Cleanup of kevent usage

- reduce kevent64 to kevent usage: implies time management in
  dispatch_timers_program2 moves from absolute to relative and to msecs
  as that's what kevent can handle right now
- properly defined NOTE_xxxxx macros
- configure.ac change to define HAVE_KEVENT64

Squashed commit of the following:

commit dfe7b8b
Merge: e25ec26 6293e78
Author: Hubertus Franke <frankeh@us.ibm.com>
Date:   Wed Dec 9 15:38:11 2015 -0500

    Merge branch 'linux-port-hdd' of github.ibm.com:ibmswift/swift-corelibs-libdispatch into linux-port-hdd

commit e25ec26
Author: Hubertus Franke <frankeh@us.ibm.com>
Date:   Wed Dec 9 15:37:38 2015 -0500

    reduce the impact of kevent64

commit 6293e78
Author: David Grove <groved@us.ibm.com>
Date:   Wed Dec 9 17:59:59 2015 +0000

    kqueue check now also looks for kevent64 and sets config.h accordingly

commit 53a8aa6
Merge: b02031c cff30c4
Author: David Grove <groved@us.ibm.com>
Date:   Wed Dec 9 15:16:21 2015 +0000

    Merge branch 'linux-port-hdd' of github.ibm.com:ibmswift/swift-corelibs-libdispatch into linux-port-hdd

commit cff30c4
Author: Hubertus Franke <frankeh@us.ibm.com>
Date:   Wed Dec 9 06:59:09 2015 -0500

    check only one event is returned in kevent() call to allow type coercion

commit 884bd36
Author: Hubertus Franke <frankeh@us.ibm.com>
Date:   Tue Dec 8 22:58:41 2015 -0500

    kevent64 shim turns time negative in absolute to relative conversion. Checked for it

commit e48115b
Author: Hubertus Franke <frankeh@us.ibm.com>
Date:   Tue Dec 8 21:49:29 2015 -0500

    fix periodic timers through kevent rewrite and fix definition for linux

commit b02031c
Merge: 7f64b1c 14f0250
Author: David Grove <groved@us.ibm.com>
Date:   Sun Dec 6 19:21:44 2015 +0000

    Merge branch 'master' of github.com:apple/swift-corelibs-libdispatch into linux-port-hdd

commit 7f64b1c
Author: David Grove <groved@us.ibm.com>
Date:   Sat Dec 5 16:55:30 2015 +0000

    fix mistake made in merge

commit d2f10b3
Merge: fae40d1 394d9a1
Author: David Grove <groved@us.ibm.com>
Date:   Sat Dec 5 16:38:51 2015 +0000

    Merge branch 'master' into linux-port-hdd

commit fae40d1
Merge: a93074c acd56f6
Author: David Grove <groved@us.ibm.com>
Date:   Fri Dec 4 20:49:43 2015 +0000

    Merge branch 'master' into linux-port-hdd

commit a93074c
Author: David Grove <groved@us.ibm.com>
Date:   Fri Dec 4 20:44:13 2015 +0000

    cleanups

commit 10b9e94
Author: David Grove <groved@us.ibm.com>
Date:   Fri Dec 4 20:36:14 2015 +0000

    don't add os/base.h

commit bc04960
Author: David Grove <groved@us.ibm.com>
Date:   Fri Dec 4 20:27:25 2015 +0000

    WIP cleanup

commit b741481
Author: David Grove <groved@us.ibm.com>
Date:   Fri Dec 4 20:02:14 2015 +0000

    addressing commenrts from pull request

commit 6de4767
Author: David Grove <groved@us.ibm.com>
Date:   Fri Dec 4 18:08:40 2015 +0000

    use __APPLE__ instead of HAVE_MACH

commit f87caf9
Author: David Grove <groved@us.ibm.com>
Date:   Fri Dec 4 18:05:06 2015 +0000

    Copy BSD sys/queue.h to shims/sys_queue.h and remove HACK around SAFE macros

commit e3652d6
Author: David Grove <groved@us.ibm.com>
Date:   Fri Dec 4 16:26:21 2015 +0000

    Expand comments and reorganize;  remove mistaken redefine of DISPATCH_EXPORT macros

commit dd656be
Author: David Grove <groved@us.ibm.com>
Date:   Thu Dec 3 22:20:46 2015 +0000

    revert back to matching kevent64_s definition from OS X man page for kevent

commit 02616b0
Merge: 2453edc 650f82a
Author: Hubertus Franke <frankeh@us.ibm.com>
Date:   Thu Dec 3 17:04:24 2015 -0500

    merged conflicts

commit 2453edc
Author: Hubertus Franke <frankeh@us.ibm.com>
Date:   Thu Dec 3 17:00:27 2015 -0500

    fixed kevent, running till dispatch with bugs still in queue counts

commit 650f82a
Author: David Grove <groved@us.ibm.com>
Date:   Thu Dec 3 01:16:32 2015 +0000

    license headers on added files

commit 16d8a2c
Author: David Grove <groved@us.ibm.com>
Date:   Wed Dec 2 22:26:40 2015 +0000

    fix stubbed functions to have the right prototype and abort in their bodies when called

commit a6ede63
Author: David Grove <groved@us.ibm.com>
Date:   Wed Dec 2 17:07:16 2015 +0000

    update stubs and typedefs after merge of pull-request 2 from master

commit f38ebb9
Author: David Grove <groved@us.ibm.com>
Date:   Wed Dec 2 17:05:57 2015 +0000

    remove workaround; type now defined in proper header file

commit e0f0522
Merge: 8d8bb46 39ac720
Author: David Grove <groved@us.ibm.com>
Date:   Wed Dec 2 16:46:42 2015 +0000

