| # Fuchsia Performance Trace Writing Utilities |
| |
| This directory contains host-side libraries and developer utilities for generating and converting trace files into Fuchsia FXT format. |
| |
| ## Packages |
| |
| ### `trace_writing` |
| |
| A standalone Python library for constructing Fuchsia binary FXT traces programmatically: |
| - `trace_writing.fxt.Builder`: In-memory FXT builder supporting records for initialization, processes, threads, durations, instants, counters, async events, flows, and context switches. |
| |
| ## Scripts |
| |
| ### `json2fxt.py` |
| |
| A Python utility to convert legacy Fuchsia JSON trace formats (e.g. Google Chrome trace-viewer format containing standard thread/process metadata and flow events) into standard Fuchsia FXT binary traces. |
| |
| This is extremely useful for: |
| 1. **Test Data Migration**: Migrating any remaining legacy JSON test trace assets to direct binary FXT format. |
| 2. **Format Verification**: Validating the correctness of direct FXT loaders by comparing parsed outputs against legacy outputs from the same baseline. |
| |
| #### Usage |
| |
| 1. Include the host tool in your build configuration: |
| `fx set ... --with-host //src/performance/lib/trace_writing:json2fxt` |
| 2. Build the tool: |
| `fx build` |
| 3. Run the tool: |
| `fx json2fxt <input_legacy_trace.json> <output_binary_trace.fxt>` |
| |
| #### References |
| |
| * [Fuchsia FXT Record Format Specification](https://fuchsia.dev/fuchsia-src/reference/tracing/format/records) |
