site_archiver@lists.apple.com Delivered-To: cocoa-dev@lists.apple.com [self cancelAllOperations]; [self waitUntilAllOperationsAreFinished]; Cancelling the operations is asynchronous since an in-progress op may take a little while to finish up. Mike. On 31 Mar 2010, at 22:32, Jerry Krinock wrote:

I execute the following code in a subclass of NSOperationQueue:

if (error) { NSLog(@"Cancelling all operations due to error") ; [self cancelAllOperations] ; } NSLog(@"#1 Remaining operations in %p:\n%@", self, [self operations]) ; NSLog(@"#2 Remaining operations in %p:\n%@", self, [self operations]) ;

The console result:

2010-03-31 14:06:11.581 TestApp[10342:7d0f] Cancelling all operations due to error 2010-03-31 14:06:11.583 TestApp[10342:7d0f] #1 Remaining operations in 0x1a38e6a0: ( <NSInvocationOperation: 0x1a38d740>, SSYOperation 0x1a38d7e0 selector=saveDocument, <NSInvocationOperation: 0x1a386510>, SSYOperation 0x1a3a5510 selector=terminateWork, <NSInvocationOperation: 0x1a385f20> ) 2010-03-31 14:06:11.584 TestApp[10342:7d0f] #2 Remaining operations in 0x1a38e6a0: ( <NSInvocationOperation: 0x1a38d740> )

So you see in NSLog #1 there are 5 operations in the queue. This is expected, because although the documentation for -cancelAllOperations is a little vague, it does not say that it *removes* any operations from the queue.

But what happens in NSLog #2? All operations are gone except the first one. All of a sudden!

Big thanks to anyone who can offer any clues on this.

Jerry Krinock

P.S. The above code is executing on a secondary thread. Is that a possible issue? NSOperationQueue is not listed as a thread-safe class in the Threading Programming Guide. But in the class documentation it says "It is safe to use a single NSOperationQueue object from multiple threads without creating additional locks to synchronize access to that object." I tried running the above code with performSelectorOnMainThread wrappers, but got a deadlock I can't explain either. (Sample shows mach_msg_trap.)

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