FTL: Add thread safety helpers

Bug: 185536303
Test: ftl_test
Change-Id: I0f0550d0608a11b137741cd94248b5bc533a0304

2 files changed, 51 insertions, 0 deletions

diff --git a/libs/ftl/Android.bp b/libs/ftl/Android.bp
index bc2eb23677..97b522a390 100644
--- a/libs/ftl/Android.bp
+++ b/libs/ftl/Android.bp
@@ -18,6 +18,7 @@ cc_test {
         "cast_test.cpp",
         "concat_test.cpp",
         "enum_test.cpp",
+        "fake_guard_test.cpp",
         "future_test.cpp",
         "small_map_test.cpp",
         "small_vector_test.cpp",
@@ -29,6 +30,7 @@ cc_test {
         "-Werror",
         "-Wextra",
         "-Wpedantic",
+        "-Wthread-safety",
     ],
 
     header_libs: [
diff --git a/libs/ftl/fake_guard_test.cpp b/libs/ftl/fake_guard_test.cpp
new file mode 100644
index 0000000000..9d36e69444
--- /dev/null
+++ b/libs/ftl/fake_guard_test.cpp
@@ -0,0 +1,49 @@
+/*
+ * 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/fake_guard.h>
+#include <gtest/gtest.h>
+
+#include <functional>
+#include <mutex>
+
+namespace android::test {
+
+// Keep in sync with example usage in header file.
+TEST(FakeGuard, Example) {
+  struct {
+    std::mutex mutex;
+    int x FTL_ATTRIBUTE(guarded_by(mutex)) = -1;
+
+    int f() {
+      {
+        ftl::FakeGuard guard(mutex);
+        x = 0;
+      }
+
+      return FTL_FAKE_GUARD(mutex, x + 1);
+    }
+
+    std::function<int()> g() const {
+      return [this]() FTL_FAKE_GUARD(mutex) { return x; };
+    }
+  } s;
+
+  EXPECT_EQ(s.f(), 1);
+  EXPECT_EQ(s.g()(), 0);
+}
+
+}  // namespace android::test