should be good to extend functionality now

restructuring stuff
2025-12-08 14:31:59 -05:00 · 2025-12-03 21:35:08 -05:00
17 changed files with 235 additions and 650 deletions
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -1,22 +0,0 @@
 name: Rust
 on:
  push:
    branches: [ "main" ]
  pull_request:
    branches: [ "main" ]
 env:
  CARGO_TERM_COLOR: always
 jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v4
    - name: Build
      run: cargo build --verbose
    - name: Run tests
      run: cargo test --verbose
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -26,23 +26,11 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 [[package]]
 name = "getrandom"
 version = "0.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "335ff9f135e4384c8150d6f27c6daed433577f86b4750418338c01a1a2528592"
 dependencies = [
 "cfg-if",
 "libc",
 "wasi",
 ]
 [[package]]
 name = "l4lb"
 version = "0.1.0"
 dependencies = [
 "anywho",
 "rand",
 "tokio",
 ]
@@ -101,15 +89,6 @@ version = "0.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3b3cff922bd51709b605d9ead9aa71031d81447142d828eb4a6eba76fe619f9b"
 [[package]]
 name = "ppv-lite86"
 version = "0.2.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "85eae3c4ed2f50dcfe72643da4befc30deadb458a9b590d720cde2f2b1e97da9"
 dependencies = [
 "zerocopy",
 ]
 [[package]]
 name = "proc-macro2"
 version = "1.0.103"
@@ -128,36 +107,6 @@ dependencies = [
 "proc-macro2",
 ]
 [[package]]
 name = "rand"
 version = "0.8.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
 dependencies = [
 "libc",
 "rand_chacha",
 "rand_core",
 ]
 [[package]]
 name = "rand_chacha"
 version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
 dependencies = [
 "ppv-lite86",
 "rand_core",
 ]
 [[package]]
 name = "rand_core"
 version = "0.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
 dependencies = [
 "getrandom",
 ]
 [[package]]
 name = "redox_syscall"
 version = "0.5.18"
@@ -337,23 +286,3 @@ name = "windows_x86_64_msvc"
 version = "0.53.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d6bbff5f0aada427a1e5a6da5f1f98158182f26556f345ac9e04d36d0ebed650"
 [[package]]
 name = "zerocopy"
 version = "0.8.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fd74ec98b9250adb3ca554bdde269adf631549f51d8a8f8f0a10b50f1cb298c3"
 dependencies = [
 "zerocopy-derive",
 ]
 [[package]]
 name = "zerocopy-derive"
 version = "0.8.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d8a8d209fdf45cf5138cbb5a506f6b52522a25afccc534d1475dad8e31105c6a"
 dependencies = [
 "proc-macro2",
 "quote",
 "syn",
 ]
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,4 +6,3 @@ edition = "2024"
 [dependencies]
 anywho = "0.1.2"
 tokio = { version = "1.48.0", features = ["full"] }
 rand = { version = "0.8", features = ["small_rng"] }
--- a/README.md
+++ b/README.md
@@ -5,10 +5,25 @@ Production't graden't load balancer.
 ## Todo
 - [ ] architecture astronauting
  - balancer module
    - just the algorithms i guess
 - 
  - backend module
    - manages the backend pool
    - deals with health / load check
    - BackendPool for all the backends stored together
    - Backend for individual backends
    - has some methods used by balancer module to pick a suitable backend
  - proxy module 
    - all the different supported protocols to handle
    - will create a session / stream context structure (ConnectionContext)
      - not globally tracked (this might change for UDP!)
