Adding relationship order in CKFetchRecordZoneChangesOperation

CloudCore.xcodeproj/project.pbxproj

@@ -7,6 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		8D8B20EB2062E2B700F27057 /* Graph.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8D8B20EA2062E2B700F27057 /* Graph.swift */; };
 		D9089D4A1FE14E57000FC60C /* SetupOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = D9089D491FE14E57000FC60C /* SetupOperation.swift */; };
 		D97465F81FE319930060EA66 /* CloudCoreDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = D97465F71FE319930060EA66 /* CloudCoreDelegate.swift */; };
 		D97465FA1FE31A650060EA66 /* Module.swift in Sources */ = {isa = PBXBuildFile; fileRef = D97465F91FE31A650060EA66 /* Module.swift */; };
@@ -89,6 +90,7 @@
 /* End PBXContainerItemProxy section */
 
 /* Begin PBXFileReference section */
+		8D8B20EA2062E2B700F27057 /* Graph.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Graph.swift; sourceTree = "<group>"; };
 		D5B2E89F1C3A780C00C0327D /* CloudCore.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = CloudCore.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		D5C6298B1C3A8BBD007F7B7C /* Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		D9089D491FE14E57000FC60C /* SetupOperation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SetupOperation.swift; sourceTree = "<group>"; };
@@ -483,6 +485,7 @@
 				E22A53D91E4A8743009286C0 /* CloudKitAttribute.swift */,
 				E2EE20061E4E6DCE0060F769 /* ServiceAttributeName.swift */,
 				E2E296C91E49DA0800E7D6ED /* Tokens.swift */,
+				8D8B20EA2062E2B700F27057 /* Graph.swift */,
 			);
 			path = Model;
 			sourceTree = "<group>";
@@ -715,6 +718,7 @@
 				E2C02A0E1E4C99AD001B2871 /* ObjectToRecordConverter.swift in Sources */,
 				D985DE9D1FDFF9D400236870 /* PurgeLocalDatabaseOperation.swift in Sources */,
 				E2FA74481E769D9400C3489D /* RecordIDWithDatabase.swift in Sources */,
+				8D8B20EB2062E2B700F27057 /* Graph.swift in Sources */,
 				E29BB2211E4344E80020F5B6 /* CKRecord.swift in Sources */,
 				E2D390081E4A49350019BBCD /* NSEntityDescription.swift in Sources */,
 				E29BB2231E4346FF0020F5B6 /* NSManagedObject.swift in Sources */,

Source/Classes/Fetch/FetchAndSaveOperation.swift

@@ -67,25 +67,80 @@ public class FetchAndSaveOperation: Operation {
 
 		CloudCore.delegate?.didSyncFromCloud()
 	}
+
+    func dependencyGraph() -> Graph {
+
+        let cloudCoreEnabledEntities = self.persistentContainer.managedObjectModel.cloudCoreEnabledEntities
+        let entityNames = cloudCoreEnabledEntities.flatMap({$0.name})
+        let dependencyGraph: Graph = Graph(vertices: entityNames)
+
+        for entityDescription in cloudCoreEnabledEntities {
+            guard let name = entityDescription.name else {continue}
+
+            for relationshipDescription in entityDescription.relationshipsByName {
+                guard let destinationEntityName = relationshipDescription.value.destinationEntity?.name else {continue}
+
+                dependencyGraph.addEdge(from: destinationEntityName, to: name)
+            }
+        }
+        return dependencyGraph
+    }
+
+
+    func createConvertOperationsByRecordType(records:[CKRecord], context:NSManagedObjectContext) -> [String:[Operation]] {
+        var operationsByRecordType = [String:[Operation]]()
+        for record in records {
+            // Convert and write CKRecord To NSManagedObject Operation
+            let convertOperation = RecordToCoreDataOperation(parentContext: context, record: record)
+            convertOperation.errorBlock = { self.errorBlock?($0) }
+
+            var auxOperations = operationsByRecordType[record.recordType] ?? [Operation]()
+            auxOperations.append(convertOperation)
+            operationsByRecordType[record.recordType] = auxOperations
+        }
+        return operationsByRecordType
+    }
+
 
 	private func addRecordZoneChangesOperation(recordZoneIDs: [CKRecordZoneID], database: CKDatabase, context: NSManagedObjectContext) {
 		if recordZoneIDs.isEmpty { return }
 
 		let recordZoneChangesOperation = FetchRecordZoneChangesOperation(from: database, recordZoneIDs: recordZoneIDs, tokens: tokens)
 
