join should yield item immediately if either stream is ready #13
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If one of the streams is ready and the other is pending, we should just return the item from the ready stream. Otherwise, join will never resolve until both streams are ready (which could be never). Fixes danieldg#12.
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After a lot of testing against zbus, I'm confident about these fixes to address the issue at hand. It remains another discussion if the "issue" is very much intentional. The way we've so far been using it in zbus, #12 didn't pose any issues cause we were joining method calls with message streams, where both of them were pretty much guaranteed to yield values quickly. This is now about to change in zbus with my in progress work to enable match-rule-based message streams where a task is only awaken for messages that it is interested in. These specific streams therefore are not always able to produce values so if i join such a stream with a method call, the method call is guaranteed to hang without this PR. Anyway, I'm merging this now. I understand you're probably taking time off during this season so I'll try my best to hold off releasing as long as possible, in case you've better ideas on how to handle this. |
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Sorry about the delay looking at this; I took a quick look and thought it was fine, but didn't take time to really think about the edge cases until recently. |
Now that you're available, could you please address my concerns/problems I described above before undoing my work? Thanks. |
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The reason I did not release is because I did want your feedback. In the future, I will do it via MR; I didn't think about that. |
If one of the streams is ready and the other is pending, we should just return the item from the ready stream. Otherwise, join will never resolve until both streams are ready (which could be never).
Fixes #12.