[rust] cache-aware DP - approx tree (#1934)

benchmark/multi_turn_chat/long_prompt_multi_turn.py

+import itertools
+import json
+import random
+import string
+import threading
+import time
+from argparse import ArgumentParser
+
+import sglang as sgl
+from sglang.srt.hf_transformers_utils import get_tokenize
+from sglang.test.test_utils import (
+    add_common_sglang_args_and_parse,
+    select_sglang_backend,
+)
+from sglang.utils import dump_state_text
+
+random.seed(42)
+
+
+def gen_prompt(tokenizer, token_num):
+    all_available_tokens = list(tokenizer.get_vocab().values())
+    selected_tokens = random.choices(all_available_tokens, k=token_num)
+    ret = tokenizer.decode(selected_tokens)
+    return ret
+
+
+def gen_arguments(args, tokenizer):
+    multi_qas = [
+        {"system_prompt": gen_prompt(tokenizer, args.system_prompt_len), "qas": []}
+        for _ in range(args.num_qa)
+    ]
+    for i in range(args.num_qa):
+        qas = multi_qas[i]["qas"]
+        for j in range(args.turns):
+            qas.append(
+                {
+                    "prompt": gen_prompt(tokenizer, args.len_q),
+                    "new_tokens": args.len_a,
+                }
+            )
+    return multi_qas
+
+
+@sgl.function
+def multi_turns(s, system_prompt, qas):
+    s += system_prompt
+
+    for qa in qas:
+        s += qa["prompt"]
+        s += sgl.gen(max_tokens=qa["new_tokens"], ignore_eos=True)
+
+
+def main(args):
+    tokenizer = get_tokenizer(args.tokenizer, trust_remote_code=args.trust_remote_code)
+
+    multi_qas = gen_arguments(args, tokenizer)
+
+    backend = select_sglang_backend(args)
+
+    tic = time.time()
+    states = multi_turns.run_batch(
+        multi_qas,
+        temperature=0,
+        backend=backend,
+        num_threads=args.parallel,
+        progress_bar=True,
+    )
+    latency = time.time() - tic
+
+    print(f"Latency: {latency:.3f}")
+
+    dump_state_text(f"tmp_output_{args.backend}.txt", states)
+
+    with open(args.result_file, "a") as fout:
+        value = {
+            "task": "multi_turn_system_prompt_chat",
+            "backend": args.backend,
+            "num_gpus": 1,
+            "latency": round(latency, 3),
+            "num_requests": args.num_qa,
+            "num_turns": args.turns,
+            "other": {
+                "parallel": args.parallel,
+            },
+        }
+        fout.write(json.dumps(value) + "\n")
+
+
+if __name__ == "__main__":
+    parser = ArgumentParser()
+    parser.add_argument("--turns", type=int, default=8)
+    parser.add_argument("--num-qa", type=int, default=128)
+    parser.add_argument("--system-prompt-len", type=int, default=2048)
+    parser.add_argument("--len-q", type=int, default=32)
+    parser.add_argument("--len-a", type=int, default=128)
+    parser.add_argument(
+        "--tokenizer", type=str, default="meta-llama/Meta-Llama-3-8B-Instruct"
+    )
+    parser.add_argument("--trust-remote-code", action="store_true")
+    args = add_common_sglang_args_and_parse(parser)
+
+    print(args)
+    main(args)

rust/Cargo.toml

@@ -21,5 +21,6 @@ bytes = "1.8.0"
 rand = "0.8.5"
 reqwest = { version = "0.12.8", features = ["stream"] }
 futures-util = "0.3"
-serde_json = "=1.0.1"
+serde_json = "1.0"
 pyo3 = { version = "0.22.5", features = ["extension-module"] }
+tokenizers = { version = "0.20.3", features = ["http"] }