      - mainly some metadata
  - config module
    - set up all the stuff or something
 - [ ] stream / session handling (i think wrapper around tokio TcpStream)
 - [ ] basic backend pooling
 - [ ] layer 4 load balancing
 - [ ] load balancing algorithm from the paper (https://www.wcse.org/WCSE_2018/W110.pdf) 
 ## notes
 tcp, for nginx (and haproxy, its similar):
@@ -21,7 +36,7 @@ struct ngx_connection_s {
    ngx_socket_t        fd;
-    ngx_recv_pt         recv; // fn pointer to whatever recv fn used (different for dfferent platforms / protocol
+    ngx_recv_pt         recv; // fn pointer to whatever recv fn used (different for idfferent platforms / protocol
    ngx_send_pt         send; // ditto
    ngx_recv_chain_pt   recv_chain;
    ngx_send_chain_pt   send_chain;
@@ -105,11 +120,9 @@ process to load balance:
 - proxy the data (copy_bidirectional? maybe we want some metrics or logging, so might do manually)
 - cleanup when smoeone leavesr or something goes wrong (with TCP, OS / tokio will tell us, with UDP probably just timeout based, and a periodic sweep of all sessions)
-## Load balancer algorithm
+
- Choose a fixed weight coefficient for the resource parameter
+### UDP
- Spawn a thread on a load balancer to host the iperf server, used for new onboarding server connecting to the load balancer to measure their maximum bandwidth
+UDP is connectionless, and i don't think UdpSocket or UdpFramed implement the traits required for tokio copy_bidirectional
- Spawn another thread for listening to resource update from connected server
+but async write and read don't work on just regular datagrams, so probably not possible.
- Update the comprehensive load sum from eq (1), update the formula in eq (2) to (5)
+
- Choose alpha for eq (8), and run the algorithm to choose which server
+Would require us to implement our own bidirectional copying / proxying, as well as tracking "active" connections.
 - Extract the server from the server id using ```get_backend()``` 
 - Use ```tunnel()``` to proxy the packet
--- a/W110.pdf
+++ b/W110.pdf
--- a/infra/enginewhy-lb.rs
+++ b/infra/enginewhy-lb.rs
@@ -1,68 +0,0 @@
 use rperf3::{Server, Config};
 use std::net::{TcpListener, TcpStream};
 use std::thread;
 use std::io::{Read, Write};
 use std::env;
 use tokio::task;
 async fn start_iperf_server() -> Result<(), Box<dyn std::error::Error>> {
    let config = Config::server(5001);
    let server = Server::new(config);
    server.run().await?;
    Ok(())
 }
 fn handle_connection(mut stream: TcpStream) -> std::io::Result<()> {
    loop {
        let mut buffer = [0u8; 512];
        let bytes_read = stream.read(&mut buffer)?; 
        let received = String::from_utf8_lossy(&buffer[..bytes_read]);
        println!("Received: {}", received);
    }
    Ok(())
 }
 fn start_tcp_server(addr: &str) -> std::io::Result<()> {
    let listener = TcpListener::bind(addr)?;
    println!("TCP server listening on {}", addr);
    let mut handles = Vec::new();
    for stream in listener.incoming() {
        match stream {
            Ok(stream) => {
                let handle = thread::spawn(move || {
                    if let Err(e) = handle_connection(stream) {
                        eprintln!("connection handler error: {}", e);
                    }
                });
                handles.push(handle);
            }
            Err(e) => eprintln!("incoming connection failed: {}", e),
        }
    }
    // When the incoming stream iterator ends (listener closed), join all handlers.
    for h in handles {
        let _ = h.join();
    }
    Ok(())
 }
 #[tokio::main]
 async fn main() {
    // Choose IP based on `--localhost` flag for debugging
    let use_localhost = env::args().any(|a| a == "--localhost");
    let ip = if use_localhost { "127.0.0.1" } else { "192.67.67.67" };
    let tcp_addr = format!("{}:8080", ip);
    let iperf_server = task::spawn(async {
        start_iperf_server().await;
