fixlog

Zero-copy parser and interactive TUI viewer for FIX (Financial Information eXchange) logs, in Rust. Built to chew through millions of FIX messages efficiently — zero-copy from the mmapped file all the way to the rendered output — with a fast local TUI in the spirit of fixparser.targetcompid.com.

It auto-detects the log layout (separator, line prefix, encoding) instead of assuming one format, so the same binary handles raw QuickFIX logs, pipe-rendered logs, and logs wrapped in timestamp/logback prefixes. Dictionaries cover FIX 4.4, FIXT.1.1, FIX 5.0, 5.0 SP1 and 5.0 SP2.

flowchart LR
    F[("FIX log<br/>(mmap)")] --> S["sniff<br/>separator · prefix · encoding"]
    S --> P["parse<br/>zero-copy 8=FIX scan"]
    P --> R["resolve<br/>tags → names"]
    P --> I["index<br/>rayon · hot-tag map"]
    I --> Q["query · grep · --follow"]
    R --> O["CLI render · TUI · analysis"]
    Q --> O
    I --> O

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Install

Requires a recent stable Rust toolchain (tested with 1.95, edition 2024; pinned in rust-toolchain.toml).

git clone <repo> fixlog && cd fixlog
cargo build --release -p fixlog-cli      # binary → target/release/fixlog
cargo install --path crates/fixlog-cli   # …or install `fixlog` into ~/.cargo/bin

Quick start

Examples assume alias fixlog=./target/release/fixlog (or that you ran cargo install).

fixlog sniff fixtures/synthetic/minimal_4.4.log        # what layout is this log?
fixlog parse fixtures/synthetic/minimal_4.4.log --first 5
fixlog tui   fixtures/real/fix44-om.log                # interactive viewer (press : help)
fixlog grep  live.log --filter "35=8 AND 55=AAPL" -F   # tail -f, filtered
fixlog orders consolidate logs/*.log logs/*.log.gz     # aggregate fills across rotated logs

Commands

Command	What it does	Deep dive
sniff / parse / stats	Detect layout, print resolved messages (pretty/JSON), summarize a file.	parsing & format
grep (-F/--follow)	Filter with a grep-style DSL (35=D AND 55=AAPL, 55~^MS); tail live files.	query, grep & tailing
tui	Interactive viewer: virtual list, resolved detail, live filter, search, overlays, export.	interactive TUI
sessions / orders (+ consolidate) / histogram	Session gaps, order lifecycle (Gantt), consolidated fills across .gz/stdin, temporal histogram.	analysis & consolidation

fixlog tui also reads from a pipe (rg "35=D" *.log | fixlog tui) and takes --sort natural|seq|transact|sending. Inside the TUI, press ? or :help for the full keybinding cheatsheet. Filter DSL: =, !=, ~ (regex), combined with AND/OR/NOT and parens (precedence NOT > AND > OR); tag numbers only. JSON output is JSONL, pipe-friendly to jq.

Supported formats

Aspect	Support
FIX versions	4.4, FIXT.1.1 (session) + 5.0 / 5.0 SP1 / 5.0 SP2 (application)
Separator	SOH (\x01), |, ^, ; — auto-detected
Line prefix	any (timestamp, logback, PID…) — the parser scans for 8=FIX
Line ending	LF, CRLF
Encoding	UTF-8 / ASCII (non-UTF-8 bytes shown lossy)
Invalid checksums	non-fatal — the message is still emitted, logged at -vv

Adding a FIX version is ~10 lines: drop the QuickFIX XML into dictionaries/ and register it in crates/fixlog-dict/build.rs.

Performance (highlights)

Parse ~1 GiB/s on long messages; parallel index build up to ~5× single-thread; TUI frame ~737 µs on 1M messages (~22× under the 16 ms budget); hot-tag equality filters ~156 µs (~3000× vs full scan). Full, per-phase benchmark tables live in docs/agent/state.md.

Documentation

• docs/architecture.md — code layout, crate graph, data flow, key libraries, gotchas.
• docs/runbook.md — build, install, run, env vars, troubleshooting.
• docs/conventions.md — code style, errors, testing, commits.
• docs/features/ — per-capability docs (the table above links into these).
• docs/agent/ — dense, LLM-facing internals per crate; state.md is authoritative on current status and backlog.

Development

cargo run -p fixlog-cli -- tui <file>                        # run without installing
cargo test --all                                            # full suite
cargo clippy --all-targets --all-features -- -D warnings    # lint (must be clean)
cargo fmt --all
cargo bench -p fixlog-parser --bench parse                  # benches: parser / index / frame

Fixtures: fixtures/synthetic/ is versioned for golden tests; fixtures/real/ and fixtures/orders/ hold real logs and are gitignored (never commit FIX data). See fixtures/README.md.

License

MIT OR Apache-2.0.