fcb8d040e8
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
80 lines
3.0 KiB
C++
80 lines
3.0 KiB
C++
/*
|
|
* Copyright (C) 2019-present ScyllaDB
|
|
*/
|
|
|
|
/*
|
|
* SPDX-License-Identifier: AGPL-3.0-or-later
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include "bytes.hh"
|
|
|
|
class schema;
|
|
class partition_key;
|
|
class clustering_row;
|
|
|
|
class column_computation;
|
|
using column_computation_ptr = std::unique_ptr<column_computation>;
|
|
|
|
/*
|
|
* Column computation represents a computation performed in order to obtain a value for a computed column.
|
|
* Computed columns description is also available at docs/system_schema_keyspace.md. They hold values
|
|
* not provided directly by the user, but rather computed: from other column values and possibly other sources.
|
|
* This class is able to serialize/deserialize column computations and perform the computation itself,
|
|
* based on given schema, partition key and clustering row. Responsibility for providing enough data
|
|
* in the clustering row in order for computation to succeed belongs to the caller. In particular,
|
|
* generating a value might involve performing a read-before-write if the computation is performed
|
|
* on more values than are present in the update request.
|
|
*/
|
|
class column_computation {
|
|
public:
|
|
virtual ~column_computation() = default;
|
|
|
|
static column_computation_ptr deserialize(bytes_view raw);
|
|
|
|
virtual column_computation_ptr clone() const = 0;
|
|
|
|
virtual bytes serialize() const = 0;
|
|
virtual bytes_opt compute_value(const schema& schema, const partition_key& key, const clustering_row& row) const = 0;
|
|
};
|
|
|
|
/*
|
|
* Computes token value of partition key and returns it as bytes.
|
|
*
|
|
* Should NOT be used (use token_column_computation), because ordering
|
|
* of bytes is different than ordering of tokens (signed vs unsigned comparison).
|
|
*
|
|
* The type name stored for computations of this class is "token" - this was
|
|
* the original implementation. (now depracated for new tables)
|
|
*/
|
|
class legacy_token_column_computation : public column_computation {
|
|
public:
|
|
virtual column_computation_ptr clone() const override {
|
|
return std::make_unique<legacy_token_column_computation>(*this);
|
|
}
|
|
virtual bytes serialize() const override;
|
|
virtual bytes_opt compute_value(const schema& schema, const partition_key& key, const clustering_row& row) const override;
|
|
};
|
|
|
|
|
|
/*
|
|
* Computes token value of partition key and returns it as long_type.
|
|
* The return type means that it can be trivially sorted (for example
|
|
* if computed column using this computation is a clustering key),
|
|
* preserving the correct order of tokens (using signed comparisons).
|
|
*
|
|
* Please use this class instead of legacy_token_column_computation.
|
|
*
|
|
* The type name stored for computations of this class is "token_v2".
|
|
* (the name "token" refers to the depracated legacy_token_column_computation)
|
|
*/
|
|
class token_column_computation : public column_computation {
|
|
public:
|
|
virtual column_computation_ptr clone() const override {
|
|
return std::make_unique<token_column_computation>(*this);
|
|
}
|
|
virtual bytes serialize() const override;
|
|
virtual bytes_opt compute_value(const schema& schema, const partition_key& key, const clustering_row& row) const override;
|
|
};
|