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scylladb/readers/queue.hh
2025-05-09 07:53:29 -04:00

60 lines
1.7 KiB
C++

/*
* Copyright (C) 2022-present ScyllaDB
*/
/*
* SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
*/
#pragma once
#include "readers/mutation_reader.hh"
class queue_reader;
/// Calls to different methods cannot overlap!
/// The handle can be used only while the reader is still alive. Once
/// `push_end_of_stream()` is called, the reader and the handle can be destroyed
/// in any order. The reader can be destroyed at any time.
class queue_reader_handle {
friend std::pair<mutation_reader, queue_reader_handle> make_queue_reader(schema_ptr, reader_permit);
friend class queue_reader;
private:
queue_reader* _reader = nullptr;
std::exception_ptr _ex;
private:
explicit queue_reader_handle(queue_reader& reader) noexcept;
void abandon() noexcept;
[[nodiscard]] std::exception_ptr check_abort() const noexcept;
public:
queue_reader_handle(queue_reader_handle&& o) noexcept;
~queue_reader_handle();
queue_reader_handle& operator=(queue_reader_handle&& o);
future<> push(mutation_fragment_v2 mf);
/// Terminate the queue.
///
/// The reader will be set to EOS. The handle cannot be used anymore.
void push_end_of_stream();
/// Aborts the queue.
///
/// All future operations on the handle or the reader will raise `ep`.
void abort(std::exception_ptr ep);
/// Checks if the queue is already terminated with either a success or failure (abort)
bool is_terminated() const;
/// Get the stored exception, if any
std::exception_ptr get_exception() const noexcept;
};
std::pair<mutation_reader, queue_reader_handle> make_queue_reader(schema_ptr s, reader_permit permit);