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1 // Copyright (c) 2008, Google Inc. | 1 // Copyright (c) 2008, Google Inc. |
2 // All rights reserved. | 2 // All rights reserved. |
3 // | 3 // |
4 // Redistribution and use in source and binary forms, with or without | 4 // Redistribution and use in source and binary forms, with or without |
5 // modification, are permitted provided that the following conditions are | 5 // modification, are permitted provided that the following conditions are |
6 // met: | 6 // met: |
7 // | 7 // |
8 // * Redistributions of source code must retain the above copyright | 8 // * Redistributions of source code must retain the above copyright |
9 // notice, this list of conditions and the following disclaimer. | 9 // notice, this list of conditions and the following disclaimer. |
10 // * Redistributions in binary form must reproduce the above | 10 // * Redistributions in binary form must reproduce the above |
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29 | 29 |
30 // --- | 30 // --- |
31 // Author: Sanjay Ghemawat <opensource@google.com> | 31 // Author: Sanjay Ghemawat <opensource@google.com> |
32 | 32 |
33 #ifndef TCMALLOC_PAGE_HEAP_ALLOCATOR_H_ | 33 #ifndef TCMALLOC_PAGE_HEAP_ALLOCATOR_H_ |
34 #define TCMALLOC_PAGE_HEAP_ALLOCATOR_H_ | 34 #define TCMALLOC_PAGE_HEAP_ALLOCATOR_H_ |
35 | 35 |
36 #include <stddef.h> // for NULL, size_t | 36 #include <stddef.h> // for NULL, size_t |
37 | 37 |
38 #include "common.h" // for MetaDataAlloc | 38 #include "common.h" // for MetaDataAlloc |
39 #include "free_list.h" // for FL_Push/FL_Pop | 39 #include "internal_logging.h" // for ASSERT |
40 #include "internal_logging.h" // for ASSERT, CRASH | |
41 #include "system-alloc.h" // for TCMalloc_SystemAddGuard | |
42 | 40 |
43 namespace tcmalloc { | 41 namespace tcmalloc { |
44 | 42 |
45 // Simple allocator for objects of a specified type. External locking | 43 // Simple allocator for objects of a specified type. External locking |
46 // is required before accessing one of these objects. | 44 // is required before accessing one of these objects. |
47 template <class T> | 45 template <class T> |
48 class PageHeapAllocator { | 46 class PageHeapAllocator { |
49 public: | 47 public: |
50 // We use an explicit Init function because these variables are statically | 48 // We use an explicit Init function because these variables are statically |
51 // allocated and their constructors might not have run by the time some | 49 // allocated and their constructors might not have run by the time some |
52 // other static variable tries to allocate memory. | 50 // other static variable tries to allocate memory. |
53 void Init() { | 51 void Init() { |
54 ASSERT(sizeof(T) <= kAllocIncrement); | 52 ASSERT(sizeof(T) <= kAllocIncrement); |
55 inuse_ = 0; | 53 inuse_ = 0; |
56 free_area_ = NULL; | 54 free_area_ = NULL; |
57 free_avail_ = 0; | 55 free_avail_ = 0; |
58 free_list_ = NULL; | 56 free_list_ = NULL; |
59 // Reserve some space at the beginning to avoid fragmentation. | 57 // Reserve some space at the beginning to avoid fragmentation. |
60 Delete(New()); | 58 Delete(New()); |
61 } | 59 } |
62 | 60 |
63 T* New() { | 61 T* New() { |
64 // Consult free list | 62 // Consult free list |
65 void* result; | 63 void* result; |
66 if (free_list_ != NULL) { | 64 if (free_list_ != NULL) { |
