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scylladb/cql3/result_set.hh
2018-07-26 12:37:20 +01:00

274 lines
8.2 KiB
C++

/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Copyright (C) 2015 ScyllaDB
*
* Modified by ScyllaDB
*/
/*
* This file is part of Scylla.
*
* Scylla is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Scylla is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <deque>
#include <vector>
#include "enum_set.hh"
#include "service/pager/paging_state.hh"
#include "schema.hh"
#include "query-result-reader.hh"
#include "result_generator.hh"
#include <seastar/util/gcc6-concepts.hh>
namespace cql3 {
class metadata {
public:
enum class flag : uint8_t {
GLOBAL_TABLES_SPEC = 0,
HAS_MORE_PAGES = 1,
NO_METADATA = 2,
};
using flag_enum = super_enum<flag,
flag::GLOBAL_TABLES_SPEC,
flag::HAS_MORE_PAGES,
flag::NO_METADATA>;
using flag_enum_set = enum_set<flag_enum>;
struct column_info {
// Please note that columnCount can actually be smaller than names, even if names is not null. This is
// used to include columns in the resultSet that we need to do post-query re-orderings
// (SelectStatement.orderResults) but that shouldn't be sent to the user as they haven't been requested
// (CASSANDRA-4911). So the serialization code will exclude any columns in name whose index is >= columnCount.
std::vector<::shared_ptr<column_specification>> _names;
uint32_t _column_count;
column_info(std::vector<::shared_ptr<column_specification>> names, uint32_t column_count)
: _names(std::move(names))
, _column_count(column_count)
{ }
explicit column_info(std::vector<::shared_ptr<column_specification>> names)
: _names(std::move(names))
, _column_count(_names.size())
{ }
};
private:
flag_enum_set _flags;
private:
lw_shared_ptr<column_info> _column_info;
::shared_ptr<const service::pager::paging_state> _paging_state;
public:
metadata(std::vector<::shared_ptr<column_specification>> names_);
metadata(flag_enum_set flags, std::vector<::shared_ptr<column_specification>> names_, uint32_t column_count,
::shared_ptr<const service::pager::paging_state> paging_state);
// The maximum number of values that the ResultSet can hold. This can be bigger than columnCount due to CASSANDRA-4911
uint32_t value_count() const;
void add_non_serialized_column(::shared_ptr<column_specification> name);
private:
bool all_in_same_cf() const;
public:
void set_has_more_pages(::shared_ptr<const service::pager::paging_state> paging_state);
void set_skip_metadata();
flag_enum_set flags() const;
uint32_t column_count() const { return _column_info->_column_count; }
::shared_ptr<const service::pager::paging_state> paging_state() const;
const std::vector<::shared_ptr<column_specification>>& get_names() const {
return _column_info->_names;
}
};
::shared_ptr<const cql3::metadata> make_empty_metadata();
class prepared_metadata {
public:
enum class flag : uint8_t {
GLOBAL_TABLES_SPEC = 0,
};
using flag_enum = super_enum<flag,
flag::GLOBAL_TABLES_SPEC>;
using flag_enum_set = enum_set<flag_enum>;
private:
flag_enum_set _flags;
std::vector<::shared_ptr<column_specification>> _names;
std::vector<uint16_t> _partition_key_bind_indices;
public:
prepared_metadata(const std::vector<::shared_ptr<column_specification>>& names,
const std::vector<uint16_t>& partition_key_bind_indices);
flag_enum_set flags() const;
const std::vector<::shared_ptr<column_specification>>& names() const;
const std::vector<uint16_t>& partition_key_bind_indices() const;
};
GCC6_CONCEPT(
template<typename Visitor>
concept bool ResultVisitor = requires(Visitor& visitor) {
visitor.start_row();
visitor.accept_value(std::optional<query::result_bytes_view>());
visitor.end_row();
};
)
class result_set {
::shared_ptr<metadata> _metadata;
std::deque<std::vector<bytes_opt>> _rows;
friend class result;
public:
result_set(std::vector<::shared_ptr<column_specification>> metadata_);
result_set(::shared_ptr<metadata> metadata);
size_t size() const;
bool empty() const;
void add_row(std::vector<bytes_opt> row);
void add_column_value(bytes_opt value);
void reverse();
void trim(size_t limit);
template<typename RowComparator>
void sort(const RowComparator& cmp) {
std::sort(_rows.begin(), _rows.end(), std::ref(cmp));
}
metadata& get_metadata();
const metadata& get_metadata() const;
// Returns a range of rows. A row is a range of bytes_opt.
const std::deque<std::vector<bytes_opt>>& rows() const;
template<typename Visitor>
GCC6_CONCEPT(requires ResultVisitor<Visitor>)
void visit(Visitor&& visitor) const {
auto column_count = get_metadata().column_count();
for (auto& row : _rows) {
visitor.start_row();
for (auto i = 0u; i < column_count; i++) {
auto& cell = row[i];
visitor.accept_value(cell ? std::optional<query::result_bytes_view>(*cell) : std::optional<query::result_bytes_view>());
}
visitor.end_row();
}
}
class builder;
};
class result_set::builder {
result_set _result;
std::vector<bytes_opt> _current_row;
public:
explicit builder(shared_ptr<metadata> mtd)
: _result(std::move(mtd)) { }
void start_row() { }
void accept_value(std::optional<query::result_bytes_view> value) {
if (!value) {
_current_row.emplace_back();
return;
}
_current_row.emplace_back(value->linearize());
}
void end_row() {
_result.add_row(std::exchange(_current_row, { }));
}
result_set get_result_set() && { return std::move(_result); }
};
class result {
std::unique_ptr<cql3::result_set> _result_set;
result_generator _result_generator;
shared_ptr<const cql3::metadata> _metadata;
public:
explicit result(std::unique_ptr<cql3::result_set> rs)
: _result_set(std::move(rs))
, _metadata(_result_set->_metadata)
{ }
explicit result(result_generator generator, shared_ptr<const metadata> m)
: _result_generator(std::move(generator))
, _metadata(std::move(m))
{ }
const cql3::metadata& get_metadata() const { return *_metadata; }
cql3::result_set result_set() const {
if (_result_set) {
return *_result_set;
} else {
auto builder = result_set::builder(make_shared<cql3::metadata>(*_metadata));
_result_generator.visit(builder);
return std::move(builder).get_result_set();
}
}
template<typename Visitor>
GCC6_CONCEPT(requires ResultVisitor<Visitor>)
void visit(Visitor&& visitor) const {
if (_result_set) {
_result_set->visit(std::forward<Visitor>(visitor));
} else {
_result_generator.visit(std::forward<Visitor>(visitor));
}
}
};
}