Add support to evict DNS and RTT stale entries

[msherif1234]

Its possible we can have DNS queries w/o any responses or RTT entries w/o replies those entries will be there for ever, since we can't use LRU because we don't know when entries will be deleted and its very large memory footprint we will evict those entries in the user space every time we evict flows hash table by default every 5 seconds.

This is follow up for #162

No CPU or memory obvious impact with this PR

[msherif1234]

/ok-to-test

[github-actions]

New image:
quay.io/netobserv/netobserv-ebpf-agent:b57d218

It will expire after two weeks.

To deploy this build, run from the operator repo, assuming the operator is running:

USER=netobserv VERSION=b57d218 make set-agent-image

[codecov]

Codecov Report

Merging #163 (3cae3e5) into main (d3f035d) will decrease coverage by 0.43%.
The diff coverage is 23.68%.

@@            Coverage Diff             @@
##             main     #163      +/-   ##
==========================================
- Coverage   39.25%   38.82%   -0.43%     
==========================================
  Files          31       31              
  Lines        2214     2246      +32     
==========================================
+ Hits          869      872       +3     
- Misses       1296     1325      +29     
  Partials       49       49              

Flag	Coverage Δ
unittests	38.82% <23.68%> (-0.43%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
pkg/ebpf/tracer.go	0.00% <0.00%> (ø)
pkg/agent/agent.go	37.84% <100.00%> (ø)
pkg/flow/tracer_map.go	80.00% <100.00%> (+0.58%)	⬆️
pkg/test/tracer_fake.go	68.96% <100.00%> (+1.10%)	⬆️

[dushyantbehl]

@msherif1234 can we add a check here like clear the entries which are 5s/10s earlier and are still there (which means they are stale I mean)?
we need to check this against Mono clock.

[msherif1234]

/ok-to-test

[github-actions]

New image:
quay.io/netobserv/netobserv-ebpf-agent:adfe386

It will expire after two weeks.

To deploy this build, run from the operator repo, assuming the operator is running:

USER=netobserv VERSION=adfe386 make set-agent-image

[dushyantbehl]

Thanks @msherif1234 for adding the timeout. I just feel one small thing that since we are handling three maps with one funciton maybe we can make a map manager and handle all three inside of it..
Currently the flow is passed via LookupAndDeleteMap function which acts on bpf metrics and is a bit misleading. WDYT?

other than that looks good to me.

[msherif1234]

Thanks @msherif1234 for adding the timeout. I just feel one small thing that since we are handling three maps with one funciton maybe we can make a map manager and handle all three inside of it.. Currently the flow is passed via LookupAndDeleteMap function which acts on bpf metrics and is a bit misleading. WDYT?

other than that looks good to me.

I created new interface to handle features map I think is more cleaner WDYT ?

[dushyantbehl]

Thanks @msherif1234 for adding the timeout. I just feel one small thing that since we are handling three maps with one funciton maybe we can make a map manager and handle all three inside of it.. Currently the flow is passed via LookupAndDeleteMap function which acts on bpf metrics and is a bit misleading. WDYT?
other than that looks good to me.

I created new interface to handle features map I think is more cleaner WDYT ?

Looks good to me thanks!
/lgtm

[msherif1234]

/approve

[openshift-ci]

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