optimize readdir() open calls to be dealt with directly via 'fd'

[harshavardhana]

Community Contribution License

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under the terms of the Apache 2 license.
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contributions to the project maintainers under the Apache 2 license.

Description

optimize readdir() open calls to be dealt with directly via 'fd'

Motivation and Context

avoid poll.FD{} CPU issues

How to test this PR?

Not easier

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Optimization (provides speedup with no functional changes)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• Fixes a regression (If yes, please add commit-id or PR # here)
• Unit tests added/updated
• Internal documentation updated
• Create a documentation update request here

[klauspost]

Neat!

readDirWithOpts should probably have the same change.

[klauspost]

I am like 75% "let's add it" and "25% nah, too risky"...

[klauspost]

Maybe this.. Can't see it hurting us. But overall 👍🏼