Add AsyncSequence helpers #1939
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| public typealias AsyncIterator = Iterator | ||
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| @usableFromInline | ||
| let upstream: Upstream |
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Nit: this may as well be var. It doesn't really matter but it can't hurt.
| /// - Parameter maxBytes: The maximum number of bytes that the result ByteBuffer is allowed to have. | ||
| /// - Returns: A ``NIO/ByteBuffer`` that holds all the bytes of the AsyncSequence | ||
| @inlinable | ||
| public func consume(maxBytes: Int) async throws -> ByteBuffer? { |
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Hmm, is returning nil here a good idea? I'm a bit inclined to want to return an empty buffer.
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consume feels to me like we're actually "reading" the bytes, collect might be more appropriate.
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I wonder if an additional lower-level variant accepting an inout ByteBuffer would also be useful? Callers could for example, reserve capacity or collect from multiple sequences into the same buffer without an intermediate copy.
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This seems like it would be more useful as a general "collect bytes from this stream of buffers" API on ByteBuffer itself.
Which means I think there might be benefit to moving it, and loosening the constraints to allow for async sequences of any buffer type (Data, Array, etc).
| switch try await upstream.next() { | ||
| case .some(let nextBuffer) where nextBuffer.readableBytes == 0: | ||
| // we received an empty buffer. for this reason, let's continue and get the | ||
| // next buffer fro, the sequence |
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| // next buffer fro, the sequence | |
| // next buffer from the sequence |
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| case .some(var nextBuffer): | ||
| assert(nextBuffer.readableBytes > 0) | ||
| let result = nextBuffer.readInteger(as: UInt8.self) |
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Should this be banged? We assert that there must readable bytes so reading one mustn't fail
| import struct NIO.ByteBuffer | ||
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| @available(macOS 12, iOS 15, tvOS 15, watchOS 8, *) | ||
| public struct NIOByteBufferToUInt8AsyncSequence<Upstream: AsyncSequence>: AsyncSequence where Upstream.Element == ByteBuffer { |
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I don't love the name. URLSession uses AsyncBytes (i.e. URLSession.AsyncBytes) which I think is quite clear. How about ByteBuffer.AsyncBytes?
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Is this not basically an async version of FlattenSequence/.joined() from the standard library, specialised for ByteBuffer?
So... ByteBuffer.FlattenSequence, perhaps?
| /// Consume an ``Swift/AsyncSequence`` of ``NIO/ByteBuffer``s into a single `ByteBuffer`. | ||
| /// | ||
| /// - Parameter maxBytes: The maximum number of bytes that the result ByteBuffer is allowed to have. | ||
| /// - Returns: A ``NIO/ByteBuffer`` that holds all the bytes of the AsyncSequence |
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Not necessarily all the bytes
| /// - Parameter maxBytes: The maximum number of bytes that the result ByteBuffer is allowed to have. | ||
| /// - Returns: A ``NIO/ByteBuffer`` that holds all the bytes of the AsyncSequence | ||
| @inlinable | ||
| public func consume(maxBytes: Int) async throws -> ByteBuffer? { |
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consume feels to me like we're actually "reading" the bytes, collect might be more appropriate.
| extension AsyncSequence where Element == ByteBuffer { | ||
| /// Transform an AsyncSequence of ByteBuffers into an AsyncSequence of single bytes. | ||
| @inlinable | ||
| public func toBytes() -> NIOByteBufferToUInt8AsyncSequence<Self> { |
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Should this be a computed property?
for try await byte in body.bytes {
// ...
}vs.
for try await byte in body.toBytes() {
// ...
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joined() seems like a better name for this, to mirror both FlattenSequence and the String concatenation helper from the standard library.
| /// - Parameter maxBytes: The maximum number of bytes that the result ByteBuffer is allowed to have. | ||
| /// - Returns: A ``NIO/ByteBuffer`` that holds all the bytes of the AsyncSequence | ||
| @inlinable | ||
| public func consume(maxBytes: Int) async throws -> ByteBuffer? { |
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I wonder if an additional lower-level variant accepting an inout ByteBuffer would also be useful? Callers could for example, reserve capacity or collect from multiple sequences into the same buffer without an intermediate copy.
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This PR does not have any tests yet. It is here, to demonstrate some
AsyncSequenceandByteBufferhelpers that we might want to add to make our consumers lifes' easier.Motivation:
In the [RFC] for an async/await API in AsyncHTTPClient @adam-fowler asked, if there could be a helper method to transform an AsyncSequence of
ByteBuffers into a singleByteBuffer. Following our strict rule of implementing conformances only to types you we own we must add those convenience helpers to SwiftNIO directly.Modifications:
func consume(maxBytes: Int) async throws -> ByteBufferthat consumes an AsyncSequence ofByteBuffers into a singleByteBufferfunc bytes()that translates anAsyncSequenceofByteBuffers into an AsyncSequence of Bytes (UInt8)