Function partition_batch

nodedb/src/control/trigger/batch/partition.rs:41–70

Partition a batch of rows by a key extracted from each row. `key_fn` maps each row to a partition key (e.g., the branch a row takes in an IF/ELSE trigger body). Rows with the same key go to the same partition. If the number of unique keys exceeds `max_partitions`, returns `CircuitBroken` and the caller should fall back to row-at-a-time.

(
    rows: &[TriggerBatchRow],
    max_partitions: usize,
    key_fn: F,
)

/// If the number of unique keys exceeds `max_partitions`, returns
/// `CircuitBroken` and the caller should fall back to row-at-a-time.
pub fn partition_batch<F>(
    rows: &[TriggerBatchRow],
    max_partitions: usize,
    key_fn: F,
) -> PartitionResult
where
    F: Fn(&TriggerBatchRow) -> String,
{
    let mut partitions: std::collections::HashMap<String, Vec<usize>> =
        std::collections::HashMap::new();

    for (idx, row) in rows.iter().enumerate() {
        let key = key_fn(row);
        partitions.entry(key).or_default().push(idx);

        // Early exit if we exceed the limit.
        if partitions.len() > max_partitions {
            return PartitionResult::CircuitBroken {
                partition_count: partitions.len(),
            };
        }
    }

    let result = partitions
        .into_iter()
        .map(|(key, row_indices)| BatchPartition { key, row_indices })
        .collect();

    PartitionResult::Partitions(result)
}

/// Partition rows by a field value from NEW fields.
///