[176] | 1 | /* -*- C++ -*- */ |
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| 2 | |
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| 3 | #ifndef _LOOSESLOTHEAP_H_ |
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| 4 | #define _LOOSESLOTHEAP_H_ |
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| 5 | |
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| 6 | #include <assert.h> |
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| 7 | |
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| 8 | #include "bigchunk.h" |
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| 9 | |
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| 10 | /* |
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| 11 | LooseSlotHeap: A "Loose" slot heap. |
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| 12 | |
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| 13 | malloc returns objects of size slotSize, allocated from the super heap |
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| 14 | in chunkSize units. |
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| 15 | |
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| 16 | free returns objects of size slotSize. |
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| 17 | |
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| 18 | When the slot heap is at least 1/emptyFraction empty, a |
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| 19 | chunk that is at least that empty is freed to the super heap. |
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| 20 | Note that the chunk's memory MAY NOT SAFELY be recycled in toto -- |
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| 21 | it must be parceled out using the chunk interface. |
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| 22 | |
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| 23 | The intent of this heap is to allow mostly-empty chunks to move up |
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| 24 | to a staging area (the super heap) where they may be reused by other |
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| 25 | "loose" slot heaps. |
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| 26 | |
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| 27 | */ |
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| 28 | |
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| 29 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
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| 30 | class LooseSlotHeap { |
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| 31 | public: |
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| 32 | |
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| 33 | inline LooseSlotHeap (void); |
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| 34 | inline ~LooseSlotHeap (void); |
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| 35 | |
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| 36 | // Get a slotSize object. |
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| 37 | inline void * malloc (size_t sz); |
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| 38 | |
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| 39 | // Free a slotSize object. |
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| 40 | static inline void free (void * ptr); |
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| 41 | |
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| 42 | private: |
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| 43 | |
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| 44 | Super theHeap; |
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| 45 | |
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| 46 | typedef BigChunk<chunkSize, slotSize, LooseSlotHeap> chunkType; |
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| 47 | |
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| 48 | inline void localFree (void * ptr); |
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| 49 | |
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| 50 | void checkClassInvariant (void) { |
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| 51 | #ifndef NDEBUG |
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| 52 | assert (inUse >= 0); |
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| 53 | assert (inUse <= space); |
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| 54 | assert (lastIndex >= 0); |
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| 55 | assert (lastIndex <= emptyFraction); |
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| 56 | // Now check to make sure that inUse & space are correct. |
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| 57 | int localInUse = 0; |
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| 58 | int localSpace = 0; |
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| 59 | for (int i = 0; i < emptyFraction + 1; i++) { |
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| 60 | chunkType * ch = myChunks[i]; |
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| 61 | while (ch != NULL) { |
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| 62 | assert (ch->getHeap() == this); |
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| 63 | localInUse += ch->getNumSlotsInUse(); |
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| 64 | localSpace += ch->getNumSlots(); |
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| 65 | ch = ch->getNext(); |
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| 66 | } |
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| 67 | } |
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| 68 | assert (localSpace == space); |
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| 69 | assert (localInUse == inUse); |
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| 70 | #endif |
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| 71 | } |
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| 72 | |
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| 73 | // How full is this block? |
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| 74 | // 0 == empty to no more than 1/emptyFraction full. |
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| 75 | // emptyFraction == completely full. |
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| 76 | static inline int getFullness (chunkType * ch); |
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| 77 | |
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| 78 | // Move a chunk, if necessary, into the right list |
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| 79 | // based on its emptiness. |
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| 80 | // Returns the index of which list it is put or left in. |
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| 81 | inline int update (chunkType * ch, int prevIndex); |
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| 82 | |
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| 83 | // The array of chunks, "radix sorted" by emptiness. |
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| 84 | // completely empty chunks are in index 0. |
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| 85 | // completely full chunks are in index emptyFraction. |
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| 86 | chunkType * myChunks[emptyFraction + 1]; |
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| 87 | |
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| 88 | // The last index (from 0) in the above array that has a chunk. |
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| 89 | int lastIndex; |
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| 90 | |
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| 91 | // How much space is in use in all of the chunks. |
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| 92 | int inUse; |
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| 93 | |
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| 94 | // How much space there is (free or not) in all of the chunks. |
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| 95 | int space; |
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| 96 | }; |
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| 97 | |
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| 98 | |
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| 99 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
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| 100 | LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::LooseSlotHeap (void) |
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| 101 | : space (0), |
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| 102 | inUse (0), |
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| 103 | lastIndex (emptyFraction - 1) |
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| 104 | { |
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| 105 | // Initialize the chunk pointers (all initially empty). |
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| 106 | for (int i = 0; i < emptyFraction + 1; i++) { |
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| 107 | myChunks[i] = NULL; |
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| 108 | } |
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| 109 | } |
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| 110 | |
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| 111 | |
