fix(resurrection): do not parse resurrection layouts on startup (#4292)

* fix(resurrection): do not parse resurrection layouts on startup

* proper error when file is corrupt

* docs(changelog): add PR

* fix attach command

* style(fmt): rustfmt

CHANGELOG.md

@@ -17,6 +17,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 * fix: don't serialize when only ui elements present and provide post command disovery hook (https://github.com/zellij-org/zellij/pull/4276)
 * fix: use plugin `/host` folder as cwd when opening new panes (https://github.com/zellij-org/zellij/pull/4290)
 * fix: better command detection when serializing layouts for resurrection (https://github.com/zellij-org/zellij/pull/4287)
+* fix: slow startup on very large caches (https://github.com/zellij-org/zellij/pull/4292)
 * fix: don't show popups in the welcome screen (https://github.com/zellij-org/zellij/pull/4294)
 
 ## [0.42.2] - 2025-04-15

src/commands.rs

@@ -90,7 +90,7 @@ pub(crate) fn delete_all_sessions(yes: bool, force: bool) {
     } else {
         resurrectable_sessions
             .iter()
-            .filter(|(name, _, _)| !active_sessions.contains(name))
+            .filter(|(name, _)| !active_sessions.contains(name))
             .cloned()
             .collect()
     };
@@ -699,7 +699,15 @@ pub(crate) fn start_client(opts: CliArgs) {
                     .and_then(|s| session_exists(&s).ok())
                     .unwrap_or(false);
                 let resurrection_layout =
-                    session_name.as_ref().and_then(|s| resurrection_layout(&s));
+                    session_name
+                        .as_ref()
+                        .and_then(|s| match resurrection_layout(&s) {
+                            Ok(layout) => layout,
+                            Err(e) => {
+                                eprintln!("{}", e);
+                                process::exit(2);
+                            },
+                        });
                 if (create || should_create_detached)
                     && !session_exists
                     && resurrection_layout.is_none()

zellij-client/src/web_client/session_management.rs

@@ -113,7 +113,10 @@ pub fn spawn_session_if_needed(
     } else {
         let force_run_commands = false;
         let resurrection_layout =
-            resurrection_layout(&session_name).map(|mut resurrection_layout| {
+            resurrection_layout(&session_name)
+                .ok()
+                .flatten()
+                .map(|mut resurrection_layout| {
                     if force_run_commands {
                         resurrection_layout.recursively_add_start_suspended(Some(false));
                     }

zellij-client/src/web_client/types.rs

@@ -62,6 +62,8 @@ impl SessionManager for RealSessionManager {
         session_name: &str,
     ) -> Option<zellij_utils::input::layout::Layout> {
         zellij_utils::sessions::resurrection_layout(session_name)
+            .ok()
+            .flatten()
     }
 
     fn spawn_session_if_needed(

zellij-utils/src/sessions.rs

@@ -21,7 +21,7 @@ pub fn get_sessions() -> Result<Vec<(String, Duration)>, io::ErrorKind> {
         Ok(files) => {
             let mut sessions = Vec::new();
             files.for_each(|file| {
-                let file = file.unwrap();
+                if let Ok(file) = file {
                     let file_name = file.file_name().into_string().unwrap();
                     let ctime = std::fs::metadata(&file.path())
                         .ok()
@@ -32,6 +32,7 @@ pub fn get_sessions() -> Result<Vec<(String, Duration)>, io::ErrorKind> {
                     if file.file_type().unwrap().is_socket() && assert_socket(&file_name) {
                         sessions.push((file_name, duration));
                     }
+                }
             });
             Ok(sessions)
         },
@@ -40,7 +41,7 @@ pub fn get_sessions() -> Result<Vec<(String, Duration)>, io::ErrorKind> {
     }
 }
 
