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@ -85,5 +85,38 @@ fn main() {
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(Yeah, I did all in a single file. Sue me.) |
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[async is channel, not spawn] |
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Quick explanation: Here, there are two threads, one for the producer and one |
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for the consumer; the MPSC (Multiple Producer, Single Consumer) channel is the |
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communication channel between those two. With the exception that it has only |
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one consumer, it is pretty close to the way I learnt producer/consumer |
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architecture at uni (not in Rust, but C, using mutexes). |
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## Where it falls apart |
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Now, the first thing one would do, knowing about "greenthreads" and |
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`tokio::spawn` is just to replace `thread::spawn` for the Tokio API and think |
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it is done. |
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And that's where my initial mental model broke down. |
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'Cause, you see, async is not the threads; **async is the channel**. And by |
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that I mean that each task is put in a queue (the event loop queue) and then |
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processed. Instead of just having data (in our example, an integer), it has |
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data and code; the code is the task and the data is whatever Rust moves into |
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the task. |
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## I saw multitasking correctly |
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One thing I believe I did right was to "mentalize" the way the event loop works |
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akin to Windows 3.11, which was really prone to become completely unresponsive |
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from time to time. The reason for that is that the event loop keeps running |
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things till someone says "Ok, I give up my time and someone else can run their |
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stuff" -- a.k.a. "cooperative multitasking". |
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Async works akin to cooperative multitasking, but instead of having the |
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developer add a bunch of "event loop, you can run something else" statements, |
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this is done in I/O layer, for one simple reason: Your code would, normally, |
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block on those, and the event loop will take care of running this in a |
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non-blocking fashion. |
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## |
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