fix race condition in test_threads

test/test_threads.cpp

@@ -33,32 +33,88 @@ POSSIBILITY OF SUCH DAMAGE.
 #include <boost/bind.hpp>
 #include <list>
 #include "libtorrent/thread.hpp"
+#include <boost/smart_ptr/detail/atomic_count.hpp>
 #include "test.hpp"
 
+using boost::detail::atomic_count;
 using namespace libtorrent;
 
-void fun(condition_variable* s, libtorrent::mutex* m, int i)
+void fun(condition_variable* s, libtorrent::mutex* m, int* waiting, int i)
 {
 	fprintf(stderr, "thread %d waiting\n", i);
 	libtorrent::mutex::scoped_lock l(*m);
+	*waiting += 1;
 	s->wait(l);
 	fprintf(stderr, "thread %d done\n", i);
 }
 
+void increment(condition_variable* s, libtorrent::mutex* m, int* waiting, atomic_count* c)
+{
+	libtorrent::mutex::scoped_lock l(*m);
+	*waiting += 1;
+	s->wait(l);
+	l.unlock();
+	for (int i = 0; i < 1000000; ++i)
+		++*c;
+}
+
+void decrement(condition_variable* s, libtorrent::mutex* m, int* waiting, atomic_count* c)
+{
+	libtorrent::mutex::scoped_lock l(*m);
+	*waiting += 1;
+	s->wait(l);
+	l.unlock();
+	for (int i = 0; i < 1000000; ++i)
+		--*c;
+}
+
 int test_main()
 {
 	condition_variable cond;
 	libtorrent::mutex m;
 	std::list<thread*> threads;
+	int waiting = 0;
 	for (int i = 0; i < 20; ++i)
 	{
-		threads.push_back(new thread(boost::bind(&fun, &cond, &m, i)));
+		threads.push_back(new thread(boost::bind(&fun, &cond, &m, &waiting, i)));
 	}
 
 	// make sure all threads are waiting on the condition_variable
-	sleep(10);
-
 	libtorrent::mutex::scoped_lock l(m);
+	while (waiting < 20)
+	{
+		l.unlock();
+		sleep(10);
+		l.lock();
+	}
+
+	cond.notify_all();
+	l.unlock();
+
+	for (std::list<thread*>::iterator i = threads.begin(); i != threads.end(); ++i)
+	{
+		(*i)->join();
+		delete *i;
+	}
+	threads.clear();
+
+	waiting = 0;
+	atomic_count c(0);
+	for (int i = 0; i < 3; ++i)
+	{
+		threads.push_back(new thread(boost::bind(&increment, &cond, &m, &waiting, &c)));
+		threads.push_back(new thread(boost::bind(&decrement, &cond, &m, &waiting, &c)));
+	}
+
+	// make sure all threads are waiting on the condition_variable
+	l.lock();
+	while (waiting < 6)
+	{
+		l.unlock();
+		sleep(10);
+		l.lock();
+	}
+
 	cond.notify_all();
 	l.unlock();
 
@@ -68,6 +124,8 @@ int test_main()
 		delete *i;
 	}
 
+	TEST_CHECK(c == 0);
+
 	return 0;
 }