improve timing issue detections

the original "Time jumped" messages are too coarse to interpret
exactly what was going wrong inside of CTDB.

This patch removes the original logs and adds two other logs that
differentiate between the time it took to work on an event and
the time it took to get the next event.

(This used to be ctdb commit fd8d54292f10b35bc4960d64cfa6843ce9aba225)

6 files changed, 61 insertions, 15 deletions

diff --git a/ctdb/lib/tevent/tevent.c b/ctdb/lib/tevent/tevent.c
index 2f6e591baa..88ae01c40a 100644
--- a/ctdb/lib/tevent/tevent.c
+++ b/ctdb/lib/tevent/tevent.c
@@ -590,8 +590,6 @@ extern pid_t ctdbd_pid;
 int tevent_common_loop_wait(struct tevent_context *ev,
 			    const char *location)
 {
-	static time_t t=0;
-	time_t new_t;
 
 	/*
 	 * loop as long as we have events pending
@@ -608,19 +606,6 @@ int tevent_common_loop_wait(struct tevent_context *ev,
 				     ret, strerror(errno));
 			return ret;
 		}
-		if (getpid() == ctdbd_pid) {
-			new_t=time(NULL);
-			if (t != 0) {
-				if (t > new_t) {
-					tevent_debug(ev, TEVENT_DEBUG_FATAL, __location__ " ERROR Time skipped backward by %d seconds\n", (int)(t-new_t));
-				}
-				/* We assume here that we get at least one event every 3 seconds */
-				if (new_t > (t+3)) {
-					tevent_debug(ev, TEVENT_DEBUG_FATAL, __location__ " ERROR Time jumped forward by %d seconds\n", (int)(new_t-t));
-				}
-			}
-			t=new_t;
-		}
 	}
 
 	tevent_debug(ev, TEVENT_DEBUG_WARNING,
diff --git a/ctdb/lib/tevent/tevent_epoll.c b/ctdb/lib/tevent/tevent_epoll.c
index 3abb0e63e5..e443f9fa6c 100644
--- a/ctdb/lib/tevent/tevent_epoll.c
+++ b/ctdb/lib/tevent/tevent_epoll.c
@@ -250,7 +250,9 @@ static int epoll_event_loop(struct epoll_event_context *epoll_ev, struct timeval
 		return 0;
 	}
 
+	tevent_before_wait(epoll_ev->ev);
 	ret = epoll_wait(epoll_ev->epoll_fd, events, MAXEVENTS, timeout);
+	tevent_after_wait(epoll_ev->ev);
 
 	if (ret == -1 && errno == EINTR && epoll_ev->ev->signal_events) {
 		if (tevent_common_check_signal(epoll_ev->ev)) {
diff --git a/ctdb/lib/tevent/tevent_select.c b/ctdb/lib/tevent/tevent_select.c
index 128a7d6b5d..f25ce05a25 100644
--- a/ctdb/lib/tevent/tevent_select.c
+++ b/ctdb/lib/tevent/tevent_select.c
@@ -157,7 +157,9 @@ static int select_event_loop_select(struct select_event_context *select_ev, stru
 		return 0;
 	}
 
+	tevent_before_wait(select_ev->ev);
 	selrtn = select(select_ev->maxfd+1, &r_fds, &w_fds, NULL, tvalp);
+	tevent_after_wait(select_ev->ev);
 
 	if (selrtn == -1 && errno == EINTR &&
 	    select_ev->ev->signal_events) {
diff --git a/ctdb/lib/tevent/tevent_standard.c b/ctdb/lib/tevent/tevent_standard.c
index 3f2d6d5b28..abebbd8d38 100644
--- a/ctdb/lib/tevent/tevent_standard.c
+++ b/ctdb/lib/tevent/tevent_standard.c
@@ -261,7 +261,9 @@ static int epoll_event_loop(struct std_event_context *std_ev, struct timeval *tv
 		return 0;
 	}
 
+	tevent_before_wait(std_ev->ev);
 	ret = epoll_wait(std_ev->epoll_fd, events, MAXEVENTS, timeout);
+	tevent_after_wait(std_ev->ev);
 
 	if (ret == -1 && errno == EINTR && std_ev->ev->signal_events) {
 		if (tevent_common_check_signal(std_ev->ev)) {
diff --git a/ctdb/lib/tevent/tevent_util.c b/ctdb/lib/tevent/tevent_util.c
index f78cd8f707..28c9da346a 100644
--- a/ctdb/lib/tevent/tevent_util.c
+++ b/ctdb/lib/tevent/tevent_util.c
@@ -88,3 +88,54 @@ int ev_set_blocking(int fd, bool set)
 	return fcntl( fd, F_SETFL, val);
 #undef FLAG_TO_SET
 }
+
+static struct timeval tevent_before_wait_ts;
+static struct timeval tevent_after_wait_ts;
+
+/*
+ * measure the time difference between multiple arrivals
+ * to the point where we wait for new events to come in
+ *
+ * allows to measure how long it takes to work on a 
+ * event
+ */
+void tevent_before_wait(struct event_context *ev) {
+
+	struct timeval diff;
+	struct timeval now = tevent_timeval_current();
+
+	if (!tevent_timeval_is_zero(&tevent_after_wait_ts)) {
+		diff = tevent_timeval_until(&tevent_after_wait_ts, &now);
+		if (diff.tv_sec > 3) {
+			tevent_debug(ev, TEVENT_DEBUG_FATAL,  __location__ 
+				     " Handling event took %d seconds!",
+				     (int) diff.tv_sec);
+		}
+	}
+
+	tevent_before_wait_ts = tevent_timeval_current();
+
+}
+
+/*
+ * measure how long the select()/epoll() call took
+ *
+ * allows to measure how long we are waiting for new events
+ */
+void tevent_after_wait(struct event_context *ev) {
+
+	struct timeval diff;
+	struct timeval now = tevent_timeval_current();
+
+	if (!tevent_timeval_is_zero(&tevent_before_wait_ts)) {
+		diff = tevent_timeval_until(&tevent_before_wait_ts, &now);
+		if (diff.tv_sec > 3) {
+			tevent_debug(ev, TEVENT_DEBUG_FATAL,  __location__
+				     " No event for %d seconds!",
+				     (int) diff.tv_sec);
+		}
+	}
+
+	tevent_after_wait_ts = tevent_timeval_current();
+
+}
diff --git a/ctdb/lib/tevent/tevent_util.h b/ctdb/lib/tevent/tevent_util.h
index 46a4506dac..2852e9f26a 100644
--- a/ctdb/lib/tevent/tevent_util.h
+++ b/ctdb/lib/tevent/tevent_util.h
@@ -184,6 +184,10 @@ const char **ev_str_list_add(const char **list, const char *s);
 int ev_set_blocking(int fd, bool set);
 size_t ev_str_list_length(const char **list);
 
+void tevent_before_wait(struct event_context *ev);
+void tevent_after_wait(struct event_context *ev);
+
+
 /* Defined here so we can build against older talloc versions that don't
  * have this define yet. */
 #ifndef TALLOC_FREE