Implement internal logger

Sources/SwiftQueue/JobBuilder.swift

@@ -93,8 +93,8 @@ public final class JobBuilder {
         return self
     }
 
-    internal func build(job: Job) -> SqOperation {
-        return SqOperation(job: job, info: info)
+    internal func build(job: Job, logger: SwiftQueueLogger) -> SqOperation {
+        return SqOperation(job: job, info: info, logger: logger)
     }
 
     /// Add job to the JobQueue
@@ -107,6 +107,6 @@ public final class JobBuilder {
         let queue = manager.getQueue(queueName: info.group)
         let job = queue.createHandler(type: info.type, params: info.params)
 
-        queue.addOperation(build(job: job))
+        queue.addOperation(build(job: job, logger: manager.logger))
     }
 }

Sources/SwiftQueue/JobInfo.swift

@@ -40,7 +40,6 @@ struct JobInfo {
 
     init?(dictionary: [String: Any]) {
         guard let type = dictionary["type"] as? String else {
-            assertionFailure("Unable to retrieve Job type")
             return nil
         }
 

Sources/SwiftQueue/SqOperation.swift

@@ -14,6 +14,8 @@ internal final class SqOperation: Operation {
 
     var lastError: Swift.Error?
 
+    let logger: SwiftQueueLogger
+
     override var name: String? { get { return info.uuid } set { } }
 
     private var jobIsExecuting: Bool = false
@@ -36,9 +38,10 @@ internal final class SqOperation: Operation {
         }
     }
 
-    internal init(job: Job, info: JobInfo) {
+    internal init(job: Job, info: JobInfo, logger: SwiftQueueLogger) {
         self.handler = job
         self.info = info
+        self.logger = logger
 
         self.constraints = [
             DeadlineConstraint(),
@@ -56,6 +59,7 @@ internal final class SqOperation: Operation {
 
     override func start() {
         super.start()
+        logger.log(.verbose, jobId: info.uuid, message: "Job has been started by the system")
         isExecuting = true
         run()
     }
@@ -65,19 +69,22 @@ internal final class SqOperation: Operation {
     }
 
     func cancel(with: Swift.Error) {
+        logger.log(.verbose, jobId: info.uuid, message: "Job has been canceled")
         lastError = with
         onTerminate()
         super.cancel()
     }
 
     func onTerminate() {
+        logger.log(.verbose, jobId: info.uuid, message: "Job will not run anymore")
         if isExecuting {
             isFinished = true
         }
     }
 
     // cancel before schedule and serialise
     internal func abort(error: Swift.Error) {
+        logger.log(.verbose, jobId: info.uuid, message: "Job has not been scheduled due to \(error.localizedDescription)")
         lastError = error
         // Need to be called manually since the task is actually not in the queue. So cannot call cancel()
         handler.onRemove(result: .fail(error))
@@ -94,6 +101,7 @@ internal final class SqOperation: Operation {
         do {
             try self.willRunJob()
         } catch let error {
+            logger.log(.warning, jobId: info.uuid, message: "Job cannot run due to \(error.localizedDescription)")
             // Will never run again
             cancel(with: error)
             return
@@ -102,14 +110,17 @@ internal final class SqOperation: Operation {
         guard self.checkIfJobCanRunNow() else {
             // Constraint fail.
             // Constraint will call run when it's ready
+            logger.log(.verbose, jobId: info.uuid, message: "Job cannot run now. Execution is postponed")
             return
         }
 
+        logger.log(.verbose, jobId: info.uuid, message: "Job is running")
         handler.onRun(callback: self)
     }
 
     internal func remove() {
         let result = lastError.map(JobCompletion.fail) ?? JobCompletion.success
+        logger.log(.verbose, jobId: info.uuid, message: "Job is removed from the queue result=\(result)")
         handler.onRemove(result: result)
     }
 
@@ -129,6 +140,7 @@ extension SqOperation: JobResult {
     }
 
     private func completionFail(error: Swift.Error) {
+        logger.log(.warning, jobId: info.uuid, message: "Job completed with error \(error.localizedDescription)")
         lastError = error
 
         switch info.retries {
@@ -166,6 +178,7 @@ extension SqOperation: JobResult {
     }
 
     private func completionSuccess() {
+        logger.log(.verbose, jobId: info.uuid, message: "Job completed successfully")
         lastError = nil
         info.currentRepetition = 0
 
