Add Timer as an alternative to osi alarm

* Add a private method MessageLoopThread.DoInThreadDelayed to post a
  delayed task in message loop, as an alternative approach to osi alarm
  clock
* Add a unit test for MessageLoopThread to check ShutDown() waits until
  current task finishes
* Add Timer using MessageLoopThread.DoInThreadDelayed
* Timer provides similar API as osi alarm, and uses same OS clock (boot
  timer) as alarm
* Add benchmark and unit tests to ensure the performance is comparable
  to the existing osi alarm

Test: Run unit test and benchmark test
      ./test/run_unit_tests.sh bluetooth_test_common
      ./test/run_benchmarks.sh bluetooth_benchmark_timer_performance
      --benchmark_repetitions=10 --benchmark_report_aggregates_only=true
Bug: 110303473
Change-Id: I6f2e7ae2f80f9889fc5fe3c8cd6b9b2670938b46

1 files changed, 32 insertions, 0 deletions

diff --git a/system/common/message_loop_thread_unittest.cc b/system/common/message_loop_thread_unittest.cc
index 0924ebe14e..67a0cfd37d 100644
--- a/system/common/message_loop_thread_unittest.cc
+++ b/system/common/message_loop_thread_unittest.cc
@@ -61,6 +61,11 @@ class MessageLoopThreadTest : public ::testing::Test {
     execution_promise.set_value();
   }
 
+  void SleepAndGetName(std::promise<std::string> name_promise, int sleep_ms) {
+    std::this_thread::sleep_for(std::chrono::milliseconds(sleep_ms));
+    GetName(std::move(name_promise));
+  }
+
  protected:
   static bool CanSetCurrentThreadPriority() {
     struct __user_cap_header_struct linux_user_header = {
@@ -78,6 +83,16 @@ class MessageLoopThreadTest : public ::testing::Test {
   }
 };
 
+TEST_F(MessageLoopThreadTest, get_weak_ptr) {
+  base::WeakPtr<MessageLoopThread> message_loop_thread_ptr;
+  {
+    MessageLoopThread message_loop_thread("test_thread");
+    message_loop_thread_ptr = message_loop_thread.GetWeakPtr();
+    ASSERT_NE(message_loop_thread_ptr, nullptr);
+  }
+  ASSERT_EQ(message_loop_thread_ptr, nullptr);
+}
+
 TEST_F(MessageLoopThreadTest, test_running_thread) {
   MessageLoopThread message_loop_thread("test_thread");
   message_loop_thread.StartUp();
@@ -248,3 +263,20 @@ TEST_F(MessageLoopThreadTest, test_to_string_method) {
   ASSERT_STREQ(thread_string_after_shutdown.c_str(),
                thread_string_before_start.c_str());
 }
+
+// Verify the message loop thread will shutdown after callback finishes
+TEST_F(MessageLoopThreadTest, shut_down_while_in_callback) {
+  std::string name = "test_thread";
+  MessageLoopThread message_loop_thread(name);
+  message_loop_thread.StartUp();
+  std::promise<std::string> name_promise;
+  std::future<std::string> name_future = name_promise.get_future();
+  uint32_t delay_ms = 5;
+  message_loop_thread.DoInThread(
+      FROM_HERE, base::BindOnce(&MessageLoopThreadTest::SleepAndGetName,
+                                base::Unretained(this), std::move(name_promise),
+                                delay_ms));
+  message_loop_thread.ShutDown();
+  std::string my_name = name_future.get();
+  ASSERT_EQ(name, my_name);
+}