1use anyhow::{Context, 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 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 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 new(
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
162 let (outbound_tx, outbound_rx) = channel::unbounded::<String>();
163 let (output_done_tx, output_done_rx) = barrier::channel();
164
165 let notification_handlers =
166 Arc::new(Mutex::new(HashMap::<_, NotificationHandler>::default()));
167 let response_handlers =
168 Arc::new(Mutex::new(Some(HashMap::<_, ResponseHandler>::default())));
169
170 let stdout_input_task = cx.spawn({
171 let notification_handlers = notification_handlers.clone();
172 let response_handlers = response_handlers.clone();
173 let transport = transport.clone();
174 async move |cx| {
175 Self::handle_input(transport, notification_handlers, response_handlers, cx)
176 .log_err()
177 .await
178 }
179 });
180 let stderr_input_task = cx.spawn({
181 let transport = transport.clone();
182 async move |_| Self::handle_stderr(transport).log_err().await
183 });
184 let input_task = cx.spawn(async move |_| {
185 let (stdout, stderr) = futures::join!(stdout_input_task, stderr_input_task);
186 stdout.or(stderr)
187 });
188
189 let output_task = cx.background_spawn({
190 let transport = transport.clone();
191 Self::handle_output(
192 transport,
193 outbound_rx,
194 output_done_tx,
195 response_handlers.clone(),
196 )
197 .log_err()
198 });
199
200 Ok(Self {
201 server_id,
202 notification_handlers,
203 response_handlers,
204 name: server_name.into(),
205 next_id: Default::default(),
206 outbound_tx,
207 executor: cx.background_executor().clone(),
208 io_tasks: Mutex::new(Some((input_task, output_task))),
209 output_done_rx: Mutex::new(Some(output_done_rx)),
210 transport,
211 })
212 }
213
214 /// Handles input from the server's stdout.
215 ///
216 /// This function continuously reads lines from the provided stdout stream,
217 /// parses them as JSON-RPC responses or notifications, and dispatches them
218 /// to the appropriate handlers. It processes both responses (which are matched
219 /// to pending requests) and notifications (which trigger registered handlers).
220 async fn handle_input(
221 transport: Arc<dyn Transport>,
222 notification_handlers: Arc<Mutex<HashMap<&'static str, NotificationHandler>>>,
223 response_handlers: Arc<Mutex<Option<HashMap<RequestId, ResponseHandler>>>>,
224 cx: &mut AsyncApp,
225 ) -> anyhow::Result<()> {
226 let mut receiver = transport.receive();
227
228 while let Some(message) = receiver.next().await {
229 if let Ok(response) = serde_json::from_str::<AnyResponse>(&message) {
230 if let Some(handlers) = response_handlers.lock().as_mut() {
231 if let Some(handler) = handlers.remove(&response.id) {
232 handler(Ok(message.to_string()));
233 }
234 }
235 } else if let Ok(notification) = serde_json::from_str::<AnyNotification>(&message) {
236 let mut notification_handlers = notification_handlers.lock();
237 if let Some(handler) = notification_handlers.get_mut(notification.method.as_str()) {
238 handler(notification.params.unwrap_or(Value::Null), cx.clone());
239 }
240 }
241 }
242
243 smol::future::yield_now().await;
244
245 Ok(())
246 }
247
248 /// Handles the stderr output from the context server.
249 /// Continuously reads and logs any error messages from the server.
250 async fn handle_stderr(transport: Arc<dyn Transport>) -> anyhow::Result<()> {
251 while let Some(err) = transport.receive_err().next().await {
252 log::warn!("context server stderr: {}", err.trim());
253 }
254
255 Ok(())
256 }
257
258 /// Handles the output to the context server's stdin.
259 /// This function continuously receives messages from the outbound channel,
260 /// writes them to the server's stdin, and manages the lifecycle of response handlers.
