[METRON-1790] Unsubscribe from every observable in the pcap panel UI component

• Type: Improvement
• Status: Done
• Priority: Minor
• Resolution: Done
• Fix Version/s: 0.7.0
• Assignee: Tamas Fodor
• Reporter: Tamas Fodor
• Created: 21/Sep/18 09:14
• Updated: 11/Dec/18 16:05
• Resolved: 11/Dec/18 16:05

Description

There are a lot of http requests performed in the pcap panel ui component and we just unsubscribe from some of them when the component is no longer rendered on the screen. It could cause memory consumption issues. Because of the active subscriptions, the garbage collector is not able to remove these objects from the memory, however they're not needed to be there anymore.

There's another benefit of unsubscribing from these http calls. If the user leaves the pcap tab but there are pending requests, the unsubscribe method cancels the active xhrs immediately so it won't wait for fulfilment unnecessarily.

https://github.com/apache/metron/blob/master/metron-interface/metron-alerts/src/app/pcap/pcap-panel/pcap-panel.component.ts#L54

I would also refactor that part when we convert an observable to a promise. I would keep it as an observable. By doing this, we would be able to unsubscribe from it as well in the destructor method. Promises are not cancelable.

https://github.com/apache/metron/blob/master/metron-interface/metron-alerts/src/app/pcap/pcap-panel/pcap-panel.component.ts#L70

Resources:

https://angular.io/guide/lifecycle-hooks#ondestroy

This is the place to free resources that won't be garbage collected automatically. Unsubscribe from Observables and DOM events. Stop interval timers.

Issue Links

• links to: GitHub Pull Request #1208