@@ -195,20 +208,17 @@ extension SqOperation: JobResult {
 
 extension SqOperation {
 
-    convenience init?(dictionary: [String: Any], creator: JobCreator) {
+    convenience init?(json: String, creator: JobCreator, logger: SwiftQueueLogger) {
+        let dictionary = fromJSON(json) as? [String: Any] ?? [:]
+
         guard let info = JobInfo(dictionary: dictionary) else {
-            assertionFailure("Unable to un-serialise job")
+            logger.log(.error, jobId: "UNKNOWN", message: "Unable to un-serialise job [\(json)]")
             return nil
         }
 
         let job = creator.create(type: info.type, params: info.params)
 
-        self.init(job: job, info: info)
-    }
-
-    convenience init?(json: String, creator: JobCreator) {
-        let dict = fromJSON(json) as? [String: Any] ?? [:]
-        self.init(dictionary: dict, creator: creator)
+        self.init(job: job, info: info, logger: logger)
     }
 
     func toJSONString() -> String? {

Sources/SwiftQueue/SqOperationQueue.swift

@@ -11,10 +11,13 @@ internal final class SqOperationQueue: OperationQueue {
 
     private let queueName: String
 
-    init(_ queueName: String, _ creator: JobCreator, _ persister: JobPersister? = nil, _ isPaused: Bool = false) {
+    private let logger: SwiftQueueLogger
+
+    init(_ queueName: String, _ creator: JobCreator, _ persister: JobPersister? = nil, _ isPaused: Bool = false, logger: SwiftQueueLogger) {
         self.creator = creator
         self.persister = persister
         self.queueName = queueName
+        self.logger = logger
 
         super.init()
 
@@ -27,7 +30,7 @@ internal final class SqOperationQueue: OperationQueue {
 
     private func loadSerializedTasks(name: String) {
         persister?.restore(queueName: name).flatMapCompact { string -> SqOperation? in
-            SqOperation(json: string, creator: creator)
+            return SqOperation(json: string, creator: creator, logger: logger)
         }.sorted {
             $0.info.createTime < $1.info.createTime
         }.forEach(addOperation)

Sources/SwiftQueue/SwiftQueueLogger.swift

@@ -0,0 +1,76 @@
+//
+// Created by Lucas Nelaupe on 18/4/18.
+//
+
+import Foundation
+
+/// Specify different importance of logging
+public enum LogLevel: Int {
+
+    /// Basic information about scheduling, running job and completion
+    case verbose = 1
+    /// Important but non fatal information
+    case warning = 2
+    /// Something went wrong during the scheduling or the execution
+    case error = 3
+
+}
+
+internal extension LogLevel {
+    var description: String {
+        switch self {
+        case .verbose:
+            return "verbose"
+        case .warning:
+            return "warning"
+        case .error:
+            return "error"
+        }
+    }
+}
+
+/// Func
+public protocol SwiftQueueLogger {
+
+    /// Function called by the library to log an event
+    func log(_ level: LogLevel, jobId: @autoclosure () -> String, message: @autoclosure () -> String)
+
+}
+
+/// Class to compute the log and print to the console
+open class ConsoleLogger: SwiftQueueLogger {
+
+    private let min: LogLevel
+
+    /// Define minimum level to log. By default, it will log everything
+    init(min: LogLevel = .verbose) {
+        self.min = min
+    }
+
+    /// Check for log level and create the output message
+    public final func log(_ level: LogLevel, jobId: @autoclosure () -> String, message: @autoclosure () -> String) {
+        if min.rawValue <= level.rawValue {
+            printComputed(output: "[SwiftQueue] level=\(level.description) jobId=\(jobId()) message=\(message())")
+        }
+    }
+
+    /// Print with default `print()` function. Can be override to changed the output
+    open func printComputed(output: String) {
+        print(output)
+    }
+
+}
+
+/// Class to ignore all kind of logs
+public class NoLogger: SwiftQueueLogger {
+
+    /// Singleton instance to avoid multiple instance across all queues
+    public static let shared = NoLogger()
+
+    private init() {}
+
+    /// Default implementation that will not log anything
+    public func log(_ level: LogLevel, jobId: @autoclosure () -> String, message: @autoclosure () -> String) {
+        // Nothing to do
+    }
+}

