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
37template <typename T, size_t Size = sizeof(T)>
38class ThreadLocalBuffer {
39 public:
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
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
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