Cancel
Stops the queue from dequeueing any further tasks, and notifies the specified handler when all in-flight tasks finish.
Declaration
kern_return_t Cancel(IODispatchQueueCancelHandler handler);Parameters
- handler:
The block to execute when the queue finishes all in-flight work.
Return Value
kIOReturnSuccess on success, or another value if an error occurs. For a list of error codes, see Error Codes.
Discussion
This method asynchronously tells the dispatch queue to stop the execution of queued tasks, and returns immediately. If a task is already executing, that task runs to completion. After all tasks finish, the dispatch queue executes the block in the handler parameter.