Sources/SwiftQueue/SwiftQueueManager.swift

@@ -7,7 +7,7 @@ import Foundation
 
 /// Global manager to perform operations on all your queues/
 /// You will have to keep this instance. We highly recommend you to store this instance in a Singleton
-/// Creating and instance of this class will automatically un-serialise your jobs and schedule them 
+/// Creating and instance of this class will automatically un-serialise your jobs and schedule them
 public final class SwiftQueueManager {
 
     private let creator: JobCreator
@@ -17,14 +17,17 @@ public final class SwiftQueueManager {
 
     private var isPaused = true
 
+    internal let logger: SwiftQueueLogger
+
     /// Create a new QueueManager with creators to instantiate Job
-    public init(creator: JobCreator, persister: JobPersister? = nil) {
+    public init(creator: JobCreator, persister: JobPersister? = nil, logger: SwiftQueueLogger = NoLogger.shared) {
         self.creator = creator
         self.persister = persister
+        self.logger = logger
 
         if let data = persister {
             for queueName in data.restore() {
-                manage[queueName] = SqOperationQueue(queueName, creator, persister, isPaused)
+                manage[queueName] = SqOperationQueue(queueName, creator, persister, isPaused, logger: logger)
             }
         }
         start()
@@ -51,7 +54,7 @@ public final class SwiftQueueManager {
     }
 
     private func createQueue(queueName: String) -> SqOperationQueue {
-        let queue = SqOperationQueue(queueName, creator, persister, isPaused)
+        let queue = SqOperationQueue(queueName, creator, persister, isPaused, logger: logger)
         manage[queueName] = queue
         return queue
     }