rust/py_src/dp_demo.py

+import argparse
+import os
+import signal
+import subprocess
+import sys
+import time
+from typing import Dict, List
+
+import requests
+from sglang_router import PolicyType, Router
+
+# Global processes list for cleanup
+_processes: List[subprocess.Popen] = []
+
+
+def cleanup_processes(signum=None, frame=None):
+    """Cleanup function to kill all worker processes."""
+    print("\nCleaning up processes...")
+    for process in _processes:
+        try:
+            # Kill the entire process group
+            pgid = os.getpgid(process.pid)
+            os.killpg(pgid, signal.SIGKILL)
+            process.wait()
+        except:
+            pass
+    sys.exit(1)
+
+
+# Register signal handlers
+signal.signal(signal.SIGINT, cleanup_processes)
+signal.signal(signal.SIGTERM, cleanup_processes)
+
+
+def parse_args():
+    """Parse command line arguments."""
+    parser = argparse.ArgumentParser(description="Launch SGLang Router Server")
+    parser.add_argument(
+        "--host", type=str, default="localhost", help="Host address to bind the server"
+    )
+    parser.add_argument(
+        "--port", type=int, default=30000, help="Base port number for workers"
+    )
+    parser.add_argument(
+        "--dp",
+        type=int,
+        default=2,
+        help="Number of worker processes (degree of parallelism)",
+    )
+    parser.add_argument(
+        "--model-path", type=str, required=True, help="Path to the model"
+    )
+    parser.add_argument(
+        "--local-tokenizer-path",
+        type=str,
+        required=True,
+        help="Path to the local tokenizer",
+    )
+    return parser.parse_args()
+
+
+def launch_workers(args) -> tuple[List[subprocess.Popen], List[str]]:
+    """Launch all worker processes concurrently using subprocess."""
+    processes = []
+    worker_urls = []
+
+    # Launch each worker process
+    for i in range(args.dp):
+        port = args.port + i
+        url = f"http://{args.host}:{port}"
+        worker_urls.append(url)
+        # TODO: replace this with launch_server, and move this file to sglang/ because it depends on sglang
+        # We don't
+        command = f"export CUDA_VISIBLE_DEVICES={i}; python -m sglang.launch_server --model-path {args.model_path} --host {args.host} --port {port}"
+        print(command)
+        process = subprocess.Popen(command, shell=True)
+        processes.append(process)
+        _processes.append(process)  # Add to global list for cleanup
+
+    return processes, worker_urls
+
+
+def wait_for_healthy_workers(worker_urls: List[str], timeout: int = 300) -> bool:
+    """Block until all workers are healthy or timeout is reached."""
+    start_time = time.time()
+    healthy_workers: Dict[str, bool] = {url: False for url in worker_urls}
+
+    while time.time() - start_time < timeout:
+        print("checking healthiness...")
+        all_healthy = True
+
+        for url in worker_urls:
+            if not healthy_workers[url]:  # Only check workers that aren't healthy yet
+                try:
+                    response = requests.get(f"{url}/health")
+                    if response.status_code == 200:
+                        print(f"Worker at {url} is healthy")
+                        healthy_workers[url] = True
+                    else:
+                        all_healthy = False
+                except requests.RequestException:
+                    all_healthy = False
+
+        if all_healthy:
+            print("All workers are healthy!")
+            return True
+
+        time.sleep(5)
+
+    # If we get here, we've timed out
+    unhealthy_workers = [url for url, healthy in healthy_workers.items() if not healthy]
+    print(f"Timeout waiting for workers: {unhealthy_workers}")
+    return False
+
+
+def main():
+    """Main function to launch the router and workers."""
+    args = parse_args()
+    processes = None
+
+    try:
+        # Launch all workers concurrently
+        processes, worker_urls = launch_workers(args)
+
+        # Block until all workers are healthy
+        if not wait_for_healthy_workers(worker_urls):
+            raise RuntimeError("Failed to start all workers")
+
+        # Initialize and start the router
+        router = Router(
+            worker_urls=worker_urls,
+            policy=PolicyType.ApproxTree,
+            tokenizer_path=args.local_tokenizer_path,
+        )
+
+        print("Starting router...")
+        router.start()
+
+        # Keep the main process running
+        try:
+            while True:
+                time.sleep(1)
+        except KeyboardInterrupt:
+            print("\nShutting down...")
+
+    except Exception as e:
+        print(f"Error: {e}")
+    finally:
+        # Cleanup: Kill all worker processes
+        if processes:
+            for process in processes:
+                process.kill()
+
+
+if __name__ == "__main__":
+    main()

rust/py_src/main.py

+from sglang_router import PolicyType, Router
+
+router = Router(
+    worker_urls=[
+        "http://localhost:30000",
+        "http://localhost:30001",
+    ],
+    policy=PolicyType.ApproxTree,
+    tokenizer_path="/shared/public/elr-models/meta-llama/Meta-Llama-3.1-8B-Instruct/07eb05b21d191a58c577b4a45982fe0c049d0693/tokenizer.json",
+)
+
+router.start()

rust/readme.md

@@ -2,6 +2,11 @@
 
 SGLang router is a standalone module implemented in Rust to achieve data parallelism across SGLang instances.
 
