setup shutdown hooks on ServiceLifecycle::startAndWait (#69)

motivation: fix startAndWait to work as advertised

changes:
* extract shutdown setup to a func and call it from both start and startAndWait
* add test
* fix api doc
* fixi jazzy xenial issue (fixes ci)

Author: tomerd

Sources/Lifecycle/Lifecycle.swift

@@ -105,25 +105,14 @@ public struct ServiceLifecycle {
     /// - parameters:
     ///    - callback: The handler which is called after the start operation completes. The parameter will be `nil` on success and contain the `Error` otherwise.
     public func start(_ callback: @escaping (Error?) -> Void) {
-        self.configuration.shutdownSignal?.forEach { signal in
-            self.lifecycle.log("setting up shutdown hook on \(signal)")
-            let signalSource = ServiceLifecycle.trap(signal: signal, handler: { signal in
-                self.lifecycle.log("intercepted signal: \(signal)")
-                self.shutdown()
-            })
-            self.lifecycle.shutdownGroup.notify(queue: .global()) {
-                signalSource.cancel()
-            }
-        }
+        self.setupShutdownHook()
         self.lifecycle.start(on: self.configuration.callbackQueue, callback)
     }
 
     /// Starts the provided `LifecycleItem` array and waits (blocking) until a shutdown `Signal` is captured or `shutdown` is called on another thread.
     /// Startup is performed in the order of items provided.
-    ///
-    /// - parameters:
-    ///    - configuration: Defines lifecycle `Configuration`
     public func startAndWait() throws {
+        self.setupShutdownHook()
         try self.lifecycle.startAndWait(on: self.configuration.callbackQueue)
     }
 
@@ -140,6 +129,19 @@ public struct ServiceLifecycle {
     public func wait() {
         self.lifecycle.wait()
     }
+
+    private func setupShutdownHook() {
+        self.configuration.shutdownSignal?.forEach { signal in
+            self.lifecycle.log("setting up shutdown hook on \(signal)")
+            let signalSource = ServiceLifecycle.trap(signal: signal, handler: { signal in
+                self.lifecycle.log("intercepted signal: \(signal)")
+                self.shutdown()
+            })
+            self.lifecycle.shutdownGroup.notify(queue: .global()) {
+                signalSource.cancel()
+            }
+        }
+    }
 }
 
 extension ServiceLifecycle {

Tests/LifecycleTests/ServiceLifecycleTests+XCTest.swift

@@ -28,6 +28,7 @@ extension ServiceLifecycleTests {
             ("testStartThenShutdown", testStartThenShutdown),
             ("testShutdownWithSignal", testShutdownWithSignal),
             ("testStartAndWait", testStartAndWait),
+            ("testStartAndWaitShutdownWithSignal", testStartAndWaitShutdownWithSignal),
             ("testBadStartAndWait", testBadStartAndWait),
             ("testNesting", testNesting),
             ("testNesting2", testNesting2),

Tests/LifecycleTests/ServiceLifecycleTests.swift

@@ -91,6 +91,55 @@ final class ServiceLifecycleTests: XCTestCase {
         XCTAssertEqual(item.state, .shutdown, "expected item to be shutdown")
     }
 
+    func testStartAndWaitShutdownWithSignal() {
+        if ProcessInfo.processInfo.environment["SKIP_SIGNAL_TEST"].flatMap(Bool.init) ?? false {
+            print("skipping testStartAndWaitShutdownWithSignal")
+            return
+        }
+
+        class Item: LifecycleTask {
+            private let semaphore: DispatchSemaphore
+            var state = State.idle
+
+            init(_ semaphore: DispatchSemaphore) {
+                self.semaphore = semaphore
+            }
+
+            var label: String {
+                return "\(self)"
+            }
+
+            func start(_ callback: (Error?) -> Void) {
+                self.state = .started
+                self.semaphore.signal()
+                callback(nil)
+            }
+
+            func shutdown(_ callback: (Error?) -> Void) {
+                self.state = .shutdown
+                callback(nil)
+            }
+
+            enum State {
+                case idle
+                case started
+                case shutdown
+            }
+        }
+
+        let signal = ServiceLifecycle.Signal.ALRM
+        let lifecycle = ServiceLifecycle(configuration: .init(shutdownSignal: [signal]))
+        let semaphore = DispatchSemaphore(value: 0)
+        DispatchQueue(label: "test").asyncAfter(deadline: .now() + 0.1) {
+            semaphore.wait()
+            kill(getpid(), signal.rawValue)
+        }
+        let item = Item(semaphore)
+        lifecycle.register(item)
+        XCTAssertNoThrow(try lifecycle.startAndWait())
+        XCTAssertEqual(item.state, .shutdown, "expected item to be shutdown")
+    }
+
     func testBadStartAndWait() {
         class BadItem: LifecycleTask {
             var label: String {

docker/Dockerfile

@@ -18,7 +18,7 @@ RUN apt-get update && apt-get install -y lsof dnsutils netcat-openbsd net-tools
 
 # ruby and jazzy for docs generation
 RUN apt-get update && apt-get install -y ruby ruby-dev libsqlite3-dev
-RUN gem install jazzy --no-ri --no-rdoc
+RUN if [ "${ubuntu_version}" != "xenial" ] ; then gem install jazzy --no-ri --no-rdoc ; fi
 
 # tools
 RUN mkdir -p $HOME/.tools

docker/docker-compose.1804.50.yaml

@@ -11,6 +11,8 @@ services:
 
   test:
     image: swift-service-lifecycle:18.04-5.0
-
+    environment:
+      - SKIP_SIGNAL_TEST=true
+  
   shell:
     image: swift-service-lifecycle:18.04-5.0

docker/docker-compose.1804.52.yaml

@@ -11,6 +11,8 @@ services:
 
   test:
     image: swift-service-lifecycle:18.04-5.2
+    environment:
+      - SKIP_SIGNAL_TEST=true
 
   shell:
     image: swift-service-lifecycle:18.04-5.2

docker/docker-compose.1804.53.yaml

@@ -10,6 +10,8 @@ services:
 
   test:
     image: swift-service-lifecycle:18.04-5.3
+    environment:
+      - SKIP_SIGNAL_TEST=true
 
   shell:
     image: swift-service-lifecycle:18.04-5.3