## 1.1.0

### Added
* Add **swiftlint** & **swiftformat** to build phases
*  ```OneWaySynchronizer.cancel()```
* ```OwsError.cancelledError```
* ```OneWaySynchronizerProcessor.owsPrepareDownload(of descriptions: [OneWaySynchronizerItemDescription], completion: @escaping OwsItemsCompletion)```

Author: ladeiko

.travis.yml

@@ -0,0 +1,10 @@
+language: swift
+osx_image: xcode9.4
+branches:
+  only:
+    - master
+before_install:
+  - gem install cocoapods --pre --no-rdoc --no-ri --no-document --quiet
+  - pod repo update  
+script:
+  - cd Demo && make

CHANGELOG.md

@@ -1,4 +1,14 @@
 # CHANGELOG
 
+## 1.1.0
+### Added
+* Add **swiftlint** & **swiftformat** to build phases
+*  ```OneWaySynchronizer.cancel()```
+* ```OwsError.cancelledError```
+* ```OneWaySynchronizerProcessor.owsPrepareDownload(of descriptions: [OneWaySynchronizerItemDescription], completion: @escaping OwsItemsCompletion)```
+
+### Changed
+* Reformat sources
+
 ## 1.0.0
 Initial release

Demo/Makefile

@@ -0,0 +1,7 @@
+
+.PHONY: test
+
+test:
+	pod repo update
+	pod install
+	xcodebuild test -quiet -scheme OneWaySynchronizerDemo -workspace ./OneWaySynchronizerDemo.xcworkspace/ -destination 'platform=iOS Simulator,name=iPhone 8' || exit 1

Demo/OneWaySynchronizerDemo.xcodeproj/project.pbxproj

@@ -40,6 +40,8 @@
 		1246EBD420F4D8A6008F3352 /* OneWaySynchronizerDemoTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OneWaySynchronizerDemoTests.swift; sourceTree = "<group>"; };
 		1246EBD620F4D8A6008F3352 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		1246EBDF20F4D900008F3352 /* MyService.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MyService.swift; sourceTree = "<group>"; };
+		129DEBC320F60F2400B23035 /* CHANGELOG.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; name = CHANGELOG.md; path = ../CHANGELOG.md; sourceTree = "<group>"; };
+		129DEBC420F60F2400B23035 /* README.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; name = README.md; path = ../README.md; sourceTree = "<group>"; };
 		560D357930ECF0DBA262F9BB /* Pods-OneWaySynchronizerDemo.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-OneWaySynchronizerDemo.release.xcconfig"; path = "Pods/Target Support Files/Pods-OneWaySynchronizerDemo/Pods-OneWaySynchronizerDemo.release.xcconfig"; sourceTree = "<group>"; };
 		764034DE1CC28CB89E84D4E3 /* Pods_OneWaySynchronizerDemoTests.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Pods_OneWaySynchronizerDemoTests.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		81F2DF9B2667791791120E40 /* Pods-OneWaySynchronizerDemo.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-OneWaySynchronizerDemo.debug.xcconfig"; path = "Pods/Target Support Files/Pods-OneWaySynchronizerDemo/Pods-OneWaySynchronizerDemo.debug.xcconfig"; sourceTree = "<group>"; };
@@ -71,6 +73,8 @@
 		1246EBB320F4D8A5008F3352 = {
 			isa = PBXGroup;
 			children = (
+				129DEBC320F60F2400B23035 /* CHANGELOG.md */,
+				129DEBC420F60F2400B23035 /* README.md */,
 				1246EBBE20F4D8A5008F3352 /* OneWaySynchronizerDemo */,
 				1246EBD320F4D8A6008F3352 /* OneWaySynchronizerDemoTests */,
 				1246EBBD20F4D8A5008F3352 /* Products */,
@@ -139,6 +143,8 @@
 			buildConfigurationList = 1246EBD920F4D8A6008F3352 /* Build configuration list for PBXNativeTarget "OneWaySynchronizerDemo" */;
 			buildPhases = (