+## Architecture
+
+1. `src/`: rust impl of the router
+2. `py_src/`: lightweight python interafce on top of rust python binding. This will be published as `sglang-router` pypi package
+
 ## Installation
 
 WIP. Ideally just
@@ -83,6 +88,23 @@ $ maturin develop
 🛠 Installed sglang_router-0.0.0
 ```
 
+4. Alternatively, if you don't want to create a venv, you can also build the binding as a wheel and install it
+
+```bash
+$ maturin build --interpreter python
+...
+   Compiling pyo3 v0.22.6
+   Compiling pyo3-macros v0.22.6
+   Compiling sglang_router v0.0.0 (/home/jobuser/sglang/rust)
+    Finished `dev` profile [unoptimized + debuginfo] target(s) in 9.67s
+🖨  Copied external shared libraries to package sglang_router.libs directory:
+    /usr/lib/libssl.so.1.1.1k
+    /usr/lib/libcrypto.so.1.1.1k
+📦 Built wheel for CPython 3.10 to <wheel path>
+
+$ pip install <wheel path>
+```
+
 ## Usage
 
 1. Launch worker instances

sglang @ 760552e0

+Subproject commit 760552e068edb58d9cd6e68aa1b714c247027d92

rust/src/lib.rs

+// Python Binding
 use pyo3::prelude::*;
 pub mod router;
 mod server;
 pub mod tree;
 
-// Python binding
+#[pyclass(eq)]
+#[derive(Clone, PartialEq)]
+pub enum PolicyType {
+    Random,
+    RoundRobin,
+    ApproxTree,
+}
+
 #[pyclass]
 struct Router {
     host: String,
     port: u16,
     worker_urls: Vec<String>,
-    policy: String,
+    policy: PolicyType,
+    tokenizer_path: Option<String>,
+    cache_threshold: Option<f32>,
 }
 
 #[pymethods]
 impl Router {
     #[new]
-    fn new(host: String, port: u16, worker_urls: Vec<String>, policy: String) -> Self {
-        Router {
+    #[pyo3(signature = (
+        worker_urls,
+        policy = PolicyType::RoundRobin,
+        host = String::from("127.0.0.1"),
+        port = 3001,
+        tokenizer_path = None,
+        cache_threshold = Some(0.50)
+    ))]
+    fn new(
+        worker_urls: Vec<String>,
+        policy: PolicyType,
+        host: String,
+        port: u16,
+        tokenizer_path: Option<String>,
+        cache_threshold: Option<f32>,
+    ) -> PyResult<Self> {
+        // Validate required parameters for approx_tree policy
+        if matches!(policy, PolicyType::ApproxTree) {
+            if tokenizer_path.is_none() {
+                return Err(PyErr::new::<pyo3::exceptions::PyValueError, _>(
+                    "tokenizer_path is required for approx_tree policy",
+                ));
+            }
+        }
+
+        Ok(Router {
             host,
             port,
             worker_urls,
             policy,
-        }
+            tokenizer_path,
+            cache_threshold,
+        })
     }
 
     fn start(&self) -> PyResult<()> {
         let host = self.host.clone();
         let port = self.port;
         let worker_urls = self.worker_urls.clone();
-        let policy = self.policy.clone();
+
+        let policy_config = match &self.policy {
+            PolicyType::Random => router::PolicyConfig::RandomConfig,
+            PolicyType::RoundRobin => router::PolicyConfig::RoundRobinConfig,
+            PolicyType::ApproxTree => router::PolicyConfig::ApproxTreeConfig {
+                tokenizer_path: self
+                    .tokenizer_path
+                    .clone()
+                    .expect("tokenizer_path is required for approx_tree policy"),
+                cache_threshold: self
+                    .cache_threshold
+                    .expect("cache_threshold is required for approx_tree policy"),
+            },
+        };
 
         actix_web::rt::System::new().block_on(async move {
-            server::startup(host, port, worker_urls, policy)
+            server::startup(host, port, worker_urls, policy_config)
                 .await
                 .unwrap();
         });
@@ -40,9 +89,9 @@ impl Router {
     }
 }
 
-// python usage: `from sglang_router import Router`
 #[pymodule]
 fn sglang_router(m: &Bound<'_, PyModule>) -> PyResult<()> {
+    m.add_class::<PolicyType>()?;
