1use anyhow::{anyhow, Context, Result};
2use collections::HashMap;
3use futures::{channel::oneshot, select, FutureExt, StreamExt};
4use gpui::{AppContext as _, AsyncApp, BackgroundExecutor, Task};
5use parking_lot::Mutex;
6use postage::barrier;
7use serde::{de::DeserializeOwned, Deserialize, Serialize};
8use serde_json::{value::RawValue, Value};
9use smol::channel;
10use std::{
11 fmt,
12 path::PathBuf,
13 sync::{
14 atomic::{AtomicI32, Ordering::SeqCst},
15 Arc,
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 move |cx| {
175 Self::handle_input(transport, notification_handlers, response_handlers, cx)
176 .log_err()
177 }
178 });
179 let stderr_input_task = cx.spawn(|_| Self::handle_stderr(transport.clone()).log_err());
180 let input_task = cx.spawn(|_| async move {
181 let (stdout, stderr) = futures::join!(stdout_input_task, stderr_input_task);
182 stdout.or(stderr)
183 });
184
185 let output_task = cx.background_spawn({
186 let transport = transport.clone();
187 Self::handle_output(
188 transport,
189 outbound_rx,
190 output_done_tx,
191 response_handlers.clone(),
192 )
193 .log_err()
194 });
195
196 Ok(Self {
197 server_id,
198 notification_handlers,
199 response_handlers,
200 name: server_name.into(),
201 next_id: Default::default(),
202 outbound_tx,
203 executor: cx.background_executor().clone(),
204 io_tasks: Mutex::new(Some((input_task, output_task))),
205 output_done_rx: Mutex::new(Some(output_done_rx)),
206 transport,
207 })
208 }
209
210 /// Handles input from the server's stdout.
211 ///
212 /// This function continuously reads lines from the provided stdout stream,
213 /// parses them as JSON-RPC responses or notifications, and dispatches them
214 /// to the appropriate handlers. It processes both responses (which are matched
215 /// to pending requests) and notifications (which trigger registered handlers).
216 async fn handle_input(
217 transport: Arc<dyn Transport>,
218 notification_handlers: Arc<Mutex<HashMap<&'static str, NotificationHandler>>>,
219 response_handlers: Arc<Mutex<Option<HashMap<RequestId, ResponseHandler>>>>,
220 cx: AsyncApp,
221 ) -> anyhow::Result<()> {
222 let mut receiver = transport.receive();
223
224 while let Some(message) = receiver.next().await {
225 if let Ok(response) = serde_json::from_str::<AnyResponse>(&message) {
226 if let Some(handlers) = response_handlers.lock().as_mut() {
227 if let Some(handler) = handlers.remove(&response.id) {
228 handler(Ok(message.to_string()));
229 }
230 }
231 } else if let Ok(notification) = serde_json::from_str::<AnyNotification>(&message) {
232 let mut notification_handlers = notification_handlers.lock();
233 if let Some(handler) = notification_handlers.get_mut(notification.method.as_str()) {
234 handler(notification.params.unwrap_or(Value::Null), cx.clone());
235 }
236 }
237 }
238
239 smol::future::yield_now().await;
240
241 Ok(())
242 }
243
244 /// Handles the stderr output from the context server.
245 /// Continuously reads and logs any error messages from the server.
246 async fn handle_stderr(transport: Arc<dyn Transport>) -> anyhow::Result<()> {
247 while let Some(err) = transport.receive_err().next().await {
248 log::warn!("context server stderr: {}", err.trim());
249 }
250
251 Ok(())
252 }
253
254 /// Handles the output to the context server's stdin.
255 /// This function continuously receives messages from the outbound channel,
256 /// writes them to the server's stdin, and manages the lifecycle of response handlers.
