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Merge pull request #62 from moaible/retry_when_operator
Add 'retryWhen' operator
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,90 @@ | ||
| /* | ||
| * Hydra | ||
| * Fullfeatured lightweight Promise & Await Library for Swift | ||
| * | ||
| * Created by: Hiromi Motodera | ||
| * Email: [email protected] | ||
| * Twitter: @moaible | ||
| * | ||
| * Copyright © 2017 Daniele Margutti | ||
| * | ||
| * | ||
| * Permission is hereby granted, free of charge, to any person obtaining a copy | ||
| * of this software and associated documentation files (the "Software"), to deal | ||
| * in the Software without restriction, including without limitation the rights | ||
| * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | ||
| * copies of the Software, and to permit persons to whom the Software is | ||
| * furnished to do so, subject to the following conditions: | ||
| * | ||
| * The above copyright notice and this permission notice shall be included in | ||
| * all copies or substantial portions of the Software. | ||
| * | ||
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | ||
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | ||
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | ||
| * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | ||
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | ||
| * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | ||
| * THE SOFTWARE. | ||
| * | ||
| */ | ||
|
|
||
| import Foundation | ||
|
|
||
| public extension Promise { | ||
|
|
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| public func retryWhen(_ attempts: Int = 3, _ condition: @escaping ((Int, Error) -> Promise<Bool>) = { _,_ in Promise<Bool>(resolved: true) }) -> Promise<Value> { | ||
| guard attempts >= 1 else { | ||
| // Must be a valid attempts number | ||
| return Promise<Value>(rejected: PromiseError.invalidInput) | ||
| } | ||
|
|
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| var innerPromise: Promise<Value>? = nil | ||
| var remainingAttempts = attempts | ||
| // We'll create a next promise which will be resolved when attempts to resolve self (source promise) | ||
| // is reached (with a fulfill or a rejection). | ||
| let nextPromise = Promise<Value>(in: self.context, token: self.invalidationToken) { (resolve, reject, operation) in | ||
| innerPromise = self.recover(in: self.context) { [unowned self] (error) -> (Promise<Value>) in | ||
| // If promise is rejected we'll decrement the attempts counter | ||
| remainingAttempts -= 1 | ||
| guard remainingAttempts >= 1 else { | ||
| // if the max number of attempts is reached | ||
| // we will end nextPromise with the last seen error | ||
| throw error | ||
| } | ||
| return Promise<Value> { resolve, reject, _ in | ||
| condition (remainingAttempts, error).then(in: self.context) { (shouldRetry) in | ||
| guard shouldRetry else { | ||
| reject(error) | ||
| return | ||
| } | ||
| // Reset the state of the promise | ||
| // (okay it's true, a Promise cannot change state as you know...this | ||
| // is a bit trick which will remain absolutely internal to the library itself) | ||
| self.resetState() | ||
| // Re-execute the body of the source promise to re-execute the async operation | ||
| self.runBody() | ||
| self.retryWhen(remainingAttempts, condition).then(in: self.context) { (result) in | ||
| resolve(result) | ||
| }.catch { (retriedError) in | ||
| reject(retriedError) | ||
| } | ||
| }.catch { (_) in | ||
| // reject soruce promise error | ||
| reject(error) | ||
| } | ||
| } | ||
| } | ||
| // If promise resolves nothing else to do, resolve the nextPromise! | ||
| let onResolve = Observer.onResolve(self.context, resolve) | ||
| let onReject = Observer.onReject(self.context, reject) | ||
| let onCancel = Observer.onCancel(self.context, operation.cancel) | ||
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| // Observe changes from source promise | ||
| innerPromise?.add(observers: onResolve, onReject, onCancel) | ||
| innerPromise?.runBody() | ||
| } | ||
| nextPromise.runBody() | ||
| return nextPromise | ||
| } | ||
| } |
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