×
Namespaces

Variants
Actions
(Difference between revisions)

Archived:RMutex - Symbian mutex class

From Nokia Developer Wiki
Jump to: navigation, search
tanjaluodes (Talk | contribs)
m
hamishwillee (Talk | contribs)
m (Hamishwillee - Bot change of template (Template:CodeSnippet) - now using Template:ArticleMetaData)
Line 2: Line 2:
 
__NOEDITSECTION__
 
__NOEDITSECTION__
 
{{KBCS}}
 
{{KBCS}}
{{CodeSnippet
+
{{ArticleMetaData
 
|id=CS000969
 
|id=CS000969
 
|platform=S60 3rd Edition, MR
 
|platform=S60 3rd Edition, MR
Line 10: Line 10:
 
|creationdate=May 20, 2008
 
|creationdate=May 20, 2008
 
|keywords=RMutex, RSemaphore, RThread
 
|keywords=RMutex, RSemaphore, RThread
 +
 +
|sourcecode= <!-- Link to example source code (e.g. [[Media:The Code Example ZIP.zip]]) -->
 +
|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]) -->
 +
|devicecompatability=<!-- Compatible devices (e.g.: All* (must have GPS) ) -->
 +
|signing=<!-- Empty or one of Self-Signed, DevCert, Manufacturer -->
 +
|capabilities=<!-- Capabilities required (e.g. Location, NetworkServices. -->)
 +
|author=[[User:Tepaa]]
 
}}
 
}}
  

Revision as of 11:27, 24 June 2011


Template:KBCS

Article Metadata
Tested with
Devices(s): Nokia N95
Compatibility
Platform(s): S60 3rd Edition, MR
S60 3rd Edition (initial release)
Platform Security
Capabilities: )
Article
Keywords: RMutex, RSemaphore, RThread
Created: tepaa (20 May 2008)
Last edited: hamishwillee (24 Jun 2011)

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 CS000867 - RThread example.

MMP file

The following capabilities and libraries are required:

CAPABILITY        NONE
LIBRARY euser.lib

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;
};


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();
}


Postconditions

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

See also

CS000867 - RThread Using RThread

82 page views in the last 30 days.

Was this page helpful?

Your feedback about this content is important. Let us know what you think.

 

Thank you!

We appreciate your feedback.

×