1 // Copyright 2018 The Android Open Source Project
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 #pragma once
15 
16 #include <unordered_set>
17 
18 #include <inttypes.h>
19 #include <stddef.h>
20 #include <string.h>
21 
22 namespace android {
23 namespace base {
24 
25 // Class to make it easier to set up memory regions where it is fast
26 // to allocate/deallocate buffers that have size within
27 // the specified range.
28 class Pool {
29 public:
30     // minSize/maxSize: the target range of sizes for which we want to
31     // make allocations fast. the greater the range, the more space
32     // traded off.
33     // chunksPerSize: the target maximum number of live objects of
34     // each size that are expected. the higher it is, the more space
35     // traded off.
36     //
37     // Rough space cost formula:
38     // O(chunksPerSize * log2(maxSize / minSize) * maxSize)
39     Pool(size_t minSize = 4,
40          size_t maxSize = 4096,
41          size_t chunksPerSize = 1024);
42 
43     // All memory allocated by this pool
44     // is automatically deleted when the pool
45     // is deconstructed.
46     ~Pool();
47 
48     void* alloc(size_t wantedSize);
49     void free(void* ptr);
50 
51     // Convenience function to free everything currently allocated.
52     void freeAll();
53 
54     // Convenience function to allocate an array
55     // of objects of type T.
56     template <class T>
allocArray(size_t count)57     T* allocArray(size_t count) {
58         size_t bytes = sizeof(T) * count;
59         void* res = alloc(bytes);
60         return (T*) res;
61     }
62 
strDup(const char * toCopy)63     char* strDup(const char* toCopy) {
64         size_t bytes = strlen(toCopy) + 1;
65         void* res = alloc(bytes);
66         memset(res, 0x0, bytes);
67         memcpy(res, toCopy, bytes);
68         return (char*)res;
69     }
70 
strDupArray(const char * const * arrayToCopy,size_t count)71     char** strDupArray(const char* const* arrayToCopy, size_t count) {
72         char** res = allocArray<char*>(count);
73 
74         for (size_t i = 0; i < count; i++) {
75             res[i] = strDup(arrayToCopy[i]);
76         }
77 
78         return res;
79     }
80 
dupArray(const void * buf,size_t bytes)81     void* dupArray(const void* buf, size_t bytes) {
82         void* res = alloc(bytes);
83         memcpy(res, buf, bytes);
84         return res;
85     }
86 
87 private:
88     class Impl;
89     Impl* mImpl = nullptr;
90 
91     std::unordered_set<void*> mFallbackPtrs;
92 };
93 
94 } // namespace base
95 } // namespace android
96