feat: support three different formats

[zymxxxs]

This PR solves a bug and adds a feature

• unable to process Date field in header
• according the RCF 3.3.1 description, support three different formats (https://tools.ietf.org/html/rfc2616#section-3.3.1)

old code screenshot

new code screenshot

[zymxxxs]

@swift-ci test linux

[millenomi]

There are costs associated with changing the settings of a formatter, and I’d rather just have three different formatters ready here.

[zymxxxs]

    private var _dateFormat: String? { willSet { _reset() } }
    open var dateFormat: String! {
        get {
            guard let format = _dateFormat else {
                return CFDateFormatterGetFormat(_cfObject)._swiftObject
            }
            return format
        }
        set {
            _dateFormat = newValue
        }
    }

looks like anything was cost

[millenomi]

Sorry, I don’t understand your comment.

I was referring to the resources that CFDateFormatterSet… will destroy and recreate every time it’s called. I’d rather just have three different date formatters so we can amortize that call.

[millenomi]

(That call is in _reset().)

[zymxxxs]

OK，I got it

[spevans]

Could you add some tests to in the three different date formats to test all three different formatters as well please.

[zymxxxs]

@spevans

The currently modified code is in the canCache method. There is no test code. I'm not sure where to write the test code? Is it possible to write in a TestURLSession file or do you have any good suggestions?

[spevans]

Since the only thing that needs to be tested is actually parsing dates in different formats I would suggest adding some tests into TestHTTPURLResponse that directly call the _HTTPURLProtocol.date(from: dateString) method with dates in different formats.

Since it is internal you will need to put the tests inside a
#if NS_FOUNDATION_ALLOWS_TESTABLE_IMPORT / #endif
block and also add

   #if canImport(SwiftFoundation) && !DEPLOYMENT_RUNTIME_OBJC
       @testable import SwiftFoundation
   #else
       @testable import Foundation
   #endif

to the top of the test file.

You could setup some tests for TestURLSession but that would really be testing the caching validation mechanism and not specifically the date parsing. Also note that at the moment TestURLSession is currently disabled. It will be re-enabled once I have fixed a few more URLSession bugs and stopped some of the tests being flaky.

[millenomi]

Also: I commented previously that changing the .dateFormat of an existing formatter is throwing away resources, and that I would much prefer a patch where three date for matters are created and cached. Can we have that?

It’s a tiny thing but we have our work cut out for us in SCF to improve performance, and not adding an obvious time-and-space issue is one way we can avoid worsening things.

[zymxxxs]

@millenomi commit

Is this ok?

[millenomi]

I hadn’t seen that! That works.

[millenomi]

(I still agree with @spevans that we need tests.)

[zymxxxs]

sorry, I have been busy recently. I forgot about this and I will add UT as soon as possible

[shahmishal]

The Swift project moved the default branch to main and deleted master branch, so GitHub automatically closed the PR. Please re-create pull request with main branch.

More detail about the branch update - https://forums.swift.org/t/updating-branch-names/40412