e62a18304e
Extension of data_source, with the ability to a.) Seek in any direction, i.e. move backwards. Thus not pure stream. b.) Read a limited number of bytes. The very transparent reason for the interface is to have a base abstraction for providing a read-only file layer for networked resources.
60 lines
2.0 KiB
C++
60 lines
2.0 KiB
C++
/*
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* Copyright (C) 2025-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
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*/
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#pragma once
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#include <chrono>
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#include <seastar/core/iostream.hh>
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class seekable_data_source_impl : public seastar::data_source_impl {
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public:
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virtual seastar::future<seastar::temporary_buffer<char>> get(size_t limit) = 0;
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virtual seastar::future<> seek(uint64_t pos) = 0;
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virtual seastar::future<uint64_t> size() {
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return seastar::make_ready_future<uint64_t>(0);
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}
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virtual seastar::future<std::chrono::system_clock::time_point> timestamp() {
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return seastar::make_ready_future<std::chrono::system_clock::time_point>();
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}
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};
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class seekable_data_source : public seastar::data_source {
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public:
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seekable_data_source(std::unique_ptr<seekable_data_source_impl> src)
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: seastar::data_source(std::move(src))
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{}
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seastar::future<seastar::temporary_buffer<char>> get(size_t limit) noexcept {
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try {
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return static_cast<seekable_data_source_impl*>(impl())->get(limit);
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} catch (...) {
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return seastar::current_exception_as_future<seastar::temporary_buffer<char>>();
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}
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}
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seastar::future<> seek(uint64_t pos) noexcept {
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try {
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return static_cast<seekable_data_source_impl*>(impl())->seek(pos);
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} catch (...) {
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return seastar::current_exception_as_future<>();
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}
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}
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seastar::future<uint64_t> size() noexcept {
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try {
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return static_cast<seekable_data_source_impl*>(impl())->size();
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} catch (...) {
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return seastar::current_exception_as_future<uint64_t>();
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}
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}
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seastar::future<std::chrono::system_clock::time_point> timestamp() noexcept {
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try {
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return static_cast<seekable_data_source_impl*>(impl())->timestamp();
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} catch (...) {
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return seastar::current_exception_as_future<std::chrono::system_clock::time_point>();
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}
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}
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};
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