//
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// SerialDispatchQueueScheduler.swift
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// RxSwift
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//
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// Created by Krunoslav Zaher on 2/8/15.
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// Copyright © 2015 Krunoslav Zaher. All rights reserved.
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//
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import Dispatch
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import Foundation
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/**
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Abstracts the work that needs to be performed on a specific `dispatch_queue_t`. It will make sure
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that even if concurrent dispatch queue is passed, it's transformed into a serial one.
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It is extremely important that this scheduler is serial, because
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certain operator perform optimizations that rely on that property.
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Because there is no way of detecting is passed dispatch queue serial or
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concurrent, for every queue that is being passed, worst case (concurrent)
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will be assumed, and internal serial proxy dispatch queue will be created.
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This scheduler can also be used with internal serial queue alone.
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In case some customization need to be made on it before usage,
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internal serial queue can be customized using `serialQueueConfiguration`
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callback.
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*/
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public class SerialDispatchQueueScheduler : SchedulerType {
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public typealias TimeInterval = Foundation.TimeInterval
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public typealias Time = Date
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/// - returns: Current time.
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public var now : Date {
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Date()
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}
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let configuration: DispatchQueueConfiguration
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/**
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Constructs new `SerialDispatchQueueScheduler` that wraps `serialQueue`.
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- parameter serialQueue: Target dispatch queue.
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- parameter leeway: The amount of time, in nanoseconds, that the system will defer the timer.
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*/
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init(serialQueue: DispatchQueue, leeway: DispatchTimeInterval = DispatchTimeInterval.nanoseconds(0)) {
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self.configuration = DispatchQueueConfiguration(queue: serialQueue, leeway: leeway)
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}
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/**
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Constructs new `SerialDispatchQueueScheduler` with internal serial queue named `internalSerialQueueName`.
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Additional dispatch queue properties can be set after dispatch queue is created using `serialQueueConfiguration`.
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- parameter internalSerialQueueName: Name of internal serial dispatch queue.
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- parameter serialQueueConfiguration: Additional configuration of internal serial dispatch queue.
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- parameter leeway: The amount of time, in nanoseconds, that the system will defer the timer.
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*/
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public convenience init(internalSerialQueueName: String, serialQueueConfiguration: ((DispatchQueue) -> Void)? = nil, leeway: DispatchTimeInterval = DispatchTimeInterval.nanoseconds(0)) {
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let queue = DispatchQueue(label: internalSerialQueueName, attributes: [])
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serialQueueConfiguration?(queue)
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self.init(serialQueue: queue, leeway: leeway)
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}
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/**
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Constructs new `SerialDispatchQueueScheduler` named `internalSerialQueueName` that wraps `queue`.
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- parameter queue: Possibly concurrent dispatch queue used to perform work.
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- parameter internalSerialQueueName: Name of internal serial dispatch queue proxy.
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- parameter leeway: The amount of time, in nanoseconds, that the system will defer the timer.
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*/
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public convenience init(queue: DispatchQueue, internalSerialQueueName: String, leeway: DispatchTimeInterval = DispatchTimeInterval.nanoseconds(0)) {
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// Swift 3.0 IUO
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let serialQueue = DispatchQueue(label: internalSerialQueueName,
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attributes: [],
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target: queue)
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self.init(serialQueue: serialQueue, leeway: leeway)
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}
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/**
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Constructs new `SerialDispatchQueueScheduler` that wraps one of the global concurrent dispatch queues.
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- parameter qos: Identifier for global dispatch queue with specified quality of service class.
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- parameter internalSerialQueueName: Custom name for internal serial dispatch queue proxy.
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- parameter leeway: The amount of time, in nanoseconds, that the system will defer the timer.
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*/
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@available(macOS 10.10, *)
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public convenience init(qos: DispatchQoS, internalSerialQueueName: String = "rx.global_dispatch_queue.serial", leeway: DispatchTimeInterval = DispatchTimeInterval.nanoseconds(0)) {
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self.init(queue: DispatchQueue.global(qos: qos.qosClass), internalSerialQueueName: internalSerialQueueName, leeway: leeway)
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}
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/**
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Schedules an action to be executed immediately.
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- parameter state: State passed to the action to be executed.
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- parameter action: Action to be executed.
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- returns: The disposable object used to cancel the scheduled action (best effort).
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*/
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public final func schedule<StateType>(_ state: StateType, action: @escaping (StateType) -> Disposable) -> Disposable {
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self.scheduleInternal(state, action: action)
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}
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func scheduleInternal<StateType>(_ state: StateType, action: @escaping (StateType) -> Disposable) -> Disposable {
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self.configuration.schedule(state, action: action)
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}
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/**
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Schedules an action to be executed.
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- parameter state: State passed to the action to be executed.
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- parameter dueTime: Relative time after which to execute the action.
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- parameter action: Action to be executed.
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- returns: The disposable object used to cancel the scheduled action (best effort).
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*/
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public final func scheduleRelative<StateType>(_ state: StateType, dueTime: RxTimeInterval, action: @escaping (StateType) -> Disposable) -> Disposable {
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self.configuration.scheduleRelative(state, dueTime: dueTime, action: action)
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}
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/**
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Schedules a periodic piece of work.
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- parameter state: State passed to the action to be executed.
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- parameter startAfter: Period after which initial work should be run.
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- parameter period: Period for running the work periodically.
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- parameter action: Action to be executed.
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- returns: The disposable object used to cancel the scheduled action (best effort).
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*/
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public func schedulePeriodic<StateType>(_ state: StateType, startAfter: RxTimeInterval, period: RxTimeInterval, action: @escaping (StateType) -> StateType) -> Disposable {
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self.configuration.schedulePeriodic(state, startAfter: startAfter, period: period, action: action)
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}
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}
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