1use anyhow::{Context as _, Result, anyhow};
2use collections::HashMap;
3use futures::{FutureExt, StreamExt, channel::oneshot, select};
4use gpui::{AppContext as _, AsyncApp, BackgroundExecutor, Task};
5use parking_lot::Mutex;
6use postage::barrier;
7use serde::{Deserialize, Serialize, de::DeserializeOwned};
8use serde_json::{Value, value::RawValue};
9use smol::channel;
10use std::{
11 fmt,
12 path::PathBuf,
13 sync::{
14 Arc,
15 atomic::{AtomicI32, Ordering::SeqCst},
16 },
17 time::{Duration, Instant},
18};
19use util::TryFutureExt;
20
21use crate::transport::{StdioTransport, Transport};
22
23const JSON_RPC_VERSION: &str = "2.0";
24const REQUEST_TIMEOUT: Duration = Duration::from_secs(60);
25
26// Standard JSON-RPC error codes
27pub const PARSE_ERROR: i32 = -32700;
28pub const INVALID_REQUEST: i32 = -32600;
29pub const METHOD_NOT_FOUND: i32 = -32601;
30pub const INVALID_PARAMS: i32 = -32602;
31pub const INTERNAL_ERROR: i32 = -32603;
32
33type ResponseHandler = Box<dyn Send + FnOnce(Result<String, Error>)>;
34type NotificationHandler = Box<dyn Send + FnMut(Value, AsyncApp)>;
35
36#[derive(Debug, Clone, Eq, PartialEq, Hash, Serialize, Deserialize)]
37#[serde(untagged)]
38pub enum RequestId {
39 Int(i32),
40 Str(String),
41}
42
43pub(crate) struct Client {
44 server_id: ContextServerId,
45 next_id: AtomicI32,
46 outbound_tx: channel::Sender<String>,
47 name: Arc<str>,
48 notification_handlers: Arc<Mutex<HashMap<&'static str, NotificationHandler>>>,
49 response_handlers: Arc<Mutex<Option<HashMap<RequestId, ResponseHandler>>>>,
50 #[allow(clippy::type_complexity)]
51 #[allow(dead_code)]
52 io_tasks: Mutex<Option<(Task<Option<()>>, Task<Option<()>>)>>,
53 #[allow(dead_code)]
54 output_done_rx: Mutex<Option<barrier::Receiver>>,
55 executor: BackgroundExecutor,
56 #[allow(dead_code)]
57 transport: Arc<dyn Transport>,
58}
59
60#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
61#[repr(transparent)]
62pub(crate) struct ContextServerId(pub Arc<str>);
63
64fn is_null_value<T: Serialize>(value: &T) -> bool {
65 if let Ok(Value::Null) = serde_json::to_value(value) {
66 true
67 } else {
68 false
69 }
70}
71
72#[derive(Serialize, Deserialize)]
73struct Request<'a, T> {
74 jsonrpc: &'static str,
75 id: RequestId,
76 method: &'a str,
77 #[serde(skip_serializing_if = "is_null_value")]
78 params: T,
79}
80
81#[derive(Serialize, Deserialize)]
82struct AnyResponse<'a> {
83 jsonrpc: &'a str,
84 id: RequestId,
85 #[serde(default)]
86 error: Option<Error>,
87 #[serde(borrow)]
88 result: Option<&'a RawValue>,
89}
90
91#[derive(Deserialize)]
92#[allow(dead_code)]
93struct Response<T> {
94 jsonrpc: &'static str,
95 id: RequestId,
96 #[serde(flatten)]
97 value: CspResult<T>,
98}
99
100#[derive(Deserialize)]
101#[serde(rename_all = "snake_case")]
102enum CspResult<T> {
103 #[serde(rename = "result")]
104 Ok(Option<T>),
105 #[allow(dead_code)]
106 Error(Option<Error>),
107}
108
109#[derive(Serialize, Deserialize)]
110struct Notification<'a, T> {
111 jsonrpc: &'static str,
112 #[serde(borrow)]
113 method: &'a str,
114 params: T,
115}
116
117#[derive(Debug, Clone, Deserialize)]
118struct AnyNotification<'a> {
119 jsonrpc: &'a str,
120 method: String,
121 #[serde(default)]
122 params: Option<Value>,
123}
124
125#[derive(Debug, Serialize, Deserialize)]
126struct Error {
127 message: String,
128}
129
130#[derive(Debug, Clone, Deserialize)]
131pub struct ModelContextServerBinary {
132 pub executable: PathBuf,
133 pub args: Vec<String>,
134 pub env: Option<HashMap<String, String>>,
135}
136
137impl Client {
138 /// Creates a new Client instance for a context server.
