LogLens Core 🔍

The lightning-fast, structured log parsing engine built in Rust.

loglens-core is a high-performance library designed to parse, query, and analyze structured logs (JSON, Nginx, Logfmt) at scale. It powers the LogLens CLI.

🚀 Features

• Zero-Config Parsing: Automatically detects and parses JSON or Logfmt lines without manual schema definition.
• Structured Query Engine: Filter logs with complex logic using a familiar syntax: level == "error" && latency > 500.
• High Throughput: Optimized for reading gigabytes of logs in seconds, making it suitable for high-volume production environments.
• Time-Aware: Native understanding of timestamps for time-range filtering.

📦 Installation

Add this to your Cargo.toml:

[dependencies]
loglens-core = "0.1.0"

⚡ Usage Example

Here is how you can use loglens-core to parse a log line and run a structured query against it:

use loglens_core::{evaluate, LogEntry, parsers::parse_log_line};

fn main() {
    // A sample JSON log line
    let log_line = r#"{"level": "error", "latency": 502, "msg": "Database timeout", "timestamp": "2023-10-27T10:00:00Z"}"#;

    // 1. Parse the raw string into a structured LogEntry
    // This automatically detects if it is JSON or Logfmt
    let entry = parse_log_line(log_line);

    // 2. Define a query
    // Returns true if latency is greater than 500 AND level is "error"
    let query = "latency > 500 && level is error";
    
    // 3. Evaluate the query against the parsed entry
    if let LogEntry::Structured(value) = entry {
        // 'evaluate' returns a Result<bool, QueryError>
        match evaluate(&value, log_line, query) {
            Ok(true) => println!("✅ Match found!"),
            Ok(false) => println!("❌ No match."),
            Err(e) => eprintln!("Query error: {}", e),
        }
    } else {
        println!("Could not parse as structured log.");
    }
}

🖥️ Want the full CLI experience?

This library is the engine behind LogLens, a terminal-based log explorer that replaces jq and tail -f with a powerful TUI.

LogLens Pro features:

• 📊 Interactive TUI: Filter and explore logs with keyboard shortcuts.
• 👀 Live Watch: Real-time filtering and highlighting (loglens watch).
• 📈 Instant Stats: Automatic field analysis and error rate calculation.

Install LogLens via Homebrew

brew tap Caelrith/loglens
brew install loglens

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

📄 License

This project is licensed under the MIT License.