libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.sharedtimedmutex.requirements/thread.sharedtimedmutex.class/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 // ALLOW_RETRIES: 3
  13
  14 // <shared_mutex>
  15
  16 // class shared_timed_mutex;
  17
  18 // void lock_shared();
  19
  20
  21 #include <atomic>
  22 #include <cassert>
  23 #include <chrono>
  24 #include <cstdlib>
  25 #include <shared_mutex>
  26 #include <thread>
  27 #include <vector>
  28
  29 #include "make_test_thread.h"
  30 #include "test_macros.h"
  31
  32 std::shared_timed_mutex m;
  33
  34 typedef std::chrono::system_clock Clock;
  35 typedef Clock::time_point time_point;
  36 typedef Clock::duration duration;
  37 typedef std::chrono::milliseconds ms;
  38 typedef std::chrono::nanoseconds ns;
  39
  40 std::atomic<unsigned> countDown;
  41 time_point readerStart; // Protected by the above mutex 'm'
  42 time_point writerStart; // Protected by the above mutex 'm'
  43
  44 ms WaitTime = ms(250);
  45
  46 void readerMustWait() {
  47   --countDown;
  48   m.lock_shared();
  49   time_point t1 = Clock::now();
  50   time_point t0 = readerStart;
  51   m.unlock_shared();
  52   assert(t0.time_since_epoch() > ms(0));
  53   assert(t1 - t0 >= WaitTime);
  54 }
  55
  56 void reader() {
  57   --countDown;
  58   m.lock_shared();
  59   m.unlock_shared();
  60 }
  61
  62 void writerMustWait() {
  63   --countDown;
  64   m.lock();
  65   time_point t1 = Clock::now();
  66   time_point t0 = writerStart;
  67   m.unlock();
  68   assert(t0.time_since_epoch() > ms(0));
  69   assert(t1 - t0 >= WaitTime);
  70 }
  71
  72 int main(int, char**)
  73 {
  74   int threads = 5;
  75
  76   countDown.store(threads);
  77   m.lock();
  78   std::vector<std::thread> v;
  79   for (int i = 0; i < threads; ++i)
  80     v.push_back(support::make_test_thread(readerMustWait));
  81   while (countDown > 0)
  82     std::this_thread::yield();
  83   readerStart = Clock::now();
  84   std::this_thread::sleep_for(WaitTime);
  85   m.unlock();
  86   for (auto& t : v)
  87     t.join();
  88
  89   countDown.store(threads + 1);
  90   m.lock_shared();
  91   for (auto& t : v)
  92     t = support::make_test_thread(reader);
  93   std::thread q = support::make_test_thread(writerMustWait);
  94   while (countDown > 0)
  95     std::this_thread::yield();
  96   writerStart = Clock::now();
  97   std::this_thread::sleep_for(WaitTime);
  98   m.unlock_shared();
  99   for (auto& t : v)
 100     t.join();
 101   q.join();
 102
 103   return 0;
 104 }