    });
    let tcp_ip = tcp_addr.clone();
    let tcp_server = thread::spawn(move || {
        start_tcp_server(&tcp_ip).unwrap();
    });
    iperf_server.await.unwrap();
    tcp_server.join().unwrap();
 }
--- a/infra/enginewhy-server.rs
+++ b/infra/enginewhy-server.rs
@@ -1,168 +0,0 @@
 use sysinfo::{CpuRefreshKind, RefreshKind, System};
 use sysinfo::{Networks};
 use sysinfo::{Disks};
 use std::thread;
 use std::time::Duration;
 use std::net::{TcpStream};
 use std::env;
 use std::collections::HashMap;
 use std::io::Write;
 use serde_json::Value;
 use rperf3::{Client, Config, Protocol};
 // Default server addresses
 const DEFAULT_REMOTE_IP: &str = "192.67.67.67";
 const DEFAULT_LOCAL_IP: &str = "127.0.0.1";
 const PORT: u16 = 8080;
 const IPERF_PORT: u16 = 5001;
 fn get_io_usage_percentage() -> Result<f64, String> {
    let mut sys = Disks::new_with_refreshed_list();
    // Refresh disk information
    sys.refresh(true);
    // Get first disk (usually main disk)
    if let Some(disk) = sys.list().first() {
        let initial_read = disk.usage().total_read_bytes;
        let initial_write = disk.usage().total_written_bytes;
        thread::sleep(Duration::from_secs(1));   // 1s
        sys.refresh(true);
        let disk = sys.list().first().ok_or("Disk disappeared")?;
        let new_read = disk.usage().total_read_bytes;
        let new_write = disk.usage().total_written_bytes;
        // Calculate Bps
        let read_per_sec = (new_read - initial_read) as f64; 
        let write_per_sec = (new_write - initial_write) as f64;
        // Get disk type to estimate max speed (these are rough estimates)
        let max_speed = match disk.kind() {
            sysinfo::DiskKind::SSD => 500_000_000.0, // 500 MBps
            sysinfo::DiskKind::HDD => 200_000_000.0, // 200 MBps
            _ => 300_000_000.0, // Default
        };
        let io_percentage = f64::min(100.0, ((read_per_sec + write_per_sec) / max_speed) * 100.0);
        Ok(io_percentage) 
    } else {
        Err("No disks found".to_string())
    }
 }
 async fn measure_iperf_bandwidth(server_ip: &str, port: u16) -> Result<f64, Box<dyn std::error::Error>> {
    // Configure the test (use the provided port)
    let config = Config::client(server_ip.to_string(), port)
        .with_duration(Duration::from_secs(10));
    // Run the test
    let client = Client::new(config)?;
    client.run().await?;
    // Get results
    let measurements = client.get_measurements();
    let bandwidth_bps = measurements.total_bits_per_second();
    println!("iperf3 reported max bandwidth: {:.2} Mbps", bandwidth_bps / 1_000_000.0);
    Ok(bandwidth_bps)
 }
 #[tokio::main]
 async fn main() -> std::io::Result<()> {
    // Determine server IP from CLI: `--localhost` -> local, otherwise remote
    let args: Vec<String> = env::args().collect();
    let server_ip = if args.iter().any(|a| a == "--localhost") {
        DEFAULT_LOCAL_IP.to_string()
    } else {
        DEFAULT_REMOTE_IP.to_string()
    };
    let mut stream = TcpStream::connect(format!("{}:{}", server_ip, PORT))?;
    println!("server connected to {}:{}", server_ip, PORT);
    // Initialize the system struct
    let mut sys = System::new_with_specifics(
        RefreshKind::nothing().with_cpu(CpuRefreshKind::everything()),
    );
    let mut networks = Networks::new();
    networks.refresh(true);
    // Probe max bandwidth using iperf3
    let mut max_bps: f64 = 0.0;
    match measure_iperf_bandwidth(&server_ip, IPERF_PORT).await {
        Ok(bps) => {
            max_bps = bps;
            println!("iperf3 reported max bandwidth: {:.2} bits/sec ({:.2} Mbps)", max_bps, max_bps / 1e6);
        }   
        Err(e) => println!("iperf3 failed: {}", e),
    }
    // Wait a bit because CPU usage is based on diff.
    std::thread::sleep(sysinfo::MINIMUM_CPU_UPDATE_INTERVAL);
    loop {
        sys.refresh_all();
        sys.refresh_cpu_usage(); // Refreshing CPU usage.
