1use std::sync::Arc;
2
3use anyhow::Result;
4use assistant_tool::ToolWorkingSet;
5use chrono::{DateTime, Utc};
6use collections::{BTreeMap, HashMap, HashSet};
7use futures::StreamExt as _;
8use gpui::{App, AppContext, Context, Entity, EventEmitter, SharedString, Task};
9use language_model::{
10 LanguageModel, LanguageModelCompletionEvent, LanguageModelRegistry, LanguageModelRequest,
11 LanguageModelRequestMessage, LanguageModelRequestTool, LanguageModelToolResult,
12 LanguageModelToolUseId, MaxMonthlySpendReachedError, MessageContent, PaymentRequiredError,
13 Role, StopReason,
14};
15use project::Project;
16use scripting_tool::{ScriptingSession, ScriptingTool};
17use serde::{Deserialize, Serialize};
18use util::{post_inc, TryFutureExt as _};
19use uuid::Uuid;
20
21use crate::context::{attach_context_to_message, ContextId, ContextSnapshot};
22use crate::thread_store::SavedThread;
23use crate::tool_use::{PendingToolUse, ToolUse, ToolUseState};
24
25#[derive(Debug, Clone, Copy)]
26pub enum RequestKind {
27 Chat,
28 /// Used when summarizing a thread.
29 Summarize,
30}
31
32#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Serialize, Deserialize)]
33pub struct ThreadId(Arc<str>);
34
35impl ThreadId {
36 pub fn new() -> Self {
37 Self(Uuid::new_v4().to_string().into())
38 }
39}
40
41impl std::fmt::Display for ThreadId {
42 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
43 write!(f, "{}", self.0)
44 }
45}
46
47#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy, Serialize, Deserialize)]
48pub struct MessageId(pub(crate) usize);
49
50impl MessageId {
51 fn post_inc(&mut self) -> Self {
52 Self(post_inc(&mut self.0))
53 }
54}
55
56/// A message in a [`Thread`].
57#[derive(Debug, Clone)]
58pub struct Message {
59 pub id: MessageId,
60 pub role: Role,
61 pub text: String,
62}
63
64/// A thread of conversation with the LLM.
65pub struct Thread {
66 id: ThreadId,
67 updated_at: DateTime<Utc>,
68 summary: Option<SharedString>,
69 pending_summary: Task<Option<()>>,
70 messages: Vec<Message>,
71 next_message_id: MessageId,
72 context: BTreeMap<ContextId, ContextSnapshot>,
73 context_by_message: HashMap<MessageId, Vec<ContextId>>,
74 completion_count: usize,
75 pending_completions: Vec<PendingCompletion>,
76 project: Entity<Project>,
77 tools: Arc<ToolWorkingSet>,
78 tool_use: ToolUseState,
79 scripting_session: Entity<ScriptingSession>,
80 scripting_tool_use: ToolUseState,
81}
82
83impl Thread {
84 pub fn new(
85 project: Entity<Project>,
86 tools: Arc<ToolWorkingSet>,
87 cx: &mut Context<Self>,
88 ) -> Self {
89 let scripting_session = cx.new(|cx| ScriptingSession::new(project.clone(), cx));
90
91 Self {
92 id: ThreadId::new(),
93 updated_at: Utc::now(),
94 summary: None,
95 pending_summary: Task::ready(None),
96 messages: Vec::new(),
97 next_message_id: MessageId(0),
98 context: BTreeMap::default(),
99 context_by_message: HashMap::default(),
100 completion_count: 0,
101 pending_completions: Vec::new(),
102 project,
103 tools,
104 tool_use: ToolUseState::new(),
105 scripting_session,
106 scripting_tool_use: ToolUseState::new(),
