| 1 | // Copyright (C) 2001-2003 |
|---|---|
| 2 | // William E. Kempf |
| 3 | // |
| 4 | // Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 5 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| 6 | |
| 7 | #include <boost/thread/mutex.hpp> |
| 8 | #include <boost/thread/thread.hpp> |
| 9 | #include <iostream> |
| 10 | |
| 11 | boost::mutex io_mutex; // The iostreams are not guaranteed to be thread-safe! |
| 12 | |
| 13 | class counter |
| 14 | { |
| 15 | public: |
| 16 | counter() : count(0) { } |
| 17 | |
| 18 | int increment() { |
| 19 | boost::unique_lock<boost::mutex> scoped_lock(mutex); |
| 20 | return ++count; |
| 21 | } |
| 22 | |
| 23 | private: |
| 24 | boost::mutex mutex; |
| 25 | int count; |
| 26 | }; |
| 27 | |
| 28 | counter c; |
| 29 | |
| 30 | void change_count() |
| 31 | { |
| 32 | int i = c.increment(); |
| 33 | boost::unique_lock<boost::mutex> scoped_lock(io_mutex); |
| 34 | std::cout << "count == "<< i << std::endl; |
| 35 | } |
| 36 | |
| 37 | int main(int, char*[]) |
| 38 | { |
| 39 | const int num_threads = 4; |
| 40 | boost::thread_group thrds; |
| 41 | for (int i=0; i < num_threads; ++i) |
| 42 | thrds.create_thread(threadfunc: &change_count); |
| 43 | |
| 44 | thrds.join_all(); |
| 45 | |
| 46 | return 0; |
| 47 | } |
| 48 |