-pub fn get_resurrectable_sessions() -> Vec<(String, Duration, Layout)> {
+pub fn get_resurrectable_sessions() -> Vec<(String, Duration)> {
     match fs::read_dir(&*ZELLIJ_SESSION_INFO_CACHE_DIR) {
         Ok(files_in_session_info_folder) => {
             let files_that_are_folders = files_in_session_info_folder
@@ -50,30 +51,12 @@ pub fn get_resurrectable_sessions() -> Vec<(String, Duration, Layout)> {
                 .filter_map(|folder_name| {
                     let layout_file_name =
                         session_layout_cache_file_name(&folder_name.display().to_string());
-                    let raw_layout = match std::fs::read_to_string(&layout_file_name) {
-                        Ok(raw_layout) => raw_layout,
-                        Err(_e) => {
-                            return None;
-                        },
-                    };
                     let ctime = match std::fs::metadata(&layout_file_name)
                         .and_then(|metadata| metadata.created())
                     {
                         Ok(created) => Some(created),
                         Err(_e) => None,
                     };
-                    let layout = match Layout::from_kdl(
-                        &raw_layout,
-                        Some(layout_file_name.display().to_string()),
-                        None,
-                        None,
-                    ) {
-                        Ok(layout) => layout,
-                        Err(e) => {
-                            log::error!("Failed to parse resurrection layout file: {}", e);
-                            return None;
-                        },
-                    };
                     let elapsed_duration = ctime
                         .map(|ctime| {
                             Duration::from_secs(ctime.elapsed().ok().unwrap_or_default().as_secs())
@@ -82,7 +65,7 @@ pub fn get_resurrectable_sessions() -> Vec<(String, Duration, Layout)> {
                     let session_name = folder_name
                         .file_name()
                         .map(|f| std::path::PathBuf::from(f).display().to_string())?;
-                    Some((session_name, elapsed_duration, layout))
+                    Some((session_name, elapsed_duration))
                 })
                 .collect()
         },
@@ -291,7 +274,7 @@ pub fn list_sessions(no_formatting: bool, short: bool, reverse: bool) {
             let resurrectable_sessions = get_resurrectable_sessions();
             let mut all_sessions: HashMap<String, (Duration, bool)> = resurrectable_sessions
                 .iter()
-                .map(|(name, timestamp, _layout)| (name.clone(), (timestamp.clone(), true)))
+                .map(|(name, timestamp)| (name.clone(), (timestamp.clone(), true)))
                 .collect();
             for (session_name, duration) in running_sessions {
                 all_sessions.insert(session_name.clone(), (duration, false));
@@ -362,17 +345,34 @@ pub fn session_exists(name: &str) -> Result<bool, io::ErrorKind> {
 }
 
 // if the session is resurrecable, the returned layout is the one to be used to resurrect it
-pub fn resurrection_layout(session_name_to_resurrect: &str) -> Option<Layout> {
+pub fn resurrection_layout(session_name_to_resurrect: &str) -> Result<Option<Layout>, String> {
-    let resurrectable_sessions = get_resurrectable_sessions();
+    let layout_file_name = session_layout_cache_file_name(&session_name_to_resurrect);
-    resurrectable_sessions
+    let raw_layout = match std::fs::read_to_string(&layout_file_name) {
-        .iter()
+        Ok(raw_layout) => raw_layout,
-        .find_map(|(name, _timestamp, layout)| {
+        Err(_e) => {
-            if name == session_name_to_resurrect {
+            return Ok(None);
-                Some(layout.clone())
+        },
-            } else {
+    };
-                None
+    match Layout::from_kdl(
+        &raw_layout,
+        Some(layout_file_name.display().to_string()),
+        None,
+        None,
+    ) {
+        Ok(layout) => Ok(Some(layout)),
+        Err(e) => {
+            log::error!(
+                "Failed to parse resurrection layout file {}: {}",
+                layout_file_name.display(),
+                e
+            );
+            return Err(format!(
+                "Failed to parse resurrection layout file {}: {}.",
+                layout_file_name.display(),
+                e
+            ));
+        },
     }
-        })
 }
 
 pub fn assert_session(name: &str) {