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<concept id="GUID-24477051-265A-5FE5-B479-ACB3EE27B825" xml:lang="en"><title>Synchronisation

Techniques</title><shortdesc>Describes the use of <codeph>RThread::Rendezvous()</codeph> to

synchronize threads.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>There are a number of techniques to synchronize or coordinate the activities

of your threads with one another: </p>

<ul>

<li id="GUID-E5EC8F8C-2129-5750-AFDC-F4B15E3874C9"><p> <xref href="GUID-24477051-265A-5FE5-B479-ACB3EE27B825.dita#GUID-24477051-265A-5FE5-B479-ACB3EE27B825/GUID-68FCE30C-5487-501E-842C-6895717FD636">Thread Rendezvous</xref> </p> </li>

</ul>

<section id="GUID-68FCE30C-5487-501E-842C-6895717FD636"><title>Thread Rendezvous</title> <p>The <xref href="GUID-B0E661BC-4058-3256-B9C3-5A4FD52F6DE5.dita#GUID-B0E661BC-4058-3256-B9C3-5A4FD52F6DE5/GUID-83AADCC6-1AD8-32D8-A6E6-B86B47C97DC2"><apiname>RThread::Rendezvous()</apiname></xref> function

allows a thread to signal that it has reached a point in its execution. This

works in a similar way to the <xref href="GUID-77B673ED-F7EE-3D50-88A7-F8FBFCB2D64E.dita"><apiname>Logon()</apiname></xref> function, except

that <xref href="GUID-77B673ED-F7EE-3D50-88A7-F8FBFCB2D64E.dita"><apiname>Logon()</apiname></xref> signals the termination of a thread, and <xref href="GUID-45C22917-DC6E-3C95-BFE5-B8E9B316D4E3.dita"><apiname>Rendezvous()</apiname></xref> signals

that a particular point within the thread has been reached. </p> <p>The classic

use for this function is in a server, where the main thread must wait until

the initialisation of the server thread has completed before continuing. </p> </section>

<section id="GUID-7A87E7D5-255B-4626-ADB0-7A8F3F839C3C"><title>Using Rendezvous</title> <p>The

following example shows code a function creating a thread and then waiting

for it to reach a certain point before continuing. The code shown here is

taken from <filepath>…\examples\base\threadsandprocesses\Rendezvous\</filepath>,

which you can build and run. </p> <codeblock id="GUID-292F2672-390D-5D14-9615-8894315A1645" xml:space="preserve">      // create threads to wait for

    RThread thread;

        // indicate completion status

    TRequestStatus myThreadRendezvousStatus;

        // pass 500 as the parameter to MyThread        

    TInt r=thread.Create(KMsgMyThreadName, MyThread, KDefaultStackSize, KHeapSize,KHeapSize,(TAny*) 2000000, EOwnerThread); 

    if (r!=KErrNone)

        {   

        console->Printf(KMsgCreateThreadFailed);

            return;

        }

        // create rendezvous

    thread.Rendezvous(myThreadRendezvousStatus);

        //EXCECUTE THREAD!

    console->Printf(KMsgStartThread);                    

    thread.Resume();

    User::WaitForRequest(myThreadRendezvousStatus);

    if(myThreadRendezvousStatus==KErrNone)

        {

        console->Printf(KMsgThreadRendezvousReached);

        }

        else

        {

        console->Printf(KMsgSomethingIsWrong);   

        }   

    thread.Close();

    console-&gt;Printf(KMsgEndOfTest);</codeblock> <p>The following function

is the <codeph>MyThread()</codeph> function created in the previous example.

The <codeph>MyThread()</codeph> function calls the rendezvous function to

signal that the rendezvous point has been reached, <codeph>MyThread()</codeph> can

then continue. </p> <codeblock id="GUID-94F0244E-B3E8-54F0-9BD8-6BB8942BA30F" xml:space="preserve">TInt MyThread(TAny* aParameter)

    {

        // simulate some processing

    User::After((TInt)aParameter);      

            // signal Rendezvous

    RThread::Rendezvous(KErrNone);

        // simulate some processing

    User::After((TInt)aParameter);      

    return(KErrNone);

    }</codeblock> <note><p> <codeph>MyThread()</codeph> can fail before signalling

the <xref href="GUID-251A11AD-1D92-3F9C-AAEF-3D0FC9728C7E.dita"><apiname>Rendezvous</apiname></xref>, for example, if <codeph>MyThread()</codeph> panics

with a <codeph>KERN-EXEC 3</codeph>, then the <xref href="GUID-251A11AD-1D92-3F9C-AAEF-3D0FC9728C7E.dita"><apiname>Rendezvous</apiname></xref> completes

with the reason code <codeph>KErrDied</codeph> or another system wide error

code other than <codeph>KErrNone</codeph>. </p></note><p>If <xref href="GUID-B3606A64-D3FB-3B92-8675-FBFD57675564.dita"><apiname>MyThread()</apiname></xref> enters

a never ending loop before the rendezvous is reached, then this situation

cannot be detected and results in the calling thread waiting indefinitely

for the rendezvous. This can be avoided by careful programming. </p> </section>

</conbody></concept>