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| 112 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
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| 113 | LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::~LooseSlotHeap (void) |
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| 114 | { |
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| 115 | // Free every chunk. |
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| 116 | chunkType * ch, * tmp; |
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| 117 | for (int i = 0; i < emptyFraction + 1; i++) { |
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| 118 | ch = myChunks[i]; |
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| 119 | while (ch != NULL) { |
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| 120 | tmp = ch; |
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| 121 | ch = ch->getNext(); |
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| 122 | theHeap.free (tmp); |
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| 123 | } |
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| 124 | } |
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| 125 | } |
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| 126 | |
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| 127 | |
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| 128 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
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| 129 | int LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::getFullness (chunkType * ch) |
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| 130 | { |
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| 131 | int fullness = (emptyFraction * ch->getNumSlotsInUse())/ch->getNumSlots(); |
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| 132 | //printf ("numslots avail = %d, num slots total = %d, fullness = %d\n", ch->getNumSlotsFree(), ch->getNumSlots(), fullness); |
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| 133 | return fullness; |
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| 134 | } |
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| 135 | |
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| 136 | |
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| 137 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
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| 138 | void * LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::malloc (size_t sz) |
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| 139 | { |
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| 140 | checkClassInvariant(); |
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| 141 | //printf ("Loose malloc %d (slot size = %d)\n", sz, slotSize); |
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| 142 | assert (sz <= slotSize); |
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| 143 | void * ptr = NULL; |
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| 144 | chunkType * ch = NULL; |
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| 145 | // Always try to allocate from the most-full chunk (resetting |
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| 146 | // lastIndex as we go). |
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| 147 | lastIndex = emptyFraction - 1; // FIX ME! |
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| 148 | while (lastIndex >= 0) { |
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| 149 | ch = myChunks[lastIndex]; |
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| 150 | if (ch == NULL) { |
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| 151 | lastIndex--; |
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| 152 | } else { |
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| 153 | // Got one. |
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| 154 | break; |
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| 155 | } |
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| 156 | } |
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| 157 | if (lastIndex < 0) { |
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| 158 | assert (ch == NULL); |
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| 159 | // There were no chunks available. |
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| 160 | assert ((space - inUse) == 0); |
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| 161 | // Make one with memory from the "super" heap. |
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| 162 | printf ("!!!\n"); |
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| 163 | ch = (chunkType*) theHeap.malloc (chunkSize); |
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| 164 | ch->setHeap (this); |
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| 165 | assert (ch->getNumSlotsFree() > 0); |
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| 166 | printf ("Super malloc %d\n", chunkSize); |
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| 167 | lastIndex = getFullness(ch); |
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| 168 | register chunkType*& head = myChunks[lastIndex]; |
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| 169 | assert (head == NULL); |
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| 170 | ch->setPrev (NULL); |
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| 171 | ch->setNext (NULL); |
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| 172 | head = ch; |
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| 173 | inUse += ch->getNumSlotsInUse(); |
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| 174 | space += ch->getNumSlots(); |
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| 175 | assert (ch->getNumSlotsFree() <= ch->getNumSlots()); |
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| 176 | // FOR NOW!! FIX ME!!! |
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| 177 | assert (ch->getNumSlotsFree() == ch->getNumSlots()); |
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| 178 | printf ("Space, in use was %d, %d\n", space, inUse); |
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| 179 | printf ("Space, in use NOW %d, %d\n", space, inUse); |
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| 180 | } |
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| 181 | assert (ch != NULL); |
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| 182 | assert (ch->getNumSlotsFree() > 0); |
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| 183 | int prevFullness = getFullness (ch); |
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| 184 | int prevInUse = ch->getNumSlotsInUse(); |
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| 185 | assert (ch->getHeap() == this); |
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| 186 | ptr = ch->getSlot(); |
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| 187 | inUse++; |
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| 188 | assert (prevInUse + 1 == ch->getNumSlotsInUse()); |
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| 189 | int newFullness = getFullness (ch); |
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| 190 | if (prevFullness != newFullness) { |
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| 191 | int n = update (ch, prevFullness); |
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| 192 | assert (n == newFullness); |
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| 193 | } |
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| 194 | chunkType * bch = (chunkType *) chunkType::getChunk(ptr); |
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| 195 | assert (bch == ch); |
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| 196 | assert (ptr != NULL); |
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| 197 | checkClassInvariant(); |
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| 198 | return ptr; |
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| 199 | } |
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| 200 | |
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| 201 | |
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| 202 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
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| 203 | void LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::free (void * ptr) { |
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| 204 | chunkType * ch |
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| 205 | = (chunkType *) chunkType::getChunk (ptr); |
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| 206 | assert (ch != NULL); |
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| 207 | (ch->getHeap())->localFree (ptr); |
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| 208 | } |
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| 209 | |
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| 210 | |
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| 211 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
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| 212 | void LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::localFree (void * ptr) { |
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| 213 | checkClassInvariant(); |
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| 214 | printf ("free! (in use = %d, space = %d)\n", inUse, space); |
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| 215 | // Mark the slot in the chunk as free. |