        let mut cpu_usage: f64 = 0.0;
        for cpu in sys.cpus() {
            cpu_usage += cpu.cpu_usage() as f64;
        }
        cpu_usage /= sys.cpus().len() as f64;
        println!("CPU usage is {}%", cpu_usage);
        // Memory usage
        let total_mem = sys.total_memory();
        let used_mem = sys.used_memory();
        let mem_usage = total_mem as f64 / used_mem as f64;
        println!("Memory usage is {}%", mem_usage);
        // Network bandwidth usage
        let mut bandwidth: f64 = 0.0;  // Bps
        for (interface_name, network) in &networks {
            if interface_name == "wlp2s0" {
                bandwidth = network.transmitted() as f64;
                println!("[{interface_name}] transferred {:?} %", bandwidth / max_bps * 100.0);
            }
        }
        networks.refresh(true);
        // Calculate percent usage of measured max bandwidth (if available)
        let net_usage_pct: f64 = if max_bps > 0.0 {
            f64::min(100.0, (bandwidth / max_bps) * 100.0)
        } else { 0.0 };
        // IO usage
        let mut io_usage = 0.0;
        match get_io_usage_percentage() {
            Ok(percentage) => {
                io_usage = percentage;
                println!("I/O usage is {}%", percentage)
            },
            Err(e) => println!("Error: {}", e)
        }
        println!();
        // Identify this process (client) by the local socket address used to connect
        let server_identifier = match stream.local_addr() {
            Ok(addr) => addr.to_string(),
            Err(_) => format!("localhost:{}", PORT),
        };
        let mut packet: HashMap<String, Value> = HashMap::new();
        packet.insert("server_ip".to_string(), Value::String(server_identifier));
        packet.insert("cpu".to_string(), Value::from(cpu_usage));    // %
        packet.insert("mem".to_string(), Value::from(mem_usage));    // %
        packet.insert("net".to_string(), Value::from(net_usage_pct));
        packet.insert("io".to_string(), Value::from(io_usage));
        let serialized_packet = serde_json::to_string(&packet)?;
        let _ = stream.write(serialized_packet.as_bytes());
        thread::sleep(Duration::from_secs(10));
    }
 }
--- a/src/backend/mod.rs
+++ b/src/backend/mod.rs
@@ -0,0 +1,58 @@
 use core::fmt;
 use std::net::SocketAddr;
 use std::sync::RwLock;
 use std::sync::Arc;
 use std::sync::atomic::{AtomicUsize, Ordering};
 #[derive(Debug)]
 pub struct Backend {
    pub id: String,
    pub address: SocketAddr,
    pub active_connections: AtomicUsize,
 }
 impl Backend {
    pub fn new(id: String, address: SocketAddr) -> Self {
        Self {
            id: id.to_string(),
            address,
            active_connections: AtomicUsize::new(0),
        }
    }
    // Ordering::Relaxed means the ops could be in any order, but since this
    // is just a metric, and we assume the underlying system is sane
    // enough not to behave poorly, so SeqCst is probably overkill.
    pub fn inc_connections(&self) {
        self.active_connections.fetch_add(1, Ordering::Relaxed);
        println!("{} has {} connections open", self.id, self.active_connections.load(Ordering::Relaxed));
    }
    pub fn dec_connections(&self) {
        self.active_connections.fetch_sub(1, Ordering::Relaxed);
        println!("{} has {} connections open", self.id, self.active_connections.load(Ordering::Relaxed));
    }
 }
 impl fmt::Display for Backend {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{} ({})", self.address, self.id)
    }
 }
 #[derive(Clone, Debug)]
 pub struct BackendPool {
    pub backends: Arc<RwLock<Vec<Arc<Backend>>>>,
 }
 impl BackendPool {
    pub fn new() -> Self {
        BackendPool {
            backends: Arc::new(RwLock::new(Vec::new())),
        }
    }
    pub fn add(&self, backend: Backend) {
        self.backends.write().unwrap().push(Arc::new(backend));
    }
 }
--- a/src/balancer/adaptive_weight.rs
+++ b/src/balancer/adaptive_weight.rs
@@ -1,211 +0,0 @@
 use crate::netutils::Backend;
 use rand::prelude::*;
 use rand::rngs::SmallRng;
 use std::sync::Arc;
 #[derive(Debug, Clone)]
 pub struct ServerMetrics {
    // metrics are percents (0..100)
    pub cpu: f64, 
    pub mem: f64, 
    pub net: f64, 
    pub io: f64,  
 }
 impl ServerMetrics {
    pub fn new() -> Self {
        ServerMetrics { cpu: 0.0, mem: 0.0, net: 0.0, io: 0.0 }
    }
    pub fn update(&mut self, cpu: f64, mem: f64, net: f64, io: f64) {
        self.cpu = cpu;
        self.mem = mem;
        self.net = net;
        self.io = io;
    }
 }
 #[derive(Debug, Clone)]
 pub struct ServerState {
    pub backend: Backend,
    pub metrics: ServerMetrics,
    pub weight: f64,
 }
 impl ServerState {
    pub fn new(backend: Backend) -> Self {
        ServerState { backend, metrics: ServerMetrics::new(), weight: 1.0 }
    }
 }
 pub struct AdaptiveBalancer {
    servers: Vec<ServerState>,
    // resource coefficients (cpu, mem, net, io) - sum to 1.0
    coeffs: [f64; 4],
    alpha: f64,
    rng: SmallRng,
 }
 impl AdaptiveBalancer {
    pub fn new(backends: Vec<Backend>, coeffs: [f64; 4], alpha: f64) -> Self {
        let servers = backends.into_iter().map(ServerState::new).collect();
        let rng = SmallRng::from_entropy();
        AdaptiveBalancer { servers, coeffs, alpha, rng }
    }
    pub fn add_backend(&mut self, backend: Backend) {
        self.servers.push(ServerState::new(backend));
    }
    /// Update metrics reported by a backend identified by its display/address.
