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scylladb/collection_mutation.hh

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/*
* Copyright (C) 2019 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 "utils/chunked_vector.hh"
#include "schema_fwd.hh"
#include "gc_clock.hh"
#include "atomic_cell.hh"
class abstract_type;
class compaction_garbage_collector;
class row_tombstone;
class collection_mutation;
// An auxiliary struct used to (de)construct collection_mutations.
// Unlike collection_mutation which is a serialized blob, this struct allows to inspect logical units of information
// (tombstone and cells) inside the mutation easily.
struct collection_mutation_description {
tombstone tomb;
utils::chunked_vector<std::pair<bytes, atomic_cell>> cells;
// Expires cells based on query_time. Expires tombstones based on max_purgeable and gc_before.
// Removes cells covered by tomb or this->tomb.
bool compact_and_expire(column_id id, row_tombstone tomb, gc_clock::time_point query_time,
can_gc_fn&, gc_clock::time_point gc_before, compaction_garbage_collector* collector = nullptr);
// Packs the data to a serialized blob.
collection_mutation serialize(const abstract_type&) const;
};
// Similar to collection_mutation_description, except that it doesn't store the cells' data, only observes it.
struct collection_mutation_view_description {
tombstone tomb;
utils::chunked_vector<std::pair<bytes_view, atomic_cell_view>> cells;
// Copies the observed data, storing it in a collection_mutation_description.
collection_mutation_description materialize(const abstract_type&) const;
// Packs the data to a serialized blob.
collection_mutation serialize(const abstract_type&) const;
};
// Given a linearized collection_mutation_view, returns an auxiliary struct allowing the inspection of each cell.
// The struct is an observer of the data given by the collection_mutation_view and doesn't extend its lifetime.
// The function needs to be given the type of stored data to reconstruct the structural information.
collection_mutation_view_description deserialize_collection_mutation(const abstract_type&, bytes_view);
class collection_mutation_view {
public:
atomic_cell_value_view data;
// Is this a noop mutation?
bool is_empty() const;
// Given a function that operates on a collection_mutation_view_description,
// calls it on the corresponding description of `this`.
template <typename F>
inline decltype(auto) with_deserialized(const abstract_type& type, F f) const {
return data.with_linearized([&] (bytes_view bv) {
return f(deserialize_collection_mutation(type, std::move(bv)));
});
}
};
// A serialized mutation of a collection of cells.
// Used to represent mutations of collections (lists, maps, sets) or non-frozen user defined types.
// It contains a sequence of cells, each representing a mutation of a single entry (element or field) of the collection.
// Each cell has an associated 'key' (or 'path'). The meaning of each (key, cell) pair is:
// for sets: the key is the serialized set element, the cell contains no data (except liveness information),
// for maps: the key is the serialized map element's key, the cell contains the serialized map element's value,
// for lists: the key is a timeuuid identifying the list entry, the cell contains the serialized value,
// for user types: the key is an index identifying the field, the cell contains the value of the field.
// The mutation may also contain a collection-wide tombstone.
class collection_mutation {
public:
using imr_object_type = imr::utils::object<data::cell::structure>;
imr_object_type _data;
collection_mutation() {}
collection_mutation(const abstract_type&, collection_mutation_view);
collection_mutation(const abstract_type&, bytes_view);
operator collection_mutation_view() const;
};