convert backends to heartbeat API

As heartbeats are based on a monotonic clock that is different
on each system, the previously used random delay to avoid all
netdata servers sending their data simultaneously is not needed
anymore.

Also compute backend latency using monotonic clock.

Signed-off-by: Rémi Lefèvre <remi.lefevre@parrot.com>

diff --git a/src/backends.c b/src/backends.c
index 1272d0473d585d01c38ab77de132025170884dbc..9b91b7f0a5ddac65bfc9b226977820045e0253d8 100644 (file)
--- a/src/backends.c
+++ b/src/backends.c
@@ -292,30 +292,19 @@ void *backends_main(void *ptr) {
     info("BACKEND configured ('%s' on '%s' sending '%s' data, every %d seconds, as host '%s', with prefix '%s')", type, destination, source, frequency, hostname, prefix);
 
     usec_t step_ut = frequency * USEC_PER_SEC;
-    usec_t random_ut = now_realtime_usec() % (step_ut / 2);
-    time_t before = (time_t)((now_realtime_usec() - step_ut) / USEC_PER_SEC);
-    time_t after = before;
+    time_t after = now_realtime_sec();
     int failures = 0;
+    heartbeat_t hb;
+    heartbeat_init(&hb);
 
     for(;;) {
         // ------------------------------------------------------------------------
-        // wait for the next iteration point
-
-        usec_t now_ut = now_realtime_usec();
-        usec_t next_ut = now_ut - (now_ut % step_ut) + step_ut;
-        before = (time_t)(next_ut / USEC_PER_SEC);
-
-        // add a little delay (1/4 of the step) plus some randomness
-        next_ut += (step_ut / 4) + random_ut;
-
-        while(now_ut < next_ut) {
-            sleep_usec(next_ut - now_ut);
-            now_ut = now_realtime_usec();
-        }
+        // Wait for the next iteration point.
+        heartbeat_next(&hb, step_ut);
+        time_t before = now_realtime_sec();
 
         // ------------------------------------------------------------------------
         // add to the buffer the data we need to send to the backend
-
         RRDSET *st;
         int pthreadoldcancelstate;
 
@@ -399,7 +388,7 @@ void *backends_main(void *ptr) {
         // if we are not connected, connect to a backend server
 
         if(unlikely(sock == -1)) {
-            usec_t start_ut = now_realtime_usec();
+            usec_t start_ut = now_monotonic_usec();
             const char *s = destination;
             while(*s) {
                 const char *e = s;
@@ -420,7 +409,7 @@ void *backends_main(void *ptr) {
                 if(sock != -1) break;
                 s = e;
             }
-            chart_backend_latency += now_realtime_usec() - start_ut;
+            chart_backend_latency += now_monotonic_usec() - start_ut;
         }
 
         if(unlikely(netdata_exit)) break;
@@ -430,14 +419,14 @@ void *backends_main(void *ptr) {
 
         if(likely(sock != -1)) {
             size_t len = buffer_strlen(b);
-            usec_t start_ut = now_realtime_usec();
+            usec_t start_ut = now_monotonic_usec();
             int flags = 0;
 #ifdef MSG_NOSIGNAL
             flags += MSG_NOSIGNAL;
 #endif
 
             ssize_t written = send(sock, buffer_tostring(b), len, flags);
-            chart_backend_latency += now_realtime_usec() - start_ut;
+            chart_backend_latency += now_monotonic_usec() - start_ut;
             if(written != -1 && (size_t)written == len) {
                 // we sent the data successfully
                 chart_transmission_successes++;