    /// If the backend isn't found this is a no-op.
    pub fn update_metrics(&mut self, backend_addr: &str, cpu: f64, mem: f64, net: f64, io: f64) {
        for s in &mut self.servers {
            if s.backend.to_string() == backend_addr {
                s.metrics.update(cpu, mem, net, io);
                return;
            }
        }
    }
    fn metrics_to_weight(metrics: &ServerMetrics, coeffs: &[f64; 4]) -> f64 {
        coeffs[0] * metrics.cpu + coeffs[1] * metrics.mem + coeffs[2] * metrics.net + coeffs[3] * metrics.io
    }
    /// Choose a backend using weighted random selection based on current weights.
    /// Returns an Arc-wrapped Backend clone so callers can cheaply clone it.
    pub fn choose_backend(&mut self) -> Option<Arc<Backend>> {
        if self.servers.is_empty() {
            return None;
        }
        // Compute remaining capacity R_i = 100 - composite_load
        let rs: Vec<f64> = self.servers.iter().map(|s| {
            Self::metrics_to_weight(&s.metrics, &self.coeffs)
        }).collect();
        let ws: Vec<f64> = self.servers.iter().map(|s| s.weight).collect();
        let ls: Vec<u32> = self.servers.iter().map(|s| s.backend.current_load).collect();
        let r_sum: f64 = rs.iter().copied().sum::<f64>();
        let w_sum: f64 = ws.iter().copied().sum::<f64>().max(1e-12);
        let l_sum: u32 = ls.iter().copied().sum::<u32>();
        let threshold = self.alpha * (r_sum / w_sum);
        for (i, s) in self.servers.iter_mut().enumerate() {
            let ratio = if s.weight <= 0.0 { f64::INFINITY } else { rs[i] / s.weight };
            if ratio <= threshold {
                return Some(Arc::new(s.backend.clone()));
            }
        }
        // If any server satisfies Ri/Wi <= threshold, it means the server
        // is relatively overloaded and we must adjust its weight using
        // formula (6).
        let lwi: Vec<f64> = self.servers.iter().enumerate().map(|(i, s)| {
            s.backend.current_load as f64 * w_sum / ws[i] * l_sum as f64
        }).collect();
        let a_lwi: f64 = lwi.iter().copied().sum::<f64>() / lwi.len() as f64;
        for (i, s) in self.servers.iter_mut().enumerate() {
            s.weight += 1 as f64 - lwi[i] / a_lwi;
        }
        // Compute Li = Wi / Ri and choose server minimizing Li.
