Merge "SF/CE: Fix startup race in HwcAsyncWorker" into main
diff --git a/services/surfaceflinger/CompositionEngine/Android.bp b/services/surfaceflinger/CompositionEngine/Android.bp
index ed4c47d..b4ac9ba 100644
--- a/services/surfaceflinger/CompositionEngine/Android.bp
+++ b/services/surfaceflinger/CompositionEngine/Android.bp
@@ -149,6 +149,7 @@
         "tests/CompositionEngineTest.cpp",
         "tests/DisplayColorProfileTest.cpp",
         "tests/DisplayTest.cpp",
+        "tests/HwcAsyncWorkerTest.cpp",
         "tests/HwcBufferCacheTest.cpp",
         "tests/MockHWC2.cpp",
         "tests/MockHWComposer.cpp",
diff --git a/services/surfaceflinger/CompositionEngine/src/HwcAsyncWorker.cpp b/services/surfaceflinger/CompositionEngine/src/HwcAsyncWorker.cpp
index 6086f0b..91385b4 100644
--- a/services/surfaceflinger/CompositionEngine/src/HwcAsyncWorker.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/HwcAsyncWorker.cpp
@@ -24,6 +24,7 @@
 
 #include <android-base/thread_annotations.h>
 #include <cutils/sched_policy.h>
+#include <ftl/fake_guard.h>
 
 namespace android::compositionengine::impl {
 
@@ -60,7 +61,7 @@
     std::unique_lock<std::mutex> lock(mMutex);
     android::base::ScopedLockAssertion assumeLock(mMutex);
     while (!mDone) {
-        mCv.wait(lock);
+        mCv.wait(lock, [this]() FTL_FAKE_GUARD(mMutex) { return mTaskRequested || mDone; });
         if (mTaskRequested && mTask.valid()) {
             mTask();
             mTaskRequested = false;
diff --git a/services/surfaceflinger/CompositionEngine/tests/HwcAsyncWorkerTest.cpp b/services/surfaceflinger/CompositionEngine/tests/HwcAsyncWorkerTest.cpp
new file mode 100644
index 0000000..dd04df6
--- /dev/null
+++ b/services/surfaceflinger/CompositionEngine/tests/HwcAsyncWorkerTest.cpp
@@ -0,0 +1,71 @@
+/*
+ * Copyright 2024 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 <future>
+
+#include <compositionengine/impl/HwcAsyncWorker.h>
+#include <gtest/gtest.h>
+
+namespace android::compositionengine {
+namespace {
+
+using namespace std::chrono_literals;
+
+// For the edge case tests below, how much real time should be spent trying to reproduce edge cases
+// problems in a loop.
+//
+// Larger values mean problems are more likely to be detected, at the cost of making the unit test
+// run slower.
+//
+// As we expect the tests to be run continuously, even a short loop will eventually catch
+// problems, though not necessarily from changes in the same build that introduce them.
+constexpr auto kWallTimeForEdgeCaseTests = 5ms;
+
+TEST(HwcAsyncWorker, continuousTasksEdgeCase) {
+    // Ensures that a single worker that is given multiple tasks in short succession will run them.
+
+    impl::HwcAsyncWorker worker;
+    const auto endTime = std::chrono::steady_clock::now() + kWallTimeForEdgeCaseTests;
+    while (std::chrono::steady_clock::now() < endTime) {
+        auto f1 = worker.send([] { return false; });
+        EXPECT_FALSE(f1.get());
+        auto f2 = worker.send([] { return true; });
+        EXPECT_TRUE(f2.get());
+    }
+}
+
+TEST(HwcAsyncWorker, constructAndDestroyEdgeCase) {
+    // Ensures that newly created HwcAsyncWorkers can be immediately destroyed.
+
+    const auto endTime = std::chrono::steady_clock::now() + kWallTimeForEdgeCaseTests;
+    while (std::chrono::steady_clock::now() < endTime) {
+        impl::HwcAsyncWorker worker;
+    }
+}
+
+TEST(HwcAsyncWorker, newlyCreatedRunsTasksEdgeCase) {
+    // Ensures that newly created HwcAsyncWorkers will run a task if given one immediately.
+
+    const auto endTime = std::chrono::steady_clock::now() + kWallTimeForEdgeCaseTests;
+    while (std::chrono::steady_clock::now() < endTime) {
+        impl::HwcAsyncWorker worker;
+        auto f = worker.send([] { return true; });
+        f.get();
+    }
+}
+
+} // namespace
+} // namespace android::compositionengine