[PATCH 1/5] Improve libstdc++-v3 async test

[Mike Crowe]

Add tests for waiting for the future using both std::chrono::steady_clock
and std::chrono::system_clock in preparation for dealing with those clocks
properly in futex.cc.
---
 libstdc++-v3/testsuite/30_threads/async/async.cc | 36 ++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/libstdc++-v3/testsuite/30_threads/async/async.cc 
b/libstdc++-v3/testsuite/30_threads/async/async.cc
index 8071cb133fc..7326c5f7cd6 100644
--- a/libstdc++-v3/testsuite/30_threads/async/async.cc
+++ b/libstdc++-v3/testsuite/30_threads/async/async.cc
@@ -52,17 +52,53 @@ void test02()
   VERIFY( status == std::future_status::timeout );
   status = f1.wait_until(std::chrono::system_clock::now());
   VERIFY( status == std::future_status::timeout );
+  status = f1.wait_until(std::chrono::steady_clock::now());
+  VERIFY( status == std::future_status::timeout );
   l.unlock();  // allow async thread to proceed
   f1.wait();   // wait for it to finish
   status = f1.wait_for(std::chrono::milliseconds(0));
   VERIFY( status == std::future_status::ready );
   status = f1.wait_until(std::chrono::system_clock::now());
   VERIFY( status == std::future_status::ready );
+  status = f1.wait_until(std::chrono::steady_clock::now());
+  VERIFY( status == std::future_status::ready );
+}
+
+void work03()
+{
+    std::this_thread::sleep_for(std::chrono::seconds(15));
+}
+
+// This test is slow in order to try and avoid failing on a loaded
+// machine. Nevertheless, it could still fail if the kernel decides
+// not to schedule us for several seconds. It also assumes that no-one
+// will change CLOCK_REALTIME whilst the test is running.
+template<typename CLOCK>
+void test03()
+{
+  auto const start = CLOCK::now();
+  future<void> f1 = async(launch::async, &work03);
+  std::future_status status;
+
+  status = f1.wait_for(std::chrono::seconds(5));
+  VERIFY( status == std::future_status::timeout );
+
+  status = f1.wait_until(start + std::chrono::seconds(10));
+  VERIFY( status == std::future_status::timeout );
+
+  status = f1.wait_until(start + std::chrono::seconds(25));
+  VERIFY( status == std::future_status::ready );
+
+  auto const elapsed = CLOCK::now() - start;
+  VERIFY( elapsed >= std::chrono::seconds(15) );
+  VERIFY( elapsed < std::chrono::seconds(20) );
 }
 
 int main()
 {
   test01();
   test02();
+  test03<std::chrono::system_clock>();
+  test03<std::chrono::steady_clock>();
   return 0;
 }
-- 
2.11.0