    Merge branch 'master' into linux-port-hdd

commit 8d8bb46
Author: David Grove <groved@us.ibm.com>
Date:   Wed Dec 2 01:40:23 2015 +0000

    stub out missing functions and statics with dummy definitions

commit 9f4f103
Author: David Grove <groved@us.ibm.com>
Date:   Tue Dec 1 16:02:11 2015 +0000

    Update list of header files to be installed for dispatch and os.
    Move stubs.h to stubs_internal.h and include it from internal.h
    (so we don't need to install stubs to get a complete set of header files).

commit 9a39fef
Author: David Grove <groved@us.ibm.com>
Date:   Mon Nov 30 21:52:38 2015 +0000

    clang on linux just ignores -compatibility_version instead of failing
    with an unknown error message (despite the fact that ld won't actually
    understand the argument, so linking will actually fail in the end).

    This is a hack to generate workable makefiles; it may not be the right fix...

commit efa2a28
Author: David Grove <groved@us.ibm.com>
Date:   Mon Nov 30 21:51:59 2015 +0000

    ignore .la files

commit 35984ca
Author: David Grove <groved@us.ibm.com>
Date:   Mon Nov 30 21:34:28 2015 +0000

    WIP on getting code to compile

commit 2ab2c26
Author: David Grove <groved@us.ibm.com>
Date:   Mon Nov 30 21:04:26 2015 +0000

    slightly suspect changes to get semaphore.c to compile.
    The existing code was clearly wrong, but this might not be
    the right way to fix it either...

commit d7fe4b0
Author: David Grove <groved@us.ibm.com>
Date:   Mon Nov 30 20:48:04 2015 +0000

    tweaks to get it to compile

commit da3b73d
Author: David Grove <groved@us.ibm.com>
Date:   Mon Nov 30 19:06:27 2015 +0000

    WIP on stubbing out missing pieces to get code to compile

commit 4f9b58c
Author: David Grove <groved@us.ibm.com>
Date:   Mon Nov 30 18:06:33 2015 +0000

    synthesize declarations of missing observer types

commit fdeae8a
Author: David Grove <groved@us.ibm.com>
Date:   Mon Nov 30 18:05:58 2015 +0000

    guard include of mach.h with HAVE_MACH

commit f013a99
Author: David Grove <groved@us.ibm.com>
Date:   Mon Nov 30 18:05:02 2015 +0000

    ignore autotools and libtool generated files

commit f22bc4b
Author: David Grove <groved@us.ibm.com>
Date:   Mon Nov 30 18:02:50 2015 +0000

    header files to stub out types/functions for linux port

Author: dgrove-oss

configure.ac

@@ -137,9 +137,14 @@ AC_SEARCH_LIBS(pthread_create, pthread)
 # Prefer native kqueue(2); otherwise use libkqueue if present.
 #
 AC_CHECK_HEADER(sys/event.h, [],
-  [PKG_CHECK_MODULES(KQUEUE, libkqueue)]
+  [PKG_CHECK_MODULES(KQUEUE, libkqueue)
+   AC_SEARCH_LIBS(kevent, kqueue)
+   AC_SEARCH_LIBS(kevent64, kqueue,
+                 [AC_DEFINE(HAVE_KEVENT64, 1, [Define if kevent64 is present])],
+                 [AC_DEFINE(HAVE_KEVENT64, 0, [Define if kevent64 is present])])]
 )
 
+
 #
 # Checks for header files.
 #

os/linux_base.h

@@ -20,6 +20,7 @@
 #define __OS_LINUX_BASE__
 
 // #include <sys/event.h>
+#include <sys/user.h>
 
 // marker for hacks we have made to make progress
 #define __LINUX_PORT_HDD__ 1 
@@ -76,34 +77,41 @@ struct voucher_offsets_s {
 };
 
 
+// Print a warning when an unported code path executes.
+#define LINUX_PORT_ERROR()  do { printf("LINUX_PORT_ERROR_CALLED %s:%d: %s\n",__FILE__,__LINE__,__FUNCTION__); } while (0)
+
 /*
  * 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 */
-};
-
+#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
 
-// PAGE_SIZE and SIZE_T_MAX should not be hardcoded like this here.
-#define PAGE_SIZE (4096)
+// SIZE_T_MAX should not be hardcoded like this here.
 #define SIZE_T_MAX (0x7fffffff)
 