        let mut best_idx: Option<usize> = None;
        let mut best_li = u32::MAX;
        for (i, s) in self.servers.iter().enumerate() {
            let li = s.backend.current_load;
            if li < best_li {
                best_li = li;
                best_idx = Some(i);
            }
        }
        // If nothing chosen, fall back to random selection
        if best_idx.is_none() {
            let i = (self.rng.next_u32() as usize) % self.servers.len();
            return Some(Arc::new(self.servers[i].backend.clone()));
        }
        Some(Arc::new(self.servers[best_idx.unwrap()].backend.clone()))
    }
    // Expose a snapshot of server weights (for monitoring/testing)
    pub fn snapshot_weights(&self) -> Vec<(String, f64)> {
        self.servers.iter().map(|s| (s.backend.to_string(), s.weight)).collect()
    }
 }
 #[cfg(test)]
 mod tests {
    use super::*;
    #[test]
    fn basic_weight_update_and_choose() {
        let backends = vec![Backend::new("127.0.0.1:1".to_string()), Backend::new("127.0.0.1:2".to_string())];
        let mut b = AdaptiveBalancer::new(backends, [0.5, 0.2, 0.2, 0.1], 0.5);
        // initially equal weights
        let snaps = b.snapshot_weights();
        assert_eq!(snaps.len(), 2);
        // update one backend to be heavily loaded
        b.update_metrics("127.0.0.1:1", 90.0, 80.0, 10.0, 5.0);
        b.update_metrics("127.0.0.1:2", 10.0, 5.0, 1.0, 1.0);
        // Choose backend: should pick the less loaded host (127.0.0.1:2)
        let chosen = b.choose_backend().expect("should choose a backend");
        let snaps2 = b.snapshot_weights();
        println!("{:?}, {:?}", snaps, snaps2);
        assert_eq!(chosen.to_string(), "127.0.0.1:2");
    }
    #[test]
    fn choose_none_when_empty() {
        let mut b = AdaptiveBalancer::new(vec![], [0.5, 0.2, 0.2, 0.1], 0.5);
        assert!(b.choose_backend().is_none());
    }
    #[test]
    fn ratio_triggers_immediate_selection() {
        // Arrange two servers where server 1 has composite load 0 and server 2 has composite load 100.
        // With alpha = 1.0 and two servers, threshold = 1.0 * (r_sum / w_sum) = 1.0 * (100 / 2) = 50.
        // Server 1 ratio = 0 / 1 = 0 <= 50 so it should be chosen immediately.
        let backends = vec![Backend::new("127.0.0.1:1".to_string()), Backend::new("127.0.0.1:2".to_string())];
        let mut b = AdaptiveBalancer::new(backends, [0.25, 0.25, 0.25, 0.25], 1.0);
        b.update_metrics("127.0.0.1:1", 0.0, 0.0, 0.0, 0.0);
        b.update_metrics("127.0.0.1:2", 100.0, 100.0, 100.0, 100.0);
        let chosen = b.choose_backend().expect("should choose a backend");
        assert_eq!(chosen.to_string(), "127.0.0.1:1");
    }
    #[test]
    fn choose_min_current_load_when_no_ratio() {
        // Arrange three servers with identical composite loads so no server satisfies Ri/Wi <= threshold
        // (set alpha < 1 so threshold < ratio). The implementation then falls back to picking the
        // server with minimum current_load 
        let mut s1 = Backend::new("127.0.0.1:1".to_string());
        let mut s2 = Backend::new("127.0.0.1:2".to_string());
        let mut s3 = Backend::new("127.0.0.1:3".to_string());
        // set current_loads (field expected to be public)
        s1.current_load = 10;
        s2.current_load = 5;
        s3.current_load = 20;
        // Use coeffs that only consider CPU so composite load is easy to reason about.
        let mut bal = AdaptiveBalancer::new(vec![s1, s2, s3], [1.0, 0.0, 0.0, 0.0], 0.5);
        // set identical composite loads > 0 for all so ratio = x and threshold = alpha * x < x
        // you will have threshold = 25 for all 3 backend servers and ratio = 50
        // so that forces to choose the smallest current load backend
        bal.update_metrics("127.0.0.1:1", 50.0, 0.0, 0.0, 0.0);
        bal.update_metrics("127.0.0.1:2", 50.0, 0.0, 0.0, 0.0);
        bal.update_metrics("127.0.0.1:3", 50.0, 0.0, 0.0, 0.0);
        let chosen = bal.choose_backend().expect("should choose a backend");
        // expect server with smallest current_load (127.0.0.1:2)
        assert_eq!(chosen.to_string(), "127.0.0.1:2");
    }
 }
--- a/src/balancer/mod.rs
+++ b/src/balancer/mod.rs
@@ -1,2 +1,9 @@
-pub mod adaptive_weight;
+pub mod round_robin;
-pub use adaptive_weight::AdaptiveBalancer;
+
 use std::fmt::Debug;
 use std::sync::Arc;
 use crate::backend::Backend;
 pub trait Balancer: Debug + Send + Sync + 'static {
    fn choose_backend(&mut self) -> Option<Arc<Backend>>;
 }
--- a/src/balancer/random.rs
+++ b/src/balancer/random.rs
--- a/src/balancer/round_robin.rs
+++ b/src/balancer/round_robin.rs
@@ -0,0 +1,33 @@
 use std::sync::{Arc, RwLock};
 use std::fmt::Debug;
 use crate::backend::{Backend, BackendPool};
 use crate::balancer::Balancer;
 // only the main thread for receiving connections should be
 // doing the load balancing. alternatively, each thread
 // that handles load balancing should get their own instance.
