[176] | 1 | // -*- C++ -*- |
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| 2 | |
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| 3 | /** |
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| 4 | * @file manageonesuperblock.h |
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| 5 | * @author Emery Berger <http://www.cs.umass.edu/~emery> |
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| 6 | */ |
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| 7 | |
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| 8 | |
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| 9 | #ifndef _MANAGEONESUPERBLOCK_H_ |
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| 10 | #define _MANAGEONESUPERBLOCK_H_ |
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| 11 | |
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| 12 | /** |
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| 13 | * @class ManageOneSuperblock |
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| 14 | * @brief A layer that caches exactly one superblock, thus avoiding costly lookups. |
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| 15 | * @author Emery Berger <http://www.cs.umass.edu/~emery> |
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| 16 | */ |
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| 17 | |
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| 18 | namespace Hoard { |
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| 19 | |
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| 20 | template <class SuperHeap> |
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| 21 | class ManageOneSuperblock : public SuperHeap { |
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| 22 | public: |
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| 23 | |
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| 24 | typedef typename SuperHeap::SuperblockType SuperblockType; |
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| 25 | |
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| 26 | /// Get memory from the current superblock. |
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| 27 | inline void * malloc (size_t sz) { |
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| 28 | if (_current) { |
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| 29 | void * ptr = _current->malloc (sz); |
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| 30 | if (ptr) { |
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| 31 | assert (_current->getSize(ptr) >= sz); |
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| 32 | return ptr; |
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| 33 | } |
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| 34 | } |
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| 35 | return slowMallocPath (sz); |
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| 36 | } |
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| 37 | |
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| 38 | /// Try to free the pointer to this superblock first. |
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| 39 | inline void free (void * ptr) { |
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| 40 | SuperblockType * s = SuperHeap::getSuperblock (ptr); |
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| 41 | if (s == _current) { |
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| 42 | _current->free (ptr); |
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| 43 | } else { |
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| 44 | SuperHeap::free (ptr); |
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| 45 | } |
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| 46 | } |
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| 47 | |
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| 48 | /// Get the current superblock and remove it. |
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| 49 | SuperblockType * get (void) { |
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| 50 | if (_current) { |
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| 51 | SuperblockType * s = _current; |
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| 52 | _current = NULL; |
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| 53 | return s; |
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| 54 | } else { |
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| 55 | // There's none cached, so just get one from the superheap. |
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| 56 | return SuperHeap::get(); |
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| 57 | } |
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| 58 | } |
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| 59 | |
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| 60 | /// Put the superblock into the cache. |
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| 61 | inline void put (SuperblockType * s) { |
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| 62 | if (!s || (s == _current) || (!s->isValidSuperblock())) { |
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| 63 | // Ignore if we already are holding this superblock, of if we |
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| 64 | // got a NULL pointer, or if it's invalid. |
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| 65 | return; |
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| 66 | } |
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| 67 | if (_current) { |
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| 68 | // We have one already -- push it out. |
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| 69 | SuperHeap::put (_current); |
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| 70 | } |
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| 71 | _current = s; |
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| 72 | } |
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| 73 | |
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| 74 | private: |
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| 75 | |
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| 76 | /// Obtain a superblock and return an object from it. |
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| 77 | void * slowMallocPath (size_t sz) { |
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| 78 | void * ptr = NULL; |
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| 79 | while (!ptr) { |
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| 80 | if (_current) { |
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| 81 | ptr = _current->malloc (sz); |
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| 82 | if (ptr) { |
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| 83 | return ptr; |
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| 84 | } else { |
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| 85 | SuperHeap::put (_current); |
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| 86 | } |
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| 87 | } |
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| 88 | _current = SuperHeap::get(); |
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| 89 | if (!_current) { |
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| 90 | return NULL; |
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| 91 | } |
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| 92 | ptr = _current->malloc (sz); |
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| 93 | } |
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| 94 | return ptr; |
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| 95 | } |
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| 96 | |
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| 97 | /// The current superblock. |
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| 98 | SuperblockType * _current; |
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| 99 | |
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| 100 | }; |
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| 101 | |
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| 102 | } |
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| 103 | |
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| 104 | #endif |
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