Create CallbackScheduler for Vibrator HAL callbacks
This scheduler keeps a single thread looping and executing callbacks
after a delay. This mechanism is used to simulate the callbacks that
some Vibrator HALs do not support.
Bug: 153418251
Test: atest libvibratorservice_test
Change-Id: If19481dfe2eca662d33738a11257bd4509fe81ca
diff --git a/services/vibratorservice/VibratorCallbackScheduler.cpp b/services/vibratorservice/VibratorCallbackScheduler.cpp
new file mode 100644
index 0000000..3f8cd67
--- /dev/null
+++ b/services/vibratorservice/VibratorCallbackScheduler.cpp
@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2020 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 <chrono>
+#include <thread>
+
+#include <vibratorservice/VibratorCallbackScheduler.h>
+
+namespace android {
+
+namespace vibrator {
+
+// -------------------------------------------------------------------------------------------------
+
+bool DelayedCallback::isExpired() const {
+ return mExpiration <= std::chrono::steady_clock::now();
+}
+
+DelayedCallback::Timestamp DelayedCallback::getExpiration() const {
+ return mExpiration;
+}
+
+void DelayedCallback::run() const {
+ mCallback();
+}
+
+bool DelayedCallback::operator<(const DelayedCallback& other) const {
+ return mExpiration < other.mExpiration;
+}
+
+bool DelayedCallback::operator>(const DelayedCallback& other) const {
+ return mExpiration > other.mExpiration;
+}
+
+// -------------------------------------------------------------------------------------------------
+
+CallbackScheduler::~CallbackScheduler() {
+ {
+ std::lock_guard<std::mutex> lock(mMutex);
+ mFinished = true;
+ }
+ mCondition.notify_all();
+ if (mCallbackThread && mCallbackThread->joinable()) {
+ mCallbackThread->join();
+ }
+}
+
+void CallbackScheduler::schedule(std::function<void()> callback, std::chrono::milliseconds delay) {
+ {
+ std::lock_guard<std::mutex> lock(mMutex);
+ if (mCallbackThread == nullptr) {
+ mCallbackThread = std::make_unique<std::thread>(&CallbackScheduler::loop, this);
+ }
+ mQueue.emplace(DelayedCallback(callback, delay));
+ }
+ mCondition.notify_all();
+}
+
+void CallbackScheduler::loop() {
+ while (true) {
+ std::lock_guard<std::mutex> lock(mMutex);
+ if (mFinished) {
+ // Destructor was called, so let the callback thread die.
+ break;
+ }
+ while (!mQueue.empty() && mQueue.top().isExpired()) {
+ mQueue.top().run();
+ mQueue.pop();
+ }
+ if (mQueue.empty()) {
+ // Wait until a new callback is scheduled.
+ mCondition.wait(mMutex);
+ } else {
+ // Wait until next callback expires, or a new one is scheduled.
+ mCondition.wait_until(mMutex, mQueue.top().getExpiration());
+ }
+ }
+}
+
+// -------------------------------------------------------------------------------------------------
+
+}; // namespace vibrator
+
+}; // namespace android