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 |