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feat: Add resilient MPSC queues to proxy stubs to fix thread leaks and message loss on reconnect

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Riz Ashraf committed 2026-09-09 04:32:07 +01:00
1 parent 51fc3692c8
commit 05e84e98bd
2 files changed
+107 -136
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server/src/proxy.rs
+51 -55
View File
@@ -3,73 +3,66 @@ use tokio::io::AsyncBufReadExt;
use futures_util::StreamExt;
use std::sync::Arc;
use tokio::sync::RwLock;
use tokio::sync::mpsc;
pub fn run_proxy(target_url: &str) -> Result<bool, Box<dyn std::error::Error + Send + Sync>> {
let rt = tokio::runtime::Runtime::new().unwrap();
rt.block_on(async {
let client = reqwest::Client::builder().build().unwrap();
let sse_url = format!("{}/sse", target_url);
let (msg_tx, mut msg_rx) = mpsc::channel::<String>(100);
let (shutdown_tx, mut shutdown_rx) = mpsc::channel::<()>(1);
eprintln!("[PROXY] Connecting to Streamable HTTP: {}", sse_url);
let resp = match client.get(&sse_url)
.header("Accept", "text/event-stream")
.send().await {
Ok(r) => r,
Err(e) => {
eprintln!("[PROXY] Connection failed: {}", e);
return Ok(true);
}
};
if resp.status() == reqwest::StatusCode::GONE {
eprintln!("[PROXY] Streamable HTTP endpoint is gone.");
return Ok(true);
}
let post_url = Arc::new(RwLock::new(format!("{}/messages", target_url))); // Will be updated by endpoint event
let post_url_clone = Arc::clone(&post_url);
let (tx, mut rx) = tokio::sync::mpsc::channel(1);
let tx_clone = tx.clone();
let client_clone = client.clone();
tokio::task::spawn_blocking(move || {
let stdin = std::io::stdin();
let mut handle = stdin.lock();
let mut buffer = String::new();
while let Ok(bytes) = std::io::BufRead::read_line(&mut handle, &mut buffer) {
if bytes == 0 { break; }
let body = buffer.clone();
let _ = msg_tx.blocking_send(buffer.clone());
buffer.clear();
let client = client_clone.clone();
let url_arc = Arc::clone(&post_url_clone);
tokio::spawn(async move {
let mut url = "".to_string();
for _ in 0..50 {
let u = url_arc.read().await.clone();
if u.contains("sessionId") {
url = u;
break;
}
tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;
}
if url.is_empty() {
url = url_arc.read().await.clone();
}
let _ = client.post(&url)
.header("Accept", "application/json, text/event-stream")
.header("Content-Type", "application/json")
.body(body)
.send().await;
});
}
let _ = tx_clone.blocking_send(false); // Stdin EOF
let _ = shutdown_tx.blocking_send(());
});
let target_url = target_url.to_string();
let tx_clone2 = tx.clone();
let post_url = Arc::new(RwLock::new(String::new()));
let post_url_clone = Arc::clone(&post_url);
let client = reqwest::Client::builder().build().unwrap();
tokio::spawn(async move {
while let Some(msg) = msg_rx.recv().await {
loop {
let url = post_url_clone.read().await.clone();
if !url.is_empty() {
let res = client.post(&url)
.header("Accept", "application/json, text/event-stream")
.header("Content-Type", "application/json")
.body(msg.clone())
.send().await;
if res.is_ok() {
break;
}
}
tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;
}
}
});
loop {
if shutdown_rx.try_recv().is_ok() {
return Ok(false);
}
let sse_url = format!("{}/sse", target_url);
let client = reqwest::Client::builder().build().unwrap();
match client.get(&sse_url).header("Accept", "text/event-stream").send().await {
Ok(resp) => {
if resp.status() == reqwest::StatusCode::GONE {
return Ok(true);
}
let stream = resp.bytes_stream().map(|res| res.map_err(|e| std::io::Error::new(std::io::ErrorKind::Other, e)));
let mut reader = tokio::io::BufReader::new(StreamReader::new(stream));
let mut line = String::new();
@@ -98,10 +91,13 @@ pub fn run_proxy(target_url: &str) -> Result<bool, Box<dyn std::error::Error + S
}
line.clear();
}
let _ = tx_clone2.send(true).await; // Stream dropped (Leader dead)
});
let dropped = rx.recv().await.unwrap_or(true);
Ok(dropped)
*post_url.write().await = String::new();
return Ok(true);
}
Err(_) => {
return Ok(true);
}
}
}
})
}
stub/src/main.rs
+56 -81
View File
@@ -4,6 +4,7 @@ use std::sync::Arc;
use tokio::io::AsyncBufReadExt;
use tokio::sync::RwLock;
use tokio_util::io::StreamReader;
use tokio::sync::mpsc;
#[derive(Parser)]
#[command(name = "mcp-memory-stub")]
@@ -14,85 +15,81 @@ struct Cli {
wake_cmd: Option<String>,
}
fn run_proxy(target_url: &str) -> Result<bool, Box<dyn std::error::Error>> {
fn main() -> Result<(), Box<dyn std::error::Error>> {
let cli = Cli::parse();
let rt = tokio::runtime::Runtime::new()?;
rt.block_on(async {
let client = reqwest::Client::builder().build()?;
let sse_url = format!("{}/sse", target_url);
let (msg_tx, mut msg_rx) = mpsc::channel::<String>(100);
