reduce the impact of kevent64

Author: frankeh

os/linux_base.h

@@ -84,19 +84,11 @@ struct voucher_offsets_s {
  * Stub out defines for other missing types
  */
 
-// Pulled from OS X man page for kevent
-struct kevent64_s {
-    uint64_t        ident;          /* identifier for this event */
-    int16_t         filter;         /* filter for event */
-    uint16_t        flags;          /* general flags */
-    uint32_t        fflags;         /* filter-specific flags */
-    int64_t         data;           /* filter-specific data */
-    uint64_t        udata;          /* opaque user data identifier */
-    uint64_t        ext[2];         /* filter-specific extensions */
-};
-
-int kevent64(int kq, /*const*/ struct kevent64_s *changelist, int nchanges, struct kevent64_s *eventlist,
-	     int nevents, unsigned int flags, const struct timespec *timeout);
+#if !HAVE_KEVENT64
+// we fall back to use kevent
+#define kevent64_s kevent
+#define kevent64(kq,cl,nc,el,ne,f,to)  kevent(kq,cl,nc,el,ne,to)
+#endif
 
 // SIZE_T_MAX should not be hardcoded like this here.
 #define SIZE_T_MAX (0x7fffffff)
@@ -106,6 +98,8 @@ int kevent64(int kq, /*const*/ struct kevent64_s *changelist, int nchanges, stru
 
 // The following values are passed as part of the EVFILT_TIMER requests
 
+#define IGNORE_KEVENT64_EXT   /* will force the kevent64_s.ext[] to not be used -> leeway ignored */
+
 #define NOTE_SECONDS	0x01
 #define NOTE_USECONDS 	0x02
 #define NOTE_NSECONDS	0x04

src/shims/linux_stubs.c

@@ -84,6 +84,10 @@ int sysctlbyname(const char *name, void *oldp, size_t *oldlenp,
   LINUX_PORT_ERROR();
 }
 
+#if 0
+
+// this code remains here purely for debugging purposes
+// ultimately it can be deleted
 
 DISPATCH_NOINLINE
 static const char *
@@ -130,9 +134,8 @@ _evfiltstr(short filt)
 #define dbg_cond_kevent64(cond,fmt...)     do { } while(0)
 #endif
 
-#include <time.h>
 
-int kevent64(int kq, /*const*/ struct kevent64_s *changelist, int nchanges, struct kevent64_s *eventlist,
+int kevent64(int kq, const struct kevent64_s *changelist_c, int nchanges, struct kevent64_s *eventlist,
              int nevents, unsigned int flags, const struct timespec *timeout) 
 {
      // Documentation is not really clear. Instrument the code to make sure
@@ -142,6 +145,8 @@ int kevent64(int kq, /*const*/ struct kevent64_s *changelist, int nchanges, stru
      // no more than 1 change or one event is passed until we get a better handle of the
      // usage pattern of this.  (Hubertus Franke)
 
+     struct kevent64_s *changelist = (struct kevent64_s*) changelist_c; // so we can modify it
+
 #if 1 
      // lets put some checks in here to make sure we do it all correct
      // we can only convert kevent64_s -> kevent for a single entry since kevent64_s has ext[0:1] extension
@@ -159,13 +164,13 @@ int kevent64(int kq, /*const*/ struct kevent64_s *changelist, int nchanges, stru
 	     // on first attempt). We also ignore the LEEWAY. Finally we must convert from 
              // NSECS to MSECS (might have to expand to deal with OTHER NOTE_xSECS flags
 
-             changelist->data -= _dispatch_get_nanoseconds();
+             //changelist->data -= _dispatch_get_nanoseconds();
              //changelist->data -= time(NULL) * NSEC_PER_SEC;
              dbg_kevent64("kevent64(%s,%x) data=%lx:%ld\n",
                           _evfiltstr(changelist->filter),changelist->fflags,
 			  changelist->data,changelist->data);
-	     changelist->data /= 1000000UL;
-	     if ((int64_t)(changelist->data) <= 0) changelist->data = 1; // for some reason time turns negative
+	     //changelist->data /= 1000000UL;
+	     //if ((int64_t)(changelist->data) <= 0) changelist->data = 1; // for some reason time turns negative
          }
      }
 #endif
@@ -176,6 +181,8 @@ int kevent64(int kq, /*const*/ struct kevent64_s *changelist, int nchanges, stru
      return rc;
 }
 
+#endif
+
 /*
  * Stubbed out static data
  */

src/source.c

@@ -1858,13 +1858,22 @@ _dispatch_timers_get_delay(uint64_t nows[], struct dispatch_timer_s timer[],
 	return ridx;
 }
 
+
+#if HAVE_KEVENT64
+#	define kevent_set_ext1(ke,val)  (ke)->ext[1] = (val)
+#	define delay_add_wall(delay,at)  (delay) += (at)
+#else
+#	define kevent_set_ext1(ke,val)  do { } while (0)
+#	define delay_add_wall(delay,at) do { } while (0) 
+#endif
+
 static bool
 _dispatch_timers_program2(uint64_t nows[], _dispatch_kevent_qos_s *ke,
 		unsigned int qos)
 {
 	unsigned int tidx;
 	bool poll;
-	uint64_t delay, leeway;
+	uint64_t delay, leeway, nowtime;
 
 	tidx = _dispatch_timers_get_delay(nows, _dispatch_timer, &delay, &leeway,
 			(int)qos);
@@ -1881,13 +1890,21 @@ _dispatch_timers_program2(uint64_t nows[], _dispatch_kevent_qos_s *ke,
 		_dispatch_trace_next_timer_set(
 				TAILQ_FIRST(&_dispatch_kevent_timer[tidx].dk_sources), qos);
 		_dispatch_trace_next_timer_program(delay, qos);
-		delay += _dispatch_source_timer_now(nows, DISPATCH_TIMER_KIND_WALL);
+	        nowtime =_dispatch_source_timer_now(nows, DISPATCH_TIMER_KIND_WALL);
+	        delay_add_wall(delay,nowtime);
+
+	        //printf("%s: delay %ld nsecs\n",__FUNCTION__,delay);
+		// convert delay into msecs
+		delay /= 1000000L;
+                if ((int64_t)(delay) <= 0) delay = 1; // for some reason time turns negative
+                //if ((int64_t)(delay) <= 0) printf("%s: delay =%d\n",__FUNCTION__,(int64_t)delay);
+
 		if (slowpath(_dispatch_timers_force_max_leeway)) {
 			ke->data = (int64_t)(delay + leeway);
-			ke->ext[1] = 0;
+	                kevent_set_ext1(ke,0);
 		} else {
 			ke->data = (int64_t)delay;
-			ke->ext[1] = leeway;
+	                kevent_set_ext1(ke,leeway);
 		}
 		ke->flags |= EV_ADD|EV_ENABLE;
 		ke->flags &= ~EV_DELETE;