SWIFT-639 Update Kitura example (#399)

Author: kmahar

Examples/KituraExample/Package.swift

@@ -1,13 +1,14 @@
-// swift-tools-version:4.2
+// swift-tools-version:5.0
 import PackageDescription
 
 let package = Package(
     name: "KituraExample",
     dependencies: [
-        .package(url: "https://github.com/IBM-Swift/Kitura", .upToNextMajor(from: "2.6.3")),
-        .package(url: "https://github.com/mongodb/mongo-swift-driver", .upToNextMajor(from: "0.1.0"))
+        .package(url: "https://github.com/IBM-Swift/Kitura", .upToNextMajor(from: "2.9.1")),
+        .package(url: "https://github.com/mongodb/mongo-swift-driver", .upToNextMajor(from: "1.0.0")),
+        .package(url: "https://github.com/apple/swift-nio", .upToNextMajor(from: "2.14.0"))
     ],
     targets: [
-        .target(name: "KituraExample", dependencies: ["Kitura", "MongoSwift"])
+        .target(name: "KituraExample", dependencies: ["Kitura", "MongoSwift", "NIO"])
     ]
 )

Examples/KituraExample/README.md

@@ -7,5 +7,6 @@ To test it out, do the following:
 1. Navigate to the `Examples/` directory (one level up from this one.)
 1. Run `../loadExampleData.sh` to load sample data into the database.
 1. Navigate to the root directory of this example.
-1. Run `swift run`.
+1. Build with `export KITURA_NIO=1 && swift build` to enable using SwiftNIO for the networking layer.
+1. Start the server with `swift run`.
 1. Navigate to `localhost:8080/kittens` to see the example data loaded on the web page.

Examples/KituraExample/Sources/KituraExample/main.swift

@@ -1,30 +1,52 @@
 import Kitura
 import MongoSwift
+import NIO
 
 /// A Codable type that matches the data in our home.kittens collection.
-private struct Kitten: Codable {
+struct Kitten: Codable {
     var name: String
     var color: String
 }
 
-/// A single collection with type `Kitten`. This allows us to directly retrieve instances of
-/// `Kitten` from the collection.  `MongoCollection` is safe to share across threads.
-private let collection = try MongoClient().db("home").collection("kittens", withType: Kitten.self)
+// Create a single EventLoopGroup for Kitura and the MongoClient to share.
+let eventLoopGroup = MultiThreadedEventLoopGroup(numberOfThreads: 4)
+let mongoClient = try MongoClient(using: eventLoopGroup)
 
-private let router: Router = {
+defer {
+    mongoClient.syncShutdown()
+    cleanupMongoSwift()
+    try? eventLoopGroup.syncShutdownGracefully()
+}
+
+let router: Router = {
     let router = Router()
 
-    router.get("kittens") { _, response, _ in
-        let cursor = try collection.find()
-        let results = Array(cursor)
-        if let error = cursor.error {
-            throw error
+    /// A single collection with type `Kitten`. This allows us to directly retrieve instances of
+    /// `Kitten` from the collection.  `MongoCollection` is safe to share across threads.
+    let collection = mongoClient.db("home").collection("kittens", withType: Kitten.self)
+
+    router.get("kittens") { _, response, next -> Void in
+        let res = collection.find().flatMap { cursor in
+            cursor.toArray()
+        }
+
+        res.whenSuccess { results in
+            response.send(results)
+            next()
+        }
+
+        res.whenFailure { error in
+            response.error = error
+            response.send("Error: \(error)")
+            next()
         }
-        response.send(results)
     }
 
     return router
 }()
 
-Kitura.addHTTPServer(onPort: 8080, with: router)
+let server = Kitura.addHTTPServer(onPort: 8080, with: router)
+// Use the EventLoopGroup created above for the Kitura server. To call this method we must build with
+// `export KITURA_NIO=1 && swift build`.
+try server.setEventLoopGroup(eventLoopGroup)
 Kitura.run()

etc/build-examples.sh

@@ -15,6 +15,9 @@ for example_project in ${examples[@]}; do
 
     # don't exit on failure
     set +e
+    if [ ${example_project} == "KituraExample" ]; then
+        export KITURA_NIO=1
+    fi
     swift build
     build_success=$?
     set -e