 #[derive(Debug)]
 pub struct RoundRobinBalancer {
    pool: BackendPool,
    index: usize,
 }
 impl RoundRobinBalancer {
    pub fn new(pool: BackendPool) -> RoundRobinBalancer {
        Self {
            pool,
            index: 0,
        }
    }
 }
 impl Balancer for RoundRobinBalancer {
    fn choose_backend(&mut self) -> Option<Arc<Backend>> {
        let backends = self.pool.backends.read().unwrap();
        if backends.is_empty() { return None; }
        let backend = backends[self.index % backends.len()].clone();
        self.index = self.index.wrapping_add(1);
        Some(backend)
    }
 }
--- a/src/config.rs
+++ b/src/config.rs
@@ -0,0 +1,6 @@
 // TODO: "routing" rules
 // backends defined as ip + port
 // define sets of backends
 // allowed set operations for now is just union
 // rules are ip + mask and ports, maps to some of the sets
 //  defined earlier, along with a routing strategy
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,56 +1,52 @@
-macro_rules! info {
+extern crate core;
    ($($arg:tt)*) => {{
        print!("info: ");
        println!($($arg)*);
    }};
 }
 macro_rules! error {
    ($($arg:tt)*) => {
        eprint!("error: ");
        eprintln!($($arg)*);
    };
 }
 mod netutils;
 mod balancer;
-
+mod config;
-use anywho::Error;
+mod backend;
-use netutils::{Backend, tunnel};
+mod proxy;
 use std::sync::Arc;
 use tokio::net::TcpListener;
-use tokio::sync::Mutex;
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
 use std::sync::Arc;
 use std::sync::atomic::AtomicU64;
 use crate::backend::{Backend, BackendPool};
 use crate::balancer::Balancer;
 use crate::balancer::round_robin::RoundRobinBalancer;
 use crate::proxy::tcp::proxy_tcp_connection;
 static NEXT_CONN_ID: AtomicU64 = AtomicU64::new(1);
 #[tokio::main]
-async fn main() -> Result<(), Error> {
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let backends = Arc::new(vec![
+    let pool = BackendPool::new();
        Backend::new("127.0.0.1:8081".to_string()),
        Backend::new("127.0.0.1:8082".to_string()),
    ]);
-    let current_index = Arc::new(Mutex::new(0));
+    pool.add(Backend::new(
        "backend 1".into(),
        "127.0.0.1:8081".parse().unwrap(),
    ));
-    info!("enginewhy starting on 0.0.0.0:8080");
+    pool.add(Backend::new(
-    info!("backends: {:?}", backends);
+        "backend 2".into(),
        "127.0.0.1:8082".parse().unwrap(),
    ));
-    let listener = TcpListener::bind("0.0.0.0:8080").await?;
+    let mut balancer = RoundRobinBalancer::new(pool.clone());
    let listener = TcpListener::bind("127.0.0.1:8080").await?;
    loop {
-        let (client, addr) = listener.accept().await?;
+        let (socket, _) = listener.accept().await?;
        info!("new connection from {}", addr);
-        let backend = {
+        let conn_id = NEXT_CONN_ID.fetch_add(1, std::sync::atomic::Ordering::SeqCst);
            let mut index = current_index.lock().await;
            let selected_backend = backends[*index].clone();
            *index = (*index + 1) % backends.len();
            selected_backend
        };
-        info!("routing client {} to backend {}", addr, backend);
+        if let Some(backend) = balancer.choose_backend() {
-
+            tokio::spawn(async move {
-        if let Err(e) = tunnel(client, backend).await {
+                if let Err(e) = proxy_tcp_connection(conn_id, socket, backend).await {
-            error!("proxy failed for {}: {}", addr, e);
+                    eprintln!("error: conn_id={} proxy failed: {}", conn_id, e);
                }
            });
        } else {
            eprintln!("error: no backendsd for conn_id={}", conn_id);
        }
