From d36f9efe0d0fb028d6b2574b76956ce2ae22ea4f Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Sat, 11 Feb 2012 21:08:50 +0100
Subject: [PATCH] Timer: Use monotonic clock on Linux

---
 ucw/default.cfg                  |  3 +++
 ucw/libucw.pc                    |  8 +++++++-
 ucw/perl/UCW/Configure/LibUCW.pm |  5 +++++
 ucw/timer.c                      | 30 +++++++++++++++++++++++++++++-
 4 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/ucw/default.cfg b/ucw/default.cfg
index ff970e09..4d25df7d 100644
--- a/ucw/default.cfg
+++ b/ucw/default.cfg
@@ -59,6 +59,9 @@ Set("CONFIG_UCW_FB_DIRECT");
 # Use epoll (needs support in libc and kernel, default: auto-detect)
 # Set("CONFIG_UCW_EPOLL");
 
+# Use monotonic clock (default: yes on Linux, no elsewhere)
+# Set("CONFIG_UCW_MONOTONIC_CLOCK");
+
 # Which regular expression library should be used? If none is selected, we use BSD regex from libc.
 UnSet("CONFIG_UCW_POSIX_REGEX");
 UnSet("CONFIG_UCW_PCRE");
diff --git a/ucw/libucw.pc b/ucw/libucw.pc
index b84b783d..7d1c1542 100644
--- a/ucw/libucw.pc
+++ b/ucw/libucw.pc
@@ -15,6 +15,12 @@ regex=-lpcre
 regex=
 #endif
 
+#ifdef CONFIG_UCW_MONOTONIC_CLOCK
+rt=-lrt
+#else
+rt=
+#endif
+
 # Override if you want to use the -pic version
 picsuffix=
 
@@ -26,4 +32,4 @@ Name: libucw
 Description: A library of utility functions and data structures
 Version: @UCW_VERSION@
 Cflags: -I${incdir}
-Libs: -L${libdir} -lucw${picsuffix} ${threads} ${regex}
+Libs: -L${libdir} -lucw${picsuffix} ${threads} ${regex} ${rt}
diff --git a/ucw/perl/UCW/Configure/LibUCW.pm b/ucw/perl/UCW/Configure/LibUCW.pm
index 8349eb68..87157005 100644
--- a/ucw/perl/UCW/Configure/LibUCW.pm
+++ b/ucw/perl/UCW/Configure/LibUCW.pm
@@ -66,6 +66,11 @@ int main(void)
 FINIS
 });
 
+# Check if we want to use monotonic clock
+TestBool("CONFIG_UCW_MONOTONIC_CLOCK", "Checking for monotonic clock", sub {
+	return Get("CONFIG_LINUX");
+});
+
 # Darwin does not support BSD regexes, fix up
 if (IsSet("CONFIG_DARWIN")) {
 	if (!IsSet("CONFIG_UCW_POSIX_REGEX") && !IsSet("CONFIG_UCW_PCRE")) {
diff --git a/ucw/timer.c b/ucw/timer.c
index 31688dbe..f653ee56 100644
--- a/ucw/timer.c
+++ b/ucw/timer.c
@@ -1,7 +1,7 @@
 /*
  *	UCW Library -- A Simple Millisecond Timer
  *
- *	(c) 2007 Martin Mares <mj@ucw.cz>
+ *	(c) 2007--2012 Martin Mares <mj@ucw.cz>
  *
  *	This software may be freely distributed and used according to the terms
  *	of the GNU Lesser General Public License.
@@ -12,6 +12,20 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/time.h>
+#include <time.h>
+
+#ifdef CONFIG_UCW_MONOTONIC_CLOCK
+
+timestamp_t
+get_timestamp(void)
+{
+  struct timespec ts;
+  if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0)
+    die("clock_gettime failed: %m");
+  return (timestamp_t)ts.tv_sec * 1000 + ts.tv_nsec / 1000000;
+}
+
+#else
 
 timestamp_t
 get_timestamp(void)
@@ -25,6 +39,8 @@ get_timestamp(void)
 	;
 }
 
+#endif
+
 void
 init_timer(timestamp_t *timer)
 {
@@ -45,3 +61,15 @@ switch_timer(timestamp_t *oldt, timestamp_t *newt)
   *newt = get_timestamp();
   return MIN(*newt-*oldt, ~0U);
 }
+
+#ifdef TEST
+
+#include <stdio.h>
+
+int main(void)
+{
+  printf("%ju\n", (intmax_t) get_timestamp());
+  return 0;
+}
+
+#endif
-- 
2.39.2