prevent interpolation on absolute values that are collected on time

diff --git a/src/rrd.c b/src/rrd.c
index 9604337df33d06ccde7760bf656b08a694f29a30..ac96ea6d8125fe8cc067508a061cfd90b557dfcc 100755 (executable)
--- a/src/rrd.c
+++ b/src/rrd.c
@@ -1048,7 +1048,7 @@ unsigned long long rrdset_done(RRDSET *st)
        int iterations = (now_ut - last_ut) / (st->update_every * 1000000ULL);
 
        for( ; likely(next_ut <= now_ut) ; next_ut += st->update_every * 1000000ULL, iterations-- ) {
-               if(iterations < 0) error("iterations calculation wrapped!");
+               if(iterations <= 0) error("iterations calculation wrapped!");
 
                if(unlikely(st->debug)) {
                        debug(D_RRD_STATS, "%s: last ut = %0.3Lf (last updated time)", st->name, (long double)last_ut/1000000.0);
@@ -1090,28 +1090,43 @@ unsigned long long rrdset_done(RRDSET *st)
                                case RRDDIM_PCENT_OVER_ROW_TOTAL:
                                case RRDDIM_PCENT_OVER_DIFF_TOTAL:
                                default:
-                                       new_value = (calculated_number)
-                                               (       (         (rd->calculated_value - rd->last_calculated_value)
-                                                               * (calculated_number)(next_ut - first_ut)
-                                                               / (calculated_number)(now_ut - first_ut)
-                                                       )
-                                                       +  rd->last_calculated_value
-                                               );
+                                       if(iterations == 1) {
+                                               // this is the last iteration
+                                               // do not interpolate
+                                               // just show the calculated value
 
-                                       if(unlikely(st->debug))
-                                               debug(D_RRD_STATS, "%s/%s: CALC2 DEF "
-                                                       CALCULATED_NUMBER_FORMAT " = ((("
-                                                       "(" CALCULATED_NUMBER_FORMAT " - " CALCULATED_NUMBER_FORMAT ")"
-                                                       " * %llu"
-                                                       " / %llu) + " CALCULATED_NUMBER_FORMAT
-                                                       , st->id, rd->name
-                                                       , new_value
-                                                       , rd->calculated_value, rd->last_calculated_value
-                                                       , (next_ut - first_ut)
-                                                       , (now_ut - first_ut), rd->last_calculated_value
+                                               new_value = rd->calculated_value;
+                                       }
+                                       else {
+                                               // we have missed an update
+                                               // interpolate in the middle values
+
+                                               new_value = (calculated_number)
+                                                       (       (         (rd->calculated_value - rd->last_calculated_value)
+                                                                       * (calculated_number)(next_ut - first_ut)
+                                                                       / (calculated_number)(now_ut - first_ut)
+                                                               )
+                                                               +  rd->last_calculated_value
                                                        );
 
-                                       if(likely(next_ut + st->update_every * 1000000ULL > now_ut)) rd->calculated_value = new_value;
+                                               if(unlikely(st->debug))
+                                                       debug(D_RRD_STATS, "%s/%s: CALC2 DEF "
+                                                               CALCULATED_NUMBER_FORMAT " = ((("
+                                                               "(" CALCULATED_NUMBER_FORMAT " - " CALCULATED_NUMBER_FORMAT ")"
+                                                               " * %llu"
+                                                               " / %llu) + " CALCULATED_NUMBER_FORMAT
+                                                               , st->id, rd->name
+                                                               , new_value
+                                                               , rd->calculated_value, rd->last_calculated_value
+                                                               , (next_ut - first_ut)
+                                                               , (now_ut - first_ut), rd->last_calculated_value
+                                                               );
+
+                                               // this is wrong
+                                               // it fades the value towards the target
+                                               // while we know the calculated value is different
+                                               // if(likely(next_ut + st->update_every * 1000000ULL > now_ut)) rd->calculated_value = new_value;
+                                       }
                                        break;
                        }