快速“重试”逻辑要求 [英] Swift "retry" logic on request

问题描述

因此，当我的上传请求失败时，我对如何实现重试逻辑有些迷茫。

So i'm a bit lost on how to implement a retry logic when my upload request fail.

这是我的代码，我想了解如何

Here is my code i would like some guidance on how to do it

func startUploading(failure failure: (NSError) -> Void, success: () -> Void, progress: (Double) -> Void) {
        DDLogDebug("JogUploader: Creating jog: \(self.jog)")

        API.sharedInstance.createJog(self.jog,
            failure: { error in
                failure(error)
            }, success: {_ in
                success()
        })
    }

推荐答案

这是一个通用解决方案，可以应用于任何不带参数的异步函数，回调除外。我仅通过成功和失败回调，进度应该不难添加。

Here's a general solution that can be applied to any async function that has no parameters, excepting the callbacks. I simplified the logic by having only success and failure callbacks, a progress should not be that hard to add.

因此，假设您的函数是这样的：

So, assuming that your function is like this:

func startUploading(success: @escaping () -> Void, failure: @escaping (Error) -> Void) {
    DDLogDebug("JogUploader: Creating jog: \(self.jog)")

    API.sharedInstance.createJog(self.jog,
        failure: { error in
            failure(error)
        }, success: {_ in
            success()
    })
}

匹配的 retry 函数可能看起来像这样：

A matching retry function might look like this:

func retry(times: Int, task: (success: @escaping () -> Void, failure: @escaping (Error) -> Void) -> Void, success: @escaping () -> Void, failure: @escaping (Error) -> Void) {
    task(success: success, 
        failure: { error in
            // do we have retries left? if yes, call retry again
            // if not, report error
            if times > 0 {
                retry(times - 1, task: task, success: success, failure: failure)
            } else {
                failure(error)
            }
        })
}

可以这样称呼：

retry(times: 3, task: startUploading,
    success: {
        print("Succeeded")
    },
    failure: { err in
        print("Failed: \(err)")
})

上面的操作如果仍然失败，将重试 startUploading 调用三次，否则将在第一次成功时停止。

The above will retry the startUploading call three times if it keeps failing, otherwise will stop at the first success.

编辑。确实具有其他参数的函数可以简单地嵌入到闭包中：

Edit. Functions that do have other params can be simply embedded in a closure:

func updateUsername(username: String, success: @escaping () -> Void, failure: @escaping (Error) -> Void) {
    ...
}

retry(times: 3, { success, failure in updateUsername(newUsername, success, failure) },
    success: {
        print("Updated username")
    },
    failure: {
        print("Failed with error: \($0)")
    }
)

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