 				19CD3573778FFB652BE5F783 /* [CP] Check Pods Manifest.lock */,
+				129DEBC220F60E5900B23035 /* [CUSTOM] Format */,
+				129DEBC120F606C800B23035 /* [CUSTOM] Linting */,
 				1246EBB820F4D8A5008F3352 /* Sources */,
 				1246EBB920F4D8A5008F3352 /* Frameworks */,
 				1246EBBA20F4D8A5008F3352 /* Resources */,
@@ -234,6 +240,34 @@
 /* End PBXResourcesBuildPhase section */
 
 /* Begin PBXShellScriptBuildPhase section */
+		129DEBC120F606C800B23035 /* [CUSTOM] Linting */ = {
+			isa = PBXShellScriptBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputPaths = (
+			);
+			name = "[CUSTOM] Linting";
+			outputPaths = (
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "if [ \"$TRAVIS\" != \"true\" ]; then\n    if which swiftlint >/dev/null; then\n        cd ../Source && swiftlint --config ../Demo/swiftlint.yml\n    else\n        echo \"warning: SwiftLint not installed, download from https://github.com/realm/SwiftLint\"\n    fi\nfi";
+		};
+		129DEBC220F60E5900B23035 /* [CUSTOM] Format */ = {
+			isa = PBXShellScriptBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputPaths = (
+			);
+			name = "[CUSTOM] Format";
+			outputPaths = (
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "if [ \"$TRAVIS\" != \"true\" ]; then\n    if which swiftformat >/dev/null; then\n        cd ../Source && swiftformat .\n    else\n        echo \"warning: SwiftFormat not installed, download from https://github.com/nicklockwood/SwiftFormat\"\n    fi\nfi";
+		};
 		19CD3573778FFB652BE5F783 /* [CP] Check Pods Manifest.lock */ = {
 			isa = PBXShellScriptBuildPhase;
 			buildActionMask = 2147483647;

Demo/OneWaySynchronizerDemo/MyService.swift

@@ -16,6 +16,7 @@ typealias PreviewCompletion = (_ error: Error?, _ image: UIImage?) -> Void
 
 fileprivate struct RemoteItemDescription: OneWaySynchronizerItemDescription {
     var owsPrimaryKey: OneWaySynchronizerItemKey
+    var owsDownloadOrder: OneWaySynchronizerItemDownloadOrder
     var order: Int
     var title: String
     var url: String
@@ -76,7 +77,7 @@ class MyService: OneWaySynchronizerProcessor {
 
         // NOTE: Method can be called not in main thread!
 
-        completion() // No matter what thread is now running on!
+        completion() // Completion can be called from any thread!
     }
 
     func owsSyncEnd(_ completion: @escaping OwsCompletion) {
@@ -87,7 +88,7 @@ class MyService: OneWaySynchronizerProcessor {
 
             self._items.sort()
 
-            completion() // No matter what thread is now running on!
+            completion() // Completion can be called from any thread!
         }
     }
 
@@ -102,6 +103,7 @@ class MyService: OneWaySynchronizerProcessor {
             if let json = response.result.value {
                 for (i, item) in (json as! [Dictionary<String,Any>]).enumerated() {
                     items.append(RemoteItemDescription(owsPrimaryKey: String(item["id"] as! Int),
+                                                       owsDownloadOrder: 0,
                                                        order: i,
                                                        title: item["login"] as! String,
                                                        url: item["avatar_url"] as! String))
@@ -180,10 +182,15 @@ class MyService: OneWaySynchronizerProcessor {
 
             completion(nil) // No matter what thread is now running on!
