Quantum Pulse

A lightweight, customizable profiling library for Rust applications with support for custom categories and percentile statistics.

Features

• 🚀 True Zero-Cost Abstraction - Stub implementation compiles to nothing when disabled
• 🎯 Derive Macro Support - Automatic implementation with #[derive(ProfileOp)]
• 📊 Percentile Statistics - Automatic calculation of p50, p95, p99, and p99.9 percentiles using HDR histograms
• 🏷️ Type-Safe Categories - Define your own operation categories with compile-time guarantees
• 📈 Multiple Output Formats - Console and CSV export options
• ⏸️ Pausable Timers - Exclude specific periods from measurements
• 🔧 Clean API - Same interface whether profiling is enabled or disabled
• 🌐 Async Support - Full support for async/await patterns
• 🎯 No Conditionals Required - Use the same code for both production and development

Installation

Add this to your Cargo.toml:

[dependencies]
# For production builds (zero overhead)
quantum-pulse = { version = "0.1.5", default-features = false }

# For development builds (with profiling and macros)
quantum-pulse = { version = "0.1.5", features = ["full"] }

Or use feature flags in your application:

[dependencies]
quantum-pulse = { version = "0.1.5", default-features = false }

[features]
profiling = ["quantum-pulse/full"]

Quick Start

🎯 Recommended: Using the Derive Macro

The easiest and most maintainable way to use quantum-pulse is with the ProfileOp derive macro:

use quantum_pulse::{ProfileOp, profile, ProfileCollector};

// Simply derive ProfileOp and add category attributes
#[derive(Debug, ProfileOp)]
enum AppOperation {
    #[category(name = "Database", description = "Database operations")]
    QueryUser,
    
    #[category(name = "Database")]  // Reuses the description
    UpdateUser,
    
    #[category(name = "Network", description = "External API calls")]
    HttpRequest,
    
    #[category(name = "Cache", description = "Cache operations")]
    ReadCache,
    
    ComputeHash,  // No category attribute - uses variant name as category
}

fn main() {
    // Profile operations with zero boilerplate
    let user = profile!(AppOperation::QueryUser, {
        fetch_user_from_database()
    });

    let result = profile!(AppOperation::HttpRequest, {
        call_external_api()
    });

    // Generate and display report
    let report = ProfileCollector::get_summary();
    println!("Total operations: {}", report.total_operations);
}

Category Management

The ProfileOp macro intelligently manages categories:

#[derive(Debug, ProfileOp)]
enum DatabaseOps {
    #[category(name = "Query", description = "Read operations")]
    SelectUsers,
    
    #[category(name = "Query")]  // Automatically reuses "Read operations" description
    SelectPosts,
    
    #[category(name = "Mutation", description = "Write operations")]
    InsertUser,
    
    #[category(name = "Mutation")]  // Automatically reuses "Write operations" description
    UpdateUser,
    
    DeleteUser,  // Uses "DeleteUser" as both name and description
}

Alternative: Manual Implementation

For advanced use cases or when you prefer explicit control:

use quantum_pulse::{Operation, Category, profile};

#[derive(Debug)]
enum AppOperation {
    DatabaseQuery,
    NetworkRequest,
}

// Implement Operation trait manually
impl Operation for AppOperation {
    fn get_category(&self) -> &dyn Category {
        match self {
            AppOperation::DatabaseQuery => &DatabaseCategory,
            AppOperation::NetworkRequest => &NetworkCategory,
        }
    }
}

// Define custom categories
struct DatabaseCategory;
impl Category for DatabaseCategory {
    fn get_name(&self) -> &str { "Database" }
    fn get_description(&self) -> &str { "Database operations" }
}

struct NetworkCategory;
impl Category for NetworkCategory {
    fn get_name(&self) -> &str { "Network" }
    fn get_description(&self) -> &str { "Network operations" }
}

Advanced Features

Async Support

use quantum_pulse::{ProfileOp, profile_async};

#[derive(Debug, ProfileOp)]
enum AsyncOperation {
    #[category(name = "IO", description = "I/O operations")]
    FileRead,
    
    #[category(name = "Network", description = "Network operations")]
    HttpRequest,
    
    #[category(name = "Database")]
    DatabaseQuery,
}

async fn fetch_data() -> Result<Data, Error> {
    // Profile async operations seamlessly
    let data = profile_async!(AsyncOperation::HttpRequest, async {
        client.get("https://api.example.com/data").await
    }).await;
    
    profile_async!(AsyncOperation::DatabaseQuery, async {
        process_data(data).await
    }).await
}

Complex Enum Variants

The ProfileOp macro supports all enum variant types:

#[derive(Debug, ProfileOp)]
enum ComplexOperation {
    // Unit variant
    #[category(name = "Simple")]
    Basic,
    
    // Tuple variant with data
    #[category(name = "Database", description = "Database operations")]
    Query(String),
    
    // Struct variant with named fields
    #[category(name = "Cache", description = "Cache operations")]
    CacheOp { key: String, ttl: u64 },
}

fn example() {
    let op1 = ComplexOperation::Basic;
    let op2 = ComplexOperation::Query("SELECT * FROM users".to_string());
    let op3 = ComplexOperation::CacheOp { 
        key: "user:123".to_string(), 
        ttl: 3600 
    };
    
    // All variants work seamlessly with profiling
    profile!(op1, { /* work */ });
    profile!(op2, { /* work */ });
    profile!(op3, { /* work */ });
}

Report Generation

use quantum_pulse::{ProfileCollector, ReportBuilder, TimeFormat};

