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git.ipfire.org Git - thirdparty/squid.git/blob - src/FileMap.h
4 * DEBUG: section 08 Swap File Bitmap
5 * AUTHOR: Harvest Derived
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39 /** A bitmap used for managing UFS StoreEntry "file numbers".
41 * Nth bit represents whether file number N is used.
42 * The map automatically grows to hold up to 2^24 bits.
43 * New bit is "off" or zero by default, representing unused fileno.
44 * TODO: consider using std::bitset instead.
52 /** Set the num-th bit in the FileMap
54 * \warning FileMap's backing storage will be extended as needed to
55 * hold the representation, but if the bit is already set
56 * it will break the file number accounting, so the caller must
57 * ensure that setBit is only called if the bit is not already set,
58 * by using testBit on it before.
60 bool setBit(sfileno num
);
62 /// Test whether the num-th bit in the FileMap is set
63 bool testBit(sfileno num
) const;
65 /** Clear the num-th bit in the FileMap
67 * \warning that clearBit doesn't do any bounds checking, nor it
68 * checks that the bit is set before clearing. The caller will have
69 * to ensure that both are true using testBit before clearing.
71 void clearBit(sfileno num
);
73 /** locate an unused slot in the FileMap, possibly at or after position suggestion
75 * Obtain the location of an unused slot in the FileMap,
76 * growing it if needed.
77 * The suggestion is only an advice; there is no guarantee
78 * that it will be followed.
80 sfileno
allocate(sfileno suggestion
);
82 /// return the max number of slots in the FileMap
83 int capacity() const {return capacity_
;}
85 /// return the number of used slots in the FileMap
86 int numFilesInMap() const {return used_slots_
;}
88 /// grow the FileMap (size is doubled each time, up to 2^24 bits)
90 FileMap(const FileMap
&); //no copying
91 FileMap
& operator=(const FileMap
&); //no assignments
93 /// max number of files which can be tracked in the current store
95 /// used slots in the map
96 unsigned int used_slots_
;
97 /// number of "long ints" making up the filemap
99 unsigned long *bitmap
;
102 #endif /* FILEMAP_H_ */