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Reusable JSONCoders #50

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Merged
merged 2 commits into from
Mar 27, 2020
Merged

Reusable JSONCoders #50

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316f138
Reuse JSONCoders
fabianfett Mar 26, 2020
44e425c
suggestion
tomerd Mar 27, 2020
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17 changes: 11 additions & 6 deletions Sources/AWSLambdaRuntime/Lambda+Codable.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -88,25 +88,30 @@ internal struct CodableVoidLambdaClosureWrapper<In: Decodable>: LambdaHandler {
public extension EventLoopLambdaHandler where In: Decodable, Out: Encodable {
func encode(allocator: ByteBufferAllocator, value: Out) throws -> ByteBuffer? {
// nio will resize the buffer if necessary
// FIXME: reusable JSONEncoder and buffer
var buffer = allocator.buffer(capacity: 1024)
try JSONEncoder().encode(value, into: &buffer)
try Lambda.defaultJSONEncoder.encode(value, into: &buffer)
return buffer
}

func decode(buffer: ByteBuffer) throws -> In {
// FIXME: reusable JSONDecoder
try JSONDecoder().decode(In.self, from: buffer)
try Lambda.defaultJSONDecoder.decode(In.self, from: buffer)
}
}

private extension Lambda {
/// the default json encoder used in `EventLoopLambdaHandler` if Out == Encodable
static let defaultJSONEncoder = JSONEncoder()
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one step further could be to introduce a protocol so one can inject a custom encoder/decoder

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@fabianfett fabianfett Mar 26, 2020 •
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Sure but if we add them to EventLoopLambdaHandler we would add them to a protocol that doesn't NEED the coders in any way. See StringLambdaClosureWrapper as an example. I'm not sure if I would be a fan of adding this if it isn't needed a 100% of the time.

@tomerd wdyt?

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@tomerd tomerd Mar 27, 2020 •
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wdyt about:

/// Implementation of  a`ByteBuffer` to `In` decoding
public extension EventLoopLambdaHandler where In: Decodable{
    func decode(buffer: ByteBuffer) throws -> In {
        try self.decoder.decode(In.self, from: buffer)
    }
}

/// Implementation of  `Out` to `ByteBuffer` encoding
public extension EventLoopLambdaHandler where Out: Encodable  {
    func encode(allocator: ByteBufferAllocator, value: Out) throws -> ByteBuffer? {
        // nio will resize the buffer if necessary
        var buffer = allocator.buffer(capacity: 1024)
        try self.encoder.encode(value, into: &buffer)
        return buffer
    }
}

/// Implementation of  `Out` to `Void` encoding
public extension EventLoopLambdaHandler where Out == Void {
    func encode(allocator: ByteBufferAllocator, value: Void) throws -> ByteBuffer? {
        nil
    }
}

/// Default `ByteBuffer` to `In` decoder using Foundation's JSONDecoder
/// Advanced users that want to inject their own codec can do it by overriding these functions.
public extension EventLoopLambdaHandler where In: Decodable {
    var decoder: LambdaDecoder {
        Lambda.defaultJSONDecoder
    }
}

/// Default `Out` to `ByteBuffer` encoder using Foundation's JSONEncoder
/// Advanced users that want to inject their own codec can do it by overriding these functions.
public extension EventLoopLambdaHandler where Out: Encodable {
    var encoder: LambdaEncoder {
        Lambda.defaultJSONEncoder
    }
}

public protocol LambdaDecoder {
    func decode<T: Decodable>(_ type: T.Type, from buffer: ByteBuffer) throws -> T
}

public protocol LambdaEncoder {
    func encode<T: Encodable>(_ value: T, into buffer: inout ByteBuffer) throws
}

private extension Lambda {
    static let defaultJSONDecoder = JSONDecoder()
    static let defaultJSONEncoder = JSONEncoder()
}

extension JSONDecoder: LambdaDecoder {}
extension JSONEncoder: LambdaEncoder {}

maybe LambdaCoddableDecoder/LambdaCodableEncoder instead of LambdaDecoder/LambdaEncoder

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@tomerd tomerd Mar 27, 2020 •
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added a suggested commit: 44e425c feel free to remove if you dont like the direction


/// the default json decoder used in `EventLoopLambdaHandler` if In == Decodable
static let defaultJSONDecoder = JSONDecoder()
}

public extension EventLoopLambdaHandler where In: Decodable, Out == Void {
func encode(allocator: ByteBufferAllocator, value: Void) throws -> ByteBuffer? {
nil
}

func decode(buffer: ByteBuffer) throws -> In {
// FIXME: reusable JSONDecoder
try JSONDecoder().decode(In.self, from: buffer)
try Lambda.defaultJSONDecoder.decode(In.self, from: buffer)
}
}