swift-http-server: Use AsyncReader in RequestBody

[adam-fowler]

Replace AsyncSequence of ByteBuffers in RequestBody with a AsyncReader. As the AsyncReader is ~Copyable the easiest way to do this is make RequestBody a class.

Also replace all functionality that returned a ByteBuffer to return a UniqueArray.

for try await buffer in request.body {
    ...
}

becomes

request.body.forEachBuffer { buffer in
    ...
}

TODO:

• Fix I/O on closed channel errors
• Add support for consumeWithInboundCloseHandler
• Add support for processing request data
• Fix up FileIO

Streaming tests need a response writer, so will fix those later

[codecov]

Codecov Report

❌ Patch coverage is 89.06883% with 27 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (swift-http-server@2288808). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
...s/HummingbirdCore/Request/RequestAsyncReader.swift	84.04%	15 Missing ⚠️
Sources/HummingbirdCore/Request/RequestBody.swift	87.50%	6 Missing ⚠️
Sources/HummingbirdCore/Utils/Disconnected.swift	66.66%	3 Missing ⚠️
Tests/HummingbirdTests/ApplicationTests.swift	83.33%	2 Missing ⚠️
Tests/HummingbirdCoreTests/CoreTests.swift	91.66%	1 Missing ⚠️

Additional details and impacted files

@@                 Coverage Diff                  @@
##             swift-http-server     #893   +/-   ##
====================================================
  Coverage                     ?   89.39%           
====================================================
  Files                        ?      168           
  Lines                        ?    12781           
  Branches                     ?        0           
====================================================
  Hits                         ?    11426           
  Misses                       ?     1355           
  Partials                     ?        0           

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[Copilot]

🟡 Changes recommended

Key streaming-related tests are currently disabled and HTTP/2 request draining behavior needs to be made robust to prevent regressions during the migration.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR migrates RequestBody from an AsyncSequence<ByteBuffer> model to an AsyncReader-based model (with UniqueArray<UInt8> buffers), updating server/channel handling and I/O utilities to match the new move-only reader semantics.

Changes:

• Replaces request-body streaming from AsyncSequence<ByteBuffer> to RequestAsyncReader (UniqueArray<UInt8> buffers), making RequestBody a reference type to support ~Copyable.
• Updates response writing and file I/O to accept AsyncReader inputs.
• Updates benchmarks/tests for the new body representation; several streaming-related tests are temporarily disabled during the migration.

File summaries

File	Description
Tests/HummingbirdTests/PersistTests.swift	Updates body collection/string decoding for UniqueArray<UInt8>.
Tests/HummingbirdTests/MiddlewareTests.swift	Temporarily disables response-writer middleware streaming tests.
Tests/HummingbirdTests/FileIOTests.swift	Switches FileIO write test to request.body.reader.
Tests/HummingbirdTests/ApplicationTests.swift	Migrates body APIs; temporarily disables streaming/bidirectional streaming tests.
Tests/HummingbirdRouterTests/MiddlewareTests.swift	Temporarily disables response-writer middleware streaming tests.
Tests/HummingbirdCoreTests/RequestBodyTests.swift	Updates request-body tests to construct via BaseRequestAsyncReader; disables inbound-close-handler tests.
Tests/HummingbirdCoreTests/HTTP1ChannelTests.swift	Updates expectations from readableBytes to count.
Tests/HummingbirdCoreTests/CoreTests.swift	Updates request/response body writing to new reader/buffer model; adds a delayed reader helper.
Sources/PerformanceTest/main.swift	Temporarily disables request-body echo path relying on async-sequence body.
Sources/HummingbirdTesting/RouterTestFramework.swift	Updates test request construction to use BaseRequestAsyncReader.
Sources/HummingbirdHTTP2/HTTP2StreamChannel.swift	Builds RequestBody via reader-state/reader; adjusts post-response inbound waiting logic.
Sources/HummingbirdCore/Utils/Disconnected.swift	Adds _Disconnected helper for moving non-Sendable values across isolation.
Sources/HummingbirdCore/Utils/AnyAsyncSequence.swift	Removes AnyAsyncSequence helper used by old request-body async-sequence model.
Sources/HummingbirdCore/Server/HTTP/HTTPChannelHandler.swift	Switches request construction to reader-backed bodies and drains bodies post-response for keep-alive.
Sources/HummingbirdCore/Response/ResponseBodyWriter.swift	Adds write(_ reader:) overload for AsyncReader of UniqueArray<UInt8>.
Sources/HummingbirdCore/Request/RequestBodyMergedWithUnderlyingRequestPartIterator.swift	Temporarily disabled pending RequestAsyncReader migration.
Sources/HummingbirdCore/Request/RequestBody+inboundClose.swift	Temporarily disabled pending RequestAsyncReader migration (consumeWithInboundCloseHandler).
Sources/HummingbirdCore/Request/RequestBody.swift	Replaces async-sequence backing with move-only reader backing; adds collect, pipe, drain, forEachBuffer.
Sources/HummingbirdCore/Request/RequestAsyncReader.swift	Introduces RequestAsyncReader, base channel-backed implementation, and collated reader.
Sources/HummingbirdCore/Request/Request.swift	Makes body a stored RequestBody and updates collectBody semantics/signature.
Sources/Hummingbird/Server/Request.swift	Removes unavailable legacy collate shim.
Sources/Hummingbird/Middleware/MetricsMiddleware.swift	Avoids capturing non-sendable request by copying method before closure.
Sources/Hummingbird/Files/FileIO.swift	Adds writeFile(reader:path:context:) overload for AsyncReader of UniqueArray<UInt8>.
Sources/Hummingbird/Exports.swift	Updates export of RequestBody to class instead of struct.
Sources/Hummingbird/Error/RequestAsyncReaderError+HTTPError.swift	Maps RequestAsyncReaderError to HTTP errors (e.g. payload too large).
Sources/Hummingbird/Codable/URLEncodedForm/URLEncodedForm+Request.swift	Updates request decoding to work from UniqueArray<UInt8> span.
Sources/Hummingbird/Codable/JSON/JSONCoding.swift	Updates JSON decoding to work from UniqueArray<UInt8> span.
Benchmarks/HummingbirdBenchmarks/RouterBenchmarks.swift	Updates benchmark request-body generation and body-size assertions.

Review details

Suppressed comments (1)

Tests/HummingbirdTests/MiddlewareTests.swift:149

• Response-body-writer middleware tests are commented out, which removes coverage for ResponseBodyWriter composition during the RequestAsyncReader migration. Replacing these with reader-based request streaming assertions would help ensure the new ResponseBodyWriter.write(_ reader:) path works end-to-end.

    /* TODO: Fixup for RequestAsyncReader
    @Test func testMiddlewareResponseBodyWriter() async throws {
        struct TransformWriter: ResponseBodyWriter {
            var parentWriter: any ResponseBodyWriter

• Files reviewed: 28/28 changed files
• Comments generated: 6
• Review effort level: Lite

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