Responsiveness under Working Conditions #242
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,4 +1,4 @@ | ||
| version: 1 | ||
| builder: | ||
| configs: | ||
| - documentation_targets: [NIOExtras, NIOHTTPCompression, NIOSOCKS, NIOHTTPTypes, NIOHTTPTypesHTTP1, NIOHTTPTypesHTTP2, NIOResumableUpload, NIOHTTPResponsiveness] |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,228 @@ | ||
| //===----------------------------------------------------------------------===// | ||
| // | ||
| // This source file is part of the SwiftNIO open source project | ||
| // | ||
| // Copyright (c) 2024 Apple Inc. and the SwiftNIO project authors | ||
| // Licensed under Apache License v2.0 | ||
| // | ||
| // See LICENSE.txt for license information | ||
| // See CONTRIBUTORS.txt for the list of SwiftNIO project authors | ||
| // | ||
| // SPDX-License-Identifier: Apache-2.0 | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
|
|
||
| import HTTPTypes | ||
| import NIOCore | ||
| import NIOHTTPTypes | ||
|
|
||
| /// HTTP request handler sending a configurable stream of zeroes | ||
| public final class HTTPDrippingDownloadHandler: ChannelDuplexHandler { | ||
| public typealias InboundIn = HTTPRequestPart | ||
| public typealias OutboundOut = HTTPResponsePart | ||
| public typealias OutboundIn = Never | ||
|
|
||
| // Predefine buffer to reuse over and over again when sending chunks to requester. NIO allows | ||
| // us to give it reference counted buffers. Reusing like this allows us to avoid allocations. | ||
| static let downloadBodyChunk = ByteBuffer(repeating: 0, count: 65536) | ||
|
|
||
| private var frequency: TimeAmount | ||
| private var size: Int | ||
| private var count: Int | ||
| private var delay: TimeAmount | ||
| private var code: HTTPResponse.Status | ||
|
|
||
| private enum Phase { | ||
| /// We haven't gotten the request head - nothing to respond to | ||
| case waitingOnHead | ||
| /// We got the request head and are delaying the response | ||
| case delayingResponse | ||
| /// We're dripping response chunks to the peer, tracking how many chunks we have left | ||
| case dripping(DrippingState) | ||
| /// We either sent everything to the client or the request ended short | ||
| case done | ||
| } | ||
|
|
||
| private struct DrippingState { | ||
| var chunksLeft: Int | ||
| var currentChunkBytesLeft: Int | ||
| } | ||
|
|
||
| private var phase = Phase.waitingOnHead | ||
| private var scheduled: Scheduled<Void>? | ||
| private var pendingRead = false | ||
| private var pendingWrite = false | ||
| private var activelyWritingChunk = false | ||
|
|
||
| /// Initializes an `HTTPDrippingDownloadHandler`. | ||
| /// - Parameters: | ||
| /// - count: How many chunks should be sent. Note that the underlying HTTP | ||
| /// stack may split or combine these chunks into data frames as | ||
| /// they see fit. | ||
| /// - size: How large each chunk should be | ||
| /// - frequency: How much time to wait between sending each chunk | ||
| /// - delay: How much time to wait before sending the first chunk | ||
| /// - code: What HTTP status code to send | ||
| public init( | ||
| count: Int = 0, | ||
| size: Int = 0, | ||
| frequency: TimeAmount = .zero, | ||
| delay: TimeAmount = .zero, | ||
| code: HTTPResponse.Status = .ok | ||
| ) { | ||
| self.frequency = frequency | ||
| self.size = size | ||
| self.count = count | ||
| self.delay = delay | ||
| self.code = code | ||
| } | ||
|
|
||
| public convenience init?(queryArgsString: Substring.UTF8View) { | ||
| self.init() | ||
|
|
||
| let pairs = queryArgsString.split(separator: UInt8(ascii: "&")) | ||
| for pair in pairs { | ||
| var pairParts = pair.split(separator: UInt8(ascii: "="), maxSplits: 1).makeIterator() | ||
| guard let first = pairParts.next(), let second = pairParts.next() else { | ||
| continue | ||
| } | ||
|
|
||
| guard let secondNum = Int(Substring(second)) else { | ||
| return nil | ||
| } | ||
|
|
||
| switch Substring(first) { | ||
| case "frequency": | ||
| self.frequency = .seconds(Int64(secondNum)) | ||
| case "size": | ||
| self.size = secondNum | ||
| case "count": | ||
| self.count = secondNum | ||
| case "delay": | ||
| self.delay = .seconds(Int64(secondNum)) | ||
| case "code": | ||
| self.code = HTTPResponse.Status(code: secondNum) | ||
| default: | ||
| continue | ||
| } | ||
| } | ||
| } | ||
|
|
||
| public func channelRead(context: ChannelHandlerContext, data: NIOAny) { | ||
| let part = self.unwrapInboundIn(data) | ||
|
|
||
| switch part { | ||
| case .head: | ||
| self.phase = .delayingResponse | ||
|
|
||
| if self.delay == TimeAmount.zero { | ||
| // If no delay, we might as well start responding immediately | ||
