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>
25 #include <dali/integration-api/debug.h>
26 #include <dali/internal/common/mutex-impl.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 if( pthread_mutex_init( &mImpl->mutex, NULL ) )
55 DALI_LOG_ERROR( "Unable to initialise mutex in ConditionalWait\n" );
57 if( pthread_cond_init( &mImpl->condition, NULL ) )
59 DALI_LOG_ERROR( "Unable to initialise conditional\n" );
64 ConditionalWait::~ConditionalWait()
66 if( pthread_cond_destroy( &mImpl->condition ) )
68 DALI_LOG_ERROR( "Unable to destroy conditional\n" );
70 if( pthread_mutex_destroy( &mImpl->mutex ) )
72 DALI_LOG_ERROR( "Unable to destroy mutex in ConditionalWait\n" );
77 void ConditionalWait::Notify()
79 // pthread_cond_wait requires a lock to be held
80 Internal::Mutex::Lock( &mImpl->mutex );
81 volatile unsigned int previousCount = mImpl->count;
82 mImpl->count = 0; // change state before broadcast as that may wake clients immediately
83 // broadcast does nothing if the thread is not waiting but still has a system call overhead
84 // broadcast all threads to continue
85 if( 0 != previousCount )
87 if( pthread_cond_broadcast( &mImpl->condition ) )
89 DALI_LOG_ERROR( "Error calling pthread_cond_broadcast\n" );
92 Internal::Mutex::Unlock( &mImpl->mutex );
95 void ConditionalWait::Notify( const ScopedLock& scope )
97 // Scope must be locked:
98 DALI_ASSERT_DEBUG( &scope.GetLockedWait() == this );
100 volatile unsigned int previousCount = mImpl->count;
101 mImpl->count = 0; // change state before broadcast as that may wake clients immediately
102 // broadcast does nothing if the thread is not waiting but still has a system call overhead
103 // broadcast all threads to continue
104 if( 0 != previousCount )
106 if( pthread_cond_broadcast( &mImpl->condition ) )
108 DALI_LOG_ERROR( "Error calling pthread_cond_broadcast\n" );
113 void ConditionalWait::Wait()
115 // pthread_cond_wait requires a lock to be held
116 Internal::Mutex::Lock( &mImpl->mutex );
118 // pthread_cond_wait may wake up without anyone calling Notify
121 // wait while condition changes
122 if( pthread_cond_wait( &mImpl->condition, &mImpl->mutex ) ) // releases the lock whilst waiting
124 DALI_LOG_ERROR( "Error calling pthread_cond_wait\n" );
128 while( 0 != mImpl->count );
129 // when condition returns the mutex is locked so release the lock
130 Internal::Mutex::Unlock( &mImpl->mutex );
133 void ConditionalWait::Wait( const ScopedLock& scope )
135 // Scope must be locked:
136 DALI_ASSERT_DEBUG( &scope.GetLockedWait() == this );
140 // pthread_cond_wait may wake up without anyone calling Notify so loop until
141 // count has been reset in a notify:
144 // wait while condition changes
145 if( pthread_cond_wait( &mImpl->condition, &mImpl->mutex ) ) // releases the lock whilst waiting
147 DALI_LOG_ERROR( "Error calling pthread_cond_wait\n" );
151 while( 0 != mImpl->count );
153 // We return with our mutex locked safe in the knowledge that the ScopedLock
154 // passed in will unlock it in the caller.
157 unsigned int ConditionalWait::GetWaitCount() const