107 }
108 }
109
110 pub fn from_saved(
111 id: ThreadId,
112 saved: SavedThread,
113 project: Entity<Project>,
114 tools: Arc<ToolWorkingSet>,
115 cx: &mut Context<Self>,
116 ) -> Self {
117 let next_message_id = MessageId(
118 saved
119 .messages
120 .last()
121 .map(|message| message.id.0 + 1)
122 .unwrap_or(0),
123 );
124 let tool_use =
125 ToolUseState::from_saved_messages(&saved.messages, |name| name != ScriptingTool::NAME);
126 let scripting_tool_use =
127 ToolUseState::from_saved_messages(&saved.messages, |name| name == ScriptingTool::NAME);
128 let scripting_session = cx.new(|cx| ScriptingSession::new(project.clone(), cx));
129
130 Self {
131 id,
132 updated_at: saved.updated_at,
133 summary: Some(saved.summary),
134 pending_summary: Task::ready(None),
135 messages: saved
136 .messages
137 .into_iter()
138 .map(|message| Message {
139 id: message.id,
140 role: message.role,
141 text: message.text,
142 })
143 .collect(),
144 next_message_id,
145 context: BTreeMap::default(),
146 context_by_message: HashMap::default(),
147 completion_count: 0,
148 pending_completions: Vec::new(),
149 project,
150 tools,
151 tool_use,
152 scripting_session,
153 scripting_tool_use,
154 }
155 }
156
157 pub fn id(&self) -> &ThreadId {
158 &self.id
159 }
160
161 pub fn is_empty(&self) -> bool {
162 self.messages.is_empty()
163 }
164
165 pub fn updated_at(&self) -> DateTime<Utc> {
166 self.updated_at
167 }
168
169 pub fn touch_updated_at(&mut self) {
170 self.updated_at = Utc::now();
171 }
172
173 pub fn summary(&self) -> Option<SharedString> {
174 self.summary.clone()
175 }
176
177 pub fn summary_or_default(&self) -> SharedString {
178 const DEFAULT: SharedString = SharedString::new_static("New Thread");
179 self.summary.clone().unwrap_or(DEFAULT)
180 }
181
182 pub fn set_summary(&mut self, summary: impl Into<SharedString>, cx: &mut Context<Self>) {
183 self.summary = Some(summary.into());
184 cx.emit(ThreadEvent::SummaryChanged);
185 }
186
187 pub fn message(&self, id: MessageId) -> Option<&Message> {
188 self.messages.iter().find(|message| message.id == id)
189 }
190
191 pub fn messages(&self) -> impl Iterator<Item = &Message> {
192 self.messages.iter()
193 }
194
195 pub fn is_streaming(&self) -> bool {
196 !self.pending_completions.is_empty()
197 }
198
199 pub fn tools(&self) -> &Arc<ToolWorkingSet> {
200 &self.tools
201 }
202
203 pub fn context_for_message(&self, id: MessageId) -> Option<Vec<ContextSnapshot>> {
204 let context = self.context_by_message.get(&id)?;
205 Some(
206 context
207 .into_iter()
208 .filter_map(|context_id| self.context.get(&context_id))
209 .cloned()
210 .collect::<Vec<_>>(),
211 )
212 }
213
214 /// Returns whether all of the tool uses have finished running.
215 pub fn all_tools_finished(&self) -> bool {
216 let mut all_pending_tool_uses = self
217 .tool_use
218 .pending_tool_uses()
219 .into_iter()
220 .chain(self.scripting_tool_use.pending_tool_uses());
221
222 // If the only pending tool uses left are the ones with errors, then that means that we've finished running all
223 // of the pending tools.
