Buffer channelReads in ResponseStreamState until the next channelReadComplete#388
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Lukasa reviewed Jul 6, 2021
| case waitingForRead(CircularBuffer<ByteBuffer>) | ||
| /// The state machines expects a call to `demandMoreResponseBodyParts`. The buffer is empty. It is | ||
| /// preserved for performance reasons. | ||
| case waitingForDemand(CircularBuffer<ByteBuffer>) |
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By making this a mini-state-machine, I recommend going the whole way: pull this out to a file and give it a bunch of methods that correspond to the events that can occur to it (e.g. func read). Then, the bigger state machine can just call those.
fabianfettforce-pushed the ff-buffer-in-channel branch from d76029f to 96fbbbdComparefabianfett changed the title channelReads in the HTTPRequestStateMachine until the next channelReadCompletechannelReads in ResponseStreamState until the next channelReadCompleteLukasa reviewed Jul 7, 2021
| privatevarstate:State | ||
| init(expectingBody:Bool){ | ||
| self.state =.waitingForBytes(CircularBuffer(initialCapacity: expectingBody ?16:0)) |
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Given that there is no such thing as an empty circular buffer (initialCapacity: 0 still allocates) we may as well skip the branch and just always set 16.
| mutatingfunc end()->CircularBuffer<ByteBuffer>{ | ||
| switchself.state { | ||
| case.waitingForBytes(let buffer): | ||
| // This should never happen. But we don't want to precondition this behavior. Let's just |
| expectingBody =true | ||
| } | ||
| }elseif head.headers.contains(name:"transfer-encoding"){ | ||
| expectingBody =true |
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We can delete this code per my above comment.
fabianfettforce-pushed the ff-buffer-in-channel branch from 2c49141 to a4fba69CompareLukasa approved these changes Jul 7, 2021
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Motivation
After a lengthy offline discussion @Lukasa, we concluded that it would be best, if the
HTTPRequestStateMachinewould buffer up all reads until the nextchannelReadComplete. The main reason is, we minimize potential cross thread communication, by passing collected byteBuffers onward.Modifications
ConsumerControlStatewas replaced withResponseStreamStatechannelReads are buffered up to achannelReadComplete.channelReadCompleteall buffered body parts are forwarded to the consumer