Re: Threading Problem

• Subject: Re: Threading Problem
• From: Frederick Cheung <email@hidden>
• Date: Mon, 11 Jun 2007 16:20:32 +0100
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On 11 Jun 2007, at 15:37, Dave wrote:

Hi,

I have a plug-in that process large movie files. At present when it is called it doesn't return until the whole movie has been processed (which means that the host app is locked up). I'd like to make the movie processing a separate task and have it run in the background.

The host App would then peroodically call a "GetProcessStatus" function that would return the status saying if the task is "busy" or not.

I found some sample code and am adapting it for my own use (please see code copied below). However, I'm not sure how I get the status. The sample code waited for the task to complete before returning:

myOSStatus = MPWaitOnQueue(myTerminationQueue,NULL, NULL,(void **) &myTerminationStatus,kDurationImmediate);
if (myOSStatus == noErr)
{
myDoneFlag = true;
myOSStatus = myTerminationStatus;
}
while ((myOSStatus == noErr) && (myDoneFlag == false);
}

What is the best way to do this? Is there an API call to test if the queue would wait or not?

Fred

That way, I could just call this function in my "GetStatus()" function.

Thanks a lot
All the Best
Dave

// ********************************************************************** ************************
//**
//** ProccessMovieMPTask
//**
// ********************************************************************** ************************
static OSStatus crsUtilProccessMovieMPTask(char* theProcessParameters)
{
return(noErr);
}

#define kCopyFileTaskStackSize	(32 * 1024)

// ********************************************************************** ************************
//**
//** ProccessMovieMP
//**
// ********************************************************************** ************************
static OSStatus ProccessMovieMP(FSRef* theFilePathName)
{
OSStatus myOSStatus;
OSStatus myJunk;
OSStatus myTerminationStatus;
MPQueueID myTerminationQueue;
MPTaskID myTaskID;
Boolean myDoneFlag;
EventRecord myEventRecord;

myTerminationStatus = noErr;

//params.source = source;
//params.destDir = destDir;
//params.copyBuffer = copyBuffer;
//params.copyBufferSize = copyBufferSize;

// Create the termination queue and the task itself.

//**
//**  Create the termination queue and the task itself
//**
myOSStatus = MPCreateQueue(&myTerminationQueue);
if (myOSStatus != noErr)
	goto crsUtilProccessMovieMP_999;
	
myOSStatus = MPCreateTask((TaskProc) crsUtilProccessMovieMPTask,
						&params,
						kCopyFileTaskStackSize,
						myTerminationQueue,
						nil,
						nil,
						0,
						&myTaskID);
	
if (myOSStatus != noErr)
	goto crsUtilProccessMovieMP_999;

myDoneFlag = false;

//**
//** Wait for the Task to Complete
//**
do
{
myOSStatus = MPWaitOnQueue(myTerminationQueue,NULL, NULL,(void **) &myTerminationStatus,kDurationImmediate);
if (myOSStatus == noErr)
{
myDoneFlag = true;
myOSStatus = myTerminationStatus;
}
while ((myOSStatus == noErr) && (myDoneFlag == false);
}

myJunk = MPDeleteQueue(myTerminationQueue);
}

crsUtilProccessMovieMP_999:
return(myOSStatus);
}

Boolean GetMovieProcessStatusMP()
{

//  return false is busy, return true if done.
}

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