1 /*-------------------------------------------------------------------------
2 * drawElements Thread Library
3 * ---------------------------
4 *
5 * Copyright 2014 The Android Open Source Project
6 *
7 * Licensed under the Apache License, Version 2.0 (the "License");
8 * you may not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 *
19 *//*!
20 * \file
21 * \brief Thread-safe singleton.
22 *//*--------------------------------------------------------------------*/
23
24 #include "deSingleton.h"
25 #include "deAtomic.h"
26 #include "deThread.h"
27
28 DE_STATIC_ASSERT(sizeof(deSingletonState) == sizeof(uint32_t));
29
deInitSingleton(volatile deSingletonState * singletonState,deSingletonConstructorFunc constructor,void * arg)30 void deInitSingleton(volatile deSingletonState *singletonState, deSingletonConstructorFunc constructor, void *arg)
31 {
32 if (*singletonState != DE_SINGLETON_STATE_INITIALIZED)
33 {
34 deSingletonState curState = (deSingletonState)deAtomicCompareExchange32(
35 (volatile uint32_t *)singletonState, (uint32_t)DE_SINGLETON_STATE_NOT_INITIALIZED,
36 (uint32_t)DE_SINGLETON_STATE_INITIALIZING);
37
38 if (curState == DE_SINGLETON_STATE_NOT_INITIALIZED)
39 {
40 constructor(arg);
41
42 deMemoryReadWriteFence();
43
44 *singletonState = DE_SINGLETON_STATE_INITIALIZED;
45
46 deMemoryReadWriteFence();
47 }
48 else if (curState == DE_SINGLETON_STATE_INITIALIZING)
49 {
50 for (;;)
51 {
52 deMemoryReadWriteFence();
53
54 if (*singletonState == DE_SINGLETON_STATE_INITIALIZED)
55 break;
56 else
57 deYield();
58 }
59 }
60
61 DE_ASSERT(*singletonState == DE_SINGLETON_STATE_INITIALIZED);
62 }
63 }
64