diff options
Diffstat (limited to 'database/rrdset.c')
| -rw-r--r-- | database/rrdset.c | 38 |
1 files changed, 26 insertions, 12 deletions
diff --git a/database/rrdset.c b/database/rrdset.c index e96d707b..0f529703 100644 --- a/database/rrdset.c +++ b/database/rrdset.c @@ -1447,9 +1447,11 @@ void rrdset_done(RRDSET *st) { continue; } - // if the new is smaller than the old (an overflow, or reset), set the old equal to the new - // to reset the calculation (it will give zero as the calculation for this second) - if(unlikely(rd->last_collected_value > rd->collected_value)) { + // If the new is smaller than the old (an overflow, or reset), set the old equal to the new + // to reset the calculation (it will give zero as the calculation for this second). + // It is imperative to set the comparison to uint64_t since type collected_number is signed and + // produces wrong results as far as incremental counters are concerned. + if(unlikely((uint64_t)rd->last_collected_value > (uint64_t)rd->collected_value)) { debug(D_RRD_STATS, "%s.%s: RESET or OVERFLOW. Last collected value = " COLLECTED_NUMBER_FORMAT ", current = " COLLECTED_NUMBER_FORMAT , st->name, rd->name , rd->last_collected_value @@ -1463,17 +1465,29 @@ void rrdset_done(RRDSET *st) { uint64_t max = (uint64_t)rd->collected_value_max; uint64_t cap = 0; - if(max > 0x00000000FFFFFFFFULL) cap = 0xFFFFFFFFFFFFFFFFULL; - else if(max > 0x000000000000FFFFULL) cap = 0x00000000FFFFFFFFULL; - else if(max > 0x00000000000000FFULL) cap = 0x000000000000FFFFULL; - else cap = 0x00000000000000FFULL; + // Signed values are handled by exploiting two's complement which will produce positive deltas + if (max > 0x00000000FFFFFFFFULL) + cap = 0xFFFFFFFFFFFFFFFFULL; // handles signed and unsigned 64-bit counters + else + cap = 0x00000000FFFFFFFFULL; // handles signed and unsigned 32-bit counters uint64_t delta = cap - last + new; - - rd->calculated_value += - (calculated_number) delta - * (calculated_number) rd->multiplier - / (calculated_number) rd->divisor; + uint64_t max_acceptable_rate = (cap / 100) * MAX_INCREMENTAL_PERCENT_RATE; + + // If the delta is less than the maximum acceptable rate and the previous value was near the cap + // then this is an overflow. There can be false positives such that a reset is detected as an + // overflow. + // TODO: remember recent history of rates and compare with current rate to reduce this chance. + if (delta < max_acceptable_rate) { + rd->calculated_value += + (calculated_number) delta + * (calculated_number) rd->multiplier + / (calculated_number) rd->divisor; + } else { + // This is a reset. Any overflow with a rate greater than MAX_INCREMENTAL_PERCENT_RATE will also + // be detected as a reset instead. + rd->calculated_value += (calculated_number)0; + } } else { rd->calculated_value += |