1.0.0 Release (#35)

* Swift 6 mode (#26)

* Swift 6 mode, refs #25

* Update workflow

* Enhance RetryPolicy API, refs #27 (#28)

* Revert Swift 6 upgrade, activate concurrency checks, closes #31 (#32)

* Enhance README regarding stateless nature of retry policies, refs #33 (#34)

Author: PierreMardon

.github/workflows/swift.yml

@@ -6,23 +6,24 @@ on:
 
 jobs:
   build:
-    runs-on: macos-13
+    runs-on: macos-14
 
     steps:
-    - uses: maxim-lobanov/setup-xcode@v1
-      with:
-        xcode-version: latest-stable
-    - name: Check XCode Version
+    - uses: actions/checkout@v4
+    - name: List available Xcode versions
+      run: ls /Applications | grep Xcode
+    - name: Set up Xcode version
+      run: sudo xcode-select -s /Applications/Xcode_16.0.app/Contents/Developer
+    - name: Show current version of Xcode
       run: xcodebuild -version
-    - uses: actions/checkout@v3
     - name: Build
       run: xcodebuild -scheme SwiftRetrier build -destination "platform=OS X"
     - name: Run tests
       run: xcodebuild -scheme SwiftRetrier test -destination "platform=OS X"
   lint:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v4
     - name: SwiftLint
       uses: raphaelbussa/swiftlint-action@main
       with:

Package.swift

@@ -8,8 +8,8 @@ let lint = false
 var extraDependencies: [Package.Dependency] = []
 var extraPlugins: [Target.PluginUsage] = []
 if lint {
-    extraDependencies = [.package(url: "https://github.com/realm/SwiftLint", exact: "0.52.4")]
-    extraPlugins = [.plugin(name: "SwiftLintPlugin", package: "SwiftLint")]
+    extraDependencies = [.package(url: "https://github.com/realm/SwiftLint.git", from: "0.55.1")]
+    extraPlugins = [.plugin(name: "SwiftLintBuildToolPlugin", package: "SwiftLint")]
 }
 
 let package = Package(
@@ -28,12 +28,19 @@ let package = Package(
         .target(
             name: "SwiftRetrier",
             dependencies: [],
+            swiftSettings: [
+                .enableExperimentalFeature("StrictConcurrency=complete")
+            ],
             plugins: [] + extraPlugins
         ),
         .testTarget(
             name: "SwiftRetrierTests",
             dependencies: ["SwiftRetrier"],
+            swiftSettings: [
+                .enableExperimentalFeature("StrictConcurrency=complete")
+            ],
             plugins: [] + extraPlugins
         )
-    ]
+    ],
+    swiftLanguageVersions: [.version("5.8")]
 )

README.md

@@ -135,6 +135,11 @@ You can add failure conditions using `giveUp*()` functions.
 You can create your own policies that conform `RetryPolicy` and they will benefit from the same modifiers.
 Have a look at `ConstantDelayRetryPolicy.swift` for a basic example.
 
