moirai-runtime 0.7.0

//! Synchronization primitives example for Moirai
//!
//! This example demonstrates:
//! - Futex mutex usage
//! - Concurrent hash map
//! - Lock-free stack and queue
//! - Barriers and wait groups

#![expect(
    clippy::unwrap_used,
    reason = "test scope: failed precondition = test failure"
)]

use moirai_sync::{Barrier, ConcurrentHashMap, FutexMutex, LockFreeStack, WaitGroup};
use moirai_utils::LockFreeQueue;
use std::sync::Arc;
use std::thread;
use std::time::{Duration, Instant};

fn main() {
    println!("Moirai Synchronization Primitives");
    println!("=================================");

    // Example 1: Futex Mutex
    println!("\n1. Futex Mutex Example:");

    let counter = Arc::new(FutexMutex::new(0));
    let mut handles = vec![];

    for i in 0..10 {
        let counter_clone = Arc::clone(&counter);
        let handle = thread::spawn(move || {
            let mut guard = counter_clone.lock();
            *guard += 1;
            println!("  Thread {}: Counter = {}", i, *guard);
        });
        handles.push(handle);
    }

    for handle in handles {
        handle.join().unwrap();
    }

    println!("  Final counter value: {}", *counter.lock());

    // Example 2: Concurrent HashMap
    println!("\n2. Concurrent HashMap Example:");

    let map = Arc::new(ConcurrentHashMap::<String, i32>::new());
    let mut handles = vec![];

    // Insert values concurrently
    for i in 0..5 {
        let map_clone = Arc::clone(&map);
        let handle = thread::spawn(move || {
            for j in 0..10 {
                let key = format!("thread_{}_item_{}", i, j);
                map_clone
                    .insert(key.clone(), i * 10 + j)
                    .expect("concurrent map insert should succeed");
                println!("  Thread {}: Inserted {}", i, key);
            }
        });
        handles.push(handle);
    }

    for handle in handles {
        handle.join().unwrap();
    }

    // Read values
    // Note: ConcurrentHashMap doesn't have a len() method
    println!("  Map operations completed");
    if let Ok(Some(value)) = map.get(&"thread_0_item_0".to_string()) {
        println!("  Sample value: thread_0_item_0 = {}", value);
    }

    // Example 3: Lock-Free Stack
    println!("\n3. Lock-Free Stack Example:");

    let stack = Arc::new(LockFreeStack::new());
    let mut handles = vec![];

    // Push values
    for i in 0..5 {
        let stack_clone = Arc::clone(&stack);
        let handle = thread::spawn(move || {
            for j in 0..5 {
                let value = i * 10 + j;
                // The stack has ample capacity for this demo; report if full.
                match stack_clone.push(value) {
                    Ok(()) => println!("  Thread {}: Pushed {}", i, value),
                    Err(v) => println!("  Thread {}: stack full, dropped {}", i, v),
                }
            }
        });
        handles.push(handle);
    }

    for handle in handles {
        handle.join().unwrap();
    }

    // Pop values
    println!("  Popping values from stack:");
    for _ in 0..5 {
        if let Some(value) = stack.pop() {
            println!("    Popped: {}", value);
        }
    }

    // Example 4: Lock-Free Queue
    println!("\n4. Lock-Free Queue Example:");

    let queue: Arc<LockFreeQueue<i32>> = Arc::new(LockFreeQueue::new());

    // Producer thread
    let queue_producer = Arc::clone(&queue);
    let producer = thread::spawn(move || {
        for i in 1..=10 {
            queue_producer.enqueue(i);
            println!("  Producer: Enqueued {}", i);
            thread::sleep(Duration::from_millis(10));
        }
    });

    // Consumer thread
    let queue_consumer = Arc::clone(&queue);
    let consumer = thread::spawn(move || {
        thread::sleep(Duration::from_millis(50)); // Let producer get ahead
        let mut consumed = 0;
        while consumed < 10 {
            if let Some(value) = queue_consumer.try_dequeue() {
                println!("  Consumer: Dequeued {}", value);
                consumed += 1;
            } else {
                thread::sleep(Duration::from_millis(20));
            }
        }
    });

    producer.join().unwrap();
    consumer.join().unwrap();

    // Example 5: Barrier
    println!("\n5. Barrier Example:");

    let barrier = Arc::new(Barrier::new(3));
    let mut handles = vec![];

    for i in 0..3 {
        let barrier_clone = Arc::clone(&barrier);
        let handle = thread::spawn(move || {
            println!("  Thread {}: Working...", i);
            thread::sleep(Duration::from_millis((i + 1) as u64 * 100));
            println!("  Thread {}: Waiting at barrier", i);

            barrier_clone.wait();

            println!("  Thread {}: Passed barrier!", i);
        });
        handles.push(handle);
    }

    for handle in handles {
        handle.join().unwrap();
    }

    // Example 6: WaitGroup
    println!("\n6. WaitGroup Example:");

    let wg = Arc::new(WaitGroup::new());

    for i in 0..5 {
        wg.add(1);
        let wg_clone = Arc::clone(&wg);

        thread::spawn(move || {
            println!("  Worker {}: Starting task", i);
            thread::sleep(Duration::from_millis((5 - i) as u64 * 50));
            println!("  Worker {}: Task complete", i);
            wg_clone.done();
        });
    }

    println!("  Main: Waiting for all workers...");
    wg.wait();
    println!("  Main: All workers completed!");

    // Example 7: Performance comparison
    println!("\n7. Performance Comparison (FutexMutex vs std::sync::Mutex):");

    /// Number of iterations for performance comparison benchmarks
    const BENCHMARK_ITERATIONS: usize = 100_000;
    /// Number of worker threads for performance comparison
    const BENCHMARK_WORKER_THREADS: usize = 4;

    let iterations = BENCHMARK_ITERATIONS;

    // FutexMutex benchmark
    let futex_mutex = Arc::new(FutexMutex::new(0));
    let start = Instant::now();

    let mut handles = vec![];
    for _ in 0..BENCHMARK_WORKER_THREADS {
        let mutex_clone = Arc::clone(&futex_mutex);
        let handle = thread::spawn(move || {
            for _ in 0..iterations / BENCHMARK_WORKER_THREADS {
                let mut guard = mutex_clone.lock();
                *guard += 1;
            }
        });
        handles.push(handle);
    }

    for handle in handles {
        handle.join().unwrap();
    }

    let futex_time = start.elapsed();

    // std::sync::Mutex benchmark
    let std_mutex = Arc::new(std::sync::Mutex::new(0));
    let start = Instant::now();

    let mut handles = vec![];
    for _ in 0..BENCHMARK_WORKER_THREADS {
        let mutex_clone = Arc::clone(&std_mutex);
        let handle = thread::spawn(move || {
            for _ in 0..iterations / BENCHMARK_WORKER_THREADS {
                let mut guard = mutex_clone.lock().unwrap();
                *guard += 1;
            }
        });
        handles.push(handle);
    }

    for handle in handles {
        handle.join().unwrap();
    }

    let std_time = start.elapsed();

    println!(
        "  FutexMutex:      {:?} ({} ops)",
        futex_time,
        *futex_mutex.lock()
    );
    println!(
        "  std::sync::Mutex: {:?} ({} ops)",
        std_time,
        *std_mutex.lock().unwrap()
    );
    println!(
        "  Speedup: {:.2}x",
        std_time.as_secs_f64() / futex_time.as_secs_f64()
    );
}