2 * Copyright (c) 2015 Samsung Electronics Co., Ltd.
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
19 #include <dali/devel-api/threading/conditional-wait.h>
22 #include <dali/internal/common/mutex-impl.h>
26 #include <dali/integration-api/debug.h>
31 struct ConditionalWait::ConditionalWaitImpl
33 pthread_mutex_t mutex;
34 pthread_cond_t condition;
35 volatile unsigned int count;
39 ConditionalWait::ScopedLock::ScopedLock( ConditionalWait& wait ) : mWait(wait)
41 Internal::Mutex::Lock( &wait.mImpl->mutex );
44 ConditionalWait::ScopedLock::~ScopedLock()
46 ConditionalWait& wait = mWait;
47 Internal::Mutex::Unlock( &wait.mImpl->mutex );
50 ConditionalWait::ConditionalWait()
51 : mImpl( new ConditionalWaitImpl )
53 pthread_mutex_init( &mImpl->mutex, NULL );
54 pthread_cond_init( &mImpl->condition, NULL );
58 ConditionalWait::~ConditionalWait()
60 pthread_cond_destroy( &mImpl->condition );
61 pthread_mutex_destroy( &mImpl->mutex );
65 void ConditionalWait::Notify()
67 // pthread_cond_wait requires a lock to be held
68 Internal::Mutex::Lock( &mImpl->mutex );
69 volatile unsigned int previousCount = mImpl->count;
70 mImpl->count = 0; // change state before broadcast as that may wake clients immediately
71 // broadcast does nothing if the thread is not waiting but still has a system call overhead
72 // broadcast all threads to continue
73 if( 0 != previousCount )
75 pthread_cond_broadcast( &mImpl->condition );
77 Internal::Mutex::Unlock( &mImpl->mutex );
80 void ConditionalWait::Wait()
82 // pthread_cond_wait requires a lock to be held
83 Internal::Mutex::Lock( &mImpl->mutex );
85 // pthread_cond_wait may wake up without anyone calling Notify
88 // wait while condition changes
89 pthread_cond_wait( &mImpl->condition, &mImpl->mutex ); // releases the lock whilst waiting
91 while( 0 != mImpl->count );
92 // when condition returns the mutex is locked so release the lock
93 Internal::Mutex::Unlock( &mImpl->mutex );
96 void ConditionalWait::Wait( const ScopedLock& scope )
98 // Scope must be locked:
99 DALI_ASSERT_DEBUG( &scope.GetLockedWait() == this );
103 // pthread_cond_wait may wake up without anyone calling Notify so loop until
104 // count has been reset in a notify:
107 // wait while condition changes
108 pthread_cond_wait( &mImpl->condition, &mImpl->mutex ); // releases the lock whilst waiting
110 while( 0 != mImpl->count );
112 // We return with our mutex locked safe in the knowledge that the ScopedLock
113 // passed in will unlock it in the caller.
116 unsigned int ConditionalWait::GetWaitCount() const