perdix 0.1.0

High-performance GPU-accelerated ring buffer for AI terminal multiplexing
Documentation 
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use crate::buffer::{Header, Slot};
use std::sync::atomic::Ordering;
use std::thread;
use std::time::{Duration, Instant};

pub struct CpuProducer {
    header: *mut Header,
    slots: *mut Slot,
    #[allow(dead_code)]
    #[allow(dead_code)]
    n_slots: usize,
    delay_ms: Option<u64>,
}

unsafe impl Send for CpuProducer {}

impl CpuProducer {
    pub fn new(
        header: *mut Header,
        slots: *mut Slot,
        n_slots: usize,
        delay_ms: Option<u64>,
    ) -> Self {
        Self {
            header,
            slots,
            n_slots,
            delay_ms,
        }
    }

    pub fn produce_messages(&mut self, n_msgs: u64) {
        let start = Instant::now();

        for i in 0..n_msgs {
            // Reserve sequence number atomically (mimics GPU atomicAdd)
            let seq = unsafe {
                (*self.header)
                    .producer
                    .write_idx
                    .fetch_add(1, Ordering::AcqRel)
            };

            // Calculate slot index with wrap-around
            let slot_idx = (seq & unsafe { (*self.header).config.wrap_mask }) as usize;

            // Write to slot
            unsafe {
                let slot = &mut *self.slots.add(slot_idx);

                // Create test payload
                let payload_str = format!("CPU Message #{:04} [seq={}]", i, seq);
                let payload_bytes = payload_str.as_bytes();
                let len = payload_bytes.len().min(192);

                // Copy payload
                slot.payload[..len].copy_from_slice(&payload_bytes[..len]);
                // Write non-atomic fields using volatile writes for unified memory
                std::ptr::write_volatile(&mut slot.len, len as u32);
                std::ptr::write_volatile(&mut slot.flags, 0);

                // Memory fence equivalent (ensures write visibility)
                std::sync::atomic::fence(Ordering::Release);

                // Publish sequence number (slot is ready)
                // Publish sequence using volatile write
                std::ptr::write_volatile(&mut slot.seq, seq);
            }

            // Optional delay to simulate processing time
            if let Some(delay) = self.delay_ms {
                thread::sleep(Duration::from_millis(delay));
            }

            // Progress indicator every 1000 messages
            if i > 0 && i % 1000 == 0 {
                let elapsed = start.elapsed();
                let rate = i as f64 / elapsed.as_secs_f64();
                println!("CPU Producer: {} messages, {:.0} msg/s", i, rate);
            }
        }

        let elapsed = start.elapsed();
        println!(
            "CPU Producer: Completed {} messages in {:.2}s ({:.0} msg/s)",
            n_msgs,
            elapsed.as_secs_f64(),
            n_msgs as f64 / elapsed.as_secs_f64()
        );
    }
}

pub fn start_cpu_producer(
    header: *mut Header,
    slots: *mut Slot,
    n_slots: usize,
    n_msgs: u64,
    delay_ms: Option<u64>,
) -> thread::JoinHandle<()> {
    // Convert pointers to usize to make them Send
    let header_addr = header as usize;
    let slots_addr = slots as usize;

    thread::spawn(move || {
        // Reconstruct pointers inside the thread
        let header = header_addr as *mut Header;
        let slots = slots_addr as *mut Slot;
        let mut producer = CpuProducer::new(header, slots, n_slots, delay_ms);
        producer.produce_messages(n_msgs);
    })
}

// Batch producer for higher throughput
pub struct BatchCpuProducer {
    header: *mut Header,
    slots: *mut Slot,
    _n_slots: usize,
    batch_size: usize,
}

unsafe impl Send for BatchCpuProducer {}

impl BatchCpuProducer {
    pub fn new(header: *mut Header, slots: *mut Slot, n_slots: usize, batch_size: usize) -> Self {
        Self {
            header,
            slots,
            _n_slots: n_slots,
            batch_size,
        }
    }

    pub fn produce_batch(&mut self, n_msgs: u64) {
        let start = Instant::now();
        let mut messages_produced = 0u64;

        while messages_produced < n_msgs {
            let batch_count = (n_msgs - messages_produced).min(self.batch_size as u64);

