fork(1) download
copy 
  1. #include <vector>
  2. #include <chrono>
  3. #include <atomic>
  4. #include <thread>
  5. #include <cassert>
  6. #include <iostream>
  7.  
  8. struct list {
  9.   struct node {
  10.     std::atomic<node*> next;
  11.  
  12.     void start_operation() {
  13.       static std::atomic_int i;
  14.       ++i;
  15.       int j = i;
  16.       using namespace std::literals;
  17.       std::this_thread::sleep_for((rand()%100/100.)*.01s);
  18.       std::cerr <<"doing it! i="<<j<<"\n";
  19.       assert(i == 1);
  20.       --i;
  21.     }
  22.   };
  23.  
  24.   std::atomic<node*> tail{ nullptr };
  25.  
  26.   void push(node* new_node) {
  27.     using namespace std::literals;
  28.  
  29.     std::this_thread::sleep_for((rand()%100/100.)*.2s);
  30.  
  31.     node* old_tail = tail.exchange(new_node);
  32.  
  33.     std::this_thread::sleep_for((rand()%100/100.)*.2s);
  34.  
  35.     if(old_tail == nullptr || old_tail->next.exchange(new_node) == old_tail) {
  36.       node* current = new_node;
  37.       while(true) {
  38.         current->start_operation();
  39.         std::this_thread::sleep_for((rand()%100/100.)*0.01s);
  40.         node* expected = nullptr;
  41.         if(current->next.compare_exchange_strong(expected, new_node)) return;
  42.         else current = expected;
  43.       }
  44.     }
  45.   }
  46. };
  47.  
  48. int main() {
  49.   srand(1);
  50.   list l;
  51.   std::vector<std::thread> ts;
  52.   for (int i=0; i<10; ++i) {
  53.     ts.emplace_back([&l,i]() {
  54.         list::node n;
  55.         std::string s="push "+std::to_string(i)+"\n";
  56.         std::cerr << s;
  57.         l.push(&n);
  58.         s="finished "+std::to_string(i)+"\n";
  59.         std::cerr << s;
  60.         using namespace std::literals;
  61.         std::this_thread::sleep_for(1s);
  62.       });
  63.   }
  64.   for (auto& t : ts)
  65.     t.join();
  66.   std::cerr << "done\n";
  67. }
  68.  
Success #stdin #stdout #stderr 0s 51544KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
Standard output is empty
stderr
copy 
push 3
push 4
push 5
push 6
push 7
push 8
push 9
push 2
push 1
push 0
finished 0
doing it! i=1
doing it! i=1
finished 6
finished 4
finished 1
finished 7
finished 8
finished 5
finished 9
finished 3
finished 2
done
https://ideone.com/BPBh60
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!