Resolve callback error and modified the entire retry logic

[Shwetajain148]

@mchaudhary @mostlyjason In this PR, I have modified the entire error retry logic and have covered the below points:

• [x] Retrying on connection errors(Maximum 5 times).
• [x] Retrying on status code other than 200(Maximum 5 times).
• [x] Display a message on console when there is any connection or server error occurs and event retry.
• [x] Display an error message on console when any event failed after retrying 5 times.
• [x] Display a message on console if the event is sent successfully after retrying.
• [x] Handled the bad token error i.e. response code 403.
• [x] Changed coding style to functional programming.
• [x] Error retrying will be in a increasing time interval i.e. in multiple of 2.
• [x] Removed all hard coded values/numbers.
• [x] Testing

Also, I took a reference of retry logic from here: https://github.com/logzio/logzio-nodejs/blob/master/lib/logzio-nodejs.js#L248-L258.

I checked the library behavior after these changes in a continue logging environment for about 8 hours and did not see any callback error. The issue is related to https://github.com/loggly/winston-loggly-bulk/issues/13.

Update: I also tested the library code in both bulk & input mode for 15 days in a continue event logging environment. My node application did not break with any error.

Please review the changes.

[eduard-piliposyan]

Any ETA when this will be merged ? We have error Callback was already called. and will be very happy to see this issue fixed.

[wlindley]

Same here, we'd love to see this merged!

[dmr-loggly]

Hey everyone, we apologize for the delay in processing this PR. I'm working right now on making sure it's brought to the right people's attention to be fixed ASAP.

[matthewchng]

@mchaudhary Will there be a patch version bump to release this change? The current version 2.2.1 was updated 3 months ago. Thanks.