224 all_pending_tool_uses.all(|tool_use| tool_use.status.is_error())
225 }
226
227 pub fn tool_uses_for_message(&self, id: MessageId) -> Vec<ToolUse> {
228 self.tool_use.tool_uses_for_message(id)
229 }
230
231 pub fn scripting_tool_uses_for_message(&self, id: MessageId) -> Vec<ToolUse> {
232 self.scripting_tool_use.tool_uses_for_message(id)
233 }
234
235 pub fn tool_results_for_message(&self, id: MessageId) -> Vec<&LanguageModelToolResult> {
236 self.tool_use.tool_results_for_message(id)
237 }
238
239 pub fn scripting_tool_results_for_message(
240 &self,
241 id: MessageId,
242 ) -> Vec<&LanguageModelToolResult> {
243 self.scripting_tool_use.tool_results_for_message(id)
244 }
245
246 pub fn scripting_changed_buffers<'a>(
247 &self,
248 cx: &'a App,
249 ) -> impl ExactSizeIterator<Item = &'a Entity<language::Buffer>> {
250 self.scripting_session.read(cx).changed_buffers()
251 }
252
253 pub fn message_has_tool_results(&self, message_id: MessageId) -> bool {
254 self.tool_use.message_has_tool_results(message_id)
255 }
256
257 pub fn message_has_scripting_tool_results(&self, message_id: MessageId) -> bool {
258 self.scripting_tool_use.message_has_tool_results(message_id)
259 }
260
261 pub fn insert_user_message(
262 &mut self,
263 text: impl Into<String>,
264 context: Vec<ContextSnapshot>,
265 cx: &mut Context<Self>,
266 ) -> MessageId {
267 let message_id = self.insert_message(Role::User, text, cx);
268 let context_ids = context.iter().map(|context| context.id).collect::<Vec<_>>();
269 self.context
270 .extend(context.into_iter().map(|context| (context.id, context)));
271 self.context_by_message.insert(message_id, context_ids);
272 message_id
273 }
274
275 pub fn insert_message(
276 &mut self,
277 role: Role,
278 text: impl Into<String>,
279 cx: &mut Context<Self>,
280 ) -> MessageId {
281 let id = self.next_message_id.post_inc();
282 self.messages.push(Message {
283 id,
284 role,
285 text: text.into(),
286 });
287 self.touch_updated_at();
288 cx.emit(ThreadEvent::MessageAdded(id));
289 id
290 }
291
292 pub fn edit_message(
293 &mut self,
294 id: MessageId,
295 new_role: Role,
296 new_text: String,
297 cx: &mut Context<Self>,
298 ) -> bool {
299 let Some(message) = self.messages.iter_mut().find(|message| message.id == id) else {
300 return false;
301 };
302 message.role = new_role;
303 message.text = new_text;
304 self.touch_updated_at();
305 cx.emit(ThreadEvent::MessageEdited(id));
306 true
307 }
308
309 pub fn delete_message(&mut self, id: MessageId, cx: &mut Context<Self>) -> bool {
310 let Some(index) = self.messages.iter().position(|message| message.id == id) else {
311 return false;
312 };
313 self.messages.remove(index);
314 self.context_by_message.remove(&id);
315 self.touch_updated_at();
316 cx.emit(ThreadEvent::MessageDeleted(id));
317 true
318 }
319
320 /// Returns the representation of this [`Thread`] in a textual form.
321 ///
322 /// This is the representation we use when attaching a thread as context to another thread.
323 pub fn text(&self) -> String {
324 let mut text = String::new();
325
326 for message in &self.messages {
327 text.push_str(match message.role {
328 language_model::Role::User => "User:",
329 language_model::Role::Assistant => "Assistant:",
330 language_model::Role::System => "System:",
331 });
332 text.push('\n');
333
334 text.push_str(&message.text);
335 text.push('\n');
336 }
337
338 text
339 }
340
341 pub fn send_to_model(
342 &mut self,
343 model: Arc<dyn LanguageModel>,
344 request_kind: RequestKind,
345 cx: &mut Context<Self>,
346 ) {
347 let mut request = self.to_completion_request(request_kind, cx);
348 request.tools = {
349 let mut tools = Vec::new();
350
351 if self.tools.is_scripting_tool_enabled() {
352 tools.push(LanguageModelRequestTool {
353 name: ScriptingTool::NAME.into(),
354 description: ScriptingTool::DESCRIPTION.into(),
355 input_schema: ScriptingTool::input_schema(),
356 });
357 }
358
359 tools.extend(self.tools().enabled_tools(cx).into_iter().map(|tool| {
360 LanguageModelRequestTool {
361 name: tool.name(),
362 description: tool.description(),
363 input_schema: tool.input_schema(),
364 }
365 }));
366
367 tools
368 };
369
370 self.stream_completion(request, model, cx);
371 }
372
373 pub fn to_completion_request(
374 &self,
375 request_kind: RequestKind,
376 _cx: &App,
377 ) -> LanguageModelRequest {
378 let mut request = LanguageModelRequest {
379 messages: vec![LanguageModelRequestMessage {
380 role: Role::System,
381 content: vec![MessageContent::Text(
382 include_str!("./system_prompt.md").to_string(),
383 )],
384 cache: true,
385 }],
386 tools: Vec::new(),
387 stop: Vec::new(),
388 temperature: None,
389 };
390
391 let mut referenced_context_ids = HashSet::default();
392
393 for message in &self.messages {
394 if let Some(context_ids) = self.context_by_message.get(&message.id) {
395 referenced_context_ids.extend(context_ids);
396 }
397
398 let mut request_message = LanguageModelRequestMessage {
399 role: message.role,
400 content: Vec::new(),
401 cache: false,
402 };
403
404 match request_kind {
405 RequestKind::Chat => {
406 self.tool_use
407 .attach_tool_results(message.id, &mut request_message);
408 self.scripting_tool_use
409 .attach_tool_results(message.id, &mut request_message);
410 }
411 RequestKind::Summarize => {
412 // We don't care about tool use during summarization.