-		recordZoneChangesOperation.recordChangedBlock = {
-			// Convert and write CKRecord To NSManagedObject Operation
-			let convertOperation = RecordToCoreDataOperation(parentContext: context, record: $0)
-			convertOperation.errorBlock = { self.errorBlock?($0) }
-			self.queue.addOperation(convertOperation)
-		}
-
-		recordZoneChangesOperation.recordWithIDWasDeletedBlock = {
-			// Delete NSManagedObject with specified recordID Operation
-			let deleteOperation = DeleteFromCoreDataOperation(parentContext: context, recordID: $0)
-			deleteOperation.errorBlock = { self.errorBlock?($0) }
-			self.queue.addOperation(deleteOperation)
-		}
+        recordZoneChangesOperation.recordChangedCompletionBlock = { changedRecords, deletedRecordIDs in
+
+            // Record Changes
+            let operationsByRecordType = self.createConvertOperationsByRecordType(records: changedRecords, context: context)
+            let dependencyGraph = self.dependencyGraph()
+
+            if let topologicalSort = dependencyGraph.topologicalSort() {
+                for recordType in topologicalSort {
+                    guard let operations = operationsByRecordType[recordType] else {continue}
+                    operations.forEach { changeOperation in
+                        self.queue.addOperation(changeOperation)
+                    }
+                }
+            } else {
+
+                // Perform all changes many times to fill the all the relationships.
+                let cycleLength = dependencyGraph.detectCycles().flatMap({$0.count}).sorted().last ?? 2
+                for _ in 0...cycleLength {
+                    changedRecords.forEach {record in
+                        let convertOperation = RecordToCoreDataOperation(parentContext: context, record: record)
+                        convertOperation.errorBlock = { self.errorBlock?($0) }
+                        self.queue.addOperation(convertOperation)
+                    }
+                }
+            }
+
+            // Record Deletions
+            deletedRecordIDs.forEach {
+                // Delete NSManagedObject with specified recordID Operation
+                let deleteOperation = DeleteFromCoreDataOperation(parentContext: context, recordID: $0)
+                deleteOperation.errorBlock = { self.errorBlock?($0) }
+                self.queue.addOperation(deleteOperation)
+            }
+        }
 
 		recordZoneChangesOperation.errorBlock = { zoneID, error in
 			self.handle(recordZoneChangesError: error, in: zoneID, database: database, context: context)

Source/Classes/Fetch/SubOperations/FetchRecordZoneChangesOperation.swift

@@ -14,10 +14,11 @@ class FetchRecordZoneChangesOperation: Operation {
 	let recordZoneIDs: [CKRecordZoneID]
 	let database: CKDatabase
 	//
-
+
+    var updatedRecords = [CKRecord]()
+    var deletedRecordIDs = [CKRecordID]()
+    var recordChangedCompletionBlock: ((_ changed:[CKRecord],_ deleted:[CKRecordID]) -> Void)?
 	var errorBlock: ((CKRecordZoneID, Error) -> Void)?
-	var recordChangedBlock: ((CKRecord) -> Void)?
-	var recordWithIDWasDeletedBlock: ((CKRecordID) -> Void)?
 
 	private let optionsByRecordZoneID: [CKRecordZoneID: CKFetchRecordZoneChangesOptions]
 	private let fetchQueue = OperationQueue()
@@ -53,12 +54,12 @@ class FetchRecordZoneChangesOperation: Operation {
 		// Init Fetch Operation
 		let fetchOperation = CKFetchRecordZoneChangesOperation(recordZoneIDs: recordZoneIDs, optionsByRecordZoneID: optionsByRecordZoneID)
 
