Add support for pruning of idle pool connections (vapor#110)

* Buncha package cleanup, including adding ExistentialAny.

* Add support for automatic pruning of idle database connections with configurable check interval and idle timeout.

* Fix old Swift

* Use logger metadata

* Resolve API breakage warnings

* Some tiny bits of cleanup

Author: gwynne

.github/workflows/test.yml

@@ -12,4 +12,5 @@ env:
 
 jobs:
   unit-tests:
-     uses: vapor/ci/.github/workflows/run-unit-tests.yml@main
+    uses: vapor/ci/.github/workflows/run-unit-tests.yml@main
+    secrets: inherit

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:5.7
+// swift-tools-version:5.10
 import PackageDescription
 
 let package = Package(
@@ -19,16 +19,33 @@ let package = Package(
         .package(url: "https://github.com/apple/swift-algorithms.git", from: "1.1.0"),
     ],
     targets: [
-        .target(name: "AsyncKit", dependencies: [
-            .product(name: "Logging", package: "swift-log"),
-            .product(name: "NIOCore", package: "swift-nio"),
-            .product(name: "NIOEmbedded", package: "swift-nio"),
-            .product(name: "NIOPosix", package: "swift-nio"),
-            .product(name: "Collections", package: "swift-collections"),
-            .product(name: "Algorithms", package: "swift-algorithms"),
-        ]),
-        .testTarget(name: "AsyncKitTests", dependencies: [
-            .target(name: "AsyncKit"),
-        ]),
+        .target(
+            name: "AsyncKit",
+            dependencies: [
+                .product(name: "Logging", package: "swift-log"),
+                .product(name: "NIOCore", package: "swift-nio"),
+                .product(name: "NIOEmbedded", package: "swift-nio"),
+                .product(name: "NIOPosix", package: "swift-nio"),
+                .product(name: "Collections", package: "swift-collections"),
+                .product(name: "Algorithms", package: "swift-algorithms"),
+            ],
+            swiftSettings: swiftSettings
+        ),
+        .testTarget(
+            name: "AsyncKitTests",
+            dependencies: [
+                .target(name: "AsyncKit"),
+            ],
+            swiftSettings: swiftSettings
+        ),
     ]
 )
+
+var swiftSettings: [SwiftSetting] { [
+    .enableUpcomingFeature("ExistentialAny"),
+    .enableUpcomingFeature("ConciseMagicFile"),
+    .enableUpcomingFeature("ForwardTrailingClosures"),
+    //.enableUpcomingFeature("DisableOutwardActorInference"),
+    .enableUpcomingFeature("MemberImportVisibility"),
+    //.enableExperimentalFeature("StrictConcurrency=complete"),
+] }

README.md

@@ -3,15 +3,15 @@
   <source media="(prefers-color-scheme: dark)" srcset="https://github.com/vapor/async-kit/assets/1130717/1d4e3e08-b237-480b-913b-11d569f6f468">
   <source media="(prefers-color-scheme: light)" srcset="https://github.com/vapor/async-kit/assets/1130717/abb01b9f-f6d2-46de-be5a-59d721211bee">
   <img src="https://github.com/vapor/async-kit/assets/1130717/abb01b9f-f6d2-46de-be5a-59d721211bee" height="96" alt="AsyncKit">
-</picture> 
+</picture>
 <br>
 <br>
-<a href="https://docs.vapor.codes/4.0/"><img src="https://design.vapor.codes/images/readthedocs.svg?1" alt="Documentation"></a>
+<a href="https://docs.vapor.codes/4.0/"><img src="https://design.vapor.codes/images/readthedocs.svg" alt="Documentation"></a>
 <a href="https://discord.gg/vapor"><img src="https://design.vapor.codes/images/discordchat.svg" alt="Team Chat"></a>
-<a href="LICENSE"><img src="https://design.vapor.codes/images/mitlicense.svg?1" alt="MIT License"></a>
+<a href="LICENSE"><img src="https://design.vapor.codes/images/mitlicense.svg" alt="MIT License"></a>
 <a href="https://github.com/vapor/async-kit/actions/workflows/test.yml"><img src="https://img.shields.io/github/actions/workflow/status/vapor/async-kit/test.yml?event=push&style=plastic&logo=github&label=test&logoColor=%23ccc" alt="Continuous Integration"></a>
-<a href="https://codecov.io/github/vapor/async-kit"><img src="https://img.shields.io/codecov/c/github/vapor/async-kit?style=plastic&logo=codecov&label=Codecov&token=yDzzHja8lt"></a>
-<a href="https://swift.org"><img src="https://design.vapor.codes/images/swift57up.svg?1" alt="Swift 5.7+"></a>
+<a href="https://codecov.io/github/vapor/async-kit"><img src="https://img.shields.io/codecov/c/github/vapor/async-kit?style=plastic&logo=codecov&label=Codecov"></a>
+<a href="https://swift.org"><img src="https://design.vapor.codes/images/swift510up.svg" alt="Swift 5.10+"></a>
 </p>
 
 <br>

Sources/AsyncKit/ConnectionPool/ConnectionPoolError.swift

@@ -1,9 +1,10 @@
-/// Errors thrown by `ConnectionPool`.
+/// Errors thrown by ``EventLoopGroupConnectionPool`` and ``EventLoopConnectionPool`` regarding state.
 public enum ConnectionPoolError: Error {
     /// The connection pool has shutdown.
     case shutdown
 }
 
+/// Errors thrown by ``EventLoopGroupConnectionPool`` and ``EventLoopConnectionPool`` regarding timeouts.
 public enum ConnectionPoolTimeoutError: Error {
     /// The connection request timed out.
     case connectionRequestTimeout

Sources/AsyncKit/ConnectionPool/ConnectionPoolItem.swift

@@ -2,12 +2,12 @@ import NIOCore
 
 /// Item managed by a connection pool.
 public protocol ConnectionPoolItem: AnyObject {
-    /// EventLoop this connection belongs to.
-    var eventLoop: EventLoop { get }
-    
+    /// `EventLoop` this connection belongs to.
+    var eventLoop: any EventLoop { get }
+
     /// If `true`, this connection has closed.
     var isClosed: Bool { get }
-    
+
     /// Closes this connection.
     func close() -> EventLoopFuture<Void>
 }

Sources/AsyncKit/ConnectionPool/ConnectionPoolSource.swift

@@ -1,11 +1,11 @@
 import NIOCore
 import struct Logging.Logger
 
-/// Source of new connections for `ConnectionPool`.
+/// Source of new connections for ``EventLoopGroupConnectionPool``.
 public protocol ConnectionPoolSource {
-    /// Associated `ConnectionPoolItem` that will be returned by `makeConnection()`.
+    /// Associated ``ConnectionPoolItem`` that will be returned by ``ConnectionPoolSource/makeConnection(logger:on:)``.
     associatedtype Connection: ConnectionPoolItem
-    
+
     /// Creates a new connection.
-    func makeConnection(logger: Logger, on eventLoop: EventLoop) -> EventLoopFuture<Connection>
+    func makeConnection(logger: Logger, on eventLoop: any EventLoop) -> EventLoopFuture<Connection>
 }