Point Cloud Library (PCL)  1.14.1-dev
allocator.h
1 /*
2 Copyright (c) 2006, Michael Kazhdan and Matthew Bolitho
3 All rights reserved.
4 
5 Redistribution and use in source and binary forms, with or without modification,
6 are permitted provided that the following conditions are met:
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8 Redistributions of source code must retain the above copyright notice, this list of
9 conditions and the following disclaimer. Redistributions in binary form must reproduce
10 the above copyright notice, this list of conditions and the following disclaimer
11 in the documentation and/or other materials provided with the distribution.
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13 Neither the name of the Johns Hopkins University nor the names of its contributors
14 may be used to endorse or promote products derived from this software without specific
15 prior written permission.
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17 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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19 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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27 */
28 
29 #ifndef ALLOCATOR_INCLUDED
30 #define ALLOCATOR_INCLUDED
31 #include <vector>
32 
33 namespace pcl
34 {
35  namespace poisson
36  {
38  public:
40  };
41  /** This templated class assists in memory allocation and is well suited for instances
42  * when it is known that the sequence of memory allocations is performed in a stack-based
43  * manner, so that memory allocated last is released first. It also preallocates memory
44  * in chunks so that multiple requests for small chunks of memory do not require separate
45  * system calls to the memory manager.
46  * The allocator is templated off of the class of objects that we would like it to allocate,
47  * ensuring that appropriate constructors and destructors are called as necessary.
48  */
49  template<class T>
50  class Allocator{
51  int blockSize;
52  int index,remains;
53  std::vector<T*> memory;
54  public:
55  Allocator(void){
56  blockSize=index=remains=0;
57  }
58  ~Allocator(void){
59  reset();
60  }
61 
62  /** This method is the allocators destructor. It frees up any of the memory that
63  * it has allocated. */
64  void reset(void){
65  for(std::size_t i=0;i<memory.size();i++){delete[] memory[i];}
66  memory.clear();
67  blockSize=index=remains=0;
68  }
69  /** This method returns the memory state of the allocator. */
70  AllocatorState getState(void) const{
72  s.index=index;
73  s.remains=remains;
74  return s;
75  }
76 
77 
78  /** This method rolls back the allocator so that it makes all of the memory previously
79  * allocated available for re-allocation. Note that it does it not call the constructor
80  * again, so after this method has been called, assumptions about the state of the values
81  * in memory are no longer valid. */
82  void rollBack(void){
83  if(memory.size()){
84  for(std::size_t i=0;i<memory.size();i++){
85  for(int j=0;j<blockSize;j++){
86  memory[i][j].~T();
87  new(&memory[i][j]) T();
88  }
89  }
90  index=0;
91  remains=blockSize;
92  }
93  }
94  /** This method rolls back the allocator to the previous memory state and makes all of the memory previously
95  * allocated available for re-allocation. Note that it does it not call the constructor
96  * again, so after this method has been called, assumptions about the state of the values
97  * in memory are no longer valid. */
98  void rollBack(const AllocatorState& state){
99  if(state.index<index || (state.index==index && state.remains<remains)){
100  if(state.index<index){
101  for(int j=state.remains;j<blockSize;j++){
102  memory[state.index][j].~T();
103  new(&memory[state.index][j]) T();
104  }
105  for(int i=state.index+1;i<index-1;i++){
106  for(int j=0;j<blockSize;j++){
107  memory[i][j].~T();
108  new(&memory[i][j]) T();
109  }
110  }
111  for(int j=0;j<remains;j++){
112  memory[index][j].~T();
113  new(&memory[index][j]) T();
114  }
115  index=state.index;
116  remains=state.remains;
117  }
118  else{
119  for(int j=0;j<state.remains;j<remains){
120  memory[index][j].~T();
121  new(&memory[index][j]) T();
122  }
123  remains=state.remains;
124  }
125  }
126  }
127 
128  /** This method initiallizes the constructor and the blockSize variable specifies the
129  * the number of objects that should be pre-allocated at a time. */
130  void set( int blockSize){
131  reset();
132  this->blockSize=blockSize;
133  index=-1;
134  remains=0;
135  }
136 
137  /** This method returns a pointer to an array of elements objects. If there is left over pre-allocated
138  * memory, this method simply returns a pointer to the next free piece of memory, otherwise it pre-allocates
139  * more memory. Note that if the number of objects requested is larger than the value blockSize with which
140  * the allocator was initialized, the request for memory will fail.
141  */
142  T* newElements( int elements=1){
143  T* mem;
144  if(!elements){return NULL;}
145  if(elements>blockSize){
146  fprintf(stderr,"Allocator Error, elements bigger than block-size: %d>%d\n",elements,blockSize);
147  return NULL;
148  }
149  if(remains<elements){
150  if(index==memory.size()-1){
151  mem=new T[blockSize];
152  if(!mem){fprintf(stderr,"Failed to allocate memory\n");exit(0);}
153  memory.push_back(mem);
154  }
155  index++;
156  remains=blockSize;
157  }
158  mem=&(memory[index][blockSize-remains]);
159  remains-=elements;
160  return mem;
161  }
162  };
163 
164 
165  }
166 }
167 
168 #endif // ALLOCATOR_INCLUDE
This templated class assists in memory allocation and is well suited for instances when it is known t...
Definition: allocator.h:50
AllocatorState getState(void) const
This method returns the memory state of the allocator.
Definition: allocator.h:70
void set(int blockSize)
This method initiallizes the constructor and the blockSize variable specifies the the number of objec...
Definition: allocator.h:130
void reset(void)
This method is the allocators destructor.
Definition: allocator.h:64
void rollBack(void)
This method rolls back the allocator so that it makes all of the memory previously allocated availabl...
Definition: allocator.h:82
T * newElements(int elements=1)
This method returns a pointer to an array of elements objects.
Definition: allocator.h:142
void rollBack(const AllocatorState &state)
This method rolls back the allocator to the previous memory state and makes all of the memory previou...
Definition: allocator.h:98