-		fetchOperation.recordChangedBlock = {
-			self.recordChangedBlock?($0)
-		}
-		fetchOperation.recordWithIDWasDeletedBlock = { recordID, _ in
-			self.recordWithIDWasDeletedBlock?(recordID)
-		}
+        fetchOperation.recordChangedBlock = {
+            self.updatedRecords.append($0)
+        }
+        fetchOperation.recordWithIDWasDeletedBlock = { recordID, _ in
+            self.deletedRecordIDs.append(recordID)
+        }
 		fetchOperation.recordZoneFetchCompletionBlock = { zoneId, serverChangeToken, clientChangeTokenData, isMore, error in
 			self.tokens.tokensByRecordZoneID[zoneId] = serverChangeToken
 
@@ -69,7 +70,9 @@ class FetchRecordZoneChangesOperation: Operation {
 			if isMore {
 				let moreOperation = self.makeFetchOperation(optionsByRecordZoneID: optionsByRecordZoneID)
 				self.fetchQueue.addOperation(moreOperation)
-			}
+            } else {
+                self.recordChangedCompletionBlock?(self.updatedRecords, self.deletedRecordIDs)
+            }
 		}
 
 		fetchOperation.qualityOfService = self.qualityOfService

Source/Model/Graph.swift

@@ -0,0 +1,100 @@
+//
+//  Graph.swift
+//  CloudCore
+//
+//  Created by Juan Ignacio on 3/21/18.
+//  Copyright © 2018 Vasily Ulianov. All rights reserved.
+//
+
+// Part of this code are from the SwiftGraph project: https://github.com/davecom/SwiftGraph
+class Graph {
+
+    var vertices : [String]
+    var edges = [String:[String]]()
+
+    init(vertices:[String]) {
+        self.vertices = vertices
+        vertices.forEach {
+            self.edges[$0] = [String]()
+        }
+    }
+
+    func addEdge(from:String, to:String) {
+        edges[from]!.append(to)
+    }
+
+    func indexOfVertex(_ v:String) -> Int? {
+        return vertices.index(of: v)
+    }
+
+    func neighborsForVertex(_ v:String) -> [String]? {
+        return edges[v]
+    }
+
+    func detectCycles() -> [[String]] {
+        var cycles = [[String]]() // store of all found cycles
+        var openPaths: [[String]] = vertices.map{ [$0] } // initial open paths are single vertex lists
+
+        while openPaths.count > 0 {
+            let openPath = openPaths.removeFirst() // queue pop()
+            //if openPath.count > maxK { return cycles } // do we want to stop at a certain length k
+            if let tail = openPath.last, let head = openPath.first {
+                let neighbors = neighborsForVertex(tail)!
+                for neighbor in neighbors {
+
+                    if neighbor == head {
+                        cycles.append(openPath + [neighbor]) // found a cycle
+                    } else if !openPath.contains(neighbor) && indexOfVertex(neighbor)! > indexOfVertex(head)! {
+                        openPaths.append(openPath + [neighbor]) // another open path to explore
+                    }
+                }
+            }
+        }
+        return cycles
+    }
+
+
+    func topologicalSort() -> [String]? {
+        var sortedVertices = [String]()
+        let tsNodes = vertices.map{ TSNode<String>(vertex: $0, color: .white) }
+        var notDAG = false
+
+        func visit(_ node: TSNode<String>) {
+            guard node.color != .gray else {
+                notDAG = true
+                return
+            }
+            if node.color == .white {
+                node.color = .gray
+                for inode in tsNodes where (neighborsForVertex(node.vertex)?.contains(inode.vertex))! {
+                    visit(inode)
+                }
+                node.color = .black
+                sortedVertices.insert(node.vertex, at: 0)
+            }
+        }
+
+        for node in tsNodes where node.color == .white {
+            visit(node)
+        }
+
+        if notDAG {
+            return nil
+        }
+
+        return sortedVertices
+    }
+
+    fileprivate enum TSColor { case black, gray, white }
+
+    fileprivate class TSNode<String> {
+        fileprivate let vertex: String
+        fileprivate var color: TSColor
+
+        init(vertex: String, color: TSColor) {
+            self.vertex = vertex
+            self.color = color
+        }
+    }
+}
+