perf: replace repeated string.Contains with single-pass field parsing - #90
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Thanks for this — looks sensible, but it currently conflicts with Please rebase or merge |
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✅ Conflicts resolved! I've rebased the branch against the latest Key updates in the rebase:
The single-pass field parsing now covers both slice status messages and pan status messages, providing consistent performance improvements across all FlexRadio status processing. |
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🟡 Changes recommended
ParsePresentFields currently only treats ' ' as a delimiter (unlike the existing codec whitespace handling), which can cause incorrect field-presence detection and stale state updates.
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Pull request overview
This PR optimizes Flex SmartSDR status handling by replacing repeated string.Contains($" {field}=") checks with a single-pass field-presence parser, then using O(1) lookups to decide which parsed values should overwrite cached slice/pan state.
Changes:
- Added
ParsePresentFieldsto tokenize a status body and collect present field names into a case-insensitiveHashSet<string>. - Updated
ApplyStatusUnlockedandApplyPanStatusUnlockedto usepresentFields.Contains(...)instead of repeatedHasSliceField/HasPanFieldscans. - Added unit tests covering typical parsing cases, whitespace handling, and tokens without
=.
File summaries
| File | Description |
|---|---|
| OscarWatch/Rig/FlexSmartSdrClient.cs | Introduces ParsePresentFields and switches slice/pan field-presence checks to set membership. |
| OscarWatch.Tests/FlexSmartSdrClientParsePresentFieldsTests.cs | Adds unit tests validating ParsePresentFields behavior across common inputs and edge cases. |
Review details
- Files reviewed: 2/2 changed files
- Comments generated: 3
- Review effort level: Lite
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| while (i < span.Length && span[i] == ' ') | ||
| i++; | ||
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| if (i >= span.Length) | ||
| break; | ||
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| var tokenStart = i; | ||
| while (i < span.Length && span[i] != ' ') | ||
| i++; |
| /// <summary> | ||
| /// Parses a SmartSDR status message body into a set of field names present. | ||
| /// Status format: "slice 0 in_use=1 freq=14.200 mode=USB tx=0 active=1" | ||
| /// Fields are space-separated key=value pairs after the slice header. | ||
| /// Single pass, no allocations per field (only the HashSet itself). | ||
| /// </summary> |
| // Build a set of fields present in this status message (single pass). | ||
| var presentFields = ParsePresentFields(body); | ||
| var hasFrequency = presentFields.Contains("RF_frequency") || presentFields.Contains("freq"); |
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Thanks for the rebase note. Still not merging this one. GitHub still shows 72 files / ~4.7k lines against Please rebase onto current 73, |
ApplyStatusUnlocked previously called HasSliceField (string.Contains with interpolated string) up to 8 times per status message, causing 8 string allocations + 8 full scans per radio update (~4 Hz). Replace with ParsePresentFields: a single-pass tokeniser that builds a HashSet<string> of field names present in the status body, then all 7 field checks become O(1) lookups with zero per-field allocations. Note: upstream has added PanStreamId/pan handling since this branch was cut. The ParsePresentFields approach can also replace HasPanField for the pan status messages — happy to add that in a follow-up once this merges. Includes 6 unit tests covering typical status, FM tone fields, case-insensitive lookup, tokens without equals, empty body, and extra whitespace.
…ng() Per Peter's feedback: the optimization avoids Split() array allocations but field names still allocate strings via ToString() when added to HashSet.
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Nice one Dave — this is the focused diff we wanted (just FlexSmartSdrClient + the ParsePresentFields tests), and CI is green. Checked the merge path again: ApplyStatusUnlocked still keeps existing freq/mode/tx/active/pan when those keys are absent, and the ghost-slice (The space-only tokeniser matches the old Merging now. 73, |
Summary
ApplyStatusUnlockedpreviously calledHasSliceField(which usesstring.Containswith an interpolated string) up to 8 times per status message. This caused 8 string allocations + 8 full-string scans per radio update (~4 Hz during satellite tracking).Changes
Replaced with
ParsePresentFields: a single-pass tokeniser that builds aHashSet<string>of field names present in the status body, then all 7 field checks become O(1) lookups with zero per-field allocations.Tests
6 unit tests added covering:
All 55 Flex tests pass.