139 ///
140 /// This function initializes a new Client by spawning a child process for the context server,
141 /// setting up communication channels, and initializing handlers for input/output operations.
142 /// It takes a server ID, binary information, and an async app context as input.
143 pub fn stdio(
144 server_id: ContextServerId,
145 binary: ModelContextServerBinary,
146 cx: AsyncApp,
147 ) -> Result<Self> {
148 log::info!(
149 "starting context server (executable={:?}, args={:?})",
150 binary.executable,
151 &binary.args
152 );
153
154 let server_name = binary
155 .executable
156 .file_name()
157 .map(|name| name.to_string_lossy().to_string())
158 .unwrap_or_else(String::new);
159
160 let transport = Arc::new(StdioTransport::new(binary, &cx)?);
161 Self::new(server_id, server_name.into(), transport, cx)
162 }
163
164 /// Creates a new Client instance for a context server.
165 pub fn new(
166 server_id: ContextServerId,
167 server_name: Arc<str>,
168 transport: Arc<dyn Transport>,
169 cx: AsyncApp,
170 ) -> Result<Self> {
171 let (outbound_tx, outbound_rx) = channel::unbounded::<String>();
172 let (output_done_tx, output_done_rx) = barrier::channel();
173
174 let notification_handlers =
175 Arc::new(Mutex::new(HashMap::<_, NotificationHandler>::default()));
176 let response_handlers =
177 Arc::new(Mutex::new(Some(HashMap::<_, ResponseHandler>::default())));
178
179 let receive_input_task = cx.spawn({
180 let notification_handlers = notification_handlers.clone();
181 let response_handlers = response_handlers.clone();
182 let transport = transport.clone();
183 async move |cx| {
184 Self::handle_input(transport, notification_handlers, response_handlers, cx)
185 .log_err()
186 .await
187 }
188 });
189 let receive_err_task = cx.spawn({
190 let transport = transport.clone();
191 async move |_| Self::handle_err(transport).log_err().await
192 });
193 let input_task = cx.spawn(async move |_| {
194 let (input, err) = futures::join!(receive_input_task, receive_err_task);
195 input.or(err)
196 });
197
198 let output_task = cx.background_spawn({
199 let transport = transport.clone();
200 Self::handle_output(
201 transport,
202 outbound_rx,
203 output_done_tx,
204 response_handlers.clone(),
205 )
206 .log_err()
207 });
208
209 Ok(Self {
210 server_id,
211 notification_handlers,
212 response_handlers,
213 name: server_name,
214 next_id: Default::default(),
215 outbound_tx,
216 executor: cx.background_executor().clone(),
217 io_tasks: Mutex::new(Some((input_task, output_task))),
218 output_done_rx: Mutex::new(Some(output_done_rx)),
219 transport,
220 })
221 }
222
223 /// Handles input from the server's stdout.
224 ///
225 /// This function continuously reads lines from the provided stdout stream,
226 /// parses them as JSON-RPC responses or notifications, and dispatches them
227 /// to the appropriate handlers. It processes both responses (which are matched
228 /// to pending requests) and notifications (which trigger registered handlers).
229 async fn handle_input(
230 transport: Arc<dyn Transport>,
231 notification_handlers: Arc<Mutex<HashMap<&'static str, NotificationHandler>>>,
232 response_handlers: Arc<Mutex<Option<HashMap<RequestId, ResponseHandler>>>>,
233 cx: &mut AsyncApp,
234 ) -> anyhow::Result<()> {
235 let mut receiver = transport.receive();
236
237 while let Some(message) = receiver.next().await {
238 if let Ok(response) = serde_json::from_str::<AnyResponse>(&message) {
239 if let Some(handlers) = response_handlers.lock().as_mut() {
240 if let Some(handler) = handlers.remove(&response.id) {
241 handler(Ok(message.to_string()));
242 }
243 }
244 } else if let Ok(notification) = serde_json::from_str::<AnyNotification>(&message) {
245 let mut notification_handlers = notification_handlers.lock();
246 if let Some(handler) = notification_handlers.get_mut(notification.method.as_str()) {
247 handler(notification.params.unwrap_or(Value::Null), cx.clone());
248 }
249 }
250 }
251
252 smol::future::yield_now().await;
253
254 Ok(())
255 }
256
257 /// Handles the stderr output from the context server.
