MT#40962 refactor wheeltimer::unix_clock

Change it into a wrapper that directly calls time() to eliminate the
need of the timer thread to continuously set unix_clock to the current
time. With vDSO the call to time() is sufficiently cheap.

Move constructor to header and remove default empty destructor.

Change-Id: Ib812a993da9340b9ded4fd97c81d762d9452c3ea

core/sip/wheeltimer.cpp

@@ -42,18 +42,6 @@ timer::~timer()
     // DBG("timer::~timer(this=%p)\n",this);
 }
 
-_wheeltimer::_wheeltimer()
-    : wall_clock(0)
-{
-    struct timeval now;
-    gettimeofday(&now,NULL);
-    unix_clock.set(now.tv_sec);
-}
-
-_wheeltimer::~_wheeltimer()
-{
-}
-
 void _wheeltimer::insert_timer(timer* t)
 {
     //add new timer to user request list
@@ -103,9 +91,6 @@ void _wheeltimer::run()
     //printf("missed one tick\n");
     //}
 
-    gettimeofday(&now,NULL);
-    unix_clock.set(now.tv_sec);
-
     turn_wheel();
     timeradd(&tick,&next_tick,&next_tick);
   }

core/sip/wheeltimer.h

@@ -32,6 +32,7 @@
 
 #include "../AmThread.h"
 #include <sys/types.h>
+#include <time.h>
 #include <deque>
 
 #include "atomic_types.h"
@@ -113,17 +114,19 @@ protected:
     void run();
     void on_stop(){}
 
-    _wheeltimer();
-    ~_wheeltimer();
+    _wheeltimer()
+	: wall_clock(0) {}
 
 public:
     //clock reference
     volatile u_int32_t wall_clock; // 32 bits
-#ifdef __LP64__
-    atomic_int64 unix_clock; // 64 bits
-#else
-    atomic_int unix_clock; // 32 bits
-#endif
+    struct _uc {
+	int64_t get()
+	{
+	    return time(NULL);
+	}
+    };
+    _uc unix_clock;
 
     void insert_timer(timer* t);
     void remove_timer(timer* t);