         }
-        
 
     }
 
+    func owsPrepareDownload(of descriptions: [OneWaySynchronizerItemDescription], completion: @escaping OwsItemsCompletion) {
+        completion(nil, descriptions)
+    }
+    
+    // MARK: Public
+    
     func count() -> Int {
         return _items.count
     }

Demo/OneWaySynchronizerDemoTests/OneWaySynchronizerDemoTests.swift

@@ -43,6 +43,18 @@ func isDownloadContentError(_ err: Error?, key: OneWaySynchronizerItemKey, under
     }
 }
 
+func isCancelError(_ err: Error?) -> Bool {
+    guard let err = err as? OwsError else {
+        return false
+    }
+    switch err {
+    case .cancelledError:
+        return true
+    default:
+        return false
+    }
+}
+
 class TestItem: OneWaySynchronizerItemDescription {
 
     func vss_shouldBeUpdated(with remoteItem: TestItem) -> Bool {
@@ -51,11 +63,19 @@ class TestItem: OneWaySynchronizerItemDescription {
 
     typealias K = String
 
-    var owsPrimaryKey: String
+    var owsPrimaryKey: OneWaySynchronizerItemKey
+    var owsDownloadOrder: OneWaySynchronizerItemDownloadOrder
     let downloadError: Error?
 
+    init(key: String, order: Int, downloadError: Error? = nil ) {
+        owsPrimaryKey = key
+        owsDownloadOrder = order
+        self.downloadError = downloadError
+    }
+    
     init(key: String, downloadError: Error? = nil ) {
         owsPrimaryKey = key
+        owsDownloadOrder = 0
         self.downloadError = downloadError
     }
 }
@@ -69,11 +89,11 @@ class TestProcessor: OneWaySynchronizerProcessor {
 
     var beginCalled = 0
     var endCalled = 0
-    
     var shouldBeUpdated = Set<String>()
-    
     var downloadedPreview = Set<String>()
     var downloaded = Set<String>()
+    var downloadedOrder = [String]()
+    var downloadedPreviewOrder = [String]()
     var removed = Set<String>()
 
     var existingKeys = Array<K>()
@@ -131,18 +151,24 @@ class TestProcessor: OneWaySynchronizerProcessor {
     func owsDownloadItemPreview(forDescription description: OneWaySynchronizerItemDescription, completion: @escaping OwsSimpleCompletion) {
         objc_sync_enter(self); defer { objc_sync_exit(self) }
         downloadedPreview.insert(description.owsPrimaryKey)
+        downloadedPreviewOrder.append(description.owsPrimaryKey)
         completion(nil)
     }
 
     func owsDownloadItem(forDescription description: OneWaySynchronizerItemDescription, completion: @escaping OwsSimpleCompletion) {
         objc_sync_enter(self); defer { objc_sync_exit(self) }
         downloaded.insert(description.owsPrimaryKey)
+        downloadedOrder.append(description.owsPrimaryKey)
         if !existingKeys.contains(description.owsPrimaryKey) {
             existingKeys.append(description.owsPrimaryKey)
         }
         completion((description as! TestItem).downloadError)
     }
 
+    func owsPrepareDownload(of descriptions: [OneWaySynchronizerItemDescription], completion: @escaping OwsItemsCompletion) {
+        completion(nil, descriptions)
+    }
+
 }
 
 class OneWaySynchronizerDemoTests: XCTestCase {
@@ -165,8 +191,9 @@ class OneWaySynchronizerDemoTests: XCTestCase {
         let expectation = XCTestExpectation(description: "sync")
         var failed: [Error]?
         let processor = TestProcessor(fetchList:[
-            TestItem(key: "A"),
-            TestItem(key: "B")
+            TestItem(key: "A", order: 1),
+            TestItem(key: "B", order: 0),
+            TestItem(key: "C", order: 2)
             ])
         let service = OneWaySynchronizer(processor: processor)
         service.concurrency = 1
@@ -194,6 +221,7 @@ class OneWaySynchronizerDemoTests: XCTestCase {
         XCTAssert(processor.endCalled == 1)
         XCTAssert(failed == nil)
         XCTAssert(Set(processor.fetchList.map({$0.owsPrimaryKey})) == processor.downloaded)
+        XCTAssert(processor.downloadedOrder == ["B", "A", "C"])
         XCTAssert(processor.removeItemsCalled == 0)
         XCTAssert(processor.shouldBeUpdatedCalled == 0)
         XCTAssert(processor.removed.count == 0)
@@ -205,8 +233,9 @@ class OneWaySynchronizerDemoTests: XCTestCase {
         let expectation = XCTestExpectation(description: "sync")
         var failed: [Error]?
