1use anyhow::{Context as _, Result, anyhow};
2use collections::HashMap;
3use futures::{FutureExt, StreamExt, channel::oneshot, future, 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 pin::pin,
14 sync::{
15 Arc,
16 atomic::{AtomicI32, Ordering::SeqCst},
17 },
18 time::{Duration, Instant},
19};
20use util::{ResultExt, TryFutureExt};
21
22use crate::{
23 transport::{StdioTransport, Transport},
24 types::{CancelledParams, ClientNotification, Notification as _, notifications::Cancelled},
25};
26
27const JSON_RPC_VERSION: &str = "2.0";
28const REQUEST_TIMEOUT: Duration = Duration::from_secs(60);
29
30// Standard JSON-RPC error codes
31pub const PARSE_ERROR: i32 = -32700;
32pub const INVALID_REQUEST: i32 = -32600;
33pub const METHOD_NOT_FOUND: i32 = -32601;
34pub const INVALID_PARAMS: i32 = -32602;
35pub const INTERNAL_ERROR: i32 = -32603;
36
37type ResponseHandler = Box<dyn Send + FnOnce(Result<String, Error>)>;
38type NotificationHandler = Box<dyn Send + FnMut(Value, AsyncApp)>;
39type RequestHandler = Box<dyn Send + FnMut(RequestId, &RawValue, AsyncApp)>;
40
41#[derive(Debug, Clone, Eq, PartialEq, Hash, Serialize, Deserialize)]
42#[serde(untagged)]
43pub enum RequestId {
44 Int(i32),
45 Str(String),
46}
47
48pub(crate) struct Client {
49 server_id: ContextServerId,
50 next_id: AtomicI32,
51 outbound_tx: channel::Sender<String>,
52 name: Arc<str>,
53 notification_handlers: Arc<Mutex<HashMap<&'static str, NotificationHandler>>>,
54 request_handlers: Arc<Mutex<HashMap<&'static str, RequestHandler>>>,
55 response_handlers: Arc<Mutex<Option<HashMap<RequestId, ResponseHandler>>>>,
56 #[allow(clippy::type_complexity)]
57 #[allow(dead_code)]
58 io_tasks: Mutex<Option<(Task<Option<()>>, Task<Option<()>>)>>,
59 #[allow(dead_code)]
60 output_done_rx: Mutex<Option<barrier::Receiver>>,
61 executor: BackgroundExecutor,
62 #[allow(dead_code)]
63 transport: Arc<dyn Transport>,
64}
65
66#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
67#[repr(transparent)]
68pub(crate) struct ContextServerId(pub Arc<str>);
69
70fn is_null_value<T: Serialize>(value: &T) -> bool {
71 if let Ok(Value::Null) = serde_json::to_value(value) {
72 true
73 } else {
74 false
75 }
76}
77
78#[derive(Serialize, Deserialize)]
79pub struct Request<'a, T> {
80 pub jsonrpc: &'static str,
81 pub id: RequestId,
82 pub method: &'a str,
83 #[serde(skip_serializing_if = "is_null_value")]
84 pub params: T,
85}
86
87#[derive(Serialize, Deserialize)]
88pub struct AnyRequest<'a> {
89 pub jsonrpc: &'a str,
90 pub id: RequestId,
91 pub method: &'a str,
92 #[serde(skip_serializing_if = "is_null_value")]
93 pub params: Option<&'a RawValue>,
94}
95
96#[derive(Serialize, Deserialize)]
97struct AnyResponse<'a> {
98 jsonrpc: &'a str,
99 id: RequestId,
100 #[serde(default)]
101 error: Option<Error>,
102 #[serde(borrow)]
103 result: Option<&'a RawValue>,
104}
105
106#[derive(Serialize, Deserialize)]
107#[allow(dead_code)]
108pub(crate) struct Response<T> {
109 pub jsonrpc: &'static str,
110 pub id: RequestId,
111 #[serde(flatten)]
112 pub value: CspResult<T>,
113}
114
115#[derive(Serialize, Deserialize)]
116#[serde(rename_all = "snake_case")]
117pub(crate) enum CspResult<T> {
118 #[serde(rename = "result")]
119 Ok(Option<T>),
120 #[allow(dead_code)]
121 Error(Option<Error>),
122}
123
124#[derive(Serialize, Deserialize)]
125struct Notification<'a, T> {
126 jsonrpc: &'static str,
127 #[serde(borrow)]
128 method: &'a str,
129 params: T,
130}
131
132#[derive(Debug, Clone, Deserialize)]
133struct AnyNotification<'a> {
134 jsonrpc: &'a str,
135 method: String,
136 #[serde(default)]
137 params: Option<Value>,
138}
139
140#[derive(Debug, Serialize, Deserialize)]
141pub(crate) struct Error {
142 pub message: String,
143 pub code: i32,
144}
145
146#[derive(Debug, Clone, Deserialize)]
147pub struct ModelContextServerBinary {
148 pub executable: PathBuf,
149 pub args: Vec<String>,
150 pub env: Option<HashMap<String, String>>,
151}
152
153impl Client {
154 /// Creates a new Client instance for a context server.
