MT#62181 wheeltimer: add shutdown procedure

Add flag to stop the thread and then wait for it to actually stop.

Change-Id: Ibdcf68b7e574301dec3abcf1c2ac57182503214c

core/sip/wheeltimer.cpp

@@ -74,7 +74,7 @@ void _wheeltimer::remove_timer(timer* t)
 
 void _wheeltimer::run()
 {
-  while(true){
+  while(!stopped){
 
     // figure out whether there's anything to run, and for how long to sleep
 
@@ -112,6 +112,8 @@ void _wheeltimer::run()
     // all done, remove bucket
     buckets.erase(beg);
   }
+
+  shutdown_finished.set(true);
 }
 
 void _wheeltimer::process_current_timers(timer_list& list, std::unique_lock<std::mutex>& lock)

core/sip/wheeltimer.h

@@ -124,6 +124,9 @@ class _wheeltimer:
     // future (or if no timers exist). Needed not to miss the shutdown flag being set.
     const uint64_t max_sleep_time = 500000; // half a second
 
+    atomic_bool stopped;
+    AmCondition shutdown_finished;
+
     void place_timer(timer* t, uint64_t, uint64_t);
 
     void add_timer_to_bucket(timer* t, uint64_t);
@@ -135,15 +138,18 @@ class _wheeltimer:
 
 protected:
     void run();
-    void on_stop(){}
+    void on_stop(){
+	    stopped = true;
+	    shutdown_finished.wait_for();
+    }
 
     _wheeltimer()
-	: resolution(20000) // 20 ms == 20000 us
-    {}
+	: resolution(20000), // 20 ms == 20000 us
+	  stopped(false), shutdown_finished(false) {}
 
     _wheeltimer(uint64_t _resolution)
-	: resolution(_resolution)
-    {}
+	: resolution(_resolution),
+	  stopped(false), shutdown_finished(false) {}
 
 public:
     //clock reference