Files
scylladb/query_result_merger.hh
Avi Kivity fcb8d040e8 treewide: use Software Package Data Exchange (SPDX) license identifiers
Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.

Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.

The changes we applied mechanically with a script, except to
licenses/README.md.

Closes #9937
2022-01-18 12:15:18 +01:00

46 lines
1.2 KiB
C++

/*
* Copyright (C) 2015-present ScyllaDB
*/
/*
* SPDX-License-Identifier: AGPL-3.0-or-later
*/
#pragma once
#include <seastar/core/distributed.hh>
#include "query-result.hh"
namespace query {
// Merges non-overlapping results into one
// Implements @Reducer concept from distributed.hh
class result_merger {
std::vector<foreign_ptr<lw_shared_ptr<query::result>>> _partial;
const uint64_t _max_rows;
const uint32_t _max_partitions;
public:
explicit result_merger(uint64_t max_rows, uint32_t max_partitions)
: _max_rows(max_rows)
, _max_partitions(max_partitions)
{ }
void reserve(size_t size) {
_partial.reserve(size);
}
void operator()(foreign_ptr<lw_shared_ptr<query::result>> r) {
if (!_partial.empty() && _partial.back()->is_short_read()) {
return;
}
_partial.emplace_back(std::move(r));
}
// FIXME: Eventually we should return a composite_query_result here
// which holds the vector of query results and which can be quickly turned
// into packet fragments by the transport layer without copying the data.
foreign_ptr<lw_shared_ptr<query::result>> get();
};
}