// Quick summary
let summary = ProfileCollector::get_summary();
println!("Total operations: {}", summary.total_operations);
println!("Total time: {} µs", summary.total_time_micros);

// Detailed report with configuration
let report = ReportBuilder::new()
    .include_percentiles(true)
    .group_by_category(true)
    .time_format(TimeFormat::Milliseconds)
    .build();

println!("{}", report.to_string());

// Export to CSV
let stats = ProfileCollector::get_all_stats();
let mut csv = String::from("Operation,Count,Mean(µs)\n");
for (name, stat) in stats {
    csv.push_str(&format!("{},{},{:.2}\n", 
        name, stat.count, stat.mean().as_micros()));
}
std::fs::write("profile.csv", csv).unwrap();

Pausable Timers

For operations where you need to exclude certain periods:

use quantum_pulse::{PausableTimer, ProfileOp};

#[derive(Debug, ProfileOp)]
enum Operation {
    #[category(name = "Processing")]
    DataProcessing,
}

fn process_with_io() {
    let mut timer = PausableTimer::new(&Operation::DataProcessing);
    
    // Processing phase 1 (measured)
    process_part_1();
    
    timer.pause();
    // I/O operation (not measured)
    let data = read_from_disk();
    timer.resume();
    
    // Processing phase 2 (measured)
    process_part_2(data);
    
    // Timer automatically records on drop
}

Zero-Cost Abstractions

Quantum Pulse implements true zero-cost abstractions through compile-time feature selection:

How It Works

#[derive(Debug, ProfileOp)]
enum AppOp {
    #[category(name = "Critical")]
    ImportantWork,
}

// Your code always looks the same
let result = profile!(AppOp::ImportantWork, {
    expensive_operation()
});

// With default features (stub mode):
// - profile! macro expands to just the code block
// - No timing, no allocations, no overhead
// - Compiler optimizes it to: let result = expensive_operation();

// With "full" feature enabled:
// - Full profiling with timing and statistics
// - HDR histograms for accurate percentiles
// - Comprehensive reporting

Performance Characteristics

Pause/Unpause Profiling

Control profiling dynamically with pause!() and unpause!() macros:

use quantum_pulse::{profile, pause, unpause, ProfileOp};

#[derive(Debug, ProfileOp)]
enum AppOperation {
    #[category(name = "Core")]
    CriticalWork,
    #[category(name = "Debug")]
    DiagnosticWork,
}

// Normal profiling - operations are recorded
profile!(AppOperation::CriticalWork, {
    perform_important_work();
});

// Pause all profiling
pause!();

// This won't be recorded
profile!(AppOperation::DiagnosticWork, {
    debug_operations();
});

// Resume profiling
unpause!();

// This will be recorded again
profile!(AppOperation::CriticalWork, {
    more_important_work();
});

Use Cases

• Exclude initialization/cleanup from performance measurements
• Focus profiling on specific sections during debugging
• Reduce overhead during non-critical operations
• Selective measurement in loops or batch operations

Migration Guide

From String-based Profiling

If you're currently using string-based operation names, migrate to type-safe enums:

// Before: String-based (error-prone, no compile-time checks)
profile!("database_query", {
    query_database()
});

// After: Type-safe with ProfileOp (recommended)
#[derive(Debug, ProfileOp)]
enum DbOp {
    #[category(name = "Database")]
    Query,
}

profile!(DbOp::Query, {
    query_database()
});

From Manual Implementation

If you have existing manual Operation implementations, you can gradually migrate:

// Before: Manual implementation
#[derive(Debug)]
enum OldOp {
    Task1,
    Task2,
}

impl Operation for OldOp {
    fn get_category(&self) -> &dyn Category {
        // Manual category logic
    }
}

// After: Simply add ProfileOp derive
#[derive(Debug, ProfileOp)]
enum NewOp {
    #[category(name = "Tasks", description = "Application tasks")]
    Task1,
    
    #[category(name = "Tasks")]
    Task2,
}

Examples

Check out the examples/ directory for comprehensive examples:

• macro_derive.rs - Recommended: Using the ProfileOp derive macro
• basic.rs - Simple profiling example
• custom_categories.rs - Manual category implementation
• async_profiling.rs - Profiling async code
• trading_system.rs - Real-world trading system example

Run examples with:

# Recommended: See the derive macro in action
cargo run --example macro_derive --features full

# Other examples
cargo run --example basic --features full
cargo run --example async_profiling --features full
cargo run --example trading_system --features full

Feature Flags

• full: Enable full profiling functionality with HDR histograms and derive macros
• macros: Enable only the derive macros (included in full)
• Default (no features): Stub implementation with zero overhead

Best Practices

1. Use ProfileOp Derive: Start with the derive macro for cleaner, more maintainable code
2. Organize by Category: Group related operations under the same category name
3. Descriptive Names: Use clear, descriptive names for both categories and operations
4. Profile Boundaries: Profile at meaningful boundaries (API calls, database queries, etc.)
5. Avoid Over-Profiling: Don't profile every function - focus on potential bottlenecks

Performance Considerations

The library is designed with performance in mind:

• True Zero-Cost: Stub implementations are completely removed by the compiler
• Efficient Percentiles: Using HDR histograms for O(1) percentile calculations
• Lock-Free Operations: Using atomic operations and thread-local storage
• Smart Inlining: Critical paths marked with #[inline(always)] in stub mode
• No Runtime Checks: Feature selection happens at compile time

Benchmarks

Run benchmarks with:

cargo bench

Contributing

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

License

This project is licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or https://apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT)

at your option.

Acknowledgments

This library was designed for high-performance applications requiring microsecond-precision profiling with minimal overhead and maximum ergonomics.