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1 | #ifndef _THEAP_H_ |
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2 | #define _THEAP_H_ |
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3 | |
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4 | // A general threshold-based heap. |
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5 | |
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6 | // Threshold layer. |
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7 | // Once we have more than Threshold bytes on our freelist, |
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8 | // return memory to the superheap. |
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9 | |
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10 | // The class argument FH should be some freelist heap that subclasses NullHeap. |
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11 | |
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12 | template <class SuperHeap, class FH, int Threshold> |
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13 | class THeap : public SuperHeap { |
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14 | public: |
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15 | THeap (void) |
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16 | : total (0) |
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17 | {} |
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18 | |
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19 | ~THeap (void) |
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20 | {} |
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21 | |
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22 | inline void * malloc (size_t sz) { |
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23 | void * ptr; |
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24 | ptr = fHeap.malloc (sz); |
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25 | if (ptr == NULL) { |
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26 | // We have no memory on our freelist. |
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27 | // Get it from the superheap. |
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28 | ptr = SuperHeap::malloc (sz); |
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29 | } else { |
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30 | total -= size(ptr); |
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31 | // printf ("total = %d\n", total); |
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32 | } |
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33 | assert (size(ptr) >= sz); |
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34 | return ptr; |
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35 | } |
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36 | |
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37 | inline void free (void * ptr) { |
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38 | if (total < Threshold) { |
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39 | // printf ("FREE TO FREELIST.\n"); |
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40 | total += size(ptr); |
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41 | fHeap.free (ptr); |
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42 | //printf ("total = %d\n", total); |
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43 | } else { |
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44 | // Dump the freelist heap. |
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45 | void * p = fHeap.malloc (1); |
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46 | while (p != NULL) { |
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47 | SuperHeap::free (p); |
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48 | p = fHeap.malloc (1); |
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49 | } |
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50 | SuperHeap::free (ptr); |
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51 | total = 0; |
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52 | } |
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53 | } |
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54 | |
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55 | private: |
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56 | // Provide a free list that will return NULL if it is out of memory. |
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57 | FH fHeap; |
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58 | int total; |
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59 | }; |
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60 | |
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61 | |
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62 | #endif |
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