    }
 }
--- a/src/netutils.rs
+++ b/src/netutils.rs
@@ -1,56 +0,0 @@
 use std::fmt;
 use tokio::io;
 use tokio::net::TcpStream;
 use std::error::Error;
 #[derive(Clone, Debug)]
 pub struct Backend {
    address: String,
    pub current_load : u32
 }
 impl Backend {
    pub fn new(address: String) -> Self {
        Backend { 
            address,  
            current_load : 0 
        }
    }
 }
 impl fmt::Display for Backend {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.address)
    }
 }
 pub async fn tunnel(client_stream: TcpStream, backend: Backend) -> Result<(), Box<dyn Error>> {
    let backend_address: String = backend.address.clone();
    tokio::spawn(async move {
        let backend_stream: TcpStream = match TcpStream::connect(&backend_address).await {
            Ok(s) => {
                info!("connected to backend {backend_address}");
                s
            }
            Err(e) => {
                error!("failed connecting to backend {backend_address}: {e}");
                return;
            }
        };
        let (mut read_client, mut write_client) = client_stream.into_split();
        let (mut read_backend, mut write_backend) = backend_stream.into_split();
        let client_to_backend =
            tokio::spawn(async move { io::copy(&mut read_client, &mut write_backend).await });
        let backend_to_client =
            tokio::spawn(async move { io::copy(&mut read_backend, &mut write_client).await });
        let _ = tokio::join!(client_to_backend, backend_to_client);
    });
    Ok(())
 }
--- a/src/proxy/mod.rs
+++ b/src/proxy/mod.rs
@@ -0,0 +1,43 @@
 use std::net::SocketAddr;
 use std::sync::Arc;
 use std::time::Instant;
 use crate::backend::Backend;
 pub mod tcp;
 pub struct ConnectionContext {
    pub id: u64,
    pub client_addr: SocketAddr,
    pub start_time: Instant,
    pub backend: Arc<Backend>,
    pub bytes_transferred: u64,
 }
 impl ConnectionContext {
    pub fn new(id: u64, client_addr: SocketAddr, backend: Arc<Backend>) -> Self {
        backend.inc_connections();
        Self {
            id,
            client_addr,
            start_time: Instant::now(),
            backend,
            bytes_transferred: 0,
        }
    }
 }
 impl Drop for ConnectionContext {
    fn drop(&mut self) {
        self.backend.dec_connections();
        let duration = self.start_time.elapsed();
        println!("info: conn_id={} closed. client={} backend={} bytes={} duration={:.2?}",
            self.id,
            self.client_addr,
            self.backend.address,
            self.bytes_transferred,
            duration.as_secs_f64()
        );
    }
 }
--- a/src/proxy/tcp.rs
+++ b/src/proxy/tcp.rs
@@ -0,0 +1,26 @@
 use std::sync::Arc;
 use tokio::io;
 use tokio::net::TcpStream;
 use anywho::Error;
 use crate::backend::Backend;
 use crate::proxy::ConnectionContext;
 pub async fn proxy_tcp_connection(connection_id: u64, mut client_stream: TcpStream, backend: Arc<Backend>) -> Result<(), Error> {
    let client_addr = client_stream.peer_addr()?;
    let mut ctx = ConnectionContext::new(connection_id, client_addr, backend.clone());
    #[cfg(debug_assertions)]
    println!("info: conn_id={} connecting to {}", connection_id, ctx.backend.id);
    let mut backend_stream = TcpStream::connect(&backend.address).await?;
    let (tx, rx) = io::copy_bidirectional(
        &mut client_stream,
        &mut backend_stream,
    ).await?;
    ctx.bytes_transferred = tx + rx;
    Ok(())
 }
Author	SHA1	Message	Date
psun256	a3f50c1f0a	should be good to extend functionality now	2025-12-08 14:31:59 -05:00
psun256	07cb45fa73	restructuring stuff	2025-12-03 21:35:08 -05:00