FTL: Add wrapper for shared_mutex
std::shared_mutex on Android is missing capabilities necessary for
threading annotations. b/135688034 tracks adding them, but is blocked on
b/175635923. In the meantime, add a simple wrapper so that we can start
using annotations.
Only add the methods we currently need. Other methods can be added as
needed.
Bug: 185536303
Test: ftl_test
Change-Id: Ic7c2152bc7e46b31eecdba42fac1126b26aafd60
diff --git a/libs/ftl/shared_mutex_test.cpp b/libs/ftl/shared_mutex_test.cpp
new file mode 100644
index 0000000..6da7061
--- /dev/null
+++ b/libs/ftl/shared_mutex_test.cpp
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <ftl/shared_mutex.h>
+#include <gtest/gtest.h>
+#include <ftl/fake_guard.h>
+
+namespace android::test {
+
+TEST(SharedMutex, SharedLock) {
+ ftl::SharedMutex mutex;
+ std::shared_lock shared_lock(mutex);
+
+ { std::shared_lock shared_lock2(mutex); }
+}
+
+TEST(SharedMutex, ExclusiveLock) {
+ ftl::SharedMutex mutex;
+ std::unique_lock unique_lock(mutex);
+}
+
+TEST(SharedMutex, Annotations) {
+ struct {
+ void foo() FTL_ATTRIBUTE(requires_shared_capability(mutex)) { num++; }
+ void bar() FTL_ATTRIBUTE(requires_capability(mutex)) { num++; }
+ void baz() {
+ std::shared_lock shared_lock(mutex);
+ num++;
+ }
+ ftl::SharedMutex mutex;
+ int num = 0;
+
+ } s;
+
+ {
+ // TODO(b/257958323): Use an RAII class instead of locking manually.
+ s.mutex.lock_shared();
+ s.foo();
+ s.baz();
+ s.mutex.unlock_shared();
+ }
+ s.mutex.lock();
+ s.bar();
+ s.mutex.unlock();
+}
+
+} // namespace android::test