Fill in async timer

sdk/src/event/async_timer/dispatcher.cc

@@ -1,5 +1,7 @@
 #include "src/event/async_timer/dispatcher.h"
 
+#include <thread>
+
 OPENTELEMETRY_BEGIN_NAMESPACE
 namespace sdk
 {
@@ -13,9 +15,20 @@ std::unique_ptr<event::Timer> Dispatcher::CreateTimer(TimerCallback callback) no
   return nullptr;
 }
 
-void Dispatcher::Exit() noexcept {}
+void Dispatcher::Exit() noexcept {
+  running_ = false;
+}
 
-void Dispatcher::Run() noexcept {}
+void Dispatcher::Run() noexcept {
+  while (running_ && !events_.empty()) {
+    auto next_event = events_.begin();
+    std::this_thread::sleep_until(next_event->first);
+    if (next_event->second) {
+      next_event->second();
+    }
+    events_.erase(next_event);
+  }
+}
 }  // namespace async_timer
 }  // namespace event
 }  // namespace sdk

sdk/src/event/async_timer/dispatcher.h

@@ -26,7 +26,9 @@ class Dispatcher final : public event::Dispatcher
   void Run() noexcept override;
 
 private:
-  std::map<std::chrono::steady_clock::time_point, TimerCallback> events_;
+  friend class Timer;
+  bool running_{true};
+  std::multimap<std::chrono::steady_clock::time_point, TimerCallback> events_;
 };
 }  // namespace async_timer
 }  // namespace event

sdk/src/event/async_timer/timer.cc

@@ -7,14 +7,30 @@ namespace event
 {
 namespace async_timer
 {
-Timer::Timer(Dispatcher::EventIterator iterator) noexcept : iterator_{iterator} {}
+Timer::Timer(TimerCallback callback, Dispatcher &dispatcher) noexcept
+    : callback_{callback}, dispatcher_{dispatcher}, event_{dispatcher.events_.end()}
+{}
+
+Timer::~Timer()
+{
+  this->DisableTimer();
+}
 
 void Timer::EnableTimer(std::chrono::microseconds timeout) noexcept
 {
-  (void)timeout;
+  this->DisableTimer();
+  auto time_point = std::chrono::steady_clock::now() + timeout;
+  // Note: terminates on std::bad_alloc
+  event_ = dispatcher_.events_.emplace(time_point, callback_);
 }
 
-void Timer::DisableTimer() noexcept {}
+void Timer::DisableTimer() noexcept
+{
+  if (event_ != dispatcher_.events_.end())
+  {
+    dispatcher_.events_.erase(event_);
+  }
+}
 }  // namespace async_timer
 }  // namespace event
 }  // namespace sdk

sdk/src/event/async_timer/timer.h

@@ -11,15 +11,19 @@ namespace sdk
 namespace event
 {
 namespace async_timer {
-class Timer final : event::Timer {
+class Timer final : public event::Timer {
  public:
-  explicit Timer(Dispatcher::EventIterator iterator) noexcept;
+   Timer(TimerCallback callback, Dispatcher &dispatcher) noexcept;
 
-  void EnableTimer(std::chrono::microseconds timeout) noexcept override;
+   ~Timer();
 
-  void DisableTimer() noexcept override;
+   void EnableTimer(std::chrono::microseconds timeout) noexcept override;
+
+   void DisableTimer() noexcept override;
  private:
-  Dispatcher::EventIterator iterator_;
+  TimerCallback callback_;
+  Dispatcher& dispatcher_;
+  Dispatcher::EventIterator event_;
 };
 } // namespace async_timer
 }  // namespace event