155 ///
156 /// This function initializes a new Client by spawning a child process for the context server,
157 /// setting up communication channels, and initializing handlers for input/output operations.
158 /// It takes a server ID, binary information, and an async app context as input.
159 pub fn stdio(
160 server_id: ContextServerId,
161 binary: ModelContextServerBinary,
162 cx: AsyncApp,
163 ) -> Result<Self> {
164 log::info!(
165 "starting context server (executable={:?}, args={:?})",
166 binary.executable,
167 &binary.args
168 );
169
170 let server_name = binary
171 .executable
172 .file_name()
173 .map(|name| name.to_string_lossy().to_string())
174 .unwrap_or_else(String::new);
175
176 let transport = Arc::new(StdioTransport::new(binary, &cx)?);
177 Self::new(server_id, server_name.into(), transport, cx)
178 }
179
180 /// Creates a new Client instance for a context server.
181 pub fn new(
182 server_id: ContextServerId,
183 server_name: Arc<str>,
184 transport: Arc<dyn Transport>,
185 cx: AsyncApp,
186 ) -> Result<Self> {
187 let (outbound_tx, outbound_rx) = channel::unbounded::<String>();
188 let (output_done_tx, output_done_rx) = barrier::channel();
189
190 let notification_handlers =
191 Arc::new(Mutex::new(HashMap::<_, NotificationHandler>::default()));
192 let response_handlers =
193 Arc::new(Mutex::new(Some(HashMap::<_, ResponseHandler>::default())));
194 let request_handlers = Arc::new(Mutex::new(HashMap::<_, RequestHandler>::default()));
195
196 let receive_input_task = cx.spawn({
197 let notification_handlers = notification_handlers.clone();
198 let response_handlers = response_handlers.clone();
199 let request_handlers = request_handlers.clone();
200 let transport = transport.clone();
201 async move |cx| {
202 Self::handle_input(
203 transport,
204 notification_handlers,
205 request_handlers,
206 response_handlers,
207 cx,
208 )
209 .log_err()
210 .await
211 }
212 });
213 let receive_err_task = cx.spawn({
214 let transport = transport.clone();
215 async move |_| Self::handle_err(transport).log_err().await
216 });
217 let input_task = cx.spawn(async move |_| {
218 let (input, err) = futures::join!(receive_input_task, receive_err_task);
219 input.or(err)
220 });
221
222 let output_task = cx.background_spawn({
223 let transport = transport.clone();
224 Self::handle_output(
225 transport,
226 outbound_rx,
227 output_done_tx,
228 response_handlers.clone(),
229 )
230 .log_err()
231 });
232
233 Ok(Self {
234 server_id,
235 notification_handlers,
236 response_handlers,
237 request_handlers,
238 name: server_name,
239 next_id: Default::default(),
240 outbound_tx,
241 executor: cx.background_executor().clone(),
242 io_tasks: Mutex::new(Some((input_task, output_task))),
243 output_done_rx: Mutex::new(Some(output_done_rx)),
244 transport,
245 })
246 }
247
248 /// Handles input from the server's stdout.
249 ///
250 /// This function continuously reads lines from the provided stdout stream,
251 /// parses them as JSON-RPC responses or notifications, and dispatches them
252 /// to the appropriate handlers. It processes both responses (which are matched
253 /// to pending requests) and notifications (which trigger registered handlers).
