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Reuse DispatchQueue for multiple Invocations #49

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Merged
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Mar 26, 2020
Merged

Reuse DispatchQueue for multiple Invocations #49

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13 changes: 12 additions & 1 deletion Sources/AWSLambdaRuntime/LambdaHandler.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -25,17 +25,28 @@ import NIO
/// The `EventLoopLambdaHandler` will execute the Lambda on the same `EventLoop` as the core runtime engine, making the processing faster but requires
/// more care from the implementation to never block the `EventLoop`.
public protocol LambdaHandler: EventLoopLambdaHandler {
var offloadQueue: DispatchQueue { get }

func handle(context: Lambda.Context, payload: In, callback: @escaping (Result<Out, Error>) -> Void)
}

private extension Lambda {
static let defaultOffloadQueue = DispatchQueue(label: "LambdaHandler.offload")
}

public extension LambdaHandler {
/// The queue on which `handle` is invoked on.
var offloadQueue: DispatchQueue {
Lambda.defaultOffloadQueue
}

/// `LambdaHandler` is offloading the processing to a `DispatchQueue`
/// This is slower but safer, in case the implementation blocks the `EventLoop`
/// Performance sensitive Lambdas should be based on `EventLoopLambdaHandler` which does not offload.
func handle(context: Lambda.Context, payload: In) -> EventLoopFuture<Out> {
let promise = context.eventLoop.makePromise(of: Out.self)
// FIXME: reusable DispatchQueue
DispatchQueue(label: "LambdaHandler.offload").async {
self.offloadQueue.async {
self.handle(context: context, payload: payload, callback: promise.completeWith)
}
return promise.futureResult
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