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
101 lines
3.1 KiB
C++
101 lines
3.1 KiB
C++
/*
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* Copyright 2020-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 <seastar/core/shared_future.hh>
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#include "readers/mutation_reader.hh"
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// A reader which allows to insert a deferring operation before reading.
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// All calls will first wait for a future to resolve, then forward to a given underlying reader.
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class chained_delegating_reader : public mutation_reader::impl {
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std::unique_ptr<mutation_reader> _underlying;
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std::function<future<mutation_reader>()> _populate_reader;
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std::function<void()> _on_destroyed;
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public:
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chained_delegating_reader(schema_ptr s, std::function<future<mutation_reader>()>&& populate, reader_permit permit, std::function<void()> on_destroyed = []{})
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: impl(s, std::move(permit))
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, _populate_reader(std::move(populate))
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, _on_destroyed(std::move(on_destroyed))
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{ }
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chained_delegating_reader(chained_delegating_reader&& rd) = delete;
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~chained_delegating_reader() {
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_on_destroyed();
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}
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virtual future<> fill_buffer() override {
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if (!_underlying) {
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return _populate_reader().then([this] (mutation_reader&& rd) {
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_underlying = std::make_unique<mutation_reader>(std::move(rd));
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return fill_buffer();
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});
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}
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if (is_buffer_full()) {
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return make_ready_future<>();
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}
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return _underlying->fill_buffer().then([this] {
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_end_of_stream = _underlying->is_end_of_stream();
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_underlying->move_buffer_content_to(*this);
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});
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}
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virtual future<> fast_forward_to(position_range pr) override {
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if (!_underlying) {
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return _populate_reader().then([this, pr = std::move(pr)] (mutation_reader&& rd) mutable {
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_underlying = std::make_unique<mutation_reader>(std::move(rd));
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return fast_forward_to(pr);
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});
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}
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_end_of_stream = false;
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clear_buffer();
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return _underlying->fast_forward_to(std::move(pr));
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}
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virtual future<> next_partition() override {
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if (!_underlying) {
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return make_ready_future<>();
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}
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clear_buffer_to_next_partition();
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auto f = make_ready_future<>();
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if (is_buffer_empty()) {
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f = _underlying->next_partition();
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}
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_end_of_stream = _underlying->is_end_of_stream() && _underlying->is_buffer_empty();
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return f;
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}
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virtual future<> fast_forward_to(const dht::partition_range& pr) override {
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if (!_underlying) {
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return _populate_reader().then([this, &pr] (mutation_reader&& rd) mutable {
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_underlying = std::make_unique<mutation_reader>(std::move(rd));
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return fast_forward_to(pr);
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});
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}
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_end_of_stream = false;
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clear_buffer();
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return _underlying->fast_forward_to(pr);
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}
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virtual future<> close() noexcept override {
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if (_underlying) {
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return _underlying->close();
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}
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return make_ready_future<>();
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}
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};
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