project: Spawn terminal process on background executor (#40774)

We were spawning the process on the foreground thread before which can
block an arbitrary amount of time. Likewise we no longer block
deserialization on the terminal loading.

Release Notes:

- Improved startup time on systems with slow process spawning
capabilities

Author: Veykril

crates/agent_ui/src/agent_diff.rs

@@ -581,11 +581,13 @@ impl Item for AgentDiffPane {
         _workspace_id: Option<workspace::WorkspaceId>,
         window: &mut Window,
         cx: &mut Context<Self>,
-    ) -> Option<Entity<Self>>
+    ) -> Task<Option<Entity<Self>>>
     where
         Self: Sized,
     {
-        Some(cx.new(|cx| Self::new(self.thread.clone(), self.workspace.clone(), window, cx)))
+        Task::ready(Some(cx.new(|cx| {
+            Self::new(self.thread.clone(), self.workspace.clone(), window, cx)
+        })))
     }
 
     fn is_dirty(&self, cx: &App) -> bool {

crates/collab/src/tests/following_tests.rs

@@ -776,26 +776,30 @@ async fn test_peers_following_each_other(cx_a: &mut TestAppContext, cx_b: &mut T
         .unwrap();
 
     // Clients A and B follow each other in split panes
-    workspace_a.update_in(cx_a, |workspace, window, cx| {
-        workspace.split_and_clone(
-            workspace.active_pane().clone(),
-            SplitDirection::Right,
-            window,
-            cx,
-        );
-    });
+    workspace_a
+        .update_in(cx_a, |workspace, window, cx| {
+            workspace.split_and_clone(
+                workspace.active_pane().clone(),
+                SplitDirection::Right,
+                window,
+                cx,
+            )
+        })
+        .await;
     workspace_a.update_in(cx_a, |workspace, window, cx| {
         workspace.follow(client_b.peer_id().unwrap(), window, cx)
     });
     executor.run_until_parked();
-    workspace_b.update_in(cx_b, |workspace, window, cx| {
-        workspace.split_and_clone(
-            workspace.active_pane().clone(),
-            SplitDirection::Right,
-            window,
-            cx,
-        );
-    });
+    workspace_b
+        .update_in(cx_b, |workspace, window, cx| {
+            workspace.split_and_clone(
+                workspace.active_pane().clone(),
+                SplitDirection::Right,
+                window,
+                cx,
+            )
+        })
+        .await;
     workspace_b.update_in(cx_b, |workspace, window, cx| {
         workspace.follow(client_a.peer_id().unwrap(), window, cx)
     });
@@ -1369,9 +1373,11 @@ async fn test_auto_unfollowing(cx_a: &mut TestAppContext, cx_b: &mut TestAppCont
     );
 
     // When client B activates a different pane, it continues following client A in the original pane.
-    workspace_b.update_in(cx_b, |workspace, window, cx| {
-        workspace.split_and_clone(pane_b.clone(), SplitDirection::Right, window, cx)
-    });
+    workspace_b
+        .update_in(cx_b, |workspace, window, cx| {
+            workspace.split_and_clone(pane_b.clone(), SplitDirection::Right, window, cx)
+        })
+        .await;
     assert_eq!(
         workspace_b.update(cx_b, |workspace, _| workspace.leader_for_pane(&pane_b)),
         Some(leader_id.into())

crates/collab/src/tests/integration_tests.rs

@@ -6748,7 +6748,7 @@ async fn test_preview_tabs(cx: &mut TestAppContext) {
     pane.update(cx, |pane, cx| {
         pane.split(workspace::SplitDirection::Right, cx);
     });
-
+    cx.run_until_parked();
     let right_pane = workspace.read_with(cx, |workspace, _| workspace.active_pane().clone());
 
     pane.update(cx, |pane, cx| {

crates/collab_ui/src/channel_view.rs

@@ -498,8 +498,8 @@ impl Item for ChannelView {
         _: Option<WorkspaceId>,
         window: &mut Window,
         cx: &mut Context<Self>,
-    ) -> Option<Entity<Self>> {
-        Some(cx.new(|cx| {
+    ) -> Task<Option<Entity<Self>>> {
+        Task::ready(Some(cx.new(|cx| {
             Self::new(
                 self.project.clone(),
                 self.workspace.clone(),
@@ -508,7 +508,7 @@ impl Item for ChannelView {
                 window,
                 cx,
             )
-        }))
+        })))
     }
 
     fn navigate(

crates/diagnostics/src/buffer_diagnostics.rs

@@ -693,11 +693,11 @@ impl Item for BufferDiagnosticsEditor {
         _workspace_id: Option<workspace::WorkspaceId>,
         window: &mut Window,
         cx: &mut Context<Self>,
-    ) -> Option<Entity<Self>>
+    ) -> Task<Option<Entity<Self>>>
     where
         Self: Sized,
     {
-        Some(cx.new(|cx| {
+        Task::ready(Some(cx.new(|cx| {
             BufferDiagnosticsEditor::new(
                 self.project_path.clone(),
                 self.project.clone(),
@@ -706,7 +706,7 @@ impl Item for BufferDiagnosticsEditor {
                 window,
                 cx,
             )
-        }))
+        })))
     }
 
