1 /*
2  * Copyright (C) 2012 The Android Open Source Project
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *  * Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  *  * Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in
12  *    the documentation and/or other materials provided with the
13  *    distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #ifndef _BIONIC_THREAD_LOCAL_BUFFER_H_included
30 #define _BIONIC_THREAD_LOCAL_BUFFER_H_included
31 
32 #include <malloc.h>
33 #include <pthread.h>
34 
35 // TODO: use __thread instead?
36 
37 template <typename T, size_t Size = sizeof(T)>
38 class ThreadLocalBuffer {
39  public:
ThreadLocalBuffer()40   ThreadLocalBuffer() {
41     // We used to use pthread_once to initialize the keys, but life is more predictable
42     // if we allocate them all up front when the C library starts up, via __constructor__.
43     pthread_key_create(&key_, free);
44   }
45 
get()46   T* get() {
47     T* result = reinterpret_cast<T*>(pthread_getspecific(key_));
48     if (result == nullptr) {
49       result = reinterpret_cast<T*>(calloc(1, Size));
50       pthread_setspecific(key_, result);
51     }
52     return result;
53   }
54 
size()55   size_t size() { return Size; }
56 
57  private:
58   pthread_key_t key_;
59 };
60 
61 #endif // _BIONIC_THREAD_LOCAL_BUFFER_H_included
62