67 result = FL_Pop(&free_list_); | 65 result = free_list_; |
| 66 free_list_ = *(reinterpret_cast<void**>(result)); |
68 } else { | 67 } else { |
69 if (free_avail_ < sizeof(T)) { | 68 if (free_avail_ < sizeof(T)) { |
70 // Need more room. We assume that MetaDataAlloc returns | 69 // Need more room. We assume that MetaDataAlloc returns |
71 // suitably aligned memory. | 70 // suitably aligned memory. |
72 free_area_ = reinterpret_cast<char*>(MetaDataAlloc(kAllocIncrement)); | 71 free_area_ = reinterpret_cast<char*>(MetaDataAlloc(kAllocIncrement)); |
73 if (free_area_ == NULL) { | 72 if (free_area_ == NULL) { |
74 CRASH("FATAL ERROR: Out of memory trying to allocate internal " | 73 Log(kCrash, __FILE__, __LINE__, |
75 "tcmalloc data (%d bytes, object-size %d)\n", | 74 "FATAL ERROR: Out of memory trying to allocate internal " |
76 kAllocIncrement, static_cast<int>(sizeof(T))); | 75 "tcmalloc data (bytes, object-size)", |
| 76 kAllocIncrement, sizeof(T)); |
77 } | 77 } |
78 | 78 free_avail_ = kAllocIncrement; |
79 // This guard page protects the metadata from being corrupted by a | |
80 // buffer overrun. We currently have no mechanism for freeing it, since | |
81 // we never release the metadata buffer. If that changes we'll need to | |
82 // add something like TCMalloc_SystemRemoveGuard. | |
83 size_t guard_size = TCMalloc_SystemAddGuard(free_area_, | |
84 kAllocIncrement); | |
85 free_area_ += guard_size; | |
86 free_avail_ = kAllocIncrement - guard_size; | |
87 if (free_avail_ < sizeof(T)) { | |
88 CRASH("FATAL ERROR: Insufficient memory to guard internal tcmalloc " | |
89 "data (%d bytes, object-size %d, guard-size %d)\n", | |
90 kAllocIncrement, static_cast<int>(sizeof(T)), guard_size); | |
91 } | |
92 } | 79 } |
93 result = free_area_; | 80 result = free_area_; |
94 free_area_ += sizeof(T); | 81 free_area_ += sizeof(T); |
95 free_avail_ -= sizeof(T); | 82 free_avail_ -= sizeof(T); |
96 } | 83 } |
97 inuse_++; | 84 inuse_++; |
98 return reinterpret_cast<T*>(result); | 85 return reinterpret_cast<T*>(result); |
99 } | 86 } |
100 | 87 |
101 void Delete(T* p) { | 88 void Delete(T* p) { |
102 FL_Push(&free_list_, p); | 89 *(reinterpret_cast<void**>(p)) = free_list_; |
| 90 free_list_ = p; |
103 inuse_--; | 91 inuse_--; |
104 } | 92 } |
105 | 93 |
106 int inuse() const { return inuse_; } | 94 int inuse() const { return inuse_; } |
107 | 95 |
108 private: | 96 private: |
109 // How much to allocate from system at a time | 97 // How much to allocate from system at a time |
110 static const int kAllocIncrement = 128 << 10; | 98 static const int kAllocIncrement = 128 << 10; |
111 | 99 |
112 // Free area from which to carve new objects | 100 // Free area from which to carve new objects |
113 char* free_area_; | 101 char* free_area_; |
114 size_t free_avail_; | 102 size_t free_avail_; |
115 | 103 |
116 // Free list of already carved objects | 104 // Free list of already carved objects |
117 void* free_list_; | 105 void* free_list_; |
118 | 106 |
119 // Number of allocated but unfreed objects | 107 // Number of allocated but unfreed objects |
120 int inuse_; | 108 int inuse_; |
121 }; | 109 }; |
122 | 110 |
123 } // namespace tcmalloc | 111 } // namespace tcmalloc |
124 | 112 |
125 #endif // TCMALLOC_PAGE_HEAP_ALLOCATOR_H_ | 113 #endif // TCMALLOC_PAGE_HEAP_ALLOCATOR_H_ |
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