261 async fn handle_output(
262 transport: Arc<dyn Transport>,
263 outbound_rx: channel::Receiver<String>,
264 output_done_tx: barrier::Sender,
265 response_handlers: Arc<Mutex<Option<HashMap<RequestId, ResponseHandler>>>>,
266 ) -> anyhow::Result<()> {
267 let _clear_response_handlers = util::defer({
268 let response_handlers = response_handlers.clone();
269 move || {
270 response_handlers.lock().take();
271 }
272 });
273 while let Ok(message) = outbound_rx.recv().await {
274 log::trace!("outgoing message: {}", message);
275 transport.send(message).await?;
276 }
277 drop(output_done_tx);
278 Ok(())
279 }
280
281 /// Sends a JSON-RPC request to the context server and waits for a response.
282 /// This function handles serialization, deserialization, timeout, and error handling.
283 pub async fn request<T: DeserializeOwned>(
284 &self,
285 method: &str,
286 params: impl Serialize,
287 ) -> Result<T> {
288 let id = self.next_id.fetch_add(1, SeqCst);
289 let request = serde_json::to_string(&Request {
290 jsonrpc: JSON_RPC_VERSION,
291 id: RequestId::Int(id),
292 method,
293 params,
294 })
295 .unwrap();
296
297 let (tx, rx) = oneshot::channel();
298 let handle_response = self
299 .response_handlers
300 .lock()
301 .as_mut()
302 .ok_or_else(|| anyhow!("server shut down"))
303 .map(|handlers| {
304 handlers.insert(
305 RequestId::Int(id),
306 Box::new(move |result| {
307 let _ = tx.send(result);
308 }),
309 );
310 });
311
312 let send = self
313 .outbound_tx
314 .try_send(request)
315 .context("failed to write to context server's stdin");
316
317 let executor = self.executor.clone();
318 let started = Instant::now();
319 handle_response?;
320 send?;
321
322 let mut timeout = executor.timer(REQUEST_TIMEOUT).fuse();
323 select! {
324 response = rx.fuse() => {
325 let elapsed = started.elapsed();
326 log::trace!("took {elapsed:?} to receive response to {method:?} id {id}");
327 match response? {
328 Ok(response) => {
329 let parsed: AnyResponse = serde_json::from_str(&response)?;
330 if let Some(error) = parsed.error {
331 Err(anyhow!(error.message))
332 } else if let Some(result) = parsed.result {
333 Ok(serde_json::from_str(result.get())?)
334 } else {
335 Err(anyhow!("Invalid response: no result or error"))
336 }
337 }
338 Err(_) => anyhow::bail!("cancelled")
339 }
340 }
341 _ = timeout => {
342 log::error!("cancelled csp request task for {method:?} id {id} which took over {:?}", REQUEST_TIMEOUT);
343 anyhow::bail!("Context server request timeout");
344 }
345 }
346 }
347
348 /// Sends a notification to the context server without expecting a response.
349 /// This function serializes the notification and sends it through the outbound channel.
350 pub fn notify(&self, method: &str, params: impl Serialize) -> Result<()> {
351 let notification = serde_json::to_string(&Notification {
352 jsonrpc: JSON_RPC_VERSION,
353 method,
354 params,
355 })
356 .unwrap();
357 self.outbound_tx.try_send(notification)?;
358 Ok(())
359 }
360
361 pub fn on_notification<F>(&self, method: &'static str, f: F)
362 where
363 F: 'static + Send + FnMut(Value, AsyncApp),
364 {
365 self.notification_handlers
366 .lock()
367 .insert(method, Box::new(f));
368 }
369
370 pub fn name(&self) -> &str {
371 &self.name
372 }
373
374 pub fn server_id(&self) -> ContextServerId {
375 self.server_id.clone()
376 }
377}
378
379impl fmt::Display for ContextServerId {
380 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
381 self.0.fmt(f)
382 }
383}
384
385impl fmt::Debug for Client {
386 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
387 f.debug_struct("Context Server Client")
388 .field("id", &self.server_id.0)
389 .field("name", &self.name)
390 .finish_non_exhaustive()
391 }
392}