refactor: Preallocate pieceDigests slice in genMetadata for improved

[yantingqiu]

Description

Optimized the pieceDigests slice initialization in the genMetadata function by preallocating space based on t.TotalPieces. This change avoids dynamic slice resizing during runtime, which enhances the performance especially when handling large data sets.

Related Issue

Motivation and Context

Screenshots (if appropriate)

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Documentation Update (if none of the other choices apply)

Checklist

• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 52.70%. Comparing base (1c9484a) to head (afb3c7d).

Additional details and impacted files

[](https://app.codecov.io/gh/dragonflyoss/Dragonfly2/pull/3325?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dragonflyoss) ```diff @@ Coverage Diff @@ ## main #3325 +/- ## ========================================== + Coverage 52.66% 52.70% +0.03% ========================================== Files 192 192 Lines 20427 20427 ========================================== + Hits 10758 10766 +8 + Misses 8863 8859 -4 + Partials 806 802 -4 ``` | [Flag](https://app.codecov.io/gh/dragonflyoss/Dragonfly2/pull/3325/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dragonflyoss) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/dragonflyoss/Dragonfly2/pull/3325/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dragonflyoss) | `52.70% <100.00%> (+0.03%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dragonflyoss#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files](https://app.codecov.io/gh/dragonflyoss/Dragonfly2/pull/3325?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dragonflyoss) | Coverage Δ | | |---|---|---| | [client/daemon/storage/local\_storage.go](https://app.codecov.io/gh/dragonflyoss/Dragonfly2/pull/3325?src=pr&el=tree&filepath=client%2Fdaemon%2Fstorage%2Flocal_storage.go&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dragonflyoss#diff-Y2xpZW50L2RhZW1vbi9zdG9yYWdlL2xvY2FsX3N0b3JhZ2UuZ28=) | `32.37% <100.00%> (ø)` | | ... and [6 files with indirect coverage changes](https://app.codecov.io/gh/dragonflyoss/Dragonfly2/pull/3325/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dragonflyoss)