 // Define to 0 the NOTE_ values that are not present on Linux.
 // Revisit this...would it be better to ifdef out the uses instead??
-#define NOTE_VM_PRESSURE 0
-#define NOTE_ABSOLUTE 0
-#define NOTE_NSECONDS 0
-#define NOTE_LEEWAY 0
-#define NOTE_CRITICAL 0
-#define NOTE_BACKGROUND 0
+
+// 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
+#define NOTE_ABSOLUTE	0x08
+#define NOTE_CRITICAL	0x10
+#define NOTE_BACKGROUND	0x20
+#define NOTE_LEEWAY	0x40
+
+// need to catch the following usage if it happens .. 
+// we simply return '0' as a value probably not correct 
+
+#define NOTE_VM_PRESSURE ({LINUX_PORT_ERROR(); 0;})
 
 /*
  * Stub out misc linking and compilation attributes
@@ -135,8 +143,5 @@ struct kevent64_s {
 #define __OSX_AVAILABLE_BUT_DEPRECATED_MSG(a,b,c,d,msg) // 
 
 
-// Print a warning when an unported code path executes.
-#define LINUX_PORT_ERROR()  do { printf("LINUX_PORT_ERROR_CALLED %s:%d: %s\n",__FILE__,__LINE__,__FUNCTION__); } while (0)
-
 
 #endif /* __OS_LINUX_BASE__ */

src/shims/linux_stubs.c

@@ -84,11 +84,105 @@ int sysctlbyname(const char *name, void *oldp, size_t *oldlenp,
   LINUX_PORT_ERROR();
 }
 
-int kevent64(int kq, const struct kevent *changelist, int nchanges, struct kevent *eventlist, int nevents,unsigned int flags, const struct timespec *timeout)
+#if 0
+
+// this code remains here purely for debugging purposes
+// ultimately it can be deleted
+
+DISPATCH_NOINLINE
+static const char *
+_evfiltstr(short filt)
+{
+        switch (filt) {
+#define _evfilt2(f) case (f): return #f
+        _evfilt2(EVFILT_READ);
+        _evfilt2(EVFILT_WRITE);
+        _evfilt2(EVFILT_AIO);
+        _evfilt2(EVFILT_VNODE);
+        _evfilt2(EVFILT_PROC);
+        _evfilt2(EVFILT_SIGNAL);
+        _evfilt2(EVFILT_TIMER);
+#if HAVE_MACH
+        _evfilt2(EVFILT_MACHPORT);
+        _evfilt2(DISPATCH_EVFILT_MACH_NOTIFICATION);
+#endif
+        _evfilt2(EVFILT_FS);
+        _evfilt2(EVFILT_USER);
+#ifdef EVFILT_VM
+        _evfilt2(EVFILT_VM);
+#endif
+#ifdef EVFILT_SOCK
+        _evfilt2(EVFILT_SOCK);
+#endif
+#ifdef EVFILT_MEMORYSTATUS
+        _evfilt2(EVFILT_MEMORYSTATUS);
+#endif
+
+        _evfilt2(DISPATCH_EVFILT_TIMER);
+        _evfilt2(DISPATCH_EVFILT_CUSTOM_ADD);
+        _evfilt2(DISPATCH_EVFILT_CUSTOM_OR);
+        default:
+                return "EVFILT_missing";
+        }
+}
+
+#if 0
+#define dbg_kevent64(fmt...)               do { printf(fmt); } while(0)
+#define dbg_cond_kevent64(cond,fmt...)     do { if (cond) printf(fmt); } while(0)
+#else
+#define dbg_kevent64(fmt...)     	   do { } while(0)
+#define dbg_cond_kevent64(cond,fmt...)     do { } while(0)
+#endif
+
+
+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) 
 {
-     return kevent(kq,changelist,nchanges,eventlist,nevents,timeout);
+     // Documentation is not really clear. Instrument the code to make sure
+     // we can do type conversions right now between kevent64 <-> kevent, where as 
+     // kevent64 uses the ext[2] extension. So far we only see these used in the EVFILT_TIMER.
+     // right now we do this in the way into kevent, we also have to assert that 
+     // 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
+     if ((nchanges > 1) || (nevents > 1)) 
+ 	 LINUX_PORT_ERROR();
+     if (nchanges) { 
+	 dbg_kevent64("kevent64(%s,%x,%x): cl.ext[0,1]=%lx:%ld %lx:%ld cl.data=%lx:%ld\n", 
+	              _evfiltstr(changelist->filter), changelist->flags, changelist->fflags,
+		      changelist->ext[0], changelist->ext[0], 
+                      changelist->ext[1], changelist->ext[1],
+                      changelist->data, changelist->data);
+         if ((changelist->filter == EVFILT_TIMER) && (changelist->fflags & NOTE_ABSOLUTE)) {
+             // NOTE_ABSOLUTE is not recognized by the current kevent we need to convert this
+	     // into a relative. Consider fiddling with creating relative events instead (didn't work 
+	     // 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 -= 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
+         }
+     }
+#endif
+     // eventlist can not return more than 1 event type coersion doesn't work
+     int rc = kevent(kq,(struct kevent*) changelist,nchanges,(struct kevent*) eventlist,nevents,timeout);
+     if (rc > 1) 
+         LINUX_PORT_ERROR();
+     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;