IThreadSync.c revision 262059f71a68edc5e510427c63f5f1623d3672a8 
1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/* ThreadSync implementation */
18
19#include "sles_allinclusive.h"
20
21
22static SLresult IThreadSync_EnterCriticalSection(SLThreadSyncItf self)
23{
24    SL_ENTER_INTERFACE
25
26    IThreadSync *this = (IThreadSync *) self;
27    interface_lock_exclusive(this);
28    for (;;) {
29        if (this->mInCriticalSection) {
30            if (!pthread_equal(this->mOwner, pthread_self())) {
31                ++this->mWaiting;
32                interface_cond_wait(this);
33                continue;
34            }
35            // nested locks are not allowed
36            result = SL_RESULT_PRECONDITIONS_VIOLATED;
37            break;
38        }
39        this->mInCriticalSection = SL_BOOLEAN_TRUE;
40        this->mOwner = pthread_self();
41        result = SL_RESULT_SUCCESS;
42        break;
43    }
44    interface_unlock_exclusive(this);
45
46    SL_LEAVE_INTERFACE
47}
48
49
50static SLresult IThreadSync_ExitCriticalSection(SLThreadSyncItf self)
51{
52    SL_ENTER_INTERFACE
53
54    IThreadSync *this = (IThreadSync *) self;
55    interface_lock_exclusive(this);
56    if (!this->mInCriticalSection || !pthread_equal(this->mOwner, pthread_self())) {
57        result = SL_RESULT_PRECONDITIONS_VIOLATED;
58    } else {
59        this->mInCriticalSection = SL_BOOLEAN_FALSE;
60        memset(&this->mOwner, 0, sizeof(pthread_t));
61        if (this->mWaiting) {
62            --this->mWaiting;
63            interface_cond_signal(this);
64        }
65        result = SL_RESULT_SUCCESS;
66    }
67    interface_unlock_exclusive(this);
68
69    SL_LEAVE_INTERFACE
70}
71
72
73static const struct SLThreadSyncItf_ IThreadSync_Itf = {
74    IThreadSync_EnterCriticalSection,
75    IThreadSync_ExitCriticalSection
76};
77
78void IThreadSync_init(void *self)
79{
80    IThreadSync *this = (IThreadSync *) self;
81    this->mItf = &IThreadSync_Itf;
82    this->mInCriticalSection = SL_BOOLEAN_FALSE;
83    this->mWaiting = 0;
84    memset(&this->mOwner, 0, sizeof(pthread_t));
85}
86
87void IThreadSync_deinit(void *self)
88{
89    IThreadSync *this = (IThreadSync *) self;
90    if (this->mInCriticalSection) {
91        SL_LOGW("ThreadSync::EnterCriticalSection was active at Engine::Destroy");
92    }
93}
94