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      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 
     22 static SLresult IThreadSync_EnterCriticalSection(SLThreadSyncItf self)
     23 {
     24     SL_ENTER_INTERFACE
     25 
     26     IThreadSync *thiz = (IThreadSync *) self;
     27     interface_lock_exclusive(thiz);
     28     for (;;) {
     29         if (thiz->mInCriticalSection) {
     30             if (!pthread_equal(thiz->mOwner, pthread_self())) {
     31                 ++thiz->mWaiting;
     32                 interface_cond_wait(thiz);
     33                 continue;
     34             }
     35             // nested locks are not allowed
     36             result = SL_RESULT_PRECONDITIONS_VIOLATED;
     37             break;
     38         }
     39         thiz->mInCriticalSection = SL_BOOLEAN_TRUE;
     40         thiz->mOwner = pthread_self();
     41         result = SL_RESULT_SUCCESS;
     42         break;
     43     }
     44     interface_unlock_exclusive(thiz);
     45 
     46     SL_LEAVE_INTERFACE
     47 }
     48 
     49 
     50 static SLresult IThreadSync_ExitCriticalSection(SLThreadSyncItf self)
     51 {
     52     SL_ENTER_INTERFACE
     53 
     54     IThreadSync *thiz = (IThreadSync *) self;
     55     interface_lock_exclusive(thiz);
     56     if (!thiz->mInCriticalSection || !pthread_equal(thiz->mOwner, pthread_self())) {
     57         result = SL_RESULT_PRECONDITIONS_VIOLATED;
     58     } else {
     59         thiz->mInCriticalSection = SL_BOOLEAN_FALSE;
     60         memset(&thiz->mOwner, 0, sizeof(pthread_t));
     61         if (thiz->mWaiting) {
     62             --thiz->mWaiting;
     63             interface_cond_signal(thiz);
     64         }
     65         result = SL_RESULT_SUCCESS;
     66     }
     67     interface_unlock_exclusive(thiz);
     68 
     69     SL_LEAVE_INTERFACE
     70 }
     71 
     72 
     73 static const struct SLThreadSyncItf_ IThreadSync_Itf = {
     74     IThreadSync_EnterCriticalSection,
     75     IThreadSync_ExitCriticalSection
     76 };
     77 
     78 void IThreadSync_init(void *self)
     79 {
     80     IThreadSync *thiz = (IThreadSync *) self;
     81     thiz->mItf = &IThreadSync_Itf;
     82     thiz->mInCriticalSection = SL_BOOLEAN_FALSE;
     83     thiz->mWaiting = 0;
     84     memset(&thiz->mOwner, 0, sizeof(pthread_t));
     85 }
     86 
     87 void IThreadSync_deinit(void *self)
     88 {
     89     IThreadSync *thiz = (IThreadSync *) self;
     90     if (thiz->mInCriticalSection) {
     91         SL_LOGW("ThreadSync::EnterCriticalSection was active at Engine::Destroy");
     92     }
     93 }
     94