413 }
414 }
415
416 if !message.text.is_empty() {
417 request_message
418 .content
419 .push(MessageContent::Text(message.text.clone()));
420 }
421
422 match request_kind {
423 RequestKind::Chat => {
424 self.tool_use
425 .attach_tool_uses(message.id, &mut request_message);
426 self.scripting_tool_use
427 .attach_tool_uses(message.id, &mut request_message);
428 }
429 RequestKind::Summarize => {
430 // We don't care about tool use during summarization.
431 }
432 };
433
434 request.messages.push(request_message);
435 }
436
437 if !referenced_context_ids.is_empty() {
438 let mut context_message = LanguageModelRequestMessage {
439 role: Role::User,
440 content: Vec::new(),
441 cache: false,
442 };
443
444 let referenced_context = referenced_context_ids
445 .into_iter()
446 .filter_map(|context_id| self.context.get(context_id))
447 .cloned();
448 attach_context_to_message(&mut context_message, referenced_context);
449
450 request.messages.push(context_message);
451 }
452
453 request
454 }
455
456 pub fn stream_completion(
457 &mut self,
458 request: LanguageModelRequest,
459 model: Arc<dyn LanguageModel>,
460 cx: &mut Context<Self>,
461 ) {
462 let pending_completion_id = post_inc(&mut self.completion_count);
463
464 let task = cx.spawn(|thread, mut cx| async move {
465 let stream = model.stream_completion(request, &cx);
466 let stream_completion = async {
467 let mut events = stream.await?;
468 let mut stop_reason = StopReason::EndTurn;
469
470 while let Some(event) = events.next().await {
471 let event = event?;
472
473 thread.update(&mut cx, |thread, cx| {
474 match event {
475 LanguageModelCompletionEvent::StartMessage { .. } => {
476 thread.insert_message(Role::Assistant, String::new(), cx);
477 }
478 LanguageModelCompletionEvent::Stop(reason) => {
479 stop_reason = reason;
480 }
481 LanguageModelCompletionEvent::Text(chunk) => {
482 if let Some(last_message) = thread.messages.last_mut() {
483 if last_message.role == Role::Assistant {
484 last_message.text.push_str(&chunk);
485 cx.emit(ThreadEvent::StreamedAssistantText(
486 last_message.id,
487 chunk,
488 ));
489 } else {
490 // If we won't have an Assistant message yet, assume this chunk marks the beginning
491 // of a new Assistant response.
492 //
493 // Importantly: We do *not* want to emit a `StreamedAssistantText` event here, as it
494 // will result in duplicating the text of the chunk in the rendered Markdown.