     m.add_class::<Router>()?;
     Ok(())
 }

rust/src/main.rs

 // src/main.rs
-use clap::builder::PossibleValuesParser;
 use clap::Parser;
+use clap::ValueEnum;
 // declare child modules
 mod router;
 mod server;
 mod tree;
 
+use crate::router::PolicyConfig;
+
+#[derive(Debug, Clone, ValueEnum)]
+pub enum PolicyType {
+    Random,
+    RoundRobin,
+    ApproxTree,
+}
+
 #[derive(Parser, Debug)]
 #[command(author, version, about, long_about = None)]
 struct Args {
-    #[arg(long, default_value = "127.0.0.1")]
+    #[arg(
+        long,
+        default_value = "127.0.0.1",
+        help = "Host address to bind the server to"
+    )]
     host: String,
 
-    #[arg(long, default_value_t = 3001)]
+    #[arg(long, default_value_t = 3001, help = "Port number to listen on")]
     port: u16,
 
-    #[arg(long, value_delimiter = ',')]
+    #[arg(
+        long,
+        value_delimiter = ',',
+        help = "Comma-separated list of worker URLs to distribute requests to"
+    )]
     worker_urls: Vec<String>,
 
-    #[arg(long, default_value = "round_robin", value_parser = PossibleValuesParser::new(&["round_robin", "random"]))]
-    policy: String,
+    #[arg(
+        long,
+        default_value_t = PolicyType::RoundRobin,
+        value_enum,
+        help = "Load balancing policy to use: random, round_robin, or approx_tree"
+    )]
+    policy: PolicyType,
+
+    #[arg(
+        long,
+        requires = "policy",
+        required_if_eq("policy", "approx_tree"),
+        help = "Path to the tokenizer file, required when using approx_tree policy"
+    )]
+    tokenizer_path: Option<String>,
+
+    #[arg(
+        long,
+        default_value = "0.50",
+        requires = "policy",
+        required_if_eq("policy", "approx_tree"),
+        help = "Cache threshold (0.0-1.0) for approx_tree routing. Routes to cached worker if match rate exceeds threshold, otherwise routes to shortest queue worker"
+    )]
+    cache_threshold: Option<f32>,
+}
+
+impl Args {
+    fn get_policy_config(&self) -> PolicyConfig {
+        match self.policy {
+            PolicyType::Random => PolicyConfig::RandomConfig,
+            PolicyType::RoundRobin => PolicyConfig::RoundRobinConfig,
+            PolicyType::ApproxTree => PolicyConfig::ApproxTreeConfig {
+                tokenizer_path: self
+                    .tokenizer_path
+                    .clone()
+                    .expect("tokenizer_path is required for approx_tree policy"),
+                cache_threshold: self
+                    .cache_threshold
+                    .expect("cache_threshold is required for approx_tree policy"),
+            },
+        }
+    }
 }
 
 #[actix_web::main]
 async fn main() -> std::io::Result<()> {
     let args = Args::parse();
-    server::startup(args.host, args.port, args.worker_urls, args.policy).await
+    let policy_config = args.get_policy_config();
+    server::startup(args.host, args.port, args.worker_urls, policy_config).await
 }

rust/src/router.rs

+use crate::tree::RadixTree;
 use actix_web::http::header::{HeaderValue, CONTENT_TYPE};
 use actix_web::{HttpRequest, HttpResponse};
 use bytes::Bytes;
 use futures_util::TryStreamExt;
+use std::collections::HashMap;
 use std::fmt::Debug;
+use std::sync::atomic::AtomicUsize;
+use std::sync::{Arc, Mutex};
+use tokenizers::tokenizer::Tokenizer;
 
 #[derive(Debug)]
 pub enum Router {
     RoundRobin {
         worker_urls: Vec<String>,
-        current_index: std::sync::atomic::AtomicUsize,
+        current_index: AtomicUsize,
     },
     Random {
         worker_urls: Vec<String>,
     },
+    ApproxTree {
+        worker_urls: Vec<String>,
+        // TODO: don't lock the whole tree
+        url_to_tree: Arc<Mutex<HashMap<String, RadixTree>>>,
+        tokenizer: Tokenizer,
+        url_to_count: Arc<Mutex<HashMap<String, usize>>>,
+        cache_threshold: f32,
+    },
+}
+
+pub enum PolicyConfig {
+    RandomConfig,
+    RoundRobinConfig,
+    ApproxTreeConfig {
