mirror of https://github.com/trudnai/Steve2.git
86 lines
2.3 KiB
Swift
86 lines
2.3 KiB
Swift
//
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// RepeatingTimer.swift
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// Steve ][
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//
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// Created by Tamas Rudnai on 9/15/19.
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// Copyright © 2019, 2020 Tamas Rudnai. All rights reserved.
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//
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// This file is part of Steve ][ -- The Apple ][ Emulator.
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//
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// Steve ][ is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Steve ][ is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Steve ][. If not, see <https://www.gnu.org/licenses/>.
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//
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import Foundation
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/// RepeatingTimer mimics the API of DispatchSourceTimer but in a way that prevents
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/// crashes that occur from calling resume multiple times on a timer that is
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/// already resumed (noted by https://github.com/SiftScience/sift-ios/issues/52
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class RepeatingTimer {
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let timeInterval: TimeInterval
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var eventHandler: (() -> Void)?
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private enum State {
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case suspended
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case resumed
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}
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private var state: State = .suspended
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init(timeInterval: TimeInterval) {
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self.timeInterval = timeInterval
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}
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private lazy var timer: DispatchSourceTimer = {
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let t = DispatchSource.makeTimerSource()
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t.schedule(deadline: .now() + self.timeInterval, repeating: self.timeInterval)
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t.setEventHandler(handler: { [weak self] in
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self?.eventHandler?()
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})
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return t
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}()
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deinit {
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timer.setEventHandler {}
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timer.cancel()
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/*
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If the timer is suspended, calling cancel without resuming
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triggers a crash. This is documented here https://forums.developer.apple.com/thread/15902
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*/
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resume()
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eventHandler = nil
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}
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func resume() {
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if state == .resumed {
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return
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}
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state = .resumed
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timer.resume()
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}
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func suspend() {
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if state == .suspended {
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return
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}
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state = .suspended
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timer.suspend()
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}
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func kill() {
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timer.cancel()
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}
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}
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