Fix flaky VibratorCallbackSchedulerTest

Use TestCounter to wait on scheduled callbacks with a timeout.

The VibratorCallbackScheduler destructor joins on the scheduler
thread to wait for the main loop to finish, but the conditional variable
is waiting indefinitely without a predicate, which can cause it
sometimes to miss the notify call from the destructor and get stuck.

Adding a predicate condition fixes the VibratorCallbackSchedulerTest
flakiness for the timeout "No test results." failures.

Bug: 335951228
Bug: 335577082
Change-Id: If1af34f70de9fa5175aa38ebfb22f5b6d9112272
Merged-In: Id9501c10fe5209003d9b74b0f39f2bcf87de05c2
Merged-In: Ib519c3e91608c7373b2999fc596dab3413226a1e
Test: atest --rerun-until-failure 1000 VibratorCallbackSchedulerTest

3 files changed, 54 insertions, 51 deletions

diff --git a/services/vibratorservice/VibratorCallbackScheduler.cpp b/services/vibratorservice/VibratorCallbackScheduler.cpp
index 7eda9ef0c7..b2b1988d97 100644
--- a/services/vibratorservice/VibratorCallbackScheduler.cpp
+++ b/services/vibratorservice/VibratorCallbackScheduler.cpp
@@ -87,13 +87,13 @@ void CallbackScheduler::loop() {
             lock.lock();
         }
         if (mQueue.empty()) {
-            // Wait until a new callback is scheduled.
-            mCondition.wait(mMutex);
+            // Wait until a new callback is scheduled or destructor was called.
+            mCondition.wait(lock, [this] { return mFinished || !mQueue.empty(); });
         } else {
-            // Wait until next callback expires, or a new one is scheduled.
+            // Wait until next callback expires or a new one is scheduled.
             // Use the monotonic steady clock to wait for the measured delay interval via wait_for
             // instead of using a wall clock via wait_until.
-            mCondition.wait_for(mMutex, mQueue.top().getWaitForExpirationDuration());
+            mCondition.wait_for(lock, mQueue.top().getWaitForExpirationDuration());
         }
     }
 }
diff --git a/services/vibratorservice/test/VibratorCallbackSchedulerTest.cpp b/services/vibratorservice/test/VibratorCallbackSchedulerTest.cpp
index 426cd426f7..881e32152c 100644
--- a/services/vibratorservice/test/VibratorCallbackSchedulerTest.cpp
+++ b/services/vibratorservice/test/VibratorCallbackSchedulerTest.cpp
@@ -14,20 +14,13 @@
  * limitations under the License.
  */
 
-#define LOG_TAG "VibratorHalWrapperAidlTest"
-
-#include <android-base/thread_annotations.h>
-#include <android/hardware/vibrator/IVibrator.h>
-#include <condition_variable>
-
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
-#include <utils/Log.h>
-#include <thread>
-
 #include <vibratorservice/VibratorCallbackScheduler.h>
 
+#include "test_utils.h"
+
 using std::chrono::milliseconds;
 using std::chrono::steady_clock;
 using std::chrono::time_point;
@@ -39,29 +32,25 @@ using namespace testing;
 // -------------------------------------------------------------------------------------------------
 
 // Delay allowed for the scheduler to process callbacks during this test.
-static const auto TEST_TIMEOUT = 50ms;
+static const auto TEST_TIMEOUT = 100ms;
 
 class VibratorCallbackSchedulerTest : public Test {
 public:
-    void SetUp() override {
-        mScheduler = std::make_unique<vibrator::CallbackScheduler>();
-        std::lock_guard<std::mutex> lock(mMutex);
-        mExpiredCallbacks.clear();
-    }
+    void SetUp() override { mScheduler = std::make_unique<vibrator::CallbackScheduler>(); }
 
 protected:
     std::mutex mMutex;
-    std::condition_variable_any mCondition;
     std::unique_ptr<vibrator::CallbackScheduler> mScheduler = nullptr;
+    vibrator::TestCounter mCallbackCounter;
     std::vector<int32_t> mExpiredCallbacks GUARDED_BY(mMutex);
 
     std::function<void()> createCallback(int32_t id) {
-        return [=]() {
+        return [this, id]() {
             {
                 std::lock_guard<std::mutex> lock(mMutex);
                 mExpiredCallbacks.push_back(id);
             }
-            mCondition.notify_all();
+            mCallbackCounter.increment();
         };
     }
 
