Modernize TimeCheck
This replaces the usage of Thread, Mutex, Condition and KeyedVector
with their std:: counterparts.
We're also extracting the time thread from TimeCheck and adding a unit
test.
The logic in TimerThread now is easier to follow and it is more
evident that tasks would never be executed before their deadline
arrived. In the original code, this wasn't obvious.
Test: atest libmediautils_test
Bug: 188748333
Change-Id: Iac887e7d6e6758c0a0e5c56695e9671082e64b09
diff --git a/media/utils/include/mediautils/TimeCheck.h b/media/utils/include/mediautils/TimeCheck.h
index 5ba6d7c..2411f97 100644
--- a/media/utils/include/mediautils/TimeCheck.h
+++ b/media/utils/include/mediautils/TimeCheck.h
@@ -14,62 +14,33 @@
* limitations under the License.
*/
+#pragma once
-#ifndef ANDROID_TIME_CHECK_H
-#define ANDROID_TIME_CHECK_H
-
-#include <utils/KeyedVector.h>
-#include <utils/Thread.h>
#include <vector>
+#include <mediautils/TimerThread.h>
+
namespace android {
// A class monitoring execution time for a code block (scoped variable) and causing an assert
// if it exceeds a certain time
class TimeCheck {
-public:
-
+ public:
// The default timeout is chosen to be less than system server watchdog timeout
static constexpr uint32_t kDefaultTimeOutMs = 5000;
- TimeCheck(const char *tag, uint32_t timeoutMs = kDefaultTimeOutMs);
- ~TimeCheck();
- static void setAudioHalPids(const std::vector<pid_t>& pids);
- static std::vector<pid_t> getAudioHalPids();
+ TimeCheck(const char* tag, uint32_t timeoutMs = kDefaultTimeOutMs);
+ ~TimeCheck();
+ static void setAudioHalPids(const std::vector<pid_t>& pids);
+ static std::vector<pid_t> getAudioHalPids();
-private:
-
- class TimeCheckThread : public Thread {
- public:
-
- TimeCheckThread() {}
- virtual ~TimeCheckThread() override;
-
- nsecs_t startMonitoring(const char *tag, uint32_t timeoutMs);
- void stopMonitoring(nsecs_t endTimeNs);
-
- private:
-
- // RefBase
- virtual void onFirstRef() override { run("TimeCheckThread", PRIORITY_URGENT_AUDIO); }
-
- // Thread
- virtual bool threadLoop() override;
-
- Condition mCond;
- Mutex mMutex;
- // using the end time in ns as key is OK given the risk is low that two entries
- // are added in such a way that <add time> + <timeout> are the same for both.
- KeyedVector< nsecs_t, const char*> mMonitorRequests;
- };
-
- static sp<TimeCheckThread> getTimeCheckThread();
+ private:
+ static TimerThread* getTimeCheckThread();
static void accessAudioHalPids(std::vector<pid_t>* pids, bool update);
+ static void crash(const char* tag);
- const nsecs_t mEndTimeNs;
+ const TimerThread::Handle mTimerHandle;
};
-}; // namespace android
-
-#endif // ANDROID_TIME_CHECK_H
+}; // namespace android
diff --git a/media/utils/include/mediautils/TimerThread.h b/media/utils/include/mediautils/TimerThread.h
new file mode 100644
index 0000000..cf457b8
--- /dev/null
+++ b/media/utils/include/mediautils/TimerThread.h
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+#pragma once
+
+#include <condition_variable>
+#include <functional>
+#include <map>
+#include <mutex>
+#include <thread>
+
+#include <android-base/thread_annotations.h>
+
+namespace android {
+
+/**
+ * A thread for deferred execution of tasks, with cancellation.
+ */
+class TimerThread {
+ public:
+ using Handle = std::chrono::steady_clock::time_point;
+
+ TimerThread();
+ ~TimerThread();
+
+ /**
+ * Schedule a task to be executed in the future (`timeout` duration from now).
+ * Returns a handle that can be used for cancellation.
+ */
+ template <typename R, typename P>
+ Handle scheduleTask(std::function<void()>&& func, std::chrono::duration<R, P> timeout) {
+ auto deadline = std::chrono::steady_clock::now() + std::chrono::milliseconds(timeout);
+ return scheduleTaskAtDeadline(std::move(func), deadline);
+ }
+
+ /**
+ * Cancel a task, previously scheduled with scheduleTask().
+ * If the task has already executed, this is a no-op.
+ */
+ void cancelTask(Handle handle);
+
+ private:
+ using TimePoint = std::chrono::steady_clock::time_point;
+
+ std::condition_variable mCond;
+ std::mutex mMutex;
+ std::thread mThread;
+ std::map<TimePoint, std::function<void()>> mMonitorRequests GUARDED_BY(mMutex);
+ bool mShouldExit GUARDED_BY(mMutex) = false;
+
+ void threadFunc();
+ Handle scheduleTaskAtDeadline(std::function<void()>&& func, TimePoint deadline);
+};
+
+} // namespace android