62 lines
1.5 KiB
C++
62 lines
1.5 KiB
C++
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#ifndef MEMGRAPH_DATA_STRUCTURES_SKIPLIST_LOCKFREE_SKIPLIST_HPP
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#define MEMGRAPH_DATA_STRUCTURES_SKIPLIST_LOCKFREE_SKIPLIST_HPP
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#include <cstdlib>
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#include <atomic>
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#include "utils/mark_ref.hpp"
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namespace lockfree
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{
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template <class K, class T>
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class SkipList
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{
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public:
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struct Node
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{
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using ref_t = MarkRef<Node>;
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K* key;
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T* item;
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const uint8_t height;
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static Node* create(uint8_t height, K* key, T* item)
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{
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auto size = sizeof(Node) + height * sizeof(std::atomic<ref_t>);
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auto node = static_cast<Node*>(std::malloc(size));
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return new (node) Node(height, key, item);
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}
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static void destroy(Node* node)
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{
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node->~SkipNode();
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free(node);
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}
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private:
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Node(uint8_t height, K* key, T* item)
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: key(key), item(item), height(height)
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{
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for(uint8_t i = 0; i < height; ++i)
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new (&tower[i]) std::atomic<ref_t>(nullptr);
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}
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// this creates an array of the size zero. we can't put any sensible
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// value here since we don't know what size it will be untill the
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// node is allocated. we could make it a SkipNode** but then we would
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// have two memory allocations, one for node and one for the forward
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// list. this way we avoid expensive malloc/free calls and also cache
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// thrashing when following a pointer on the heap
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std::atomic<ref_t> tower[0];
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};
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//void list_search(const K& key,
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};
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}
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#endif
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