fdc1449392
flat_mutation_reader_v2 was introduced in a pair of commits in 2021:e3309322c3"Clone flat_mutation_reader related classes into v2 variants"08b5773c12"Adapt flat_mutation_reader_v2 to the new version of the API" as a replacement for flat_mutation_reader, using range_tombstone_change instead of range_tombstone to represent represent range tombstones. See those commits for more information. The transition was incremental; the last use of the original flat_mutation_reader was removed in 2022 in commit026f8cc1e7"db: Use mutation_partition_v2 in mvcc" In turn, flat_mutation_reader was introduced in 2017 in commit748205ca75"Introduce flat_mutation_reader" To transition from a mutation_reader that nested rows within a partition in a separate stream, to a flat reader that streamed partitions and rows in the same stream. Here, we reclaim the original name and rename the awkward flat_mutation_reader_v2 to mutation_reader. Note that mutation_fragment_v2 remains since we still use the original for compatibilty, sometimes. Some notes about the transition: - files were also renamed. In one case (flat_mutation_reader_test.cc), the rename target already existed, so we rename to mutation_reader_another_test.cc. - a namespace 'mutation_reader' with two definitions existed (in mutation_reader_fwd.hh). Its contents was folded into the mutation_reader class. As a result, a few #includes had to be adjusted. Closes scylladb/scylladb#19356
83 lines
2.8 KiB
C++
83 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_fwd.hh"
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#include "readers/mutation_reader_fwd.hh"
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#include "readers/mutation_reader.hh"
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#include "schema/schema_fwd.hh"
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#include "seastarx.hh"
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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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namespace query {
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class partition_slice;
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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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mutation_reader 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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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<mutation_reader, 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&, 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<mutation_reader, 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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tracing::trace_state_ptr trace_state,
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mutation_reader::forwarding fwd_mr);
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