258 /// Continuously reads and logs any error messages from the server.
259 async fn handle_err(transport: Arc<dyn Transport>) -> anyhow::Result<()> {
260 while let Some(err) = transport.receive_err().next().await {
261 log::warn!("context server stderr: {}", err.trim());
262 }
263
264 Ok(())
265 }
266
267 /// Handles the output to the context server's stdin.
268 /// This function continuously receives messages from the outbound channel,
269 /// writes them to the server's stdin, and manages the lifecycle of response handlers.
270 async fn handle_output(
271 transport: Arc<dyn Transport>,
272 outbound_rx: channel::Receiver<String>,
273 output_done_tx: barrier::Sender,
274 response_handlers: Arc<Mutex<Option<HashMap<RequestId, ResponseHandler>>>>,
275 ) -> anyhow::Result<()> {
276 let _clear_response_handlers = util::defer({
277 let response_handlers = response_handlers.clone();
278 move || {
279 response_handlers.lock().take();
280 }
281 });
282 while let Ok(message) = outbound_rx.recv().await {
283 log::trace!("outgoing message: {}", message);
284 transport.send(message).await?;
285 }
286 drop(output_done_tx);
287 Ok(())
288 }
289
290 /// Sends a JSON-RPC request to the context server and waits for a response.
291 /// This function handles serialization, deserialization, timeout, and error handling.
292 pub async fn request<T: DeserializeOwned>(
293 &self,
294 method: &str,
295 params: impl Serialize,
296 ) -> Result<T> {
297 let id = self.next_id.fetch_add(1, SeqCst);
298 let request = serde_json::to_string(&Request {
299 jsonrpc: JSON_RPC_VERSION,
300 id: RequestId::Int(id),
301 method,
302 params,
303 })
304 .unwrap();
305
306 let (tx, rx) = oneshot::channel();
307 let handle_response = self
308 .response_handlers
309 .lock()
310 .as_mut()
311 .context("server shut down")
312 .map(|handlers| {
313 handlers.insert(
314 RequestId::Int(id),
315 Box::new(move |result| {
316 let _ = tx.send(result);
317 }),
318 );
319 });
320
321 let send = self
322 .outbound_tx
323 .try_send(request)
324 .context("failed to write to context server's stdin");
325
326 let executor = self.executor.clone();
327 let started = Instant::now();
328 handle_response?;
329 send?;
330
331 let mut timeout = executor.timer(REQUEST_TIMEOUT).fuse();
332 select! {
333 response = rx.fuse() => {
334 let elapsed = started.elapsed();
335 log::trace!("took {elapsed:?} to receive response to {method:?} id {id}");
336 match response? {
337 Ok(response) => {
338 let parsed: AnyResponse = serde_json::from_str(&response)?;
339 if let Some(error) = parsed.error {
340 Err(anyhow!(error.message))
341 } else if let Some(result) = parsed.result {
342 Ok(serde_json::from_str(result.get())?)
343 } else {
344 anyhow::bail!("Invalid response: no result or error");
345 }
346 }
347 Err(_) => anyhow::bail!("cancelled")
348 }
349 }
350 _ = timeout => {
351 log::error!("cancelled csp request task for {method:?} id {id} which took over {:?}", REQUEST_TIMEOUT);
352 anyhow::bail!("Context server request timeout");
353 }
354 }
355 }
356
357 /// Sends a notification to the context server without expecting a response.
358 /// This function serializes the notification and sends it through the outbound channel.
359 pub fn notify(&self, method: &str, params: impl Serialize) -> Result<()> {
360 let notification = serde_json::to_string(&Notification {
361 jsonrpc: JSON_RPC_VERSION,
362 method,
363 params,
364 })
365 .unwrap();
366 self.outbound_tx.try_send(notification)?;
367 Ok(())
368 }
369
370 #[allow(unused)]
371 pub fn on_notification<F>(&self, method: &'static str, f: F)
372 where
373 F: 'static + Send + FnMut(Value, AsyncApp),
374 {
375 self.notification_handlers
376 .lock()
377 .insert(method, Box::new(f));
378 }
379}
380
381impl fmt::Display for ContextServerId {
382 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
383 self.0.fmt(f)
384 }
385}
386
387impl fmt::Debug for Client {
388 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
389 f.debug_struct("Context Server Client")
390 .field("id", &self.server_id.0)
391 .field("name", &self.name)
392 .finish_non_exhaustive()
393 }
394}