cache pid lock files to reduce IO operations (#6297)

## Description
Implements a new `PidLockedFiles` type for efficient file locking.
Before this we were do file IO on every did change key press event. We
now cache the results for efficiency.

Author: JoshuaBatty

sway-lsp/src/core/document.rs

@@ -1,4 +1,6 @@
 #![allow(dead_code)]
+use std::sync::Arc;
+
 use crate::{
     error::{DirectoryError, DocumentError, LanguageServerError},
     utils::document,
@@ -109,30 +111,6 @@ impl TextDocument {
     }
 }
 
-/// Marks the specified file as "dirty" by creating a corresponding flag file.
-///
-/// This function ensures the necessary directory structure exists before creating the flag file.
-pub fn mark_file_as_dirty(uri: &Url) -> Result<(), LanguageServerError> {
-    let path = document::get_path_from_url(uri)?;
-    Ok(PidFileLocking::lsp(path)
-        .lock()
-        .map_err(|e| DirectoryError::LspLocksDirFailed(e.to_string()))?)
-}
-
-/// Removes the corresponding flag file for the specified Url.
-///
-/// If the flag file does not exist, this function will do nothing.
-pub fn remove_dirty_flag(uri: &Url) -> Result<(), LanguageServerError> {
-    let path = document::get_path_from_url(uri)?;
-    let uri = uri.clone();
-    Ok(PidFileLocking::lsp(path)
-        .release()
-        .map_err(|err| DocumentError::UnableToRemoveFile {
-            path: uri.path().to_string(),
-            err: err.to_string(),
-        })?)
-}
-
 #[derive(Debug)]
 struct EditText<'text> {
     start_index: usize,
@@ -242,6 +220,57 @@ impl std::ops::Deref for Documents {
     }
 }
 
+/// Manages process-based file locking for multiple files.
+pub struct PidLockedFiles {
+    locks: DashMap<Url, Arc<PidFileLocking>>,
+}
+
+impl Default for PidLockedFiles {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl PidLockedFiles {
+    pub fn new() -> Self {
+        Self {
+            locks: DashMap::new(),
+        }
+    }
+
+    /// Marks the specified file as "dirty" by creating a corresponding flag file.
+    ///
+    /// This function ensures the necessary directory structure exists before creating the flag file.
+    /// If the file is already locked, this function will do nothing. This is to reduce the number of
+    /// unnecessary file IO operations.
+    pub fn mark_file_as_dirty(&self, uri: &Url) -> Result<(), LanguageServerError> {
+        if !self.locks.contains_key(uri) {
+            let path = document::get_path_from_url(uri)?;
+            let file_lock = Arc::new(PidFileLocking::lsp(path));
+            file_lock
+                .lock()
+                .map_err(|e| DirectoryError::LspLocksDirFailed(e.to_string()))?;
+            self.locks.insert(uri.clone(), file_lock);
+        }
+        Ok(())
+    }
+
+    /// Removes the corresponding flag file for the specified Url.
+    ///
+    /// If the flag file does not exist, this function will do nothing.
+    pub fn remove_dirty_flag(&self, uri: &Url) -> Result<(), LanguageServerError> {
+        if let Some((uri, file_lock)) = self.locks.remove(uