[CmdPal] Fix slow fuzzy search in apps extension by properly handling null-terminated strings from SHLoadIndirectString #40198
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src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Apps/Programs/UWPApplication.cs
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… null-terminated strings from SHLoadIndirectString (#40198) <!-- Enter a brief description/summary of your PR here. What does it fix/what does it change/how was it tested (even manually, if necessary)? --> ## Summary of the Pull Request This change addresses a significant performance regression caused by improper handling of null-terminated strings returned from the SHLoadIndirectString API. Previously, the output buffer was converted to string using Span<char>.ToString() without trimming at the null terminator (\0). As a result, the entire buffer (1024 characters) was converted, including trailing garbage data after the valid string. This caused the fuzzy matching logic to process unnecessarily long strings, leading to excessive CPU usage and input lag (~2 seconds delay per keystroke). The fix properly locates the first null terminator in the buffer and slices the span before converting to string, eliminating trailing garbage characters. This reduces the workload in the scoring function and resolves the input lag in the apps extension search. <!-- Please review the items on the PR checklist before submitting--> ## PR Checklist - [x] **Closes:** #40197 - [ ] **Communication:** I've discussed this with core contributors already. If the work hasn't been agreed, this work might be rejected - [ ] **Tests:** Added/updated and all pass - [ ] **Localization:** All end-user-facing strings can be localized - [ ] **Dev docs:** Added/updated - [ ] **New binaries:** Added on the required places - [ ] [JSON for signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json) for new binaries - [ ] [WXS for installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs) for new binaries and localization folder - [ ] [YML for CI pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml) for new test projects - [ ] [YML for signed pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml) - [ ] **Documentation updated:** If checked, please file a pull request on [our docs repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys) and link it here: #xxx <!-- Provide a more detailed description of the PR, other things fixed, or any additional comments/features here --> ## Detailed Description of the Pull Request / Additional comments <!-- Describe how you validated the behavior. Add automated tests wherever possible, but list manual validation steps taken as well --> ## Validation Steps Performed
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Summary of the Pull Request
This change addresses a significant performance regression caused by improper handling of null-terminated strings returned from the SHLoadIndirectString API.
Previously, the output buffer was converted to string using Span.ToString() without trimming at the null terminator (\0). As a result, the entire buffer (1024 characters) was converted, including trailing garbage data after the valid string.
This caused the fuzzy matching logic to process unnecessarily long strings, leading to excessive CPU usage and input lag (~2 seconds delay per keystroke).
The fix properly locates the first null terminator in the buffer and slices the span before converting to string, eliminating trailing garbage characters. This reduces the workload in the scoring function and resolves the input lag in the apps extension search.
PR Checklist
Detailed Description of the Pull Request / Additional comments
Validation Steps Performed