SwiftQueue.xcodeproj/project.pbxproj

@@ -32,6 +32,11 @@
 		1E68ED598FA15EF36B431571 /* Constrains+Deadline.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1E68EF96F1DE038FFF94FCD8 /* Constrains+Deadline.swift */; };
 		1E68EDC2230D2FACC61E7868 /* Constrains+Delay.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1E68E940C8373221E3EDC771 /* Constrains+Delay.swift */; };
 		1E68EE914B5B51CDB2BD7C4D /* Constraints+UniqueUUID.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1E68E002DC39E9BBE4A0A06A /* Constraints+UniqueUUID.swift */; };
+		95A210264F99EAC94629D786 /* SwiftQueueLogger.swift in Sources */ = {isa = PBXBuildFile; fileRef = 95A217FDB8197696002CE25C /* SwiftQueueLogger.swift */; };
+		95A214C332FB7115C12F88D2 /* LoggerTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 95A2193AF039008357A8D362 /* LoggerTests.swift */; };
+		95A21576964E9A1FE1EDC5DB /* SwiftQueueLogger.swift in Sources */ = {isa = PBXBuildFile; fileRef = 95A217FDB8197696002CE25C /* SwiftQueueLogger.swift */; };
+		95A21B708B2910C7CF8BD39D /* SwiftQueueLogger.swift in Sources */ = {isa = PBXBuildFile; fileRef = 95A217FDB8197696002CE25C /* SwiftQueueLogger.swift */; };
+		95A21FA05AABFA4A59096E8E /* SwiftQueueLogger.swift in Sources */ = {isa = PBXBuildFile; fileRef = 95A217FDB8197696002CE25C /* SwiftQueueLogger.swift */; };
 		B06405031FA04AA000086C69 /* UserDefaultsPersister.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1D8479A11F82A84A00B3BBFB /* UserDefaultsPersister.swift */; };
 		B06405041FA04AA000086C69 /* SwiftQueue.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1D8479A21F82A84A00B3BBFB /* SwiftQueue.swift */; };
 		B06405061FA04AA000086C69 /* Constraints.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1D8479A61F82A84B00B3BBFB /* Constraints.swift */; };
@@ -96,6 +101,8 @@
 		1E68E82C1E071C7AA1AC4BB6 /* Constrains+Network.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = "Constrains+Network.swift"; path = "SwiftQueue/Constrains+Network.swift"; sourceTree = "<group>"; };
 		1E68E940C8373221E3EDC771 /* Constrains+Delay.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = "Constrains+Delay.swift"; path = "SwiftQueue/Constrains+Delay.swift"; sourceTree = "<group>"; };
 		1E68EF96F1DE038FFF94FCD8 /* Constrains+Deadline.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = "Constrains+Deadline.swift"; path = "SwiftQueue/Constrains+Deadline.swift"; sourceTree = "<group>"; };
+		95A217FDB8197696002CE25C /* SwiftQueueLogger.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = SwiftQueueLogger.swift; path = SwiftQueue/SwiftQueueLogger.swift; sourceTree = "<group>"; };
+		95A2193AF039008357A8D362 /* LoggerTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = LoggerTests.swift; sourceTree = "<group>"; };
 		B064050E1FA04AA000086C69 /* SwiftQueue.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = SwiftQueue.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		B064051D1FA04AAC00086C69 /* SwiftQueue.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = SwiftQueue.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		B064052C1FA04CCF00086C69 /* SwiftQueue.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = SwiftQueue.framework; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -174,6 +181,7 @@
 				D0B7C62E5894FA6EE00D3160 /* PersisterTests.swift */,
 				D0B7C898344F1EB3A0815D67 /* ConstraintDeadlineTests.swift */,
 				D0B7C2A57EFC83B94E3146B3 /* Package.swift */,
+				95A2193AF039008357A8D362 /* LoggerTests.swift */,
 			);
 			name = SwiftQueueTests;
 			path = Tests/SwiftQueueTests;
@@ -217,6 +225,7 @@
 				D0B7C4E41A1BF73329A7D03D /* JobInfo.swift */,
 				D0B7CB3B79E039D3B11D8921 /* JobBuilder.swift */,
 				D0B7CB571CECEEA34DD07398 /* SqOperationQueue.swift */,
+				95A217FDB8197696002CE25C /* SwiftQueueLogger.swift */,
 			);
 			path = Sources;
 			sourceTree = SOURCE_ROOT;
@@ -360,6 +369,7 @@
 				D0B7CC03343274087B4C7955 /* JobInfo.swift in Sources */,
 				D0B7C8729FA2F6EF3A6C42F8 /* JobBuilder.swift in Sources */,
 				D0B7C9AE1E4717DE474FD804 /* SqOperationQueue.swift in Sources */,
+				95A21FA05AABFA4A59096E8E /* SwiftQueueLogger.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -380,6 +390,7 @@
 				D0B7C0848D0FF83C8B04EBB6 /* JobInfo.swift in Sources */,
 				D0B7CFA2089DFF576E0D765B /* JobBuilder.swift in Sources */,
 				D0B7C2F3F465996A939596F7 /* SqOperationQueue.swift in Sources */,
+				95A21576964E9A1FE1EDC5DB /* SwiftQueueLogger.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -400,6 +411,7 @@
 				D0B7CC89D901F6C8AD2666D9 /* JobInfo.swift in Sources */,
 				D0B7C6B8833437575C438715 /* JobBuilder.swift in Sources */,
 				D0B7C276BFD64AF0EA757C55 /* SqOperationQueue.swift in Sources */,
+				95A21B708B2910C7CF8BD39D /* SwiftQueueLogger.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -420,6 +432,7 @@
 				D0B7C996BDB2A748B6B8843A /* JobInfo.swift in Sources */,
 				D0B7C437539F0BEE35FBE8F0 /* JobBuilder.swift in Sources */,
 				D0B7CD1E797A69C89CB0ADE2 /* SqOperationQueue.swift in Sources */,
+				95A210264F99EAC94629D786 /* SwiftQueueLogger.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -436,6 +449,7 @@
 				D0B7C50629CD1E0F8F40E7F3 /* ConstraintNetworkTests.swift in Sources */,
 				D0B7C9B78BFACD1BEDA4D42E /* PersisterTests.swift in Sources */,
 				D0B7C6C3E08DF6BFD0737E4D /* ConstraintDeadlineTests.swift in Sources */,
+				95A214C332FB7115C12F88D2 /* LoggerTests.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};