Add DeinitObserver for ParasiticTask on Darwin

Schedule.xcodeproj/project.pbxproj

@@ -21,6 +21,8 @@
 /* End PBXAggregateTarget section */
 
 /* Begin PBXBuildFile section */
+		667D2DF72132C5390071DC89 /* DeinitObserver.swift in Sources */ = {isa = PBXBuildFile; fileRef = 667D2DF62132C5390071DC89 /* DeinitObserver.swift */; };
+		667D2DF92132C95D0071DC89 /* DeinitObserverTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 667D2DF82132C95D0071DC89 /* DeinitObserverTests.swift */; };
 		OBJ_45 /* Atomic.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_9 /* Atomic.swift */; };
 		OBJ_46 /* Bucket.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_10 /* Bucket.swift */; };
 		OBJ_47 /* Extensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_11 /* Extensions.swift */; };
@@ -67,6 +69,8 @@
 
 /* Begin PBXFileReference section */
 		626D761B2113F9D100FCAFFE /* README.zh_cn.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; path = README.zh_cn.md; sourceTree = "<group>"; };
+		667D2DF62132C5390071DC89 /* DeinitObserver.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DeinitObserver.swift; sourceTree = "<group>"; };
+		667D2DF82132C95D0071DC89 /* DeinitObserverTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DeinitObserverTests.swift; sourceTree = "<group>"; };
 		668685ED210DCC0E009305C3 /* .swift-version */ = {isa = PBXFileReference; lastKnownFileType = text; path = ".swift-version"; sourceTree = "<group>"; };
 		668685EE210DCC0E009305C3 /* README.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; path = README.md; sourceTree = "<group>"; };
 		668685EF210DCC0E009305C3 /* .codecov.yml */ = {isa = PBXFileReference; lastKnownFileType = text; path = .codecov.yml; sourceTree = "<group>"; };
@@ -142,6 +146,7 @@
 				OBJ_10 /* Bucket.swift */,
 				OBJ_11 /* Extensions.swift */,
 				OBJ_13 /* Lock.swift */,
+				667D2DF62132C5390071DC89 /* DeinitObserver.swift */,
 			);
 			name = Utils;
 			sourceTree = "<group>";
@@ -164,6 +169,7 @@
 				OBJ_26 /* AtomicTests.swift */,
 				OBJ_27 /* BucketTests.swift */,
 				OBJ_29 /* ExtensionsTests.swift */,
+				667D2DF82132C95D0071DC89 /* DeinitObserverTests.swift */,
 			);
 			name = UtilsTests;
 			sourceTree = "<group>";
@@ -347,6 +353,7 @@
 				OBJ_53 /* Schedule.swift in Sources */,
 				OBJ_54 /* Task.swift in Sources */,
 				OBJ_55 /* TaskHub.swift in Sources */,
+				667D2DF72132C5390071DC89 /* DeinitObserver.swift in Sources */,
 				OBJ_56 /* Time.swift in Sources */,
 				OBJ_57 /* Timeline.swift in Sources */,
 				OBJ_59 /* Weekday.swift in Sources */,
@@ -371,6 +378,7 @@
 				OBJ_80 /* ExtensionsTests.swift in Sources */,
 				OBJ_81 /* Misc.swift in Sources */,
 				OBJ_82 /* SchedulesTests.swift in Sources */,
+				667D2DF92132C95D0071DC89 /* DeinitObserverTests.swift in Sources */,
 				OBJ_83 /* TaskHubTests.swift in Sources */,
 				OBJ_84 /* TaskTests.swift in Sources */,
 				OBJ_86 /* XCTestManifests.swift in Sources */,

Sources/Schedule/DeinitObserver.swift

@@ -0,0 +1,33 @@
+//
+//  DeinitObserver.swift
+//  Schedule
+//
+//  Created by Quentin Jin on 2018/8/26.
+//
+
+import Foundation
+
+#if os(macOS) || os(iOS) || os(tvOS) || os(watchOS)
+
+class DeinitObserver<T: AnyObject> {
+
+    private weak var observed: T?
+
+    private var block: () -> Void
+
+    private init(_ block: @escaping () -> Void) {
+        self.block = block
+    }
+
+    static func observe(_ observed: T, whenDeinit: @escaping () -> Void) {
+        let observer = DeinitObserver(whenDeinit)
+        var key: Void = ()
+        objc_setAssociatedObject(observed, &key, observer, .OBJC_ASSOCIATION_RETAIN)
+    }
+
+    deinit {
+        block()
+    }
+}
+
+#endif

Sources/Schedule/ParasiticTask.swift

@@ -71,5 +71,11 @@ private final class ParasiticTask: Task {
             onElapse(task)
         }
         self.parasitifer = host
+
+        #if os(macOS) || os(iOS) || os(tvOS) || os(watchOS)
+        DeinitObserver.observe(host) { [weak self] in
+            self?.cancel()
+        }
+        #endif
     }
 }

Tests/ScheduleTests/DeinitObserverTests.swift

@@ -0,0 +1,28 @@
+//
+//  DeinitObserverTests.swift
+//  ScheduleTests
+//
+//  Created by Quentin Jin on 2018/8/26.
+//
+
+import XCTest
+@testable import Schedule
+
+final class DeinitObserverTests: XCTestCase {
+
+    func testObserver() {
+        var de = false
+        let block = {
+            let obj = NSObject()
+            DeinitObserver.observe(obj, whenDeinit: {
+                de = true
+            })
+        }
+        block()
+        XCTAssertTrue(de)
+    }
+
+    static var allTests = [
+        ("testObserver", testObserver)
+    ]
+}