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DispatchQueue Perform Safely
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| // | |
| // DispatchQueue.swift | |
| // | |
| // Created by Jaehong Kang on 12/04/2019. | |
| // Copyright © 2019 Jaehong Kang. All rights reserved. | |
| // | |
| // Licensed under the Apache License, Version 2.0 (the "License"); | |
| // you may not use this file except in compliance with the License. | |
| // You may obtain a copy of the License at | |
| // | |
| // http://www.apache.org/licenses/LICENSE-2.0 | |
| // | |
| // Unless required by applicable law or agreed to in writing, software | |
| // distributed under the License is distributed on an "AS IS" BASIS, | |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| // See the License for the specific language governing permissions and | |
| // limitations under the License. | |
| import Foundation | |
| extension DispatchQueue { | |
| private static let isCurrentQueueKey = DispatchSpecificKey<Bool>() | |
| open func perform<T>(execute closure: () throws -> T) rethrows -> T { | |
| self.setSpecific(key: DispatchQueue.isCurrentQueueKey, value: true) | |
| defer { | |
| self.setSpecific(key: DispatchQueue.isCurrentQueueKey, value: nil) | |
| } | |
| guard DispatchQueue.getSpecific(key: DispatchQueue.isCurrentQueueKey) == true else { | |
| return try self.sync(execute: closure) | |
| } | |
| return try closure() | |
| } | |
| } |
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