mirror of https://github.com/oxen-io/session-ios
Niels Andriesse
10 months ago
9 changed files with 487 additions and 3 deletions
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// |
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// Copyright (c) 2021 Open Whisper Systems. All rights reserved. |
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// |
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import Foundation |
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@objc |
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public enum AtomicError: Int, Error { |
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case invalidTransition |
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} |
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// MARK: - |
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private class Atomics { |
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fileprivate static let fairQueue = DispatchQueue(label: "Atomics") |
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fileprivate static let unfairLock = UnfairLock() |
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// Never instantiate this class. |
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private init() {} |
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class func perform<T>(isFair: Bool = false, _ block: () throws -> T) rethrows -> T { |
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if isFair { |
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return try fairQueue.sync(execute: block) |
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} else { |
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return try unfairLock.withLock(block) |
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} |
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} |
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} |
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// MARK: - |
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// Provides Objective-C compatibility for the most common atomic value type. |
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@objc |
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public class AtomicBool: NSObject { |
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private let value = AtomicValue<Bool>(false) |
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@objc(initWithValue:) |
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public required init(_ value: Bool) { |
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self.value.set(value) |
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} |
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@objc |
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public func get() -> Bool { |
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return value.get() |
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} |
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@objc |
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public func set(_ value: Bool) { |
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self.value.set(value) |
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} |
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// Sets value to "toValue" IFF it currently has "fromValue", |
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// otherwise throws. |
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private func transition(from fromValue: Bool, to toValue: Bool) throws { |
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return try value.transition(from: fromValue, to: toValue) |
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} |
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@objc |
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public func tryToSetFlag() -> Bool { |
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do { |
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try transition(from: false, to: true) |
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return true |
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} catch { |
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return false |
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} |
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} |
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@objc |
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public func tryToClearFlag() -> Bool { |
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do { |
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try transition(from: true, to: false) |
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return true |
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} catch { |
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return false |
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} |
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} |
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} |
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// MARK: - |
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@objc |
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public class AtomicUInt: NSObject { |
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private let value = AtomicValue<UInt>(0) |
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@objc |
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public required init(_ value: UInt = 0) { |
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self.value.set(value) |
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} |
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@objc |
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public func get() -> UInt { |
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return value.get() |
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} |
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@objc |
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public func set(_ value: UInt) { |
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self.value.set(value) |
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} |
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@discardableResult |
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@objc |
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public func increment() -> UInt { |
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return value.map { $0 + 1 } |
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} |
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@discardableResult |
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@objc |
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public func decrementOrZero() -> UInt { |
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return value.map { max($0, 1) - 1 } |
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} |
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@discardableResult |
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@objc |
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public func add(_ delta: UInt) -> UInt { |
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return value.map { $0 + delta } |
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} |
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} |
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// MARK: - |
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public final class AtomicValue<T> { |
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private var value: T |
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public required convenience init(_ value: T) { |
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self.init(value, allowOptionalType: false) |
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} |
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fileprivate init(_ value: T, allowOptionalType: Bool) { |
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self.value = value |
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} |
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public func get() -> T { |
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Atomics.perform { |
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return self.value |
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} |
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} |
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public func set(_ value: T) { |
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Atomics.perform { |
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self.value = value |
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} |
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} |
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// Transform the current value using a block. |
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@discardableResult |
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public func map(_ block: @escaping (T) -> T) -> T { |
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Atomics.perform { |
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let newValue = block(self.value) |
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self.value = newValue |
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return newValue |
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} |
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} |
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} |
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// MARK: - |
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extension AtomicValue: Codable where T: Codable { |
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public convenience init(from decoder: Decoder) throws { |
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let singleValueContainer = try decoder.singleValueContainer() |
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self.init(try singleValueContainer.decode(T.self)) |
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} |
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public func encode(to encoder: Encoder) throws { |
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var singleValueContainer = encoder.singleValueContainer() |
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try singleValueContainer.encode(value) |
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} |
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} |
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// MARK: - |
