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scylladb/cql3/values.hh
Avi Kivity f3eade2f62 treewide: relicense to ScyllaDB-Source-Available-1.0
Drop the AGPL license in favor of a source-available license.
See the blog post [1] for details.

[1] https://www.scylladb.com/2024/12/18/why-were-moving-to-a-source-available-license/
2024-12-18 17:45:13 +02:00

305 lines
10 KiB
C++

/*
* Copyright (C) 2017-present ScyllaDB
*/
/*
* SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
*/
#pragma once
#include "types/types.hh"
#include "types/collection.hh"
#include "bytes.hh"
#include <optional>
#include <variant>
#include <fmt/core.h>
#include <seastar/util/variant_utils.hh>
#include "utils/fragmented_temporary_buffer.hh"
#include "utils/overloaded_functor.hh"
namespace cql3 {
struct null_value {
friend bool operator==(const null_value&, const null_value) { return true; }
};
class raw_value;
/// \brief View to a raw CQL protocol value.
///
/// \see raw_value
class raw_value_view {
std::variant<fragmented_temporary_buffer::view, managed_bytes_view, null_value> _data;
// Temporary storage is only useful if a raw_value_view needs to be instantiated
// with a value which lifetime is bounded only to the view itself.
// This hack is introduced in order to avoid storing temporary storage
// in an external container, which may cause memory leaking problems.
// This pointer is disengaged for regular raw_value_view instances.
// Data is stored in a shared pointer for two reasons:
// - pointers are cheap to copy
// - it makes the view keep its semantics - it's safe to copy a view multiple times
// and all copies still refer to the same underlying data.
lw_shared_ptr<managed_bytes> _temporary_storage = nullptr;
raw_value_view(null_value data)
: _data{std::move(data)}
{}
raw_value_view(fragmented_temporary_buffer::view data)
: _data{data}
{}
raw_value_view(managed_bytes_view data)
: _data{data}
{}
// This constructor is only used by make_temporary() and it acquires ownership
// of the given buffer. The view created that way refers to its own temporary storage.
explicit raw_value_view(managed_bytes&& temporary_storage);
public:
static raw_value_view make_null() {
return raw_value_view{null_value{}};
}
static raw_value_view make_value(fragmented_temporary_buffer::view view) {
return raw_value_view{view};
}
static raw_value_view make_value(managed_bytes_view view) {
return raw_value_view{view};
}
static raw_value_view make_value(bytes_view view) {
return raw_value_view{managed_bytes_view(view)};
}
static raw_value_view make_temporary(raw_value&& value);
bool is_null() const {
return std::holds_alternative<null_value>(_data);
}
// An empty value is not null, but it has 0 bytes of data.
// An empty int value can be created in CQL using blobasint(0x).
bool is_empty_value() const {
if (is_null()) {
return false;
}
return size_bytes() == 0;
}
bool is_value() const {
return _data.index() <= 1;
}
explicit operator bool() const {
return is_value();
}
template <typename Func>
requires std::invocable<Func, const managed_bytes_view&> && std::invocable<Func, const fragmented_temporary_buffer::view&>
decltype(auto) with_value(Func f) const {
switch (_data.index()) {
case 0: return f(std::get<fragmented_temporary_buffer::view>(_data));
default: return f(std::get<managed_bytes_view>(_data));
}
}
template <typename Func>
requires std::invocable<Func, bytes_view>
decltype(auto) with_linearized(Func f) const {
return with_value([&] (const FragmentedView auto& v) {
return ::with_linearized(v, std::forward<Func>(f));
});
}
size_t size_bytes() const {
return with_value([&] (const FragmentedView auto& v) {
return v.size_bytes();
});
}
template <typename ValueType>
ValueType deserialize(const abstract_type& t) const {
return value_cast<ValueType>(with_value([&] (const FragmentedView auto& v) { return t.deserialize(v); }));
}
template <typename ValueType>
ValueType deserialize(const collection_type_impl& t) const {
return value_cast<ValueType>(with_value([&] (const FragmentedView auto& v) { return t.deserialize(v); }));
}
void validate(const abstract_type& t) const {
return with_value([&] (const FragmentedView auto& v) { return t.validate(v); });
}
template <typename ValueType>
ValueType validate_and_deserialize(const collection_type_impl& t) const {
return with_value([&] (const FragmentedView auto& v) {
t.validate(v);
return value_cast<ValueType>(t.deserialize(v));
});
}
template <typename ValueType>
ValueType validate_and_deserialize(const abstract_type& t) const {
return with_value([&] (const FragmentedView auto& v) {
