[Flight] Properly close stream when no chunks need to be written after prerender #33982
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…r prerender There is an edge case when prerendering where if you have nothing to write you can end up in a state where the prerender is in status closed before you can provide a destination. In this case the destination is never closed becuase it assumes it already would have been. This condition can happen now because of the introduction of the deubg stream. Before this a request would never entere closed status if there was no active destination. When a destination was added it would perform a flush and possibly close the stream. Now, it is possible to flush without a destination because you might have debug chunks to stream and you can end up closing the stream independent of an active destination. There are a number of ways we can solve this but the one that seems to adhere best to the original design is to only set the status to CLOSED when a destination is active. This means that if you don't have an active destination when the pendingChunks count hits zero it will not enter CLOSED status until you startFlowing.
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sebmarkbage
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There is an edge case when prerendering where if you have nothing to write you can end up in a state where the prerender is in status closed before you can provide a destination. In this case the destination is never closed becuase it assumes it already would have been.
This condition can happen now because of the introduction of the deubg stream. Before this a request would never entere closed status if there was no active destination. When a destination was added it would perform a flush and possibly close the stream. Now, it is possible to flush without a destination because you might have debug chunks to stream and you can end up closing the stream independent of an active destination.
There are a number of ways we can solve this but the one that seems to adhere best to the original design is to only set the status to CLOSED when a destination is active. This means that if you don't have an active destination when the pendingChunks count hits zero it will not enter CLOSED status until you startFlowing.