254 async fn handle_input(
255 transport: Arc<dyn Transport>,
256 notification_handlers: Arc<Mutex<HashMap<&'static str, NotificationHandler>>>,
257 request_handlers: Arc<Mutex<HashMap<&'static str, RequestHandler>>>,
258 response_handlers: Arc<Mutex<Option<HashMap<RequestId, ResponseHandler>>>>,
259 cx: &mut AsyncApp,
260 ) -> anyhow::Result<()> {
261 let mut receiver = transport.receive();
262
263 while let Some(message) = receiver.next().await {
264 log::trace!("recv: {}", &message);
265 if let Ok(request) = serde_json::from_str::<AnyRequest>(&message) {
266 let mut request_handlers = request_handlers.lock();
267 if let Some(handler) = request_handlers.get_mut(request.method) {
268 handler(
269 request.id,
270 request.params.unwrap_or(RawValue::NULL),
271 cx.clone(),
272 );
273 }
274 } else if let Ok(response) = serde_json::from_str::<AnyResponse>(&message) {
275 if let Some(handlers) = response_handlers.lock().as_mut() {
276 if let Some(handler) = handlers.remove(&response.id) {
277 handler(Ok(message.to_string()));
278 }
279 }
280 } else if let Ok(notification) = serde_json::from_str::<AnyNotification>(&message) {
281 let mut notification_handlers = notification_handlers.lock();
282 if let Some(handler) = notification_handlers.get_mut(notification.method.as_str()) {
283 handler(notification.params.unwrap_or(Value::Null), cx.clone());
284 }
285 } else {
286 log::error!("Unhandled JSON from context_server: {}", message);
287 }
288 }
289
290 smol::future::yield_now().await;
291
292 Ok(())
293 }
294
295 /// Handles the stderr output from the context server.
296 /// Continuously reads and logs any error messages from the server.
297 async fn handle_err(transport: Arc<dyn Transport>) -> anyhow::Result<()> {
298 while let Some(err) = transport.receive_err().next().await {
299 log::warn!("context server stderr: {}", err.trim());
300 }
301
302 Ok(())
303 }
304
305 /// Handles the output to the context server's stdin.
306 /// This function continuously receives messages from the outbound channel,
307 /// writes them to the server's stdin, and manages the lifecycle of response handlers.
308 async fn handle_output(
309 transport: Arc<dyn Transport>,
310 outbound_rx: channel::Receiver<String>,
311 output_done_tx: barrier::Sender,
312 response_handlers: Arc<Mutex<Option<HashMap<RequestId, ResponseHandler>>>>,
313 ) -> anyhow::Result<()> {
314 let _clear_response_handlers = util::defer({
315 let response_handlers = response_handlers.clone();
316 move || {
317 response_handlers.lock().take();
318 }
319 });
320 while let Ok(message) = outbound_rx.recv().await {
321 log::trace!("outgoing message: {}", message);
322 transport.send(message).await?;
323 }
324 drop(output_done_tx);
325 Ok(())
326 }
327
328 /// Sends a JSON-RPC request to the context server and waits for a response.
329 /// This function handles serialization, deserialization, timeout, and error handling.
330 pub async fn request<T: DeserializeOwned>(
331 &self,
332 method: &str,
333 params: impl Serialize,
334 ) -> Result<T> {
335 self.request_with(method, params, None, Some(REQUEST_TIMEOUT))
336 .await
337 }
338
339 pub async fn request_with<T: DeserializeOwned>(
340 &self,
341 method: &str,
342 params: impl Serialize,
343 cancel_rx: Option<oneshot::Receiver<()>>,
344 timeout: Option<Duration>,
345 ) -> Result<T> {
346 let id = self.next_id.fetch_add(1, SeqCst);
347 let request = serde_json::to_string(&Request {
348 jsonrpc: JSON_RPC_VERSION,
349 id: RequestId::Int(id),
350 method,
351 params,
352 })
353 .unwrap();
354
355 let (tx, rx) = oneshot::channel();
356 let handle_response = self
357 .response_handlers
358 .lock()
359 .as_mut()
360 .context("server shut down")
361 .map(|handlers| {
362 handlers.insert(
363 RequestId::Int(id),
364 Box::new(move |result| {
365 let _ = tx.send(result);
366 }),
367 );
368 });
369
370 let send = self
371 .outbound_tx
372 .try_send(request)
373 .context("failed to write to context server's stdin");
374
375 let executor = self.executor.clone();
376 let started = Instant::now();
377 handle_response?;
378 send?;
379
380 let mut timeout_fut = pin!(
381 if let Some(timeout) = timeout {
382 future::Either::Left(executor.timer(timeout))
383 } else {
384 future::Either::Right(future::pending())
385 }
386 .fuse()
387 );
388
389 let mut cancel_fut = pin!(
390 match cancel_rx {
391 Some(rx) => future::Either::Left(async {
392 rx.await.log_err();
393 }),
394 None => future::Either::Right(future::pending()),
395 }
396 .fuse()
397 );
398
399 select! {
400 response = rx.fuse() => {
401 let elapsed = started.elapsed();
402 log::trace!("took {elapsed:?} to receive response to {method:?} id {id}");
403 match response? {
404 Ok(response) => {
405 let parsed: AnyResponse = serde_json::from_str(&response)?;
