64427b9164
This is just a strange method I came across. It effectively does nothing but clear_buffer().
68 lines
2.2 KiB
C++
68 lines
2.2 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 "readers/flat_mutation_reader_v2.hh"
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class delegating_reader_v2 : public flat_mutation_reader_v2::impl {
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flat_mutation_reader_v2_opt _underlying_holder;
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flat_mutation_reader_v2* _underlying;
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public:
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// when passed a lvalue reference to the reader
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// we don't own it and the caller is responsible
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// for evenetually closing the reader.
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delegating_reader_v2(flat_mutation_reader_v2& r)
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: impl(r.schema(), r.permit())
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, _underlying_holder()
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, _underlying(&r)
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{ }
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// when passed a rvalue reference to the reader
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// we assume ownership of it and will close it
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// in close().
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delegating_reader_v2(flat_mutation_reader_v2&& r)
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: impl(r.schema(), r.permit())
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, _underlying_holder(std::move(r))
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, _underlying(&*_underlying_holder)
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{ }
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virtual future<> fill_buffer() override {
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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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_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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clear_buffer_to_next_partition();
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auto maybe_next_partition = make_ready_future<>();
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if (is_buffer_empty()) {
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maybe_next_partition = _underlying->next_partition();
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}
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return maybe_next_partition.then([this] {
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_end_of_stream = _underlying->is_end_of_stream() && _underlying->is_buffer_empty();
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});
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}
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virtual future<> fast_forward_to(const dht::partition_range& pr) override {
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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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return _underlying_holder ? _underlying_holder->close() : make_ready_future<>();
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}
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};
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flat_mutation_reader_v2 make_delegating_reader(flat_mutation_reader_v2&);
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