         let processor = TestProcessor(fetchList:[
-            TestItem(key: "A"),
-            TestItem(key: "B")
+            TestItem(key: "A", order: 1),
+            TestItem(key: "B", order: 0),
+            TestItem(key: "C", order: 2)
             ])
         let service = OneWaySynchronizer(processor: processor)
         service.concurrency = 1
@@ -219,10 +248,12 @@ class OneWaySynchronizerDemoTests: XCTestCase {
         wait(for: [expectation], timeout: 10)
         XCTAssert(failed == nil)
         XCTAssert(Set(processor.fetchList.map({$0.owsPrimaryKey})) == processor.downloaded)
+        XCTAssert(processor.downloadedOrder == ["B", "A", "C"])
+        XCTAssert(processor.downloadedPreviewOrder == ["B", "A", "C"])
         XCTAssert(processor.removeItemsCalled == 0)
         XCTAssert(processor.shouldBeUpdatedCalled == 0)
         XCTAssert(processor.removed.count == 0)
-        XCTAssert(processor.downloadedPreview == Set(["A", "B"]))
+        XCTAssert(processor.downloadedPreview == Set(["A", "B", "C"]))
     }
 
     func testSuccessOnlyWithPreview() {
@@ -277,6 +308,55 @@ class OneWaySynchronizerDemoTests: XCTestCase {
         XCTAssert(processor.downloadedPreview.count == 0)
     }
 
+    func testCancellation() {
+        
+        let startExpectation = XCTestExpectation(description: "start")
+        let endExpectation = XCTestExpectation(description: "start")
+        
+        let expectation = XCTestExpectation(description: "sync")
+        var failed: [Error]?
+        let processor = TestProcessor(fetchList:[
+            TestItem(key: "A", order: 1),
+            TestItem(key: "B", order: 0),
+            TestItem(key: "C", order: 2)
+            ])
+        let service = OneWaySynchronizer(processor: processor)
+        service.concurrency = 1
+        let localObserver = NotificationCenter.default.addObserver(forName: .OneWaySynchronizerDidChangeSyncStatusNotification, object: service, queue: OperationQueue.main) { (notification) in
+            XCTAssert(Thread.isMainThread)
+            if (notification.object as! OneWaySynchronizer).isSyncing {
+                startExpectation.fulfill()
+            }
+            else {
+                endExpectation.fulfill()
+            }
+        }
+        
+        service.sync { (error) in
+            failed = error
+            expectation.fulfill()
+        }
+        
+        service.cancel() // cancel ASAP
+        
+        wait(for: [expectation], timeout: 10)
+        wait(for: [startExpectation, endExpectation], timeout: 10)
+        
+        NotificationCenter.default.removeObserver(localObserver)
+        
+        XCTAssert(processor.beginCalled == 1)
+        XCTAssert(processor.endCalled == 1)
+        XCTAssert(failed != nil)
+        XCTAssert(failed!.count == 1)
+        XCTAssert(isCancelError(failed![0]))
+        XCTAssert(processor.downloaded.count == 0)
+        XCTAssert(processor.downloadedOrder.count == 0)
+        XCTAssert(processor.removeItemsCalled == 0)
+        XCTAssert(processor.shouldBeUpdatedCalled == 0)
+        XCTAssert(processor.removed.count == 0)
+        XCTAssert(processor.downloadedPreview.count == 0)
+    }
+    
     func testFetchFailure() {
 
         let expectation = XCTestExpectation(description: "sync")

Demo/swiftlint.yml

@@ -0,0 +1,5 @@
+disabled_rules:
+  - line_length
+  - file_length
+  - type_body_length
+  - identifier_name

OneWaySynchronizer.podspec

@@ -1,7 +1,7 @@
 Pod::Spec.new do |s|
 
   s.name         = "OneWaySynchronizer"
-  s.version      = "1.0.0"
+  s.version      = "1.1.0"
   s.summary      = "OneWaySynchronizer - the simplest way to sync data from remote host into local storage."
 
   s.homepage         = "https://github.com/ladeiko/OneWaySynchronizer"