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Delay in reading files, part 3. Pure Carbon this time.

Subject: Delay in reading files, part 3. Pure Carbon this time.
From: "Theodore H. Smith" <email@hidden>
Date: Tue, 13 Sep 2005 11:42:27 +0100
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OK, I think I've narrowed this problem down. But I still don't have the answer.

This code here:

int main() {
    WriteFile( kMyPlace, kMyName, kToWrite );

FSRef ref; OSErr err = FSPathMakeRef( (const unsigned char*) kMyPlace"/"kMyName, &ref, NULL ); if (err) { WriteFile( kMyPlace, "CantReadWhatIWrote", "argh!!!" ); } else { WriteFile( kMyPlace, "ICanReadIt", "yippee" ); }

    return 0;
}

I see a file called "ICanReadIt" created, meaning that I can read the file I wrote within the same program, immediately after it is written. This is what I'd expect.

However, from the parent program that calls this small program, I get this strange problem.

bool MacCheckPublishFileExists() {
    FSRef ref;
    OSStatus err = FSPathMakeRef( ProtFile, &ref, NULL );
    if (err) {
        return false;
    } else {
        return true;
    }
}

I get an non-zero err here, unless I wait for over 0.125 seconds after the auxilliary app exits.

    while (MacCheckPublishAppExists()) {
        WaitSeconds( 0.05 );
    }
    WaitSeconds( 0.13 );
    BOOL Result = MacCheckPublishFileExists();

In both cases I call FSPathMakeRef! So it can't be a case of mixing Cocoa or Carbon, can it?

I mean, the parent app is actually a Cocoa app, but in this case I'm using Carbon calls (FSPathMakeRef) to read the file.

This doesn't really make sense to me.

If I change the above code to this:

    while (MacCheckPublishAppExists()) {
        WaitSeconds( 0.05 );
    }
//    WaitSeconds( 0.13 ); // comment out this line!
    BOOL Result = MacCheckPublishFileExists();

So, we know that the app has finished. So this means by definition, that the file is written, correct? But yet we can't read the file till 0.125 seconds later.

Why???

Where is this documented? I don't see any such behaviour documented. I've never come across it before also. Am I doing something wrong? Or what's going on??


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