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Avoid extra SMB queries when formatting file names - #28038
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Dongbo Wang (daxian-dbw) wants to merge 1 commit into
Open
Dongbo Wang (daxian-dbw) wants to merge 1 commit into
Dongbo Wang (daxian-dbw) wants to merge 1 commit into
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Dongbo Wang (daxian-dbw)
September 21, 2026 20:59
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🟢 Approval recommended
No unresolved review issues were identified, and regression coverage was added.
Review effort: Lite
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What changed in this PR
Improves file-name formatting performance by avoiding unnecessary SMB metadata queries for ordinary items.
Changes:
- Uses cached attributes to short-circuit reparse-point inspection.
- Adds regression coverage for cached metadata behavior.
| File | Description |
|---|---|
test/powershell/Modules/Microsoft.PowerShell.Management/Get-Item.Tests.ps1 |
Verifies cached non-reparse items do not reopen their paths. |
src/System.Management.Automation/namespaces/FileSystemProvider.cs |
Avoids unnecessary metadata queries during formatting. |
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PR Summary
NameString.FindFirstFilequery per ordinary item when formatting directory listings, which is particularly expensive on SMB shares.PR Context
Fixes #27088.
IsReparsePointLikeSymlinkmust inspect the reparse tag to distinguish symbolic links and junctions from cloud-drive placeholders. Default formatting previously invoked that expensive check for every item, including ordinary non-links.NameStringnow uses the already-populatedAttributesmetadata to short-circuit ordinary items while preserving detailed classification for actual reparse points.Benchmark
Measured 4,897 entries over the local UNC path
\\localhost\c$\Windows\System32. Each result is the median of three warmed-up runs.NameStringA same-binary control using the fixed debug build isolates the avoided operation:
NameStringIsReparsePointLikeSymlinkprobeThis confirms that the approximately 3.9-second cost came from calling
FindFirstFileonce per item. Absolute formatting times vary between release and debug builds, but the per-item SMB query is eliminated.PR Checklist
.h,.cpp,.cs,.ps1and.psm1files have the correct copyright header