let (shutdown_tx, mut shutdown_rx) = mpsc::channel::<()>(1);
eprintln!("[PROXY] Connecting to Streamable HTTP: {}", sse_url);
let resp = match client.get(&sse_url)
.header("Accept", "text/event-stream")
.send().await {
Ok(r) => r,
Err(e) => {
eprintln!("[PROXY] Connection failed: {}", e);
return Ok(true);
}
};
if resp.status() == reqwest::StatusCode::GONE {
eprintln!("[PROXY] Streamable HTTP endpoint is gone.");
return Ok(true);
}
let post_url = Arc::new(RwLock::new(format!("{}/messages", target_url))); // Will be updated by endpoint event
let post_url_clone = Arc::clone(&post_url);
let (tx, mut rx) = tokio::sync::mpsc::channel(1);
let tx_clone = tx.clone();
let client_clone = client.clone();
tokio::task::spawn_blocking(move || {
let stdin = std::io::stdin();
let mut handle = stdin.lock();
let mut buffer = String::new();
while let Ok(bytes) = std::io::BufRead::read_line(&mut handle, &mut buffer) {
if bytes == 0 { break; }
let body = buffer.clone();
let _ = msg_tx.blocking_send(buffer.clone());
buffer.clear();
eprintln!("[PROXY] Stdin read: {}", body.trim());
let client = client_clone.clone();
let url_arc = Arc::clone(&post_url_clone);
}
let _ = shutdown_tx.blocking_send(());
});
let target_url = cli.target;
let post_url = Arc::new(RwLock::new(String::new()));
let post_url_clone = Arc::clone(&post_url);
let client = reqwest::Client::builder().build()?;
tokio::spawn(async move {
let mut url = "".to_string();
for _ in 0..50 {
let u = url_arc.read().await.clone();
if u.contains("sessionId") {
url = u;
break;
}
tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;
}
if url.is_empty() {
url = url_arc.read().await.clone();
}
eprintln!("[PROXY] POSTing to {}", url);
while let Some(msg) = msg_rx.recv().await {
let mut attempts = 0;
loop {
let url = post_url_clone.read().await.clone();
if !url.is_empty() {
let res = client.post(&url)
.header("Accept", "application/json, text/event-stream")
.header("Content-Type", "application/json")
.body(body)
.body(msg.clone())
.send().await;
eprintln!("[PROXY] POST response: {:?}", res.map(|r| r.status()));
});
if res.is_ok() {
break;
}
}
tokio::time::sleep(tokio::time::Duration::from_millis(500)).await;
attempts += 1;
if attempts % 10 == 0 {
eprintln!("[PROXY] Waiting for server to accept messages...");
}
}
}
eprintln!("[PROXY] Stdin closed");
let _ = tx_clone.blocking_send(false);
});
let target_url = target_url.to_string();
let tx_clone2 = tx.clone();
tokio::spawn(async move {
let wake_cmd = cli.wake_cmd;
loop {
if shutdown_rx.try_recv().is_ok() {
break;
}
let sse_url = format!("{}/sse", target_url);
let client = reqwest::Client::builder().build()?;
match client.get(&sse_url).header("Accept", "text/event-stream").send().await {
Ok(resp) => {
if resp.status() == reqwest::StatusCode::GONE {
eprintln!("[PROXY] Target gone, exiting.");
break;
}
let stream = resp.bytes_stream().map(|res| res.map_err(|e| std::io::Error::new(std::io::ErrorKind::Other, e)));
let mut reader = tokio::io::BufReader::new(StreamReader::new(stream));
let mut line = String::new();
let mut is_message = false;
let mut is_endpoint = false;
while let Ok(bytes) = reader.read_line(&mut line).await {
if bytes == 0 { break; }
let trimmed = line.trim();
eprintln!("[PROXY] Stream read: {}", trimmed);
if trimmed.starts_with("event: message") {
is_message = true;
is_endpoint = false;
@@ -107,29 +104,16 @@ fn run_proxy(target_url: &str) -> Result<bool, Box<dyn std::error::Error>> {
let ep = &trimmed[6..];
let mut p = post_url.write().await;
*p = format!("{}{}", target_url, ep);
eprintln!("[PROXY] Endpoint updated: {}", *p);
is_endpoint = false;
}
}
line.clear();
}
eprintln!("[PROXY] Stream closed");
let _ = tx_clone2.send(true).await;
});
let dropped = rx.recv().await.unwrap_or(true);
Ok(dropped)
})
*post_url.write().await = String::new();
tokio::time::sleep(tokio::time::Duration::from_millis(500)).await;
}
fn main() {
let cli = Cli::parse();
loop {
if let Err(_) = std::net::TcpStream::connect(cli.target.replace("http://", "").replace("https://", "")) {
eprintln!("[PROXY] Target {} offline, sleeping", cli.target);
if let Some(ref cmd) = cli.wake_cmd {
eprintln!("[PROXY] Executing wake command...");
Err(_) => {
if let Some(ref cmd) = wake_cmd {
let parts: Vec<&str> = cmd.split_whitespace().collect();
if !parts.is_empty() {
let _ = std::process::Command::new(parts[0])
@@ -137,19 +121,10 @@ fn main() {
.spawn();
}
}
std::thread::sleep(std::time::Duration::from_secs(1));
}
match run_proxy(&cli.target) {
Ok(true) => {
std::thread::sleep(std::time::Duration::from_millis(50));
}
Ok(false) => {
break;
}
Err(_) => {
std::thread::sleep(std::time::Duration::from_millis(1000));
tokio::time::sleep(tokio::time::Duration::from_secs(1)).await;
}
}
}
Ok(())
})
}