+⚠️ Policies should be stateless. To ensure that, I recommend implementing them with `struct` types.
+
+If a policy needs to know about attempts history, ensure you propagate what's needed when implementing
+`policyAfter(attemptFailure:, delay:) -> any RetryPolicy`.
+
 To create a DSL entry point using your policy:
 
 ```swift

Sources/SwiftRetrier/Core/ConstantDelayPolicy/ConstantDelayRetryPolicy.swift

@@ -1,6 +1,6 @@
 import Foundation
 
-open class ConstantDelayRetryPolicy: RetryPolicy {
+public struct ConstantDelayRetryPolicy: RetryPolicy {
 
     public let delay: TimeInterval
 
@@ -16,7 +16,7 @@ open class ConstantDelayRetryPolicy: RetryPolicy {
         .retry(delay: retryDelay(for: attemptFailure))
     }
 
-    public func freshCopy() -> RetryPolicy {
+    public func policyAfter(attemptFailure: AttemptFailure, delay: TimeInterval) -> any RetryPolicy {
         self
     }
 }

Sources/SwiftRetrier/Core/ExponentialBackoffPolicy/ExponentialBackoffRetryPolicy.swift

@@ -1,8 +1,8 @@
 import Foundation
 
-open class ExponentialBackoffRetryPolicy: RetryPolicy {
+public struct ExponentialBackoffRetryPolicy: RetryPolicy {
 
-    public enum Jitter {
+    public enum Jitter: Sendable {
         case none
         case full
         case decorrelated(growthFactor: Double = ExponentialBackoffConstants.defaultDecorrelatedJitterGrowthFactor)
@@ -11,14 +11,16 @@ open class ExponentialBackoffRetryPolicy: RetryPolicy {
     public let timeSlot: TimeInterval
     public let maxDelay: TimeInterval
     public let jitter: Jitter
-    private var previousDelay: TimeInterval?
+    private let previousDelay: TimeInterval?
 
     public init(timeSlot: TimeInterval = ExponentialBackoffConstants.defaultTimeSlot,
                 maxDelay: TimeInterval = ExponentialBackoffConstants.defaultMaxDelay,
-                jitter: Jitter = ExponentialBackoffConstants.defaultJitter) {
+                jitter: Jitter = ExponentialBackoffConstants.defaultJitter,
+                previousDelay: TimeInterval? = nil) {
         self.timeSlot = timeSlot
         self.maxDelay = maxDelay
         self.jitter = jitter
+        self.previousDelay = previousDelay
     }
 
     public func exponentiationBySquaring<T: BinaryInteger>(_ base: T, _ multiplier: T, _ exponent: T) -> T {
@@ -57,7 +59,6 @@ open class ExponentialBackoffRetryPolicy: RetryPolicy {
         } else {
             delay = fullJitterDelay(attemptIndex: attemptIndex)
         }
-        previousDelay = delay
         return delay
     }
 
@@ -72,15 +73,15 @@ open class ExponentialBackoffRetryPolicy: RetryPolicy {
         }
     }
 
-    open func retryDelay(for attemptFailure: AttemptFailure) -> TimeInterval {
+    public func retryDelay(for attemptFailure: AttemptFailure) -> TimeInterval {
         min(maxDelay, uncappedDelay(attemptIndex: attemptFailure.index))
     }
 
     public func shouldRetry(on attemptFailure: AttemptFailure) -> RetryDecision {
         .retry(delay: retryDelay(for: attemptFailure))
     }
 
-    public func freshCopy() -> RetryPolicy {
-        ExponentialBackoffRetryPolicy(timeSlot: timeSlot, maxDelay: maxDelay, jitter: jitter)
+    public func policyAfter(attemptFailure: AttemptFailure, delay: TimeInterval) -> any RetryPolicy {
+        ExponentialBackoffRetryPolicy(timeSlot: timeSlot, maxDelay: maxDelay, jitter: jitter, previousDelay: delay)
     }
 }

Sources/SwiftRetrier/Core/Model/Job.swift

@@ -1 +1 @@
-public typealias Job<Value> = () async throws -> Value
+public typealias Job<Value> = @Sendable () async throws -> Value

Sources/SwiftRetrier/Core/Model/Policies/AttemptFailure.swift

@@ -1,6 +1,6 @@
 import Foundation
 
-public struct AttemptFailure {
+public struct AttemptFailure: Sendable {
     public let trialStart: Date
     public let index: UInt
     public let error: Error

Sources/SwiftRetrier/Core/Model/Policies/RetryDecision.swift

@@ -1,6 +1,6 @@
 import Foundation
 
-public enum RetryDecision {
+public enum RetryDecision: Sendable {
     case giveUp
     case retry(delay: TimeInterval)
 }

Sources/SwiftRetrier/Core/Model/Policies/RetryPolicy.swift

@@ -1,7 +1,6 @@
 import Foundation
 
-public protocol RetryPolicy {
+public protocol RetryPolicy: Sendable {
     func shouldRetry(on attemptFailure: AttemptFailure) -> RetryDecision
-    func retryDelay(for attemptFailure: AttemptFailure) -> TimeInterval
-    func freshCopy() -> RetryPolicy
+    func policyAfter(attemptFailure: AttemptFailure, delay: TimeInterval) -> any RetryPolicy
 }

Sources/SwiftRetrier/Core/Model/Retriers/Retrier.swift

@@ -1,8 +1,8 @@
 import Foundation
 import Combine
 
-public protocol Retrier: Cancellable, AnyObject {
-    associatedtype Output
+public protocol Retrier: Cancellable, AnyObject, Sendable {
+    associatedtype Output: Sendable
 
     func publisher() -> AnyPublisher<RetrierEvent<Output>, Never>
 }