55 lines
2.1 KiB
C++
55 lines
2.1 KiB
C++
/*
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* Copyright (C) 2012-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*/
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#pragma once
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#include "schema/schema_fwd.hh"
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#include "dht/ring_position.hh"
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#include "readers/flat_mutation_reader_fwd.hh"
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class reader_permit;
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class reader_selector {
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protected:
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schema_ptr _s;
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dht::ring_position_view _selector_position;
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public:
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reader_selector(schema_ptr s, dht::ring_position_view rpv) noexcept : _s(std::move(s)), _selector_position(std::move(rpv)) {}
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virtual ~reader_selector() = default;
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// Call only if has_new_readers() returned true.
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virtual std::vector<flat_mutation_reader_v2> create_new_readers(const std::optional<dht::ring_position_view>& pos) = 0;
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virtual std::vector<flat_mutation_reader_v2> fast_forward_to(const dht::partition_range& pr) = 0;
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// Can be false-positive but never false-negative!
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bool has_new_readers(const std::optional<dht::ring_position_view>& pos) const noexcept {
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dht::ring_position_comparator cmp(*_s);
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return !_selector_position.is_max() && (!pos || cmp(*pos, _selector_position) >= 0);
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}
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};
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// Creates a mutation reader which combines data return by supplied readers.
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// Returns mutation of the same schema only when all readers return mutations
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// of the same schema.
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flat_mutation_reader_v2 make_combined_reader(schema_ptr schema,
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reader_permit permit,
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std::vector<flat_mutation_reader_v2>,
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streamed_mutation::forwarding fwd_sm = streamed_mutation::forwarding::no,
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mutation_reader::forwarding fwd_mr = mutation_reader::forwarding::yes);
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flat_mutation_reader_v2 make_combined_reader(schema_ptr schema,
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reader_permit permit,
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std::unique_ptr<reader_selector>,
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streamed_mutation::forwarding,
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mutation_reader::forwarding);
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flat_mutation_reader_v2 make_combined_reader(schema_ptr schema,
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reader_permit permit,
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flat_mutation_reader_v2&& a,
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flat_mutation_reader_v2&& b,
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streamed_mutation::forwarding fwd_sm = streamed_mutation::forwarding::no,
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mutation_reader::forwarding fwd_mr = mutation_reader::forwarding::yes);
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