+        tokenizer_path: String,
+        cache_threshold: f32,
+    },
+}
+
+fn get_token_ids_from_request(body: &Bytes, tokenizer: &Tokenizer) -> Vec<u32> {
+    // 1. convert body to json
+    let json = serde_json::from_slice::<serde_json::Value>(body).unwrap();
+    // 2. get the text field
+    let text = json.get("text").and_then(|t| t.as_str()).unwrap_or("");
+    // 3. tokenize the text field
+    let tokens = tokenizer.encode(text, false).unwrap();
+
+    tokens.get_ids().to_vec()
 }
 
 impl Router {
-    pub fn new(worker_urls: Vec<String>, policy: String) -> Self {
-        match policy.to_lowercase().as_str() {
-            "random" => Router::Random { worker_urls },
-            "round_robin" => Router::RoundRobin {
+    pub fn new(worker_urls: Vec<String>, policy_config: PolicyConfig) -> Self {
+        match policy_config {
+            PolicyConfig::RandomConfig => Router::Random { worker_urls },
+            PolicyConfig::RoundRobinConfig => Router::RoundRobin {
                 worker_urls,
                 current_index: std::sync::atomic::AtomicUsize::new(0),
             },
-            _ => panic!(
-                "Unknown routing policy: {}. The available policies are 'random' and 'round_robin'",
-                policy
-            ),
+            PolicyConfig::ApproxTreeConfig {
+                tokenizer_path,
+                cache_threshold,
+            } => {
+                let mut url_to_tree = HashMap::new();
+                let mut url_to_count = HashMap::new();
+
+                for url in &worker_urls {
+                    url_to_tree.insert(url.clone(), RadixTree::new());
+                    url_to_count.insert(url.clone(), 0);
+                }
+
+                Router::ApproxTree {
+                    worker_urls,
+                    url_to_tree: Arc::new(Mutex::new(url_to_tree)),
+                    // TODO: rust ::from_pretrained cannot load from local file, so use ::from_file to load local file
+                    tokenizer: Tokenizer::from_file(tokenizer_path).unwrap(),
+                    url_to_count: Arc::new(Mutex::new(url_to_count)),
+                    cache_threshold,
+                }
+            }
         }
     }
 
     pub fn get_first(&self) -> Option<String> {
         match self {
-            Router::RoundRobin { worker_urls, .. } | Router::Random { worker_urls } => {
+            Router::RoundRobin { worker_urls, .. }
+            | Router::Random { worker_urls }
+            | Router::ApproxTree { worker_urls, .. } => {
                 if worker_urls.is_empty() {
                     None
                 } else {
@@ -48,26 +100,96 @@ impl Router {
         req: HttpRequest,
         body: Bytes,
     ) -> HttpResponse {
+        let mut input_ids: Vec<u32> = Vec::new();
+        if let Router::ApproxTree { tokenizer, .. } = self {
+            input_ids = get_token_ids_from_request(&body, tokenizer);
+        }
+
         let worker_url = match self {
             Router::RoundRobin {
                 worker_urls,
                 current_index,
             } => {
-                current_index
+                let idx = current_index
                     .fetch_update(
                         std::sync::atomic::Ordering::SeqCst,
                         std::sync::atomic::Ordering::SeqCst,
                         |x| Some((x + 1) % worker_urls.len()),
                     )
-                    .expect_err("Error updating index in round robin");
+                    .unwrap();
 
-                &worker_urls[current_index.load(std::sync::atomic::Ordering::SeqCst)]
+                worker_urls[idx].clone()
             }
+
             Router::Random { worker_urls } => {
-                &worker_urls[rand::random::<usize>() % worker_urls.len()]
+                worker_urls[rand::random::<usize>() % worker_urls.len()].clone()
+            }
+
+            Router::ApproxTree {
+                worker_urls,
+                url_to_tree,
