Do the monotonic clock ourselves1.4.7-rc11.4.7

I've still removed the "set the time now" stuff that the flush_all commands
do. They push to one second in the past, and with some startup fudge the tests
all pass.

Relying on libevent's firing of clock_handler was drifting ~5ms per tick.
Fudging it further wouldn't be a great idea.

2 files changed, 26 insertions, 2 deletions

diff --git a/configure.ac b/configure.ac
index 066d06c..1e3893e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -418,6 +418,7 @@ AC_CHECK_FUNCS(mlockall)
 AC_CHECK_FUNCS(getpagesizes)
 AC_CHECK_FUNCS(memcntl)
 AC_CHECK_FUNCS(sigignore)
+AC_CHECK_FUNCS(clock_gettime)
 
 AC_DEFUN([AC_C_ALIGNMENT],
 [AC_CACHE_CHECK(for alignment, ac_cv_c_alignment,
diff --git a/memcached.c b/memcached.c
index 21ee227..f52c32d 100644
--- a/memcached.c
+++ b/memcached.c
@@ -4106,6 +4106,10 @@ static struct event clockevent;
 static void clock_handler(const int fd, const short which, void *arg) {
     struct timeval t = {.tv_sec = 1, .tv_usec = 0};
     static bool initialized = false;
+#if defined(HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
+    static bool monotonic = false;
+    static time_t monotonic_start;
+#endif
 
     if (initialized) {
         /* only delete the event if it's actually there. */
@@ -4114,14 +4118,33 @@ static void clock_handler(const int fd, const short which, void *arg) {
         initialized = true;
         /* process_started is initialized to time() - 2. We initialize to 1 so
          * flush_all won't underflow during tests. */
-        current_time = 1;
+#if defined(HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
+        struct timespec ts;
+        if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0) {
+            monotonic = true;
+            monotonic_start = ts.tv_sec - 2;
+        }
+#endif
     }
 
     evtimer_set(&clockevent, clock_handler, 0);
     event_base_set(main_base, &clockevent);
     evtimer_add(&clockevent, &t);
 
-    current_time++;
+#if defined(HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
+    if (monotonic) {
+        struct timespec ts;
+        if (clock_gettime(CLOCK_MONOTONIC, &ts) == -1)
+            return;
+        current_time = (rel_time_t) (ts.tv_sec - monotonic_start);
+        return;
+    }
+#endif
+    {
+        struct timeval tv;
+        gettimeofday(&tv, NULL);
+        current_time = (rel_time_t) (tv.tv_sec - process_started);
+    }
 }
 
 static void usage(void) {