Function aggregate_with_cancel 

pub fn aggregate_with_cancel(
    lmpg: &Lmpg,
    req: &AggregateRequest,
    is_cancelled: &dyn Fn() -> bool,
) -> Result<(Vec<GroupBucket>, u64), QueryError>

Aggregate execution with cooperative cancellation at root and bucket boundaries. Returns the completed buckets plus the total number of matched roots (the total reported by the data plane, matching a search result’s total).

Errors

Returns QueryError::Cancelled when the probe requests a stop, and QueryError::ResourceLimit when more than MAX_AGGREGATE_BUCKETS distinct groups would be created. Storage/engine and predicate errors are propagated from the underlying reads.

Panics

Panics only if a bucket just inserted by ensure_bucket cannot be retrieved, which is unreachable.