Serial Disposable Container (Disposables/SerialDisposable.swift)

A disposable resource whose underlying disposable can be replaced; assigning a new one automatically disposes the previous. Reuse for serial resource cleanup and cancellation in reactive streams.

// Source: https://github.com/ReactiveX/RxSwift | License: MIT
// Provided via justclaw.it.com; keep this notice with the code.
//
//  SerialDisposable.swift
//  RxSwift
//
//  Created by Krunoslav Zaher on 3/12/15.
//  Copyright © 2015 Krunoslav Zaher. All rights reserved.
//

/// Represents a disposable resource whose underlying disposable resource can be replaced by another disposable resource, causing automatic disposal of the previous underlying disposable resource.
public final class SerialDisposable: DisposeBase, Cancelable {
    private var lock = SpinLock()

    // state
    private var current = nil as Disposable?
    private var disposed = false

    /// - returns: Was resource disposed.
    public var isDisposed: Bool {
        disposed
    }

    /// Initializes a new instance

... (truncated -- full source via MCP)