+                url_to_count,
+                cache_threshold,
+                ..
+            } => {
+                // TODO: pipeline the locks. Release one earlier.
+
+                let mut max_matched_rate = 0.0;
+                let mut max_matched_idx = 0;
+
+                let locked_url_to_tree = url_to_tree.lock().unwrap();
+
+                // 1. Find the highest matched worker
+                for (i, url) in worker_urls.iter().enumerate() {
+                    let tree = locked_url_to_tree.get(url).unwrap();
+                    let matched = tree.prefix_match(&input_ids[..]).len();
+                    let matched_rate = matched as f32 / input_ids.len() as f32;
+
+                    if matched_rate > max_matched_rate {
+                        max_matched_rate = matched_rate;
+                        max_matched_idx = i;
+                    }
+                }
+
+                // 2. If the rate is higher than the threshold, select the worker. If not, select the worker with the shortest queue
+                if max_matched_rate > *cache_threshold {
+                    worker_urls[max_matched_idx].clone()
+                } else {
+                    // pick the shortest queue from url_to_count
+                    let locked_url_to_count = url_to_count.lock().unwrap();
+
+                    let mut min_count = std::usize::MAX;
+                    let mut min_count_id = 0;
+
+                    for (i, url) in worker_urls.iter().enumerate() {
+                        let count = locked_url_to_count.get(url).unwrap();
+                        if *count < min_count {
+                            min_count = *count;
+                            min_count_id = i;
+                        }
+                    }
+
+                    worker_urls[min_count_id].clone()
+                }
             }
         };
 
+        if let Router::ApproxTree {
+            url_to_tree,
+            url_to_count,
+            ..
+        } = self
+        {
+            // Insert input_ids to the tree
+            let mut locked_url_to_tree = url_to_tree.lock().unwrap();
+            let selected_tree = locked_url_to_tree.get_mut(&worker_url).unwrap();
+            selected_tree.insert(&input_ids[..]);
+
+            let mut locked_url_to_count = url_to_count.lock().unwrap();
+            let count = locked_url_to_count.get_mut(&worker_url).unwrap();
+            *count += 1;
+        }
+
         // Check if client requested streaming
         let is_stream = serde_json::from_slice::<serde_json::Value>(&body)
             .map(|v| v.get("stream").and_then(|s| s.as_bool()).unwrap_or(false))
@@ -94,11 +216,19 @@ impl Router {
             .unwrap_or(actix_web::http::StatusCode::INTERNAL_SERVER_ERROR);
 
         if !is_stream {
+            // TODO: do the correction on the tree based on the cached input_ids
+            if let Router::ApproxTree { url_to_count, .. } = self {
+                let mut locked_url_to_count = url_to_count.lock().unwrap();
+                let count = locked_url_to_count.get_mut(&worker_url).unwrap();
+                *count -= 1;
+            }
+
             match res.bytes().await {
                 Ok(body) => HttpResponse::build(status).body(body.to_vec()),
                 Err(_) => HttpResponse::InternalServerError().finish(),
             }
         } else {
+            // TODO: do the correction on the tree based on the cached input_ids. The streaming might be tricker to handle
             HttpResponse::build(status)
                 .insert_header((CONTENT_TYPE, HeaderValue::from_static("text/event-stream")))
                 .streaming(res.bytes_stream().map_err(|_| {

rust/src/server.rs

+use crate::router::PolicyConfig;
 use crate::router::Router;
 use actix_web::{get, post, web, App, HttpRequest, HttpResponse, HttpServer, Responder};
 use bytes::Bytes;
@@ -9,9 +10,13 @@ pub struct AppState {
 }
 
 impl AppState {
