mirror of
https://github.com/MariaDB/server.git
synced 2025-01-16 03:52:35 +01:00
26e599cd32
introduced a generosity factor that makes the search less greedy. it dramatically improves the recall by making the search a bit slower (for the same recall one can use half the M and smaller ef). had to add Queue::safe_push() method that removes one of the furthest elements (not necessarily the furthest) in the queue to keep it from overflowing.
64 lines
2.1 KiB
C++
64 lines
2.1 KiB
C++
/* Copyright (c) 2024, MariaDB plc
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
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#ifndef QUEUE_INCLUDED
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#define QUEUE_INCLUDED
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#include <my_global.h>
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#include "queues.h"
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/**
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A typesafe wrapper of QUEUE, a priority heap
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*/
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template<typename Element, typename Param=void>
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class Queue
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{
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public:
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typedef int (*Queue_compare)(Param *, const Element *, const Element *);
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Queue() { m_queue.root= 0; }
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~Queue() { delete_queue(&m_queue); }
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int init(uint max_elements, bool max_at_top, Queue_compare compare,
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Param *param= 0)
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{
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return init_queue(&m_queue, max_elements, 0, max_at_top,
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(queue_compare)compare, (void *)param, 0, 0);
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}
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size_t elements() const { return m_queue.elements; }
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bool is_inited() const { return is_queue_inited(&m_queue); }
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bool is_full() const { return queue_is_full(&m_queue); }
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bool is_empty() const { return elements() == 0; }
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Element *top() const { return (Element*)queue_top(&m_queue); }
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void push(const Element *element) { queue_insert(&m_queue, (uchar*)element); }
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void safe_push(const Element *element)
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{
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if (is_full()) m_queue.elements--; // remove one of the furthest elements
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queue_insert(&m_queue, (uchar*)element);
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}
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Element *pop() { return (Element *)queue_remove_top(&m_queue); }
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void clear() { queue_remove_all(&m_queue); }
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void propagate_top() { queue_replace_top(&m_queue); }
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void replace_top(const Element *element)
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{
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queue_top(&m_queue)= (uchar*)element;
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propagate_top();
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}
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private:
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QUEUE m_queue;
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};
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#endif
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