[libc++] Refactor the tests for mutex, recursive mutex and their timed counterparts (llvm#104852)

This refactoring is done to remove flakyness as described in
llvm#89083.

Author: ldionne

libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.class/assign.compile.fail.cpp renamed to libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.class/assign.compile.pass.cpp

@@ -6,19 +6,15 @@
 //
 //===----------------------------------------------------------------------===//
 
+// UNSUPPORTED: no-threads
+
 // <mutex>
 
 // class mutex;
 
 // mutex& operator=(const mutex&) = delete;
 
 #include <mutex>
+#include <type_traits>
 
-int main(int, char**)
-{
-    std::mutex m0;
-    std::mutex m1;
-    m1 = m0;
-
-  return 0;
-}
+static_assert(!std::is_copy_assignable<std::mutex>::value, "");

libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.class/copy.compile.fail.cpp renamed to libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.class/ctor.copy.compile.pass.cpp

@@ -6,18 +6,15 @@
 //
 //===----------------------------------------------------------------------===//
 
+// UNSUPPORTED: no-threads
+
 // <mutex>
 
 // class mutex;
 
 // mutex(const mutex&) = delete;
 
 #include <mutex>
+#include <type_traits>
 
-int main(int, char**)
-{
-    std::mutex m0;
-    std::mutex m1(m0);
-
-  return 0;
-}
+static_assert(!std::is_copy_constructible<std::mutex>::value, "");

libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.class/default.pass.cpp renamed to libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.class/ctor.default.pass.cpp

@@ -5,24 +5,28 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
 // UNSUPPORTED: no-threads
 
 // <mutex>
 
 // class mutex;
 
-// mutex();
+// mutex() noexcept;
 
 #include <mutex>
+#include <cassert>
 #include <type_traits>
 
-#include "test_macros.h"
+static_assert(std::is_nothrow_default_constructible<std::mutex>::value, "");
+
+int main(int, char**) {
+  // The mutex is unlocked after default construction
+  {
+    std::mutex m;
+    assert(m.try_lock());
+    m.unlock();
+  }
 
-int main(int, char**)
-{
-  static_assert(std::is_nothrow_default_constructible<std::mutex>::value, "");
-  std::mutex m;
-  ((void)m);
   return 0;
 }

libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.class/lock.pass.cpp

@@ -5,50 +5,77 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
+// UNSUPPORTED: c++03
 // UNSUPPORTED: no-threads
-// ALLOW_RETRIES: 2
 
 // <mutex>
 
 // class mutex;
 
 // void lock();
 
-#include <cassert>
-#include <chrono>
-#include <cstdlib>
 #include <mutex>
+#include <atomic>
+#include <cassert>
 #include <thread>
+#include <vector>
 
 #include "make_test_thread.h"
-#include "test_macros.h"
 
-std::mutex m;
-
-typedef std::chrono::system_clock Clock;
-typedef Clock::time_point time_point;
-typedef Clock::duration duration;
-typedef std::chrono::milliseconds ms;
-typedef std::chrono::nanoseconds ns;
-
-void f()
-{
-    time_point t0 = Clock::now();
+int main(int, char**) {
+  // Lock a mutex that is not locked yet. This should succeed.
+  {
+    std::mutex m;
     m.lock();
-    time_point t1 = Clock::now();
     m.unlock();
-    ns d = t1 - t0 - ms(250);
-    assert(d < ms(50));  // within 50ms
-}
+  }
 
-int main(int, char**)
-{
+  // Lock a mutex that is already locked. This should block until it is unlocked.
+  {
+    std::atomic<bool> ready(false);
+    std::mutex m;
     m.lock();
-    std::thread t = support::make_test_thread(f);
-    std::this_thread::sleep_for(ms(250));
+    std::atomic<bool> is_locked_from_main(true);
+
+    std::thread t = support::make_test_thread([&] {
+      ready = true;
+      m.lock();
+      assert(!is_locked_from_main);
+      m.unlock();
+    });
+
+    while (!ready)
+      /* spin */;
+
+    // We would rather signal this after we unlock, but that would create a race condition.
+    // We instead signal it before we unlock, which means that it's technically possible for
+    // the thread to take the lock while main is still holding it yet for the test to still pass.
+    is_locked_from_main = false;
     m.unlock();
+
     t.join();
+  }
+
+  // Make sure that at most one thread can acquire the mutex concurrently.
+  {
+    std::atomic<int> counter(0);
+    std::mutex mutex;
+
+    std::vector<std::thread> threads;
+    for (int i = 0; i != 10; ++i) {
+      threads.push_back(support::make_test_thread([&] {
+        mutex.lock();
+        counter++;
+        assert(counter == 1);
+        counter--;
+        mutex.unlock();
+      }));
+    }
+
+    for (auto& t : threads)
+      t.join();
+  }
 