406 if let Some(error) = parsed.error {
407 Err(anyhow!(error.message))
408 } else if let Some(result) = parsed.result {
409 Ok(serde_json::from_str(result.get())?)
410 } else {
411 anyhow::bail!("Invalid response: no result or error");
412 }
413 }
414 Err(_) => anyhow::bail!("cancelled")
415 }
416 }
417 _ = cancel_fut => {
418 self.notify(
419 Cancelled::METHOD,
420 ClientNotification::Cancelled(CancelledParams {
421 request_id: RequestId::Int(id),
422 reason: None
423 })
424 ).log_err();
425 anyhow::bail!("Request cancelled")
426 }
427 _ = timeout_fut => {
428 log::error!("cancelled csp request task for {method:?} id {id} which took over {:?}", timeout);
429 anyhow::bail!("Context server request timeout");
430 }
431 }
432 }
433
434 /// Sends a notification to the context server without expecting a response.
435 /// This function serializes the notification and sends it through the outbound channel.
436 pub fn notify(&self, method: &str, params: impl Serialize) -> Result<()> {
437 let notification = serde_json::to_string(&Notification {
438 jsonrpc: JSON_RPC_VERSION,
439 method,
440 params,
441 })
442 .unwrap();
443 self.outbound_tx.try_send(notification)?;
444 Ok(())
445 }
446
447 #[allow(unused)]
448 pub fn on_notification<F>(&self, method: &'static str, f: F)
449 where
450 F: 'static + Send + FnMut(Value, AsyncApp),
451 {
452 self.notification_handlers
453 .lock()
454 .insert(method, Box::new(f));
455 }
456
457 pub fn on_request<R: crate::types::Request, F>(&self, mut f: F)
458 where
459 F: 'static + Send + FnMut(R::Params, AsyncApp) -> Task<Result<R::Response>>,
460 {
461 let outbound_tx = self.outbound_tx.clone();
462 self.request_handlers.lock().insert(
463 R::METHOD,
464 Box::new(move |id, json, cx| {
465 let outbound_tx = outbound_tx.clone();
466 match serde_json::from_str(json.get()) {
467 Ok(req) => {
468 let task = f(req, cx.clone());
469 cx.foreground_executor()
470 .spawn(async move {
471 match task.await {
472 Ok(res) => {
473 outbound_tx
474 .send(
475 serde_json::to_string(&Response {
476 jsonrpc: JSON_RPC_VERSION,
477 id,
478 value: CspResult::Ok(Some(res)),
479 })
480 .unwrap(),
481 )
482 .await
483 .ok();
484 }
485 Err(e) => {
486 outbound_tx
487 .send(
488 serde_json::to_string(&Response {
489 jsonrpc: JSON_RPC_VERSION,
490 id,
491 value: CspResult::<()>::Error(Some(Error {
492 code: -1, // todo!()
493 message: format!("{e}"),
494 })),
495 })
496 .unwrap(),
497 )
498 .await
499 .ok();
500 }
501 }
502 })
503 .detach();
504 }
505 Err(e) => {
506 cx.foreground_executor()
507 .spawn(async move {
508 outbound_tx
509 .send(
510 serde_json::to_string(&Response {
511 jsonrpc: JSON_RPC_VERSION,
512 id,
513 value: CspResult::<()>::Error(Some(Error {
514 code: -1, // todo!()
515 message: format!("{e}"),
516 })),
517 })
518 .unwrap(),
519 )
520 .await
521 .ok();
522 })
523 .detach();
524 }
525 }
526 }),
527 );
528 }
529}
530
531impl fmt::Display for ContextServerId {
532 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
533 self.0.fmt(f)
534 }
535}
536
537impl fmt::Debug for Client {
538 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
539 f.debug_struct("Context Server Client")
540 .field("id", &self.server_id.0)
541 .field("name", &self.name)
542 .finish_non_exhaustive()
543 }
544}