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Archived:RMutex - Symbian mutex class

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__NOTOC__
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[[Category:Symbian C++]][[Category:Code Snippet]][[Category:S60 3rd Edition (initial release)]][[Category:Code Snippet]]
__NOEDITSECTION__
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{{Archived|timestamp=20120313125720|user=roy.debjit| }}
{{KBCS}}
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{{ArticleMetaData
+
|id=CS000969
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|platform=S60 3rd Edition, MR
+
|devices=Nokia N95
+
|category=Symbian C++
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|subcategory=Code Examples
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|creationdate=May 20, 2008
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|keywords=RMutex, RSemaphore, RThread
+
  
 +
{{ArticleMetaData <!-- v1.2 -->
 
|sourcecode= <!-- Link to example source code (e.g. [[Media:The Code Example ZIP.zip]]) -->
 
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|installfile= <!-- Link to installation file (e.g. [[Media:The Installation File.sis]]) -->
|sdk=<!-- SDK(s) built and tested against (e.g. [http://linktosdkdownload/ Nokia Qt SDK 1.1]) -->
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|devices= Nokia N95
|devicecompatability=<!-- Compatible devices (e.g.: All* (must have GPS) ) -->
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|signing=<!-- Empty or one of Self-Signed, DevCert, Manufacturer -->
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|platform= S60 3rd Edition, MR
|capabilities=<!-- Capabilities required (e.g. Location, NetworkServices. -->)
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|devicecompatability= <!-- Compatible devices (e.g.: All* (must have GPS) ) -->
|author=[[User:Tepaa]]
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|capabilities= <!-- Capabilities required by the article/code example (e.g. Location, NetworkServices. -->
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<!-- The following are not in current metadata -->
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|subcategory= Code Examples
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|id= CS000969
 
}}
 
}}
 
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==Overview==
 
==Overview==
Using  <tt>RMutex</tt> you can make sure that, for example, threads do not change the same value at the same time.
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{{Abstract|Using  {{Icode|RMutex}} you can make sure that, for example, threads do not change the same value at the same time. {{Icode|RMutex.Wait()}} acquires a lock that opens with {{Icode|RMutex.Signal()}}.}}
<tt>RMutex.Wait()</tt> acquires a lock that opens with <tt>RMutex.Signal()</tt>.
+
  
The following code is an update to the [[CS000867 - RThread]] example.
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The following code is an update to the [[Archived:RThread - Symbian threading example]] example.
  
 
==MMP file==
 
==MMP file==
 
The following capabilities and libraries are required:
 
The following capabilities and libraries are required:
 
<code cpp>
 
<code cpp>
CAPABILITY       NONE
+
CAPABILITY NONE
LIBRARY           euser.lib
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LIBRARY euser.lib
 
</code>
 
</code>
  
 
==Header file==
 
==Header file==
Shared data <tt>iSharedValue</tt> between threads.
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Shared data {{Icode|iSharedValue}} between threads.
 
<code cpp>
 
<code cpp>
 
class CShared : CBase
 
class CShared : CBase
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     public:
 
     public:
         RMutex     iMutex;
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         RMutex iMutex;
 
         // Shared data
 
         // Shared data
         TInt       iSharedValue;
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         TInt iSharedValue;
 
     };
 
     };
 
</code>
 
</code>
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==Source file==
 
==Source file==
Create a thread and give the <tt>CShared</tt> data pointer in it.
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Create a thread and give the {{Icode|CShared}} data pointer in it.
 
<code cpp>
 
<code cpp>
 
// Create shared data
 
// Create shared data
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</code>
 
</code>
  
The thread fuction says<tt>RMutex::Wait()</tt> and then sleeps.
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The thread fuction says{{Icode|RMutex::Wait()}} and then sleeps.
 
<code cpp>
 
<code cpp>
 
TInt CMyThread::ThreadFunction(TAny* aParams)
 
TInt CMyThread::ThreadFunction(TAny* aParams)
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</code>
 
</code>
  
After sleeping the thread calls <tt>PeriodicTick()</tt> where it changes the shared
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After sleeping the thread calls {{Icode|PeriodicTick()}} where it changes the shared
data value and releases <tt>RMutex::Signal()</tt>.
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data value and releases {{Icode|RMutex::Signal()}}.
 
