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Reading all data before the NSTask terminates, synchronizing notifications

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Reading all data before the NSTask terminates, synchronizing notifications

Subject: Reading all data before the NSTask terminates, synchronizing notifications
From: Frode <email@hidden>
Date: Sun, 2 Oct 2005 01:57:18 +0200

Hello!

I noticed that under some circumstances NSTaskDidTerminateNotification is sent before all NSFileHandleReadCompletionNotification are consumed. I suppose this is possible in all circumstances, isn't it? However, I only experience this in certain cases, and to show it with brutality I use sleep() to reproduce It. But in reality, sleep() is replaced with a processData-message, that in debug build uses NSLog() to print debug-messages and that is how I noticed it.

To remmedy this synchronization issue, I have to run the run-loop until a condition is set. And I'm not very comfortable with run-loops. Is there a smarter method to synchronize the notifications? And why do I need to do this? I suppose It can occure even if I send readInBackgroundAndNotify before I process the data (here represented by a sleep()), don't you think so?

Am I supposed to temporary turn off some kind of signals when using data-available notifications from a NSTasks? (Now, this is only something I have thought of but maybee it is crazyness.)

Thanks for any help
Roger P.

-(void)commandGetData:(NSNotification *)obj { NSData *incommingData = [[obj userInfo] objectForKey:NSFileHandleNotificationDataItem]; if([incommingData length]) { // uncommented [[obj object] readInBackgroundAndNotify]; // Is this correct? fprintf(stderr, "Received %u bytes: Sleeping for 1 seconds...", [incommingData length]); sleep(1); fprintf(stderr, "done!\n"); [dataBuffer appendData:incommingData]; [[obj object] readInBackgroundAndNotify]; //??? This is wrong } else { fprintf(stderr, "Completed!\n"); readCompleted = YES; } }

-(void)commandTerminated:(NSNotification *)obj { // Synchronize notifications int i = 1; while(readCompleted == NO) { fprintf(stderr, "Synchronizing#=> ", i++); [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]]; } fprintf(stderr, "%s Shell terminated %p, %u bytes received\n", __func__, [obj object], [dataBuffer length]);

    // ...
}

This is the output (readInBackgroundAndNotify AFTER sleep()):

Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 1> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 2> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 3> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 4> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 5> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 6> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 7> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 8> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 9> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 10> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 11> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 12> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 13> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 14> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 15> Received 510 bytes: Sleeping for 1 seconds...done! Synchronizing# 16> Received 423 bytes: Sleeping for 1 seconds...done! Synchronizing# 17> Completed! -[MnWindow commandTerminated:] Shell terminated 0x32d040, 24903 bytes received

If I do it the other way (readInBackgroundAndNotify BEFORE sleep()):

Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 510 bytes: Sleeping for 1 seconds...done! Received 423 bytes: Sleeping for 1 seconds...done! Completed! -[MnWindow commandTerminated:] Shell terminated 0x3f0ad0, 24903 bytes received

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