Fix RetryMiddleware default exponential delay

[dluces]

RetryMiddleware::exponentialDelay was previously returning an integer (good) representing SECONDS of delay. The RetryMiddleware was putting that value directly into the delay option for the retried request. However, the docs say that the delay option should be in milliseconds.

If the RetryMiddleware was used without a custom delay function, the RetryMiddleware::exponentialDelay is used, meaning that the delay was going to be minimal by default.

[Nyholm]

Maybe Im reading this wrong. But this does not delay anything.

Could you write a test that make sure we do actually sleep between retries?

[dluces]

@Nyholm the delay is not handled by the middleware but by a guzzle handler directly. The middleware sets the delay option and then sends off the request to the next handler. CurlHandler and other handlers check the delay option and do usleep($options['delay'] * 1000). That is, the middleware needs to set the delay in ms and not in seconds. I don't think we should test actual delays here as that's a different project (guzzle but the handler tests or a custom project if people use custom handlers). We need to test that our delay functions do what they should (return times in ms and not in seconds).

[Fuco1]

Can we get more attention from maintainers to this issue? The middleware by default does "not" back off at all since it returns 2^1/2/3/4/5 which is <100 in milliseconds now. This bombards the servers with tens of requests per second.

[dluces]

I've just updated this PR's branch with latest master. I still think this should not be testing the actual delay mechanism as nothing related to that has been changed. Instead, it only changes how the delay time is calculated, @Nyholm

[Nyholm]

The issue is the units..

The option delay expects a delay in milliseconds (ms). We are retuning 0,1,2,4,8 ms which is correct.

This PR is increasing the delay with a factor 1000,

Could you do another rebase please?

[Nyholm]

Friendly update

[Nyholm]

I rebased the PR and added a comment