257 async fn handle_output(
258 transport: Arc<dyn Transport>,
259 outbound_rx: channel::Receiver<String>,
260 output_done_tx: barrier::Sender,
261 response_handlers: Arc<Mutex<Option<HashMap<RequestId, ResponseHandler>>>>,
262 ) -> anyhow::Result<()> {
263 let _clear_response_handlers = util::defer({
264 let response_handlers = response_handlers.clone();
265 move || {
266 response_handlers.lock().take();
267 }
268 });
269 while let Ok(message) = outbound_rx.recv().await {
270 log::trace!("outgoing message: {}", message);
271 transport.send(message).await?;
272 }
273 drop(output_done_tx);
274 Ok(())
275 }
276
277 /// Sends a JSON-RPC request to the context server and waits for a response.
278 /// This function handles serialization, deserialization, timeout, and error handling.
279 pub async fn request<T: DeserializeOwned>(
280 &self,
281 method: &str,
282 params: impl Serialize,
283 ) -> Result<T> {
284 let id = self.next_id.fetch_add(1, SeqCst);
285 let request = serde_json::to_string(&Request {
286 jsonrpc: JSON_RPC_VERSION,
287 id: RequestId::Int(id),
288 method,
289 params,
290 })
291 .unwrap();
292
293 let (tx, rx) = oneshot::channel();
294 let handle_response = self
295 .response_handlers
296 .lock()
297 .as_mut()
298 .ok_or_else(|| anyhow!("server shut down"))
299 .map(|handlers| {
300 handlers.insert(
301 RequestId::Int(id),
302 Box::new(move |result| {
303 let _ = tx.send(result);
304 }),
305 );
306 });
307
308 let send = self
309 .outbound_tx
310 .try_send(request)
311 .context("failed to write to context server's stdin");
312
313 let executor = self.executor.clone();
314 let started = Instant::now();
315 handle_response?;
316 send?;
317
318 let mut timeout = executor.timer(REQUEST_TIMEOUT).fuse();
319 select! {
320 response = rx.fuse() => {
321 let elapsed = started.elapsed();
322 log::trace!("took {elapsed:?} to receive response to {method:?} id {id}");
323 match response? {
324 Ok(response) => {
325 let parsed: AnyResponse = serde_json::from_str(&response)?;
326 if let Some(error) = parsed.error {
327 Err(anyhow!(error.message))
328 } else if let Some(result) = parsed.result {
329 Ok(serde_json::from_str(result.get())?)
330 } else {
331 Err(anyhow!("Invalid response: no result or error"))
332 }
333 }
334 Err(_) => anyhow::bail!("cancelled")
335 }
336 }
337 _ = timeout => {
338 log::error!("cancelled csp request task for {method:?} id {id} which took over {:?}", REQUEST_TIMEOUT);
339 anyhow::bail!("Context server request timeout");
340 }
341 }
342 }
343
344 /// Sends a notification to the context server without expecting a response.
345 /// This function serializes the notification and sends it through the outbound channel.
346 pub fn notify(&self, method: &str, params: impl Serialize) -> Result<()> {
347 let notification = serde_json::to_string(&Notification {
348 jsonrpc: JSON_RPC_VERSION,
349 method,
350 params,
351 })
352 .unwrap();
353 self.outbound_tx.try_send(notification)?;
354 Ok(())
355 }
356
357 pub fn on_notification<F>(&self, method: &'static str, f: F)
358 where
359 F: 'static + Send + FnMut(Value, AsyncApp),
360 {
361 self.notification_handlers
362 .lock()
363 .insert(method, Box::new(f));
364 }
365
366 pub fn name(&self) -> &str {
367 &self.name
368 }
369
370 pub fn server_id(&self) -> ContextServerId {
371 self.server_id.clone()
372 }
373}
374
375impl fmt::Display for ContextServerId {
376 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
377 self.0.fmt(f)
378 }
379}
380
381impl fmt::Debug for Client {
382 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
383 f.debug_struct("Context Server Client")
384 .field("id", &self.server_id.0)
385 .field("name", &self.name)
386 .finish_non_exhaustive()
387 }
388}