Track active projects in metrics

An active project is defined as a project where there has been at
least a buffer edit, a join request/response, or a follow update
in the last minute.

crates/collab/src/rpc/store.rs

@@ -9,6 +9,7 @@ use std::{
     mem,
     path::{Path, PathBuf},
     str,
+    time::{Duration, Instant},
 };
 use tracing::instrument;
 
@@ -41,6 +42,8 @@ pub struct Project {
     pub active_replica_ids: HashSet<ReplicaId>,
     pub worktrees: BTreeMap<u64, Worktree>,
     pub language_servers: Vec<proto::LanguageServer>,
+    #[serde(skip)]
+    last_activity: Option<Instant>,
 }
 
 #[derive(Default, Serialize)]
@@ -84,6 +87,7 @@ pub struct LeftProject {
 pub struct Metrics {
     pub connections: usize,
     pub registered_projects: usize,
+    pub active_projects: usize,
     pub shared_projects: usize,
 }
 
@@ -91,13 +95,17 @@ impl Store {
     pub fn metrics(&self) -> Metrics {
         let connections = self.connections.values().filter(|c| !c.admin).count();
         let mut registered_projects = 0;
+        let mut active_projects = 0;
         let mut shared_projects = 0;
         for project in self.projects.values() {
             if let Some(connection) = self.connections.get(&project.host_connection_id) {
                 if !connection.admin {
                     registered_projects += 1;
-                    if !project.guests.is_empty() {
-                        shared_projects += 1;
+                    if project.is_active() {
+                        active_projects += 1;
+                        if !project.guests.is_empty() {
+                            shared_projects += 1;
+                        }
                     }
                 }
             }
@@ -106,6 +114,7 @@ impl Store {
         Metrics {
             connections,
             registered_projects,
+            active_projects,
             shared_projects,
         }
     }
@@ -318,6 +327,7 @@ impl Store {
                 active_replica_ids: Default::default(),
                 worktrees: Default::default(),
                 language_servers: Default::default(),
+                last_activity: None,
             },
         );
         if let Some(connection) = self.connections.get_mut(&host_connection_id) {
@@ -338,6 +348,7 @@ impl Store {
             .get_mut(&project_id)
             .ok_or_else(|| anyhow!("no such project"))?;
         if project.host_connection_id == connection_id {
+            project.last_activity = Some(Instant::now());
             let mut old_worktrees = mem::take(&mut project.worktrees);
             for worktree in worktrees {
                 if let Some(old_worktree) = old_worktrees.remove(&worktree.id) {
@@ -460,6 +471,7 @@ impl Store {
             .get_mut(&project_id)
             .ok_or_else(|| anyhow!("no such project"))?;
         connection.requested_projects.insert(project_id);
+        project.last_activity = Some(Instant::now());
         project
             .join_requests
             .entry(requester_id)
@@ -484,6 +496,8 @@ impl Store {
             let requester_connection = self.connections.get_mut(&receipt.sender_id)?;
             requester_connection.requested_projects.remove(&project_id);
         }
+        project.last_activity = Some(Instant::now());
+
         Some(receipts)
     }
 
@@ -515,6 +529,7 @@ impl Store {
             receipts_with_replica_ids.push((receipt, replica_id));
         }
 
+        project.last_activity = Some(Instant::now());
         Some((receipts_with_replica_ids, project))
     }
 
@@ -565,6 +580,8 @@ impl Store {
             }
         }
 
+        project.last_activity = Some(Instant::now());
+
         Ok(LeftProject {
             host_connection_id: project.host_connection_id,
             host_user_id: project.host_user_id,
@@ -653,6 +670,25 @@ impl Store {
             .ok_or_else(|| anyhow!("no such project"))
     }
 
+    pub fn register_project_activity(
+        &mut self,
+        project_id: u64,
+        connection_id: ConnectionId,
+    ) -> Result<()> {
+        let project = self
+            .projects
+            .get_mut(&project_id)
+            .ok_or_else(|| anyhow!("no such project"))?;
+        if project.host_connection_id == connection_id
+            || project.guests.contains_key(&connection_id)
+        {
+            project.last_activity = Some(Instant::now());
+            Ok(())
+        } else {
+            Err(anyhow!("no such project"))?
+        }
+    }
+
     pub fn read_project(&self, project_id: u64, connection_id: ConnectionId) -> Result<&Project> {
         let project = self
             .projects
@@ -758,6 +794,13 @@ impl Store {
 }
 
 impl Project {
+    fn is_active(&self) -> bool {
+        const ACTIVE_PROJECT_TIMEOUT: Duration = Duration::from_secs(60);
+        self.last_activity.map_or(false, |last_activity| {
+            last_activity.elapsed() < ACTIVE_PROJECT_TIMEOUT
+        })
+    }
+
     pub fn guest_connection_ids(&self) -> Vec<ConnectionId> {
         self.guests.keys().copied().collect()
     }