t.validate(v);
return value_cast<ValueType>(t.deserialize(v));
});
}
friend managed_bytes_opt to_managed_bytes_opt(const cql3::raw_value_view& view) {
if (view.is_value()) {
return view.with_value([] (const FragmentedView auto& v) { return managed_bytes(v); });
}
return managed_bytes_opt();
}
friend managed_bytes_opt to_managed_bytes_opt(cql3::raw_value_view&& view) {
if (view._temporary_storage) {
return std::move(*view._temporary_storage);
}
return to_managed_bytes_opt(view);
}
friend fmt::formatter<raw_value_view>;
friend class raw_value;
};
/// \brief Raw CQL protocol value.
///
/// The `raw_value` type represents an uninterpreted value from the CQL wire
/// protocol. A raw value can hold either a null value, or a byte
/// blob that represents the value.
class raw_value {
std::variant<bytes, managed_bytes, null_value> _data;
raw_value(null_value&& data)
: _data{std::move(data)}
{}
raw_value(bytes&& data)
: _data{std::move(data)}
{}
raw_value(const bytes& data)
: _data{data}
{}
raw_value(managed_bytes&& data)
: _data{std::move(data)}
{}
raw_value(const managed_bytes& data)
: _data{data}
{}
public:
static raw_value make_null() {
return raw_value{null_value{}};
}
static raw_value make_value(const raw_value_view& view);
static raw_value make_value(managed_bytes&& mb) {
return raw_value{std::move(mb)};
}
static raw_value make_value(managed_bytes_opt&& mbo) {
return mbo ? make_value(std::move(*mbo)) : make_null();
}
static raw_value make_value(const managed_bytes& mb) {
return raw_value{mb};
}
static raw_value make_value(const managed_bytes_opt& mbo) {
if (mbo) {
return make_value(*mbo);
}
return make_null();
}
static raw_value make_value(bytes&& bytes) {
return raw_value{std::move(bytes)};
}
static raw_value make_value(const bytes& bytes) {
return raw_value{bytes};
}
static raw_value make_value(const bytes_opt& bytes) {
if (bytes) {
return make_value(*bytes);
}
return make_null();
}
bool is_null() const {
return std::holds_alternative<null_value>(_data);
}
// An empty value is not null, but it has 0 bytes of data.
// An empty int value can be created in CQL using blobasint(0x).
bool is_empty_value() const {
if (is_null()) {
return false;
}
return view().size_bytes() == 0;
}
bool is_value() const {
return _data.index() <= 1;
}
explicit operator bool() const {
return is_value();
}
bytes to_bytes() && {
return std::visit(overloaded_functor{
[](bytes&& bytes_val) { return std::move(bytes_val); },
[](managed_bytes&& managed_bytes_val) { return ::to_bytes(managed_bytes_val); },
[](null_value&&) -> bytes {
throw std::runtime_error("to_bytes() called on raw value that is null");
},
}, std::move(_data));
}
bytes_opt to_bytes_opt() && {
return std::visit(overloaded_functor{
[](bytes&& bytes_val) { return bytes_opt(bytes_val); },
[](managed_bytes&& managed_bytes_val) { return bytes_opt(::to_bytes(managed_bytes_val)); },
[](null_value&&) -> bytes_opt {
return std::nullopt;
},
}, std::move(_data));
}
managed_bytes to_managed_bytes() && {
return std::visit(overloaded_functor{
[](bytes&& bytes_val) { return managed_bytes(bytes_val); },
[](managed_bytes&& managed_bytes_val) { return std::move(managed_bytes_val); },
[](null_value&&) -> managed_bytes {
throw std::runtime_error("to_managed_bytes() called on raw value that is null");
},
}, std::move(_data));
}
managed_bytes_opt to_managed_bytes_opt() && {
return std::visit(overloaded_functor{
[](bytes&& bytes_val) { return managed_bytes_opt(bytes_val); },
[](managed_bytes&& managed_bytes_val) { return managed_bytes_opt(std::move(managed_bytes_val)); },
[](null_value&&) -> managed_bytes_opt {
return std::nullopt;
},
}, std::move(_data));
}
raw_value_view view() const;
friend class raw_value_view;
friend bool operator==(const raw_value& v1, const raw_value& v2);
};
}
inline bytes to_bytes(const cql3::raw_value_view& view)
{
return view.with_value([] (const FragmentedView auto& v) {
return linearized(v);
});
}
inline bytes_opt to_bytes_opt(const cql3::raw_value_view& view) {
if (view.is_value()) {
return to_bytes(view);
}
return bytes_opt();
}
inline bytes_opt to_bytes_opt(const cql3::raw_value& value) {
return to_bytes_opt(value.view());
}
template <> struct fmt::formatter<cql3::raw_value_view> : fmt::formatter<string_view> {
auto format(const cql3::raw_value_view& value, fmt::format_context& ctx) const -> decltype(ctx.out());
};
template <> struct fmt::formatter<cql3::raw_value> : fmt::formatter<string_view> {
auto format(const cql3::raw_value& value, fmt::format_context& ctx) const {
return fmt::format_to(ctx.out(), "{}", value.view());
}
};