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| 216 | chunkType * ch |
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| 217 | = (chunkType *) chunkType::getChunk (ptr); |
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| 218 | assert (ch != NULL); |
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| 219 | assert (ch->getHeap() == this); |
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| 220 | int prevFullness = getFullness (ch); |
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| 221 | int prevInUse = ch->getNumSlotsInUse(); |
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| 222 | ch->putSlot (ptr); |
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| 223 | inUse--; |
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| 224 | assert (prevInUse - 1 == ch->getNumSlotsInUse()); |
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| 225 | checkClassInvariant(); |
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| 226 | int newIndex = getFullness (ch); |
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| 227 | if (prevFullness != newIndex) { |
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| 228 | int n = update (ch, prevFullness); |
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| 229 | assert (n == newIndex); |
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| 230 | } |
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| 231 | // If we are more than 1/emptyFraction empty, |
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| 232 | // return a mostly-empty chunk to the super heap. |
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| 233 | if ((space - inUse > 2 * chunkSize/slotSize) |
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| 234 | && (emptyFraction * (space - inUse) > space)) { |
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| 235 | printf ("RETURNING A CHUNK!\n"); |
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| 236 | // Find an empty chunk. |
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| 237 | int emptyIndex = 0; |
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| 238 | ch = NULL; |
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| 239 | while (emptyIndex < emptyFraction) { |
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| 240 | ch = myChunks[emptyIndex]; |
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| 241 | if (ch != NULL) |
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| 242 | break; |
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| 243 | emptyIndex++; |
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| 244 | } |
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| 245 | assert (ch != NULL); |
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| 246 | checkClassInvariant(); |
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| 247 | ch->setHeap (NULL); |
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| 248 | // Remove a chunk and give it to the super heap. |
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| 249 | myChunks[emptyIndex] = myChunks[emptyIndex]->getNext(); |
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| 250 | if (myChunks[emptyIndex] != NULL) { |
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| 251 | myChunks[emptyIndex]->setPrev (NULL); |
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| 252 | } |
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| 253 | ch->setPrev (NULL); |
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| 254 | ch->setNext (NULL); |
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| 255 | // A sanity check on the chunk we're about to return. |
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| 256 | assert (ch->getNumSlotsFree() >= 0); |
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| 257 | assert (ch->getNumSlots() >= ch->getNumSlotsFree()); |
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| 258 | printf ("Updating space & in use: was %d, %d (slots in use = %d)\n", |
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| 259 | space, inUse, ch->getNumSlotsInUse()); |
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| 260 | space -= ch->getNumSlots(); |
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| 261 | inUse -= ch->getNumSlotsInUse(); |
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| 262 | printf ("Updating space & in use: NOW %d, %d\n", space, inUse); |
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| 263 | theHeap.free (ch); |
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| 264 | checkClassInvariant(); |
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| 265 | } |
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| 266 | checkClassInvariant(); |
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| 267 | } |
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| 268 | |
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| 269 | |
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| 270 | // Move a chunk, if necessary, into the right list |
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| 271 | // based on its emptiness. |
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| 272 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
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| 273 | int LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::update (chunkType * ch, int prevIndex) |
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| 274 | { |
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| 275 | // Move this chunk if necessary. |
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| 276 | #ifndef NDEBUG |
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| 277 | chunkType * bch = myChunks[prevIndex]; |
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| 278 | while (bch != NULL) { |
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| 279 | if (bch == ch) |
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| 280 | break; |
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| 281 | bch = bch->getNext(); |
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| 282 | } |
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| 283 | assert (bch == ch); |
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| 284 | #endif |
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| 285 | int newIndex = getFullness(ch); |
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| 286 | // printf ("newIndex = %d\n", newIndex); |
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| 287 | // Reset last index (for simplicity). // FIX ME?? |
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| 288 | // Remove the chunk from its current list. |
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| 289 | if (ch == myChunks[prevIndex]) { |
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| 290 | myChunks[prevIndex] = myChunks[prevIndex]->getNext(); |
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| 291 | } |
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| 292 | ///// lastIndex = emptyFraction - 1; |
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| 293 | if (ch->getPrev() != NULL) { |
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| 294 | ch->getPrev()->setNext(ch->getNext()); |
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| 295 | } |
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| 296 | if (ch->getNext() != NULL) { |
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| 297 | ch->getNext()->setPrev(ch->getPrev()); |
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| 298 | } |
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| 299 | // Add it to the newIndex list. |
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| 300 | chunkType*& head = myChunks[newIndex]; |
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| 301 | ch->setPrev (NULL); |
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| 302 | ch->setNext (head); |
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| 303 | if (head != NULL) { |
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| 304 | head->setPrev(ch); |
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| 305 | } |
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| 306 | head = ch; |
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| 307 | // Verify that the chunk is in the right list. |
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| 308 | #ifndef NDEBUG |
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| 309 | bch = myChunks[newIndex]; |
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| 310 | while (bch != NULL) { |
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| 311 | if (bch == ch) |
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| 312 | break; |
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| 313 | bch = bch->getNext(); |
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| 314 | } |
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| 315 | assert (bch == ch); |
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| 316 | #endif |
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| 317 | return newIndex; |
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| 318 | } |
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| 319 | |
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| 320 | |
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| 321 | |
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| 322 | #endif |
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