-    pub fn new(worker_urls: Vec<String>, policy: String, client: reqwest::Client) -> Self {
+    pub fn new(
+        worker_urls: Vec<String>,
+        client: reqwest::Client,
+        policy_config: PolicyConfig,
+    ) -> Self {
         // Create router based on policy
-        let router = Router::new(worker_urls, policy);
+        let router = Router::new(worker_urls, policy_config);
 
         Self { router, client }
     }
@@ -40,7 +45,6 @@ async fn forward_request(
 
 #[get("/v1/models")]
 async fn v1_model(data: web::Data<AppState>) -> impl Responder {
-    // TODO: extract forward_to_route
     let worker_url = match data.router.get_first() {
         Some(url) => url,
         None => return HttpResponse::InternalServerError().finish(),
@@ -59,7 +63,6 @@ async fn get_model_info(data: web::Data<AppState>) -> impl Responder {
     forward_request(&data.client, worker_url, "/get_model_info".to_string()).await
 }
 
-// no deser and ser, just forward and return
 #[post("/generate")]
 async fn generate(req: HttpRequest, body: Bytes, data: web::Data<AppState>) -> impl Responder {
     data.router.dispatch(&data.client, req, body).await
@@ -69,7 +72,7 @@ pub async fn startup(
     host: String,
     port: u16,
     worker_urls: Vec<String>,
-    routing_policy: String,
+    policy_config: PolicyConfig,
 ) -> std::io::Result<()> {
     println!("Starting server on {}:{}", host, port);
     println!("Worker URLs: {:?}", worker_urls);
@@ -80,7 +83,7 @@ pub async fn startup(
         .expect("Failed to create HTTP client");
 
     // Store both worker_urls and client in AppState
-    let app_state = web::Data::new(AppState::new(worker_urls, routing_policy, client));
+    let app_state = web::Data::new(AppState::new(worker_urls, client, policy_config));
 
     HttpServer::new(move || {
         App::new()

rust/src/tree.rs

 use std::collections::HashMap;
 use std::mem;
 
-#[derive(Clone)]
+#[derive(Debug)]
 pub struct Node {
-    pub children: HashMap<usize, Node>, // the key is first id of the child because each child must have unique first id
-    pub ids: Vec<usize>,
-    pub count: usize,
+    pub children: HashMap<u32, Node>, // the key is first id of the child because each child must have unique first id
+    pub ids: Vec<u32>,
+    pub count: u32,
 }
 
+#[derive(Debug)]
 pub struct RadixTree {
     pub root: Node,
 }
 
-fn common_prefix_len(a: &[usize], b: &[usize]) -> usize {
+fn common_prefix_len(a: &[u32], b: &[u32]) -> usize {
     let mut i = 0;
     while i < a.len() && i < b.len() && a[i] == b[i] {
         i += 1;
@@ -37,7 +38,7 @@ impl RadixTree {
         }
     }
 
-    pub fn insert(&mut self, input_ids: &[usize]) {
+    pub fn insert(&mut self, input_ids: &[u32]) {
         let mut curr = &mut self.root;
         curr.count += 1;
 
@@ -93,7 +94,7 @@ impl RadixTree {
         }
     }
 
-    pub fn prefix_match<'a>(&self, input_ids: &'a [usize]) -> &'a [usize] {
+    pub fn prefix_match<'a>(&self, input_ids: &'a [u32]) -> &'a [u32] {
         let mut curr = &self.root;
 
         let mut curr_idx = 0;
@@ -121,7 +122,7 @@ impl RadixTree {
         &input_ids[..curr_idx]
     }
 
-    pub fn delete(&mut self, input_ids: &[usize]) {
+    pub fn delete(&mut self, input_ids: &[u32]) {
         let mut curr = &mut self.root;
         curr.count -= 1;
 

rust/tests/test_tree.rs

@@ -67,7 +67,7 @@ fn test_prefix_match_partial() {
 fn test_prefix_match_no_match() {
     let mut tree = RadixTree::new();
     tree.insert(&[1, 2, 3, 4]);
-    let empty_slices: &[usize] = &[];
+    let empty_slices: &[u32] = &[];
     assert_eq!(tree.prefix_match(&[5, 6, 7]), empty_slices);
 }
 
@@ -124,7 +124,7 @@ fn test_delete_nonexistent() {
 #[test]
 fn test_empty_input() {
     let mut tree = RadixTree::new();
-    let empty_slice: &[usize] = &[];
+    let empty_slice: &[u32] = &[];
     tree.insert(empty_slice);
     assert_eq!(tree.prefix_match(empty_slice), empty_slice);
     tree.delete(empty_slice); // Should not panic