     fn deactivated(&mut self, window: &mut Window, cx: &mut Context<Self>) {

crates/diagnostics/src/diagnostics.rs

@@ -732,19 +732,19 @@ impl Item for ProjectDiagnosticsEditor {
         _workspace_id: Option<workspace::WorkspaceId>,
         window: &mut Window,
         cx: &mut Context<Self>,
-    ) -> Option<Entity<Self>>
+    ) -> Task<Option<Entity<Self>>>
     where
         Self: Sized,
     {
-        Some(cx.new(|cx| {
+        Task::ready(Some(cx.new(|cx| {
             ProjectDiagnosticsEditor::new(
                 self.include_warnings,
                 self.project.clone(),
                 self.workspace.clone(),
                 window,
                 cx,
             )
-        }))
+        })))
     }
 
     fn is_dirty(&self, cx: &App) -> bool {

crates/editor/src/items.rs

@@ -762,11 +762,11 @@ impl Item for Editor {
         _workspace_id: Option<WorkspaceId>,
         window: &mut Window,
         cx: &mut Context<Self>,
-    ) -> Option<Entity<Editor>>
+    ) -> Task<Option<Entity<Editor>>>
     where
         Self: Sized,
     {
-        Some(cx.new(|cx| self.clone(window, cx)))
+        Task::ready(Some(cx.new(|cx| self.clone(window, cx))))
     }
 
     fn set_nav_history(

crates/git_ui/src/commit_view.rs

@@ -4,8 +4,8 @@ use editor::{Editor, EditorEvent, MultiBuffer, SelectionEffects, multibuffer_con
 use git::repository::{CommitDetails, CommitDiff, RepoPath};
 use gpui::{
     Action, AnyElement, AnyView, App, AppContext as _, AsyncApp, AsyncWindowContext, Context,
-    Entity, EventEmitter, FocusHandle, Focusable, IntoElement, PromptLevel, Render, WeakEntity,
-    Window, actions,
+    Entity, EventEmitter, FocusHandle, Focusable, IntoElement, PromptLevel, Render, Task,
+    WeakEntity, Window, actions,
 };
 use language::{
     Anchor, Buffer, Capability, DiskState, File, LanguageRegistry, LineEnding, OffsetRangeExt as _,
@@ -561,11 +561,11 @@ impl Item for CommitView {
         _workspace_id: Option<workspace::WorkspaceId>,
         window: &mut Window,
         cx: &mut Context<Self>,
-    ) -> Option<Entity<Self>>
+    ) -> Task<Option<Entity<Self>>>
     where
         Self: Sized,
     {
-        Some(cx.new(|cx| {
+        Task::ready(Some(cx.new(|cx| {
             let editor = cx.new(|cx| {
                 self.editor
                     .update(cx, |editor, cx| editor.clone(window, cx))
@@ -577,7 +577,7 @@ impl Item for CommitView {
                 commit: self.commit.clone(),
                 stash: self.stash,
             }
-        }))
+        })))
     }
 }
 

crates/git_ui/src/project_diff.rs

@@ -625,12 +625,16 @@ impl Item for ProjectDiff {
         _workspace_id: Option<workspace::WorkspaceId>,
         window: &mut Window,
         cx: &mut Context<Self>,
-    ) -> Option<Entity<Self>>
+    ) -> Task<Option<Entity<Self>>>
     where
         Self: Sized,
     {
-        let workspace = self.workspace.upgrade()?;
-        Some(cx.new(|cx| ProjectDiff::new(self.project.clone(), workspace, window, cx)))
+        let Some(workspace) = self.workspace.upgrade() else {
+            return Task::ready(None);
+        };
+        Task::ready(Some(cx.new(|cx| {
+            ProjectDiff::new(self.project.clone(), workspace, window, cx)
+        })))
     }
 
     fn is_dirty(&self, cx: &App) -> bool {

crates/image_viewer/src/image_viewer.rs

@@ -176,15 +176,15 @@ impl Item for ImageView {
         _workspace_id: Option<WorkspaceId>,
         _: &mut Window,
         cx: &mut Context<Self>,
-    ) -> Option<Entity<Self>>
+    ) -> Task<Option<Entity<Self>>>
     where
         Self: Sized,
     {
-        Some(cx.new(|cx| Self {
+        Task::ready(Some(cx.new(|cx| Self {
             image_item: self.image_item.clone(),
             project: self.project.clone(),
             focus_handle: cx.focus_handle(),
-        }))
+        })))
     }
 
     fn has_deleted_file(&self, cx: &App) -> bool {