From 024ad276aadd08e5be967a50a31cde9ee8626efa Mon Sep 17 00:00:00 2001
From: root <root>
Date: Fri, 6 Feb 2009 20:17:43 +0000
Subject: *** empty log message ***

---
 Changes |  8 +++++++-
 ev.c    | 45 ++++++++++++++++++++++++++++++++-------------
 ev.pod  | 12 +++++++-----
 3 files changed, 46 insertions(+), 19 deletions(-)

diff --git a/Changes b/Changes
index 08eec5a..e6c0ed1 100644
--- a/Changes
+++ b/Changes
@@ -1,5 +1,11 @@
 Revision history for libev, a high-performance and full-featured event loop.
 
+	- probe for CLOCK_REALTIME support at runtime as well and fall
+          back to gettimeofday if there is an error, to support older
+          operating systems with newer header files/libraries.
+        - prefer gettimeofday over clock_gettime with USE_CLOCK_SYSCALL
+          (default most everywhere), otherwise not.
+
 3.52 Wed Jan  7 21:43:02 CET 2009
 	- fix compilation of select backend in fd_set mode when NFDBITS is
           missing (to get it to compile on QNX, reported by Rodrigo Campos).
@@ -13,7 +19,7 @@ Revision history for libev, a high-performance and full-featured event loop.
           attacks harder (but not impossible - it's windows). Make sure
           it even works under vista, which thinks that getpeer/sockname
           should return fantasy port numbers.
-        - include "libev" all assertion messages for potentially
+        - include "libev" in all assertion messages for potentially
           clearer diagnostics.
         - event_get_version (libevent compatibility) returned
           a useless string instead of the expected version string
diff --git a/ev.c b/ev.c
index 0d8ca4e..7b8a92c 100644
--- a/ev.c
+++ b/ev.c
@@ -66,7 +66,7 @@ extern "C" {
 #   define EV_USE_MONOTONIC 1
 #  endif
 #  ifndef EV_USE_REALTIME
-#   define EV_USE_REALTIME  1
+#   define EV_USE_REALTIME  0
 #  endif
 # else
 #  ifndef EV_USE_MONOTONIC
@@ -195,7 +195,7 @@ extern "C" {
 #endif
 
 #ifndef EV_USE_REALTIME
-# define EV_USE_REALTIME 0
+# define EV_USE_REALTIME !EV_USE_CLOCK_SYSCALL
 #endif
 
 #ifndef EV_USE_NANOSLEEP
@@ -399,9 +399,13 @@ typedef ev_watcher_time *WT;
 #define ev_active(w) ((W)(w))->active
 #define ev_at(w) ((WT)(w))->at
 
-#if EV_USE_MONOTONIC
+#if EV_USE_REALTIME
 /* sig_atomic_t is used to avoid per-thread variables or locking but still */
 /* giving it a reasonably high chance of working on typical architetcures */
+static EV_ATOMIC_T have_realtime; /* did clock_gettime (CLOCK_REALTIME) work? */
+#endif
+
+#if EV_USE_MONOTONIC
 static EV_ATOMIC_T have_monotonic; /* did clock_gettime (CLOCK_MONOTONIC) work? */
 #endif
 
@@ -555,14 +559,17 @@ ev_tstamp
 ev_time (void)
 {
 #if EV_USE_REALTIME
-  struct timespec ts;
-  clock_gettime (CLOCK_REALTIME, &ts);
-  return ts.tv_sec + ts.tv_nsec * 1e-9;
-#else
+  if (expect_true (have_realtime))
+    {
+      struct timespec ts;
+      clock_gettime (CLOCK_REALTIME, &ts);
+      return ts.tv_sec + ts.tv_nsec * 1e-9;
+    }
+#endif
+
   struct timeval tv;
   gettimeofday (&tv, 0);
   return tv.tv_sec + tv.tv_usec * 1e-6;
-#endif
 }
 
 ev_tstamp inline_size
@@ -1321,12 +1328,24 @@ loop_init (EV_P_ unsigned int flags)
 {
   if (!backend)
     {
+#if EV_USE_REALTIME
+      if (!have_realtime)
+        {
+          struct timespec ts;
+
+          if (!clock_gettime (CLOCK_REALTIME, &ts))
+            have_realtime = 1;
+        }
+#endif
+
 #if EV_USE_MONOTONIC
-      {
-        struct timespec ts;
-        if (!clock_gettime (CLOCK_MONOTONIC, &ts))
-          have_monotonic = 1;
-      }
+      if (!have_monotonic)
+        {
+          struct timespec ts;
+
+          if (!clock_gettime (CLOCK_MONOTONIC, &ts))
+            have_monotonic = 1;
+        }
 #endif
 
       ev_rt_now         = ev_time ();
diff --git a/ev.pod b/ev.pod
index f9de137..15b1965 100644
--- a/ev.pod
+++ b/ev.pod
@@ -3231,11 +3231,13 @@ function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>.
 =item EV_USE_REALTIME
 
 If defined to be C<1>, libev will try to detect the availability of the
-real-time clock option at compile time (and assume its availability at
-runtime if successful). Otherwise no use of the real-time clock option will
-be attempted. This effectively replaces C<gettimeofday> by C<clock_get
-(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
-note about libraries in the description of C<EV_USE_MONOTONIC>, though.
+real-time clock option at compile time (and assume its availability
+at runtime if successful). Otherwise no use of the real-time clock
+option will be attempted. This effectively replaces C<gettimeofday>
+by C<clock_get (CLOCK_REALTIME, ...)> and will not normally affect
+correctness. See the note about libraries in the description of
+C<EV_USE_MONOTONIC>, though. Defaults to the opposite value of
+C<EV_USE_CLOCK_SYSCALL>.
 
 =item EV_USE_CLOCK_SYSCALL
 
-- 
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