| self.onResponseDelayCompleted(context: context) | ||
| } else { | ||
| let this = NIOLoopBound(self, eventLoop: context.eventLoop) | ||
| let loopBoundContext = NIOLoopBound(context, eventLoop: context.eventLoop) | ||
| self.scheduled = context.eventLoop.scheduleTask(in: self.delay) { | ||
| this.value.onResponseDelayCompleted(context: loopBoundContext.value) | ||
| } | ||
| } | ||
| case .body, .end: | ||
| return | ||
| } | ||
| } | ||
|
|
||
| private func onResponseDelayCompleted(context: ChannelHandlerContext) { | ||
| guard case .delayingResponse = self.phase else { | ||
| return | ||
| } | ||
|
|
||
| var head = HTTPResponse(status: self.code) | ||
|
|
||
| // If the length isn't too big, let's include a content length header | ||
| if case (let contentLength, false) = self.size.multipliedReportingOverflow(by: self.count) { | ||
| head.headerFields = HTTPFields(dictionaryLiteral: (.contentLength, "\(contentLength)")) | ||
| } | ||
|
|
||
| context.writeAndFlush(self.wrapOutboundOut(.head(head)), promise: nil) | ||
| self.phase = .dripping( | ||
| DrippingState( | ||
| chunksLeft: self.count, | ||
| currentChunkBytesLeft: self.size | ||
| ) | ||
| ) | ||
|
|
||
| self.writeChunk(context: context) | ||
| } | ||
|
|
||
| public func channelInactive(context: ChannelHandlerContext) { | ||
| self.phase = .done | ||
| self.scheduled?.cancel() | ||
|
There was a problem hiding this comment. We should forward the |
||
| } | ||
|
|
||
| public func channelWritabilityChanged(context: ChannelHandlerContext) { | ||
| if case .dripping = self.phase, self.pendingWrite && context.channel.isWritable { | ||
| self.writeChunk(context: context) | ||
| } | ||
| } | ||
|
|
||
| private func writeChunk(context: ChannelHandlerContext) { | ||
| // Make sure we don't accidentally reenter | ||
| if self.activelyWritingChunk { | ||
| return | ||
| } | ||
| self.activelyWritingChunk = true | ||
| defer { | ||
| self.activelyWritingChunk = false | ||
| } | ||
|
|
||
| // If we're not dripping the response body, there's nothing to do | ||
| guard case .dripping(var drippingState) = self.phase else { | ||
| return | ||
| } | ||
|
|
||
| // If we've sent all chunks, send end and be done | ||
| if drippingState.chunksLeft < 1 { | ||
| self.phase = .done | ||
| context.writeAndFlush(self.wrapOutboundOut(.end(nil)), promise: nil) | ||
| return | ||
| } | ||
|
|
||
| var dataWritten = false | ||
| while drippingState.currentChunkBytesLeft > 0, context.channel.isWritable { | ||
| let toSend = min(drippingState.currentChunkBytesLeft, HTTPDrippingDownloadHandler.downloadBodyChunk.readableBytes) | ||
| let buffer = HTTPDrippingDownloadHandler.downloadBodyChunk.getSlice( | ||
| at: HTTPDrippingDownloadHandler.downloadBodyChunk.readerIndex, | ||
| length: toSend | ||
| )! | ||
| context.write(self.wrapOutboundOut(.body(buffer)), promise: nil) | ||
| drippingState.currentChunkBytesLeft -= toSend | ||
| dataWritten = true | ||
| } | ||
| if dataWritten { | ||
| context.flush() | ||
| } | ||
|
There was a problem hiding this comment. Should we delay this slightly to avoid flushing twice in case we're done? (i.e. here and after writing end) There was a problem hiding this comment. Had to be careful here and put an extra |
||
|
|
||
| // If we weren't able to send the full chunk, it's because the channel isn't writable. We yield until it is | ||
| if drippingState.currentChunkBytesLeft > 0 { | ||
| self.pendingWrite = true | ||
| self.phase = .dripping(drippingState) | ||
| return | ||
| } | ||
|
|
||
| // We sent the full chunk. If we have no more chunks to write, we're done! | ||
| drippingState.chunksLeft -= 1 | ||
| if drippingState.chunksLeft == 0 { | ||
| self.phase = .done | ||
| context.writeAndFlush(self.wrapOutboundOut(.end(nil)), promise: nil) | ||
| return | ||
| } | ||
|
|
||
| // More chunks to write.. Kick off timer | ||
| drippingState.currentChunkBytesLeft = self.size | ||
| self.phase = .dripping(drippingState) | ||
| let this = NIOLoopBound(self, eventLoop: context.eventLoop) | ||
| let loopBoundContext = NIOLoopBound(context, eventLoop: context.eventLoop) | ||
| self.scheduled = context.eventLoop.scheduleTask(in: self.frequency) { | ||
|
There was a problem hiding this comment. A recent-ish NIO got a Might be worth using that. There was a problem hiding this comment. Thanks for the suggestion. I think I used it mostly correctly, but I'm not 100% sure. I haven't built much intuition around when swift does or doesn't allocate. I did find the fact that |
||
| this.value.writeChunk(context: loopBoundContext.value) | ||
| } | ||
| } | ||
| } | ||
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,90 @@ | ||
