File indexing completed on 2024-04-14 14:11:25
0001 /* 0002 SPDX-FileCopyrightText: 2008 Akarsh Simha <akarshsimha@gmail.com> 0003 0004 SPDX-License-Identifier: GPL-2.0-or-later 0005 */ 0006 0007 #pragma once 0008 0009 #include "typedef.h" 0010 0011 class StarBlock; 0012 0013 /** 0014 * @class StarBlockFactory 0015 * 0016 * @short A factory that creates StarBlocks and recycles them in an LRU Cache 0017 * @author Akarsh Simha 0018 * @version 0.1 0019 */ 0020 0021 class StarBlockFactory 0022 { 0023 public: 0024 static StarBlockFactory *Instance(); 0025 0026 /** 0027 * Destructor 0028 * Deletes the linked list that maintains the Cache, sets the pointer to nullptr 0029 */ 0030 ~StarBlockFactory(); 0031 0032 /** 0033 * @short Return a StarBlock available for use 0034 * 0035 * This method first checks if there are any cached StarBlocks that are not in use. 0036 * If such a StarBlock is found, it returns the same for use. Else it freshly allocates 0037 * a StarBlock and returns the same. It also moves the StarBlock to the front, marking it 0038 * as the most recently used. If the StarBlock had a parent StarBlockList, this method 0039 * detaches the StarBlock from the StarBlockList 0040 * 0041 * @return A StarBlock that is available for use 0042 */ 0043 std::shared_ptr<StarBlock> getBlock(); 0044 0045 /** 0046 * @short Mark a StarBlock as most recently used and sync its drawID with the current drawID 0047 * 0048 * @return true on success, false if the StarBlock supplied was not on our list at all 0049 */ 0050 bool markFirst(std::shared_ptr<StarBlock>& block); 0051 0052 /** 0053 * @short Rank a given StarBlock after another given StarBlock in the LRU list 0054 * and sync its drawID with the current drawID 0055 * 0056 * @param after The block after which 'block' should be put 0057 * @param block The block to mark for use 0058 * @return true on success, false on failure 0059 */ 0060 bool markNext(std::shared_ptr<StarBlock>& after, std::shared_ptr<StarBlock>& block); 0061 0062 /** 0063 * @short Returns the number of StarBlocks currently produced 0064 * 0065 * @return Number of StarBlocks currently allocated 0066 */ 0067 inline int getBlockCount() const { return nBlocks; } 0068 0069 /** 0070 * @short Frees all StarBlocks that are in the cache 0071 * @return The number of StarBlocks freed 0072 */ 0073 inline int freeAll() { return deleteBlocks(nBlocks); } 0074 0075 /** 0076 * @short Frees all StarBlocks that are not used in this draw cycle 0077 * @return The number of StarBlocks freed 0078 */ 0079 int freeUnused(); 0080 0081 /** 0082 * @short Prints the structure of the cache, for debugging 0083 */ 0084 void printStructure() const; 0085 0086 quint32 drawID; // A number identifying the current draw cycle 0087 0088 private: 0089 /** 0090 * Constructor 0091 * Initializes first and last StarBlock pointers to nullptr 0092 */ 0093 StarBlockFactory(); 0094 0095 /** 0096 * @short Deletes the N least recently used blocks 0097 * 0098 * @param nblocks Number of blocks to delete 0099 * @return Number of blocks successfully deleted 0100 */ 0101 int deleteBlocks(int nblocks); 0102 0103 std::shared_ptr<StarBlock> first, last; // Pointers to the beginning and end of the linked list 0104 int nBlocks; // Number of blocks we currently have in the cache 0105 int nCache; // Number of blocks to start recycling cached blocks at 0106 0107 static StarBlockFactory *pInstance; 0108 };