Files
scylladb/cql3/selection/aggregate_function_selector.hh
Avi Kivity 3e0aacc8b5 db, cql3: functions: pass function parameters as a span instead of a vector
Spans are more flexible and can be constructed from any contiguous
container (such as small_vector), or a subrange of such a container.
This can save allocations, so change the signature to accept a span.

Spans cannot be constructed from std::initializer_list, so one such
call site is changed to use construct a span directly from the single
argument.
2023-04-19 20:38:55 +03:00

61 lines
1.8 KiB
C++

/*
* Modified by ScyllaDB
* Copyright (C) 2015-present ScyllaDB
*/
/*
* SPDX-License-Identifier: (AGPL-3.0-or-later and Apache-2.0)
*/
#include "abstract_function_selector.hh"
#include "cql3/functions/aggregate_function.hh"
#pragma once
namespace cql3 {
namespace selection {
class aggregate_function_selector : public abstract_function_selector_for<functions::aggregate_function> {
const db::functions::stateless_aggregate_function& _aggregate;
bytes_opt _accumulator;
public:
virtual bool is_aggregate() const override {
return true;
}
virtual void add_input(result_set_builder& rs) override {
// Aggregation of aggregation is not supported
size_t m = _arg_selectors.size();
_args[0] = std::move(_accumulator);
for (size_t i = 0; i < m; ++i) {
auto&& s = _arg_selectors[i];
s->add_input(rs);
_args[i + 1] = s->get_output();
s->reset();
}
_accumulator = _aggregate.aggregation_function->execute(_args);
}
virtual bytes_opt get_output() override {
return _aggregate.state_to_result_function
? _aggregate.state_to_result_function->execute(std::span(&_accumulator, 1))
: std::move(_accumulator);
}
virtual void reset() override {
_accumulator = _aggregate.initial_state;
}
aggregate_function_selector(shared_ptr<functions::function> func,
std::vector<shared_ptr<selector>> arg_selectors)
: abstract_function_selector_for<functions::aggregate_function>(
dynamic_pointer_cast<functions::aggregate_function>(func), std::move(arg_selectors), true)
, _aggregate(fun()->get_aggregate())
, _accumulator(_aggregate.initial_state) {
}
};
}
}