   return 0;
 }

libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.class/try_lock.pass.cpp

@@ -5,54 +5,46 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
+// UNSUPPORTED: c++03
 // UNSUPPORTED: no-threads
-// ALLOW_RETRIES: 2
 
 // <mutex>
 
 // class mutex;
 
 // bool try_lock();
 
-#include <cassert>
-#include <chrono>
-#include <cstdlib>
 #include <mutex>
+#include <cassert>
 #include <thread>
 
 #include "make_test_thread.h"
-#include "test_macros.h"
-
-std::mutex m;
-
-typedef std::chrono::system_clock Clock;
-typedef Clock::time_point time_point;
-typedef Clock::duration duration;
-typedef std::chrono::milliseconds ms;
-typedef std::chrono::nanoseconds ns;
-
-void f()
-{
-    time_point t0 = Clock::now();
-    assert(!m.try_lock());
-    assert(!m.try_lock());
-    assert(!m.try_lock());
-    while(!m.try_lock())
-        ;
-    time_point t1 = Clock::now();
+
+int main(int, char**) {
+  // Try to lock a mutex that is not locked yet. This should succeed.
+  {
+    std::mutex m;
+    bool succeeded = m.try_lock();
+    assert(succeeded);
     m.unlock();
-    ns d = t1 - t0 - ms(250);
-    assert(d < ms(200));  // within 200ms
-}
+  }
 
-int main(int, char**)
-{
+  // Try to lock a mutex that is already locked. This should fail.
+  {
+    std::mutex m;
     m.lock();
-    std::thread t = support::make_test_thread(f);
-    std::this_thread::sleep_for(ms(250));
-    m.unlock();
+
+    std::thread t = support::make_test_thread([&] {
+      for (int i = 0; i != 10; ++i) {
+        bool succeeded = m.try_lock();
+        assert(!succeeded);
+      }
+    });
     t.join();
 
+    m.unlock();
+  }
+
   return 0;
 }

libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.recursive/assign.compile.fail.cpp renamed to libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.recursive/assign.compile.pass.cpp

@@ -6,19 +6,15 @@
 //
 //===----------------------------------------------------------------------===//
 
+// UNSUPPORTED: no-threads
+
 // <mutex>
 
 // class recursive_mutex;
 
 // recursive_mutex& operator=(const recursive_mutex&) = delete;
 
 #include <mutex>
+#include <type_traits>
 
-int main(int, char**)
-{
-    std::recursive_mutex m0;
-    std::recursive_mutex m1;
-    m1 = m0;
-
-  return 0;
-}
+static_assert(!std::is_copy_assignable<std::recursive_mutex>::value, "");

libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.recursive/copy.compile.fail.cpp renamed to libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.recursive/ctor.copy.compile.pass.cpp

@@ -6,18 +6,15 @@
 //
 //===----------------------------------------------------------------------===//
 
+// UNSUPPORTED: no-threads
+
 // <mutex>
 
 // class recursive_mutex;
 
 // recursive_mutex(const recursive_mutex&) = delete;
 
 #include <mutex>
+#include <type_traits>
 
-int main(int, char**)
-{
-    std::recursive_mutex m0;
-    std::recursive_mutex m1(m0);
-
-  return 0;
-}
+static_assert(!std::is_copy_constructible<std::recursive_mutex>::value, "");

libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.recursive/default.pass.cpp renamed to libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.recursive/ctor.default.pass.cpp

@@ -5,7 +5,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
 // UNSUPPORTED: no-threads
 
 // <mutex>
@@ -15,12 +15,16 @@
 // recursive_mutex();
 
 #include <mutex>
+#include <cassert>
+#include <type_traits>
 
-#include "test_macros.h"
-
-int main(int, char**)
-{
+int main(int, char**) {
+  // The mutex is unlocked after default construction
+  {
     std::recursive_mutex m;
+    assert(m.try_lock());
+    m.unlock();
+  }
 
   return 0;
 }