| //===----------------------------------------------------------------------===// | ||
| // | ||
| // This source file is part of the SwiftNIO open source project | ||
| // | ||
| // Copyright (c) 2024 Apple Inc. and the SwiftNIO project authors | ||
| // Licensed under Apache License v2.0 | ||
| // | ||
| // See LICENSE.txt for license information | ||
| // See CONTRIBUTORS.txt for the list of SwiftNIO project authors | ||
| // | ||
| // SPDX-License-Identifier: Apache-2.0 | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
|
|
||
| import HTTPTypes | ||
| import NIOCore | ||
| import NIOHTTPTypes | ||
|
|
||
| /// HTTP request handler that receives arbitrary bytes and discards them | ||
| public final class HTTPReceiveDiscardHandler: ChannelInboundHandler { | ||
|
|
||
| public typealias InboundIn = HTTPRequestPart | ||
| public typealias OutboundOut = HTTPResponsePart | ||
|
|
||
| private let expectation: Int? | ||
| private var expectationViolated = false | ||
| private var received = 0 | ||
|
|
||
| /// Initializes `HTTPReceiveDiscardHandler` | ||
| /// - Parameter expectation: how many bytes should be expected. If more | ||
| /// bytes are received than expected, an error status code will | ||
| /// be sent to the client | ||
| public init(expectation: Int?) { | ||
| self.expectation = expectation | ||
| } | ||
|
|
||
| public func channelRead(context: ChannelHandlerContext, data: NIOAny) { | ||
| let part = self.unwrapInboundIn(data) | ||
|
|
||
| switch part { | ||
| case .head: | ||
| return | ||
| case .body(let buffer): | ||
| self.received += buffer.readableBytes | ||
|
|
||
| // If the expectation is violated, send 4xx | ||
| if let expectation = self.expectation, self.received > expectation { | ||
| self.onExpectationViolated(context: context, expectation: expectation) | ||
| } | ||
| case .end: | ||
| if self.expectationViolated { | ||
| // Already flushed a response, nothing else to do | ||
| return | ||
| } | ||
|
|
||
| if let expectation = self.expectation, self.received != expectation { | ||
| self.onExpectationViolated(context: context, expectation: expectation) | ||
| return | ||
| } | ||
|
|
||
| let responseBody = ByteBuffer(string: "Received \(self.received) bytes") | ||
| self.writeSimpleResponse(context: context, status: .ok, body: responseBody) | ||
| } | ||
| } | ||
|
|
||
| private func onExpectationViolated(context: ChannelHandlerContext, expectation: Int) { | ||
| self.expectationViolated = true | ||
|
|
||
| let body = ByteBuffer( | ||
| string: | ||
| "Received in excess of expectation; expected(\(expectation)) received(\(self.received))" | ||
| ) | ||
| self.writeSimpleResponse(context: context, status: .ok, body: body) | ||
|
There was a problem hiding this comment. L46 says the status should be a 4xx status code. |
||
| } | ||
|
|
||
| private func writeSimpleResponse( | ||
| context: ChannelHandlerContext, | ||
| status: HTTPResponse.Status, | ||
| body: ByteBuffer | ||
| ) { | ||
| let bodyLen = body.readableBytes | ||
| let responseHead = HTTPResponse( | ||
| status: status, | ||
| headerFields: HTTPFields(dictionaryLiteral: (.contentLength, "\(bodyLen)")) | ||
| ) | ||
| context.write(self.wrapOutboundOut(.head(responseHead)), promise: nil) | ||
| context.write(self.wrapOutboundOut(.body(body)), promise: nil) | ||
| context.writeAndFlush(self.wrapOutboundOut(.end(nil)), promise: nil) | ||
| } | ||
| } | ||
Oops, something went wrong.
Oops, something went wrong.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Can we document that this requires the use of the HTTPTypes types, not the regular NIO ones.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Can I suggest that, for now, we don't make the two "helper" handlers
public? It's generally wise for us not to commit to too much API without a clear use-case. Making somethingpublicthat was previouslyinternalis generally easy, changing something that we accidentally madepublicis much harder.There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
The two "helper" handlers you're referring to are the HTTPDrippingDownloadHandler and the HTTPReceiveDiscardHandler, right? The idea being only the ResponsivenessConfig and SimpleResponsivenessRequestMux end up being public?
I think doing that would end up making this more of an example than a building block. I find that request multiplexers are typically not very reusable (hence the prefix "Simple"). My expectation is that someone wanting to put together a robust implementation would have their own request mux and add things like limits on download size, delay durations, etc.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
That's fair enough.