81 lines
3.2 KiB
Swift
81 lines
3.2 KiB
Swift
//
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// DDPExponentialBackoff.swift
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//
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//
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// Created by Joseph Kitchener on 05/02/2016.
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// Copyright © 2016 Joseph Kitchener. All rights reserved.
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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import Foundation
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///Retry connection requests to the server. The retries exponentially increase the waiting time up to a certain threshold. The idea is that if the server is down temporarily, it is not overwhelmed with requests hitting at the same time when it comes back up.
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class DDPExponentialBackoff {
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init(retryInterval:Double = 0.01,maxWaitInterval:Double = 5,multiplier:Double = 1.5){
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self.reconnectionRetryInterval = retryInterval
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self._reconnectionRetryInterval = retryInterval
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self.maxWaitInterval = maxWaitInterval
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self.multiplier = multiplier
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}
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//Cached original interval time
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fileprivate var _reconnectionRetryInterval:Double = 0
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fileprivate var reconnectionRetryInterval:Double
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fileprivate var maxWaitInterval:Double
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fileprivate var multiplier:Double
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///Perform a closure with increasing exponential delay time up to a max wait interval
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func createBackoff(_ closure:@escaping ()->()) {
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let previousRetryInterval = self.reconnectionRetryInterval
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let newRetryInterval = min(previousRetryInterval * multiplier,maxWaitInterval)
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self.reconnectionRetryInterval = previousRetryInterval < maxWaitInterval ? newRetryInterval: maxWaitInterval
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DispatchQueue.main.asyncAfter(
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deadline: DispatchTime.now() + Double(Int64(self.reconnectionRetryInterval * Double(NSEC_PER_SEC))) / Double(NSEC_PER_SEC), execute: closure)
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// print(reconnectionRetryInterval)
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}
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//Reset backoff to orignal time
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func reset(){
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reconnectionRetryInterval = _reconnectionRetryInterval
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}
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//Sets the backoff
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func setBackoff(_ retryInterval:Double,maxWaitInterval:Double,multiplier:Double){
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self.reconnectionRetryInterval = retryInterval
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self._reconnectionRetryInterval = retryInterval
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self.maxWaitInterval = maxWaitInterval
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self.multiplier = multiplier
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}
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}
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