@@ -71,56 +60,42 @@ protected:
     }
 
     int32_t waitForCallbacks(int32_t callbackCount, milliseconds timeout) {
-        time_point<steady_clock> expirationTime = steady_clock::now() + timeout + TEST_TIMEOUT;
-        int32_t expiredCallbackCount = 0;
-        while (steady_clock::now() < expirationTime) {
-            std::lock_guard<std::mutex> lock(mMutex);
-            expiredCallbackCount = mExpiredCallbacks.size();
-            if (callbackCount <= expiredCallbackCount) {
-                return expiredCallbackCount;
-            }
-            auto currentTimeout = std::chrono::duration_cast<std::chrono::milliseconds>(
-                    expirationTime - steady_clock::now());
-            if (currentTimeout > currentTimeout.zero()) {
-                // Use the monotonic steady clock to wait for the requested timeout via wait_for
-                // instead of using a wall clock via wait_until.
-                mCondition.wait_for(mMutex, currentTimeout);
-            }
-        }
-        return expiredCallbackCount;
+        mCallbackCounter.tryWaitUntilCountIsAtLeast(callbackCount, timeout);
+        return mCallbackCounter.get();
     }
 };
 
 // -------------------------------------------------------------------------------------------------
 
 TEST_F(VibratorCallbackSchedulerTest, TestScheduleRunsOnlyAfterDelay) {
+    auto callbackDuration = 50ms;
     time_point<steady_clock> startTime = steady_clock::now();
-    mScheduler->schedule(createCallback(1), 50ms);
+    mScheduler->schedule(createCallback(1), callbackDuration);
 
-    ASSERT_EQ(1, waitForCallbacks(1, 50ms));
+    ASSERT_THAT(waitForCallbacks(1, callbackDuration + TEST_TIMEOUT), Eq(1));
     time_point<steady_clock> callbackTime = steady_clock::now();
 
-    // Callback happened at least 50ms after the beginning of the test.
-    ASSERT_TRUE(startTime + 50ms <= callbackTime);
-    ASSERT_THAT(getExpiredCallbacks(), ElementsAre(1));
+    // Callback took at least the required duration to trigger.
+    ASSERT_THAT(callbackTime, Ge(startTime + callbackDuration));
 }
 
 TEST_F(VibratorCallbackSchedulerTest, TestScheduleMultipleCallbacksRunsInDelayOrder) {
     // Schedule first callbacks long enough that all 3 will be scheduled together and run in order.
-    mScheduler->schedule(createCallback(1), 50ms);
-    mScheduler->schedule(createCallback(2), 40ms);
-    mScheduler->schedule(createCallback(3), 10ms);
+    mScheduler->schedule(createCallback(1), 50ms + 2 * TEST_TIMEOUT);
+    mScheduler->schedule(createCallback(2), 50ms + TEST_TIMEOUT);
+    mScheduler->schedule(createCallback(3), 50ms);
 
-    ASSERT_EQ(3, waitForCallbacks(3, 50ms));
+    // Callbacks triggered in the expected order based on the requested durations.
+    ASSERT_THAT(waitForCallbacks(3, 50ms + 3 * TEST_TIMEOUT), Eq(3));
     ASSERT_THAT(getExpiredCallbacks(), ElementsAre(3, 2, 1));
 }
 
 TEST_F(VibratorCallbackSchedulerTest, TestDestructorDropsPendingCallbacksAndKillsThread) {
     // Schedule callback long enough that scheduler will be destroyed while it's still scheduled.
-    mScheduler->schedule(createCallback(1), 50ms);
+    mScheduler->schedule(createCallback(1), 100ms);
     mScheduler.reset(nullptr);
 
     // Should timeout waiting for callback to run.
-    ASSERT_EQ(0, waitForCallbacks(1, 50ms));
-    ASSERT_TRUE(getExpiredCallbacks().empty());
+    ASSERT_THAT(waitForCallbacks(1, 100ms + TEST_TIMEOUT), Eq(0));
+    ASSERT_THAT(getExpiredCallbacks(), IsEmpty());
 }
diff --git a/services/vibratorservice/test/test_utils.h b/services/vibratorservice/test/test_utils.h
index 1933a118ef..c08cfc6bfa 100644
--- a/services/vibratorservice/test/test_utils.h
+++ b/services/vibratorservice/test/test_utils.h
@@ -85,6 +85,34 @@ private:
     ~TestFactory() = delete;
 };
 
+class TestCounter {
+public:
+    TestCounter(int32_t init = 0) : mMutex(), mCondVar(), mCount(init) {}
+
+    int32_t get() {
+        std::lock_guard<std::mutex> lock(mMutex);
+        return mCount;
+    }
+
+    void increment() {
+        {
+            std::lock_guard<std::mutex> lock(mMutex);
+            mCount += 1;
+        }
+        mCondVar.notify_all();
+    }
+
+    void tryWaitUntilCountIsAtLeast(int32_t count, std::chrono::milliseconds timeout) {
+        std::unique_lock<std::mutex> lock(mMutex);
+        mCondVar.wait_for(lock, timeout, [&] { return mCount >= count; });
+    }
+
+private:
+    std::mutex mMutex;
+    std::condition_variable mCondVar;
+    int32_t mCount GUARDED_BY(mMutex);
+};
+
 // -------------------------------------------------------------------------------------------------
 
 } // namespace vibrator