495 thread.insert_message(Role::Assistant, chunk, cx);
496 };
497 }
498 }
499 LanguageModelCompletionEvent::ToolUse(tool_use) => {
500 if let Some(last_assistant_message) = thread
501 .messages
502 .iter()
503 .rfind(|message| message.role == Role::Assistant)
504 {
505 if tool_use.name.as_ref() == ScriptingTool::NAME {
506 thread
507 .scripting_tool_use
508 .request_tool_use(last_assistant_message.id, tool_use);
509 } else {
510 thread
511 .tool_use
512 .request_tool_use(last_assistant_message.id, tool_use);
513 }
514 }
515 }
516 }
517
518 thread.touch_updated_at();
519 cx.emit(ThreadEvent::StreamedCompletion);
520 cx.notify();
521 })?;
522
523 smol::future::yield_now().await;
524 }
525
526 thread.update(&mut cx, |thread, cx| {
527 thread
528 .pending_completions
529 .retain(|completion| completion.id != pending_completion_id);
530
531 if thread.summary.is_none() && thread.messages.len() >= 2 {
532 thread.summarize(cx);
533 }
534 })?;
535
536 anyhow::Ok(stop_reason)
537 };
538
539 let result = stream_completion.await;
540
541 thread
542 .update(&mut cx, |thread, cx| match result.as_ref() {
543 Ok(stop_reason) => match stop_reason {
544 StopReason::ToolUse => {
545 cx.emit(ThreadEvent::UsePendingTools);
546 }
547 StopReason::EndTurn => {}
548 StopReason::MaxTokens => {}
549 },
550 Err(error) => {
551 if error.is::<PaymentRequiredError>() {
552 cx.emit(ThreadEvent::ShowError(ThreadError::PaymentRequired));
553 } else if error.is::<MaxMonthlySpendReachedError>() {
554 cx.emit(ThreadEvent::ShowError(ThreadError::MaxMonthlySpendReached));
555 } else {
556 let error_message = error
557 .chain()
558 .map(|err| err.to_string())
559 .collect::<Vec<_>>()
560 .join("\n");
561 cx.emit(ThreadEvent::ShowError(ThreadError::Message(
562 SharedString::from(error_message.clone()),
563 )));
564 }
565
566 thread.cancel_last_completion();
567 }
568 })
569 .ok();
570 });
571
572 self.pending_completions.push(PendingCompletion {
573 id: pending_completion_id,
574 _task: task,
575 });
576 }
577
578 pub fn summarize(&mut self, cx: &mut Context<Self>) {
579 let Some(provider) = LanguageModelRegistry::read_global(cx).active_provider() else {
580 return;
581 };
582 let Some(model) = LanguageModelRegistry::read_global(cx).active_model() else {
583 return;
584 };
585
586 if !provider.is_authenticated(cx) {
587 return;
588 }
589
590 let mut request = self.to_completion_request(RequestKind::Summarize, cx);
591 request.messages.push(LanguageModelRequestMessage {
592 role: Role::User,
593 content: vec![
594 "Generate a concise 3-7 word title for this conversation, omitting punctuation. Go straight to the title, without any preamble and prefix like `Here's a concise suggestion:...` or `Title:`"
595 .into(),
596 ],
597 cache: false,
598 });
599
600 self.pending_summary = cx.spawn(|this, mut cx| {
601 async move {
602 let stream = model.stream_completion_text(request, &cx);
603 let mut messages = stream.await?;
604
605 let mut new_summary = String::new();
606 while let Some(message) = messages.stream.next().await {
607 let text = message?;
608 let mut lines = text.lines();
609 new_summary.extend(lines.next());
610
611 // Stop if the LLM generated multiple lines.
612 if lines.next().is_some() {
613 break;
614 }
615 }
616
617 this.update(&mut cx, |this, cx| {
618 if !new_summary.is_empty() {
619 this.summary = Some(new_summary.into());
620 }
621
622 cx.emit(ThreadEvent::SummaryChanged);
623 })?;
624
625 anyhow::Ok(())
626 }
627 .log_err()
628 });
629 }
630
631 pub fn use_pending_tools(&mut self, cx: &mut Context<Self>) {
632 let request = self.to_completion_request(RequestKind::Chat, cx);
633 let pending_tool_uses = self
634 .tool_use
635 .pending_tool_uses()
636 .into_iter()
637 .filter(|tool_use| tool_use.status.is_idle())
638 .cloned()
639 .collect::<Vec<_>>();
640
641 for tool_use in pending_tool_uses {
642 if let Some(tool) = self.tools.tool(&tool_use.name, cx) {
643 let task = tool.run(tool_use.input, &request.messages, self.project.clone(), cx);
644
645 self.insert_tool_output(tool_use.id.clone(), task, cx);
646 }
647 }
648
649 let pending_scripting_tool_uses = self
650 .scripting_tool_use
651 .pending_tool_uses()
652 .into_iter()
653 .filter(|tool_use| tool_use.status.is_idle())
654 .cloned()
655 .collect::<Vec<_>>();
656
657 for scripting_tool_use in pending_scripting_tool_uses {
658 let task = match ScriptingTool::deserialize_input(scripting_tool_use.input) {
659 Err(err) => Task::ready(Err(err.into())),
660 Ok(input) => {
661 let (script_id, script_task) =
662 self.scripting_session.update(cx, move |session, cx| {
663 session.run_script(input.lua_script, cx)
664 });
665
666 let session = self.scripting_session.clone();
667 cx.spawn(|_, cx| async move {
668 script_task.await;
669
670 let message = session.read_with(&cx, |session, _cx| {
671 // Using a id to get the script output seems impractical.