<code cpp>
 
<code cpp>
 
TInt CMyThread::PeriodicTick(TAny* aObject)
 
TInt CMyThread::PeriodicTick(TAny* aObject)
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</code>
 
</code>
  
<tt>CShared</tt> data implementation
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{{Icode|CShared}} data implementation
 
<code cpp>
 
<code cpp>
 
CShared* CShared::NewL()
 
CShared* CShared::NewL()
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==See also==
 
==See also==
[[CS000867 - RThread]] Using RThread
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[[Archived:RThread - Symbian threading example]] Using RThread
 
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[[Category:Symbian C++]][[Category:Code Examples]][[Category:S60 3rd Edition]][[Category:Code Snippet]]
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Latest revision as of 00:10, 2 September 2012

Archived.pngArchived: This article is archived because it is not considered relevant for third-party developers creating commercial solutions today. If you think this article is still relevant, let us know by adding the template {{ReviewForRemovalFromArchive|user=~~~~|write your reason here}}.

Article Metadata
Tested with
Devices(s): Nokia N95
Compatibility
Platform(s): S60 3rd Edition, MR
S60 3rd Edition (initial release)
Article
Keywords: RMutex, RSemaphore, RThread
Created: tepaa (13 May 2008)
Last edited: lpvalente (02 Sep 2012)

Contents

[edit] Overview

Using RMutex you can make sure that, for example, threads do not change the same value at the same time. RMutex.Wait() acquires a lock that opens with RMutex.Signal().

The following code is an update to the Archived:RThread - Symbian threading example example.

[edit] MMP file

The following capabilities and libraries are required:

CAPABILITY NONE
LIBRARY euser.lib

[edit] Header file

Shared data iSharedValue between threads.

class CShared : CBase
{
public:
static CShared* NewL();
virtual ~CShared();
 
private:
CShared();
 
public:
RMutex iMutex;
// Shared data
TInt iSharedValue;
};


[edit] Source file

Create a thread and give the CShared data pointer in it.

// Create shared data
iSharedData = CShared::NewL();
 
// Create threads
iMyThread = CMyThread::NewL(*this);
iMyThread->SetShared(iSharedData);
 
iMyThread2 = CMyThread::NewL(*this);
iMyThread2->SetShared(iSharedData);

The thread fuction saysRMutex::Wait() and then sleeps.

TInt CMyThread::ThreadFunction(TAny* aParams)
{
// Add cleanup stack support.
CTrapCleanup* cleanupStack = CTrapCleanup::New();
 
// Get pointer to thread host
CMyThread* host = (CMyThread*)aParams;
 
TRAPD(err,
// Add support for active objects
CActiveScheduler* activeScheduler = new (ELeave) CActiveScheduler;
CleanupStack::PushL(activeScheduler);
CActiveScheduler::Install(activeScheduler);
 
// Create and start CPeriodic class that is executed in this thread
CPeriodic* periodic = CPeriodic::NewL(CActive::EPriorityLow);
CleanupStack::PushL(periodic);
periodic->Start(host->Interval(),host->Interval(),
TCallBack(host->PeriodicTick, host));
 
// NOTE: When adding CActiveScheduler support for threads we have to
// add at least one active object in it or it fails on
// CActiveScheduler::Start().
// CPeriodic is derived from CActive active object so that is good for
// this example.
 
// --> Thread execution starts
CActiveScheduler::Start();
// --> Thread execution ends (waiting for CActiveScheduler::Stop())
 
CleanupStack::PopAndDestroy(periodic);
CleanupStack::PopAndDestroy(activeScheduler);
);
 
 
host->ThreadExecuted(err);
delete cleanupStack;
return KErrNone;
}

After sleeping the thread calls PeriodicTick() where it changes the shared data value and releases RMutex::Signal().

TInt CMyThread::PeriodicTick(TAny* aObject)
{
CMyThread* mythread = (CMyThread*)aObject;
if (mythread)
{
// ---> Acquire the lock
mythread->Shared()->iMutex.Wait();
 
// Change shared data value
mythread->Shared()->iSharedValue++;
 
// ---> Release the lock
mythread->Shared()->iMutex.Signal();
 
// Thread is executed once so time to stop it
CActiveScheduler::Stop();
 
// After this execution continues from CActiveScheduler::Start()
}
// Does not continue again
// Note: Does not work with this CPeriodic class
return EFalse;
}

CShared data implementation

CShared* CShared::NewL()
{
CShared* self = new (ELeave) CShared();
return self;
}
CShared::CShared()
{
iMutex.CreateLocal();
}
CShared::~CShared()
{
iMutex.Close();
}


[edit] Postconditions

Threads change shared data value in turns. The other thread waits if RMutex::Wait() is called and continues after RMutes::Signal().

[edit] See also

Archived:RThread - Symbian threading example Using RThread

This page was last modified on 2 September 2012, at 00:10.
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