[176] | 1 | /* -*- C++ -*- */ |
---|
| 2 | |
---|
| 3 | #ifndef _LAZYSLOTHEAP_H_ |
---|
| 4 | #define _LAZYSLOTHEAP_H_ |
---|
| 5 | |
---|
| 6 | /* |
---|
| 7 | This heap manages memory in units of Chunks. |
---|
| 8 | malloc returns a slot within a chunk, |
---|
| 9 | while free returns slots back to a chunk. |
---|
| 10 | |
---|
| 11 | Once a chunk is COMPLETELY empty, it is returned to the superheap. |
---|
| 12 | */ |
---|
| 13 | |
---|
| 14 | #include <assert.h> |
---|
| 15 | #include <new.h> |
---|
| 16 | |
---|
| 17 | template <int chunkSize, int slotSize, class Super> |
---|
| 18 | class LazySlotHeap : public Super { |
---|
| 19 | public: |
---|
| 20 | |
---|
| 21 | LazySlotHeap (void) |
---|
| 22 | : myChunk (new (Super::malloc (sz)) Chunk<chunkSize, slotSize>()) |
---|
| 23 | {} |
---|
| 24 | |
---|
| 25 | ~LazySlotHeap (void) |
---|
| 26 | { |
---|
| 27 | // Give up our chunk. |
---|
| 28 | Super::free (myChunk); |
---|
| 29 | } |
---|
| 30 | |
---|
| 31 | inline void * malloc (size_t sz) { |
---|
| 32 | assert (sz == chunkSize); |
---|
| 33 | void * ptr = myChunk->getSlot(); |
---|
| 34 | if (ptr == NULL) { |
---|
| 35 | myChunk = new (Super::malloc (sz)) Chunk<chunkSize, slotSize>(); |
---|
| 36 | ptr = myChunk->getSlot(); |
---|
| 37 | assert (ptr != NULL); |
---|
| 38 | } |
---|
| 39 | return ; |
---|
| 40 | } |
---|
| 41 | |
---|
| 42 | inline void free (void * ptr) { |
---|
| 43 | /// Return a slot to its chunk. |
---|
| 44 | Chunk<chunkSize, slotSize> * ch = Chunk<chunkSize, slotSize>::getChunk (ptr); |
---|
| 45 | ch->putSlot (ptr); |
---|
| 46 | // Once the chunk is completely empty, free it. |
---|
| 47 | if (ch->getNumSlotsAvailable() == ch->getNumSlots()) { |
---|
| 48 | if (ch == myChunk) { |
---|
| 49 | // If this was 'our' chunk, get another one. |
---|
| 50 | myChunk = new (Super::malloc (sz)) Chunk<chunkSize, slotSize>(); |
---|
| 51 | } |
---|
| 52 | Super::free (ch); |
---|
| 53 | } |
---|
| 54 | } |
---|
| 55 | |
---|
| 56 | private: |
---|
| 57 | |
---|
| 58 | Chunk<chunkSize, slotSize> * myChunk; |
---|
| 59 | |
---|
| 60 | }; |
---|
| 61 | |
---|
| 62 | |
---|
| 63 | #endif |
---|