Multithreaded reader writers issue with ImageCache module

[eSpecialized]

• [X] I've read, understood, and done my best to follow the *CONTRIBUTING guidelines.

What did you do?

ImageCache module was found removing images from the cache concurrently. This occasionally causes crashing in our Application when the cache approaches a full state. Any add/remove actions should be wrapped under the synchronizationQueue with the barrier option.

What did you expect to happen?

ImageCache should function without issue.

What happened instead?

ImageCache crashes once cache fills on occasion.

Alamofire Environment

Alamofire version:

• Alamofire (5.0.0-beta.7)
• AlamofireImage (4.0.0-beta.4): Xcode 11 Swift 5 Platform(s) running AlamofireImage: iOS **macOS version running Xcode: Mojave

Demo Project

None provided.

Modifying any imageCache test to use multiple DispatchQueue’s to add/remove from the imageCache will present the crash bug. Notes: It should add/remove 100’s of times if not 1000’s, and surpass the cache Limit many times to cause the bug to present.

[jshier]

This has been fixed in #387 and will be released as 4.0.0-beta.6.