[176] | 1 | /* -*- C++ -*- */ |
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| 2 | |
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| 3 | #ifndef _LAZYSLOTHEAP_H_ |
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| 4 | #define _LAZYSLOTHEAP_H_ |
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| 5 | |
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| 6 | /* |
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| 7 | This heap manages memory in units of Chunks. |
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| 8 | malloc returns a slot within a chunk, |
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| 9 | while free returns slots back to a chunk. |
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| 10 | |
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| 11 | We completely exhaust the first chunk before we ever get another one. |
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| 12 | Once a chunk (except for our current one) is COMPLETELY empty, it is returned to the superheap. |
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| 13 | */ |
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| 14 | |
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| 15 | #include <assert.h> |
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| 16 | #include <new.h> |
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| 17 | |
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| 18 | #include "chunk.h" |
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| 19 | |
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| 20 | |
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| 21 | template <int chunkSize, int slotSize, class Super> |
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| 22 | class LazySlotHeap : public Super { |
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| 23 | public: |
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| 24 | |
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| 25 | LazySlotHeap (void) |
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| 26 | : myChunk (new (Super::malloc (chunkSize)) Chunk<chunkSize, slotSize>()) |
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| 27 | {} |
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| 28 | |
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| 29 | ~LazySlotHeap (void) |
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| 30 | { |
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| 31 | // Give up our chunk. |
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| 32 | Super::free (myChunk); |
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| 33 | } |
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| 34 | |
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| 35 | inline void * malloc (size_t sz) { |
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| 36 | assert (sz <= slotSize); |
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| 37 | void * ptr = myChunk->getSlot(); |
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| 38 | if (ptr == NULL) { |
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| 39 | myChunk = new (Super::malloc (chunkSize)) Chunk<chunkSize, slotSize>(); |
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| 40 | ptr = myChunk->getSlot(); |
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| 41 | assert (ptr != NULL); |
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| 42 | } |
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| 43 | return ptr; |
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| 44 | } |
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| 45 | |
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| 46 | inline void free (void * ptr) { |
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| 47 | /// Return a slot to its chunk. |
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| 48 | Chunk<chunkSize, slotSize> * ch = Chunk<chunkSize, slotSize>::getChunk (ptr); |
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| 49 | ch->putSlot (ptr); |
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| 50 | // check if it's completely empty. If so, free it. |
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| 51 | if (ch != myChunk) { |
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| 52 | // Once the chunk is completely empty, free it. |
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| 53 | if (ch->getNumSlotsAvailable() == ch->getNumSlots()) { |
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| 54 | Super::free (ch); |
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| 55 | } |
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| 56 | } |
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| 57 | |
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| 58 | #if 0 |
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| 59 | // If this chunk isn't the one we're currently holding, |
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| 60 | // free it. NB: It is NOT guaranteed to be empty! |
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| 61 | if (ch != myChunk) { |
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| 62 | Super::free (ch); |
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| 63 | } |
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| 64 | #endif |
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| 65 | #if 0 |
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| 66 | template <int chunkSize, int slotSize, class Super> |
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| 67 | class StrictSlotHeap : public LazySlotHeap { |
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| 68 | public: |
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| 69 | inline void free (void * ptr) { |
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| 70 | /// Return a slot to its chunk. |
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| 71 | Chunk<chunkSize, slotSize> * ch = Chunk<chunkSize, slotSize>::getChunk (ptr); |
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| 72 | ch->putSlot (ptr); |
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| 73 | // check if it's completely empty. If so, free it. |
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| 74 | if (ch != myChunk) { |
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| 75 | // Once the chunk is completely empty, free it. |
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| 76 | if (ch->getNumSlotsAvailable() == ch->getNumSlots()) { |
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| 77 | Super::free (ch); |
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| 78 | } |
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| 79 | } |
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| 80 | } |
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| 81 | |
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| 82 | }; |
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| 83 | #endif |
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| 84 | |
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| 85 | } |
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| 86 | |
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| 87 | inline static size_t size (void * ptr) |
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| 88 | { |
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| 89 | return slotSize; |
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| 90 | } |
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| 91 | |
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| 92 | |
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| 93 | protected: |
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| 94 | |
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| 95 | Chunk<chunkSize, slotSize> * myChunk; |
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| 96 | |
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| 97 | }; |
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| 98 | |
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| 99 | |
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| 100 | |
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| 101 | #endif |
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