672 // Why not just include it in the Task result?
673 // This is because we'll later report the script state as it runs,
674 session
675 .get(script_id)
676 .output_message_for_llm()
677 .expect("Script shouldn't still be running")
678 })?;
679
680 Ok(message)
681 })
682 }
683 };
684
685 self.insert_scripting_tool_output(scripting_tool_use.id.clone(), task, cx);
686 }
687 }
688
689 pub fn insert_tool_output(
690 &mut self,
691 tool_use_id: LanguageModelToolUseId,
692 output: Task<Result<String>>,
693 cx: &mut Context<Self>,
694 ) {
695 let insert_output_task = cx.spawn(|thread, mut cx| {
696 let tool_use_id = tool_use_id.clone();
697 async move {
698 let output = output.await;
699 thread
700 .update(&mut cx, |thread, cx| {
701 let pending_tool_use = thread
702 .tool_use
703 .insert_tool_output(tool_use_id.clone(), output);
704
705 cx.emit(ThreadEvent::ToolFinished {
706 tool_use_id,
707 pending_tool_use,
708 });
709 })
710 .ok();
711 }
712 });
713
714 self.tool_use
715 .run_pending_tool(tool_use_id, insert_output_task);
716 }
717
718 pub fn insert_scripting_tool_output(
719 &mut self,
720 tool_use_id: LanguageModelToolUseId,
721 output: Task<Result<String>>,
722 cx: &mut Context<Self>,
723 ) {
724 let insert_output_task = cx.spawn(|thread, mut cx| {
725 let tool_use_id = tool_use_id.clone();
726 async move {
727 let output = output.await;
728 thread
729 .update(&mut cx, |thread, cx| {
730 let pending_tool_use = thread
731 .scripting_tool_use
732 .insert_tool_output(tool_use_id.clone(), output);
733
734 cx.emit(ThreadEvent::ToolFinished {
735 tool_use_id,
736 pending_tool_use,
737 });
738 })
739 .ok();
740 }
741 });
742
743 self.scripting_tool_use
744 .run_pending_tool(tool_use_id, insert_output_task);
745 }
746
747 pub fn send_tool_results_to_model(
748 &mut self,
749 model: Arc<dyn LanguageModel>,
750 cx: &mut Context<Self>,
751 ) {
752 // Insert a user message to contain the tool results.
753 self.insert_user_message(
754 // TODO: Sending up a user message without any content results in the model sending back
755 // responses that also don't have any content. We currently don't handle this case well,
756 // so for now we provide some text to keep the model on track.
757 "Here are the tool results.",
758 Vec::new(),
759 cx,
760 );
761 self.send_to_model(model, RequestKind::Chat, cx);
762 }
763
764 /// Cancels the last pending completion, if there are any pending.
765 ///
766 /// Returns whether a completion was canceled.
767 pub fn cancel_last_completion(&mut self) -> bool {
768 if let Some(_last_completion) = self.pending_completions.pop() {
769 true
770 } else {
771 false
772 }
773 }
774}
775
776#[derive(Debug, Clone)]
777pub enum ThreadError {
778 PaymentRequired,
779 MaxMonthlySpendReached,
780 Message(SharedString),
781}
782
783#[derive(Debug, Clone)]
784pub enum ThreadEvent {
785 ShowError(ThreadError),
786 StreamedCompletion,
787 StreamedAssistantText(MessageId, String),
788 MessageAdded(MessageId),
789 MessageEdited(MessageId),
790 MessageDeleted(MessageId),
791 SummaryChanged,
792 UsePendingTools,
793 ToolFinished {
794 #[allow(unused)]
795 tool_use_id: LanguageModelToolUseId,
796 /// The pending tool use that corresponds to this tool.
797 pending_tool_use: Option<PendingToolUse>,
798 },
799}
800
801impl EventEmitter<ThreadEvent> for Thread {}
802
803struct PendingCompletion {
804 id: usize,
805 _task: Task<()>,
806}