[BufferOrch] Don't call SAI API for BUFFER_POOL/PROFILE handling in case the op is DEL and the SAI OID is NULL

[stephenxs]

What I did
Don't call SAI API for BUFFER_POOL/PROFILE handling in case the op is DEL and the SAI OID is NULL in order to avoid orchagent from exiting.
We need it only in 202106 or above. In 202012 the orchagent won't exit in such case.

Why I did it
Handle rare cases which cause SAI error eventually makes orchagent to exit.

How I verified it
Manually test.

Details if related
There is an optimization on orch: the SET event will be replaced by a DEL event if it is still pending in m_toSync when the DEL event is coming.
This is reasonable but can cause the SAI OID to be NULL in rare case:

• The application creates an object and then destroy it after a very short period
• The create notification is eliminated and replaced by destroying the notification
• The SAI object hasn't been created and is NULL when it is removed

This causes SAI error which eventually makes orchagent exit.
We need to avoid it in 202106 and above
(In 202012, the orchagent won't exit so it's ok to ignore the error)
The solution is not to call SAI removing interface in case SAI OID is NULL

It can happen if a user configures something which causes the accumulative headroom to exceed the limit.
In this case, the buffer profile was created and then removed in a short time.

[stephenxs]

Looks like the LGTM failed due to some temporary network issue and wasn't recovered after retriggered.

[2021-06-16 23:08:24] [build-stdout] Get:51 http://storage.googleapis.com/lgtm-apt-mirror/ubuntu eoan/main amd64 dh-exec amd64 0.23.2 [25.0 kB]
[2021-06-16 23:08:24] [build-stdout] Fetched 12.9 MB in 1min 10s (184 kB/s)
[2021-06-16 23:08:24] [build-stderr] E: Failed to fetch http://storage.googleapis.com/lgtm-apt-mirror/ubuntu/pool/main/libs/libsodium/libsodium-dev_1.0.18-1_amd64.deb  Connection failed [IP: 173.194.198.128 80]
[2021-06-16 23:08:24] [build-stderr] E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
[2021-06-16 23:08:24] [build-stderr] Error: 'lgtm-install-packages' terminated with exit code: 100

[neethajohn]

How can we test this?

[prsunny]

@stephenxs , please do not close and re-open the PR multiple times for retriggering the checks. It can be done via /azp run. I think once the code changes/review is completed, this can be taken care of.

[stephenxs]

@stephenxs , please do not close and re-open the PR multiple times for retriggering the checks. It can be done via /azp run. I think once the code changes/review is completed, this can be taken care of.

Thanks Prince. Looks like we don’t have the privilege to trigger azp rerun. Anyway I’ll avoid closing/reopening the PRs

[stephenxs]

How can we test this?

We have a regression test (test_exceeding_headroom) for buffer profile. We don’t have a chance to verify the buffer pool because we seldom remove a buffer pool. I updated it because they shared the same logic.

[neethajohn]

How can we test this?

We have a regression test (test_exceeding_headroom) for buffer profile. We don’t have a chance to verify the buffer pool because we seldom remove a buffer pool. I updated it because they shared the same logic.

@stephenxs , does this test already cover this scenario for buffer profile?

[neethajohn]

How can we test this?

We have a regression test (test_exceeding_headroom) for buffer profile. We don’t have a chance to verify the buffer pool because we seldom remove a buffer pool. I updated it because they shared the same logic.

@stephenxs , does this test already cover this scenario for buffer profile?

Discussed offline, it is covered

[liat-grozovik]

/azp run

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