85964094f6
This commit implements routines for traversal of BTI nodes in their on-disk format. The `node_reader` concept is currently unused (i.e. not asserted by any template). It will only be used in the next PR, which will implement trie cursor routines parametrized `node_reader`. But I'm including it in this PR to make it clear which functions will be needed by the higher layer.
54 lines
2.0 KiB
C++
54 lines
2.0 KiB
C++
/*
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* Copyright (C) 2024-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 "utils/cached_file.hh"
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#include "node_reader.hh"
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namespace sstables {
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[[noreturn, gnu::noinline]] void on_bti_parse_error(uint64_t pos);
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}
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namespace sstables::trie {
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// Implementation of concept `node_reader`.
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get_child_result bti_get_child(uint64_t pos, const_bytes sp, int child_idx, bool forward);
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std::byte bti_get_child_transition(uint64_t pos, const_bytes raw, int idx);
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load_final_node_result bti_read_node(int64_t pos, const_bytes sp);
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const_bytes bti_get_payload(int64_t pos, const_bytes sp);
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node_traverse_result bti_walk_down_along_key(int64_t pos, const_bytes sp, const_bytes key);
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node_traverse_sidemost_result bti_walk_down_leftmost_path(int64_t pos, const_bytes sp);
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node_traverse_sidemost_result bti_walk_down_rightmost_path(int64_t pos, const_bytes sp);
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// Deals with BTI-specific parts of trie traversal.
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// (I.e. the parts which understand the BTI serialization format).
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//
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// (We talk about "traversal" and not "deserialization" because we don't actually
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// want to deserialize the full nodes, we only want to walk over them.)
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//
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// See comments for concept `node_reader` for a description of the methods.
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struct bti_node_reader {
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using page_ptr = cached_file::ptr_type;
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page_ptr _cached_page;
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std::reference_wrapper<cached_file> _file;
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bti_node_reader(cached_file& f);
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bool cached(int64_t pos) const;
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future<> load(int64_t pos);
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trie::load_final_node_result read_node(int64_t pos);
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trie::node_traverse_result walk_down_along_key(int64_t pos, const_bytes key);
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trie::node_traverse_sidemost_result walk_down_leftmost_path(int64_t pos);
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trie::node_traverse_sidemost_result walk_down_rightmost_path(int64_t pos);
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trie::get_child_result get_child(int64_t pos, int child_idx, bool forward) const;
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const_bytes get_payload(int64_t pos) const;
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};
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static_assert(node_reader<bti_node_reader>);
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} // namespace sstables::trie
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