var-nan commented on code in PR #3262:
URL: https://github.com/apache/kvrocks/pull/3262#discussion_r2590522097
##########
src/types/redis_timeseries.cc:
##########
@@ -97,7 +101,96 @@ std::vector<TSSample>
AggregateSamplesByRangeOption(std::vector<TSSample> sample
}
return 0;
};
+ // Linear interpolation.
+ auto interpolate_sample = [](const TSSample &left_nb, uint64_t ts, const
TSSample &right_nb) {
+ auto y_diff = right_nb.v - left_nb.v;
+ auto x_diff = static_cast<double>(right_nb.ts - left_nb.ts);
+ auto x_diff_prime = static_cast<double>(ts - left_nb.ts);
+ auto y_diff_prime = (x_diff_prime * y_diff) / x_diff;
+ TSSample sample;
+ sample.ts = ts;
+ sample.v = y_diff_prime + left_nb.v;
+ return sample;
+ };
+ // Computes the TWA of empty bucket from its neighbor samples.
+ auto empty_bucket_twa = [&interpolate_sample](const TSSample &left_nb,
uint64_t bucket_left, uint64_t bucket_right,
+ const TSSample &right_nb) {
+ auto left = interpolate_sample(left_nb, bucket_left, right_nb);
+ auto right = interpolate_sample(left_nb, bucket_right, right_nb);
+ return Reducer::Area(std::array<TSSample, 2>{left, right}) /
static_cast<double>(bucket_right - bucket_left);
+ };
+
+ // Retrieve prev_sample and next_sample from samples when TWA aggregation.
+ TSSample prev_sample, next_sample;
+ bool is_twa_aggregator = aggregator.type == TSAggregatorType::TWA,
prev_available = false, next_available = false;
+ if (is_twa_aggregator) {
+ const bool discard_boundaries = !option.filter_by_ts.empty() ||
option.filter_by_value.has_value();
+ next_sample = samples.back();
+ samples.pop_back();
+ prev_sample = samples.back();
+ samples.pop_back();
+ // When FILTER_BY_TS/FILTER_BY_VALUE is enabled, discard out-of-boundary
samples.
+ prev_available = discard_boundaries ? false : !samples.empty() &&
(samples.front().ts != prev_sample.ts);
+ next_available = discard_boundaries ? false : !samples.empty() &&
(samples.back().ts != next_sample.ts);
+ }
Review Comment:
Hi @yezhizi the `prev_sample` and `next_sample` are properly initialized as
neighbors to the filtered range, as long as the entire dataset is not empty. In
other cases, those two are initialized with MAX_TIMESTAMP.
I declared the struct as
```
struct TWABounds{
TSSample prev_sample;
TSSample next_sample;
}
```
Is there any other need for them to be declared as `optional`
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