Kstars

starblockfactory.h
1/*
2 SPDX-FileCopyrightText: 2008 Akarsh Simha <akarshsimha@gmail.com>
3
4 SPDX-License-Identifier: GPL-2.0-or-later
5*/
6
7#pragma once
8
9#include "typedef.h"
10
11class StarBlock;
12
13/**
14 * @class StarBlockFactory
15 *
16 * @short A factory that creates StarBlocks and recycles them in an LRU Cache
17 * @author Akarsh Simha
18 * @version 0.1
19 */
20
22{
23 public:
24 static StarBlockFactory *Instance();
25
26 /**
27 * Destructor
28 * Deletes the linked list that maintains the Cache, sets the pointer to nullptr
29 */
31
32 /**
33 * @short Return a StarBlock available for use
34 *
35 * This method first checks if there are any cached StarBlocks that are not in use.
36 * If such a StarBlock is found, it returns the same for use. Else it freshly allocates
37 * a StarBlock and returns the same. It also moves the StarBlock to the front, marking it
38 * as the most recently used. If the StarBlock had a parent StarBlockList, this method
39 * detaches the StarBlock from the StarBlockList
40 *
41 * @return A StarBlock that is available for use
42 */
43 std::shared_ptr<StarBlock> getBlock();
44
45 /**
46 * @short Mark a StarBlock as most recently used and sync its drawID with the current drawID
47 *
48 * @return true on success, false if the StarBlock supplied was not on our list at all
49 */
50 bool markFirst(std::shared_ptr<StarBlock>& block);
51
52 /**
53 * @short Rank a given StarBlock after another given StarBlock in the LRU list
54 * and sync its drawID with the current drawID
55 *
56 * @param after The block after which 'block' should be put
57 * @param block The block to mark for use
58 * @return true on success, false on failure
59 */
60 bool markNext(std::shared_ptr<StarBlock>& after, std::shared_ptr<StarBlock>& block);
61
62 /**
63 * @short Returns the number of StarBlocks currently produced
64 *
65 * @return Number of StarBlocks currently allocated
66 */
67 inline int getBlockCount() const { return nBlocks; }
68
69 /**
70 * @short Frees all StarBlocks that are in the cache
71 * @return The number of StarBlocks freed
72 */
73 inline int freeAll() { return deleteBlocks(nBlocks); }
74
75 /**
76 * @short Frees all StarBlocks that are not used in this draw cycle
77 * @return The number of StarBlocks freed
78 */
79 int freeUnused();
80
81 /**
82 * @short Prints the structure of the cache, for debugging
83 */
84 void printStructure() const;
85
86 quint32 drawID; // A number identifying the current draw cycle
87
88 private:
89 /**
90 * Constructor
91 * Initializes first and last StarBlock pointers to nullptr
92 */
94
95 /**
96 * @short Deletes the N least recently used blocks
97 *
98 * @param nblocks Number of blocks to delete
99 * @return Number of blocks successfully deleted
100 */
101 int deleteBlocks(int nblocks);
102
103 std::shared_ptr<StarBlock> first, last; // Pointers to the beginning and end of the linked list
104 int nBlocks; // Number of blocks we currently have in the cache
105 int nCache; // Number of blocks to start recycling cached blocks at
106
107 static StarBlockFactory *pInstance;
108};
A factory that creates StarBlocks and recycles them in an LRU Cache.
~StarBlockFactory()
Destructor Deletes the linked list that maintains the Cache, sets the pointer to nullptr.
bool markNext(std::shared_ptr< StarBlock > &after, std::shared_ptr< StarBlock > &block)
Rank a given StarBlock after another given StarBlock in the LRU list and sync its drawID with the cur...
int getBlockCount() const
Returns the number of StarBlocks currently produced.
int freeAll()
Frees all StarBlocks that are in the cache.
int freeUnused()
Frees all StarBlocks that are not used in this draw cycle.
std::shared_ptr< StarBlock > getBlock()
Return a StarBlock available for use.
void printStructure() const
Prints the structure of the cache, for debugging.
bool markFirst(std::shared_ptr< StarBlock > &block)
Mark a StarBlock as most recently used and sync its drawID with the current drawID.
Holds a block of stars and various peripheral variables to mark its place in data structures.
Definition starblock.h:43
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