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1 #ifndef MEMORY_POOL_H_
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2 #define MEMORY_POOL_H_
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3
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4 #include <memory>
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5 #include <stdlib.h>
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6
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7 const int DEFAULT_EXPAND_SIZE = 32;
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8
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9 template <class T_, size_t size_ =DEFAULT_EXPAND_SIZE>
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10 class MemoryPool {
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11 public:
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12 typedef MemoryPool<T_, size_> self_type;
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13
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14 MemoryPool(void) {
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15 next_ = NULL;
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16 expandTheFreeList(size_);
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17 }
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18
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19 ~MemoryPool(void) {
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20 MemoryPool * nextPtr = next_;
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21
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22 while (nextPtr == 0) {
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23 next_ = next_->next_;
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24 delete [] nextPtr;
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25 nextPtr = next_;
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26 }
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27 }
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28
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29 void* alloc(size_t) {
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30 if (!next_) expandTheFreeList(size_);
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31
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32 self_type* head = next_;
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33 next_ = head->next_;
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34
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35 return head;
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36 }
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37
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38 void free(void* doomed) {
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39 self_type* head = static_cast<self_type*>(doomed);
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40 head->next_ = next_;
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41 next_ = head;
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42 }
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43
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44 private:
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45 void expandTheFreeList(int howMany);
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46
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47 private:
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48 self_type* next_;
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49 };
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50
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51 template <class T_, size_t size_>
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52 void MemoryPool<T_, size_>::expandTheFreeList(int howMany)
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53 {
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54 size_t size = (sizeof(T_) > sizeof(self_type*))
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55 ? sizeof(T_) : sizeof(self_type*);
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56
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57 self_type* runner = (self_type*)malloc(size);
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58
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59 next_ = runner;
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60 for (int i = 0; i < howMany; i++) {
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61 runner->next_ = (self_type*)malloc(size);
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62 runner = runner->next_;
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63 }
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64 runner->next_ = 0;
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65 }
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66
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67 template <class T_, size_t size_ =DEFAULT_EXPAND_SIZE>
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68 class UseMemoryPool {
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69 public:
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70 void* operator new(size_t size) { return pool_->alloc(size); }
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71 void operator delete(void* doomed, size_t) { pool_->free(doomed); }
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72
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73 public:
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74 static void initMemPool() {
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75 pool_.reset(new MemoryPool<T_, size_>);
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76 }
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77
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78 private:
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79 static std::auto_ptr<MemoryPool<T_, size_> > pool_;
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80
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81 };
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82
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83 template <class T_, size_t size_>
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84 std::auto_ptr<MemoryPool<T_, size_> > UseMemoryPool<T_, size_>::pool_;
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85
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86 #endif // ! MEMORY_POOL_H_
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