            // Reserve sequence numbers for entire batch atomically
            let base_seq = unsafe {
                (*self.header)
                    .producer
                    .write_idx
                    .fetch_add(batch_count, Ordering::AcqRel)
            };

            // Write batch of messages
            for i in 0..batch_count {
                let seq = base_seq + i;
                let slot_idx = (seq & unsafe { (*self.header).config.wrap_mask }) as usize;

                unsafe {
                    let slot = &mut *self.slots.add(slot_idx);

                    // Create payload
                    let payload_str =
                        format!("Batch CPU #{:04} [seq={}]", messages_produced + i, seq);
                    let payload_bytes = payload_str.as_bytes();
                    let len = payload_bytes.len().min(192);

                    slot.payload[..len].copy_from_slice(&payload_bytes[..len]);
                    // Write non-atomic fields using volatile writes
                    std::ptr::write_volatile(&mut slot.len, len as u32);
                    std::ptr::write_volatile(&mut slot.flags, 0x100); // Mark as batch-produced

                    // Memory fence
                    std::sync::atomic::fence(Ordering::Release);

                    // Publish sequence using volatile write
                    std::ptr::write_volatile(&mut slot.seq, seq);
                }
            }

            messages_produced += batch_count;

            // Progress update
            if messages_produced % 10000 == 0 {
                let elapsed = start.elapsed();
                let rate = messages_produced as f64 / elapsed.as_secs_f64();
                println!(
                    "Batch CPU Producer: {} messages, {:.0} msg/s",
                    messages_produced, rate
                );
            }
        }

        let elapsed = start.elapsed();
        println!(
            "Batch CPU Producer: Completed {} messages in {:.2}s ({:.0} msg/s)",
            n_msgs,
            elapsed.as_secs_f64(),
            n_msgs as f64 / elapsed.as_secs_f64()
        );
    }
}

// Multi-threaded CPU producer for maximum throughput
pub fn start_parallel_cpu_producer(
    header: *mut Header,
    slots: *mut Slot,
    n_slots: usize,
    n_msgs: u64,
    n_threads: usize,
) -> Vec<thread::JoinHandle<()>> {
    let msgs_per_thread = n_msgs / n_threads as u64;
    let remainder = n_msgs % n_threads as u64;

    // Convert pointers to usize for thread safety
    let header_addr = header as usize;
    let slots_addr = slots as usize;

    (0..n_threads)
        .map(|thread_id| {
            let header_addr = header_addr;
            let slots_addr = slots_addr;
            let n_slots = n_slots;
            let thread_msgs = if thread_id == 0 {
                msgs_per_thread + remainder
            } else {
                msgs_per_thread
            };

            thread::spawn(move || {
                let header = header_addr as *mut Header;
                let slots = slots_addr as *mut Slot;
                let mut producer = CpuProducer::new(header, slots, n_slots, None);
                println!(
                    "CPU Producer thread {} starting, producing {} messages",
                    thread_id, thread_msgs
                );
                producer.produce_messages(thread_msgs);
                println!("CPU Producer thread {} completed", thread_id);
            })
        })
        .collect()
}

// Performance testing utilities
pub fn benchmark_cpu_producer(
    header: *mut Header,
    slots: *mut Slot,
    n_slots: usize,
    n_msgs: u64,
) -> Duration {
    let start = Instant::now();
    let mut producer = CpuProducer::new(header, slots, n_slots, None);
    producer.produce_messages(n_msgs);
    start.elapsed()
}

pub fn benchmark_batch_producer(
    header: *mut Header,
    slots: *mut Slot,
    n_slots: usize,
    n_msgs: u64,
    batch_size: usize,
) -> Duration {
    let start = Instant::now();
    let mut producer = BatchCpuProducer::new(header, slots, n_slots, batch_size);
    producer.produce_batch(n_msgs);
    start.elapsed()
}