_list<T>::end does not access the list, so no need to take a lock.
  64     return __tzdb_.end();
  65   }
  66
  67   const_iterator cbegin() const noexcept { return begin(); }
  68   const_iterator cend() const noexcept { return end(); }
  69
  70 private:
  71 #ifndef _LIBCPP_HAS_NO_THREADS
  72   mutable shared_mutex __mutex_;
  73 #endif
  74   forward_list<tzdb> __tzdb_;
  75 };
  76
  77 //===----------------------------------------------------------------------===//
  78 //                           Public API
  79 //===----------------------------------------------------------------------===//
  80
  81 _LIBCPP_EXPORTED_FROM_ABI tzdb_list::tzdb_list(tzdb&& __tzdb) : __impl_{new __impl(std::move(__tzdb))} {}
  82
  83 _LIBCPP_EXPORTED_FROM_ABI tzdb_list::~tzdb_list() { delete __impl_; }
  84
  85 _LIBCPP_NODISCARD_EXT _LIBCPP_EXPORTED_FROM_ABI const tzdb& tzdb_list::front() const noexcept {
  86   return __impl_->front();
  87 }
  88
  89 _LIBCPP_EXPORTED_FROM_ABI tzdb_list::const_iterator tzdb_list::erase_after(const_iterator __p) {
  90   return __impl_->erase_after(__p);
  91 }
  92
  93 _LIBCPP_EXPORTED_FROM_ABI tzdb& tzdb_list::__emplace_front(tzdb&& __tzdb) {
  94   return __impl_->__emplace_front(std::move(__tzdb));
  95 }
  96
  97 _LIBCPP_NODISCARD_EXT _LIBCPP_EXPORTED_FROM_ABI tzdb_list::const_iterator tzdb_list::begin() const noexcept {
  98   return __impl_->begin();
  99 }
 100 _LIBCPP_NODISCARD_EXT _LIBCPP_EXPORTED_FROM_ABI tzdb_list::const_iterator tzdb_list::end() const noexcept {
 101   return __impl_->end();
 102 }
 103
 104 _LIBCPP_NODISCARD_EXT _LIBCPP_EXPORTED_FROM_ABI tzdb_list::const_iterator tzdb_list::cbegin() const noexcept {
 105   return __impl_->cbegin();
 106 }
 107 _LIBCPP_NODISCARD_EXT _LIBCPP_EXPORTED_FROM_ABI tzdb_list::const_iterator tzdb_list::cend() const noexcept {
 108   return __impl_->cend();
 109 }
 110
 111 } // namespace chrono
 112
 113 _LIBCPP_END_NAMESPACE_STD