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69a385fd9d
Schema related files are moved there. This excludes schema files that also interact with mutations, because the mutation module depends on the schema. Those files will have to go into a separate module. Closes #12858
84 lines
2.8 KiB
C++
84 lines
2.8 KiB
C++
/*
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* Copyright (C) 2022-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 "dht/i_partitioner.hh"
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#include "readers/flat_mutation_reader_fwd.hh"
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#include "schema/schema_fwd.hh"
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#include "seastarx.hh"
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namespace seastar {
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class io_priority_class;
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}
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class reader_permit;
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class mutation_source;
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namespace tracing {
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class trace_state_ptr;
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}
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/// Make an auto-paused evictable reader.
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///
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/// The reader is paused after each use, that is after each call to any of its
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/// members that cause actual reading to be done (`fill_buffer()` and
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/// `fast_forward_to()`). When paused, the reader is made evictable, that it is
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/// it is registered with reader concurrency semaphore as an inactive read.
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/// The reader is resumed automatically on the next use. If it was evicted, it
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/// will be recreated at the position it left off reading. This is all
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/// transparent to its user.
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/// Parameters passed by reference have to be kept alive while the reader is
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/// alive.
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flat_mutation_reader_v2 make_auto_paused_evictable_reader_v2(
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mutation_source ms,
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schema_ptr schema,
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reader_permit permit,
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const dht::partition_range& pr,
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const query::partition_slice& ps,
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const io_priority_class& pc,
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tracing::trace_state_ptr trace_state,
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mutation_reader::forwarding fwd_mr);
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class evictable_reader_v2;
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class evictable_reader_handle_v2 {
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friend std::pair<flat_mutation_reader_v2, evictable_reader_handle_v2> make_manually_paused_evictable_reader_v2(mutation_source, schema_ptr, reader_permit,
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const dht::partition_range&, const query::partition_slice&, const io_priority_class&, tracing::trace_state_ptr, mutation_reader::forwarding);
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private:
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evictable_reader_v2* _r;
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private:
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explicit evictable_reader_handle_v2(evictable_reader_v2& r);
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public:
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void pause();
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};
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/// Make a manually-paused evictable reader.
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///
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/// The reader can be paused via the evictable reader handle when desired. The
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/// intended usage is subsequent reads done in bursts, after which the reader is
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/// not used for some time. When paused, the reader is made evictable, that is,
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/// it is registered with reader concurrency semaphore as an inactive read.
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/// The reader is resumed automatically on the next use. If it was evicted, it
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/// will be recreated at the position it left off reading. This is all
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/// transparent to its user.
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/// Parameters passed by reference have to be kept alive while the reader is
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/// alive.
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std::pair<flat_mutation_reader_v2, evictable_reader_handle_v2> make_manually_paused_evictable_reader_v2(
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mutation_source ms,
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schema_ptr schema,
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reader_permit permit,
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const dht::partition_range& pr,
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const query::partition_slice& ps,
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const io_priority_class& pc,
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tracing::trace_state_ptr trace_state,
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mutation_reader::forwarding fwd_mr);
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