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extension AtomicValue where T: Equatable { |
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// Sets value to "toValue" IFF it currently has "fromValue", |
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// otherwise throws. |
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public func transition(from fromValue: T, to toValue: T) throws { |
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try Atomics.perform { |
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guard self.value == fromValue else { |
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throw AtomicError.invalidTransition |
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} |
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self.value = toValue |
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} |
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} |
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} |
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// MARK: - |
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public final class AtomicOptional<T> { |
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fileprivate let value = AtomicValue<T?>(nil, allowOptionalType: true) |
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public required init(_ value: T?) { |
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self.value.set(value) |
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} |
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public func get() -> T? { |
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return value.get() |
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} |
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public func set(_ value: T?) { |
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self.value.set(value) |
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} |
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} |
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extension AtomicOptional: Codable where T: Codable { |
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public convenience init(from decoder: Decoder) throws { |
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let singleValueContainer = try decoder.singleValueContainer() |
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if singleValueContainer.decodeNil() { |
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self.init(nil) |
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} else { |
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self.init(try singleValueContainer.decode(T.self)) |
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} |
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} |
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public func encode(to encoder: Encoder) throws { |
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var singleValueContainer = encoder.singleValueContainer() |
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try singleValueContainer.encode(value) |
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} |
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} |
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extension AtomicOptional where T: Equatable { |
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// Sets value to "toValue" IFF it currently has "fromValue", |
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// otherwise throws. |
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public func transition(from fromValue: T, to toValue: T) throws { |
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try value.transition(from: fromValue, to: toValue) |
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} |
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} |
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// MARK: - |
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public class AtomicArray<T> { |
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private var values: [T] |
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public required init(_ values: [T] = []) { |
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self.values = values |
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} |
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public func get() -> [T] { |
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Atomics.perform { |
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values |
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} |
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} |
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public func set(_ values: [T]) { |
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Atomics.perform { |
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self.values = values |
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} |
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} |
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public func append(_ value: T) { |
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Atomics.perform { |
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values.append(value) |
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} |
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} |
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public var first: T? { |
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Atomics.perform { |
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values.first |
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} |
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} |
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public var popHead: T? { |
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Atomics.perform { |
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values.removeFirst() |
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} |
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} |
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public func pushTail(_ value: T) { |
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append(value) |
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} |
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} |
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extension AtomicArray where T: Equatable { |
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public func remove(_ valueToRemove: T) { |
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Atomics.perform { |
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self.values = self.values.filter { (value: T) -> Bool in |
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valueToRemove != value |
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} |
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} |
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} |
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} |
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// MARK: - |
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public class AtomicDictionary<Key: Hashable, Value> { |
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private var values: [Key: Value] |
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public required init(_ values: [Key: Value] = [:]) { |
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self.values = values |
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} |
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public subscript(_ key: Key) -> Value? { |
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set { Atomics.perform { self.values[key] = newValue } } |
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get { Atomics.perform { self.values[key] } } |
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} |
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public func get() -> [Key: Value] { |
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Atomics.perform { self.values } |
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} |
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public func set(_ values: [Key: Value]) { |
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Atomics.perform { self.values = values } |
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} |
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} |
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// MARK: - |
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public class AtomicSet<T: Hashable> { |
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private var values = Set<T>() |
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public required init() {} |
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public func insert(_ value: T) { |
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Atomics.perform { _ = self.values.insert(value) } |
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} |
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public func contains(_ value: T) -> Bool { |
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Atomics.perform { self.values.contains(value) } |
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} |
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} |
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@ -0,0 +1,43 @@
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//
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// Copyright (c) 2021 Open Whisper Systems. All rights reserved.
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//
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#import <Foundation/Foundation.h> |
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NS_ASSUME_NONNULL_BEGIN |
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/// An Objective-C wrapper around os_unfair_lock. This is a non-FIFO, priority preserving lock. See: os/lock.h
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///
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/// @discussion Why is this necessary? os_unfair_lock has some unexpected behavior in Swift. These problems arise
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/// from Swift's handling of inout C structs. Passing the underlying struct as an inout parameter results in
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/// surprising Law of Exclusivity violations. There are two ways to work around this: Manually allocate heap storage
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/// in Swift or bridge to Objective-C. I figured bridging a simple struct is a bit easier to read.
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///
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/// Note: Errors with unfair lock are fatal and will terminate the process.
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NS_SWIFT_NAME(UnfairLock) |
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@interface UnfairLock : NSObject <NSLocking> |
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/// Locks the lock. Blocks if the lock is held by another thread.
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/// Forwards to os_unfair_lock_lock() defined in os/lock.h
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- (void)lock; |
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/// Unlocks the lock. Fatal error if the lock is owned by another thread.
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/// Forwards to os_unfair_lock_unlock() defined in os/lock.h
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- (void)unlock; |
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/// Attempts to lock the lock. Returns YES if the lock was successfully acquired.
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/// Forwards to os_unfair_lock_trylock() defined in os/lock.h
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- (BOOL)tryLock NS_SWIFT_NAME(tryLock()); |
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// Note: NS_SWIFT_NAME is required to prevent bridging from renaming to `try()`.
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/// Fatal assert that the lock is owned by the current thread.
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/// Forwards to os_unfair_lock_assert_owner defined in os/lock.h
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- (void)assertOwner; |
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/// Fatal assert that the lock is not owned by the current thread.
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/// Forwards to os_unfair_lock_assert_not_owner defined in os/lock.h
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- (void)assertNotOwner; |
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@end |
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NS_ASSUME_NONNULL_END |
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@ -0,0 +1,46 @@
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// |
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// Copyright (c) 2021 Open Whisper Systems. All rights reserved. |
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// |
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#import <SessionUtilitiesKit/UnfairLock.h> |
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#import <os/lock.h> |
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@implementation UnfairLock { |
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os_unfair_lock _lock; |
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} |
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- (instancetype)init |
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{ |
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self = [super init]; |
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if (self) { |
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_lock = OS_UNFAIR_LOCK_INIT; |
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} |
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return self; |
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} |
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- (void)lock |
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{ |
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os_unfair_lock_lock(&_lock); |
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} |
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- (void)unlock |
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{ |
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os_unfair_lock_unlock(&_lock); |
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} |
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- (BOOL)tryLock |
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{ |
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return os_unfair_lock_trylock(&_lock); |
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} |
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- (void)assertOwner |
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{ |
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os_unfair_lock_assert_owner(&_lock); |
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} |
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- (void)assertNotOwner |
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{ |
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os_unfair_lock_assert_not_owner(&_lock); |
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} |
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@end |
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@ -0,0 +1,51 @@
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// |
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// Copyright (c) 2021 Open Whisper Systems. All rights reserved. |
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// |
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import Foundation |
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public extension UnfairLock { |
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/// Acquires and releases the lock around the provided closure. Blocks the current thread until the lock can be |
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/// acquired. |
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@objc |
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@available(swift, obsoleted: 1.0) |
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final func withLockObjc(_ criticalSection: () -> Void) { |
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withLock(criticalSection) |
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} |
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/// Acquires and releases the lock around the provided closure. Blocks the current thread until the lock can be |
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/// acquired. |
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final func withLock<T>(_ criticalSection: () throws -> T) rethrows -> T { |
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lock() |
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defer { unlock() } |
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return try criticalSection() |
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} |
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/// Acquires and releases the lock around the provided closure. Returns without performing the closure if the lock |
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/// can not be acquired. |
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/// - Returns: `true` if the lock was acquired and the closure was invoked. `false` if the lock could not be |
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/// acquired. |
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@discardableResult |
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final func tryWithLock(_ criticalSection: () throws -> Void) rethrows -> Bool { |
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guard tryLock() else { return false } |
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defer { unlock() } |
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try criticalSection() |
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return true |
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} |
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/// Acquires and releases the lock around the provided closure. Returns without performing the closure if the lock |
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/// can not be acquired. |
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/// - Returns: nil if the lock could not be acquired. Otherwise, returns the returns the result of the provided |
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/// closure |
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@discardableResult |
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final func tryWithLock<T>(_ criticalSection: () throws -> T) rethrows -> T? { |
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guard tryLock() else { return nil } |
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defer { unlock() } |
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return try criticalSection() |
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} |
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} |
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