You can imagine that this registers a window class, and calls CreateWindow to create the top-level desktop window. CreateDispatcherQueueController function is then called to create the queue controller before calling some coroutine with the dispatcher queue owned by this controller.
A traditional message pump is then entered where resumption of the coroutine naturally occurs on this thread. Having done that, you can return to the elegant world of coroutines for your async or message-based workflow within your application. You can also optionally set the resumption priority. Or, in this case detecting queue shutdown, and handling it gracefully. In other words, that queuing was successful.
The user has the option to cancel the operation. Cancel ; workButton. Cancellation can, of course, happen while the coroutine is suspended. The issue is one of potentially too-coarse-grained latency in responding to cancellation. So, another option is to explicitly poll for cancellation from within your coroutine. Update the example above with the code in the listing below. The outcome is the same as the previous example, but here exiting happens explicitly, and under control.
You can use the function call operator on that token to query the cancellation state—essentially polling for cancellation. But—introduced in version This is a pre-emptive hook by which cancellation can be propagated, and makes it possible to integrate with existing concurrency libraries. In this next code example, NestedCoroutineAsync does the work, but it has no special cancellation logic in it. CancellationPropagatorAsync is essentially a wrapper on the nested coroutine; the wrapper forwards cancellation pre-emptively.
When or if CancellationPropagatorAsync is canceled, it propagates the cancellation to the nested coroutine. The above example chooses to set a provisional result for every progress report. You can choose to report provisional results any time, if at all.
It need not be coupled with a progress report. If you have both, then the second will fail. Either one of the following two kinds of completion handlers is appropriate; not both for the same async object. In that case, you can fire off the task and forget it. But observe that args is passed by value.
See the Parameter-passing section above. While awaiting DoWorkAsync, control has returned to the caller, the calling frame has gone out of scope, and you no longer know whether the handle will be valid when your coroutine resumes. Technically, our coroutine is receiving its parameters by value, as it should see Parameter-passing above.
We need to pass a strong reference in other words, ownership along with the handle. Their effect on writing concurrency code is transformational. This section discusses cases where details of asynchrony are not important, and all you want is the result there and then. Async objects tend to be very short-lived, so this is often all you need. Writing that code has always been possible, thanks to the building blocks provided by the Windows Runtime.
Tesla Inc. CEO Elon Musk promised in to demonstratea vehicle traveling in fully autonomous mode from Los Angeles to New York by the end of —a date that came and passed without such a public display. The incident led to more scrutiny of the technology and highlighted the safety challenges involved in turning a vehicle over to a robot. As some companies move from demos to deployment, it is clear that for now, a complex and costly back end of maintenance and operations is required to run these networks of vehicles.
Even amid the pessimism, many analysts say that autonomous technology still holds great potential, creating difficult decisions for car makers weighing future needs, particularly for electric-vehicle development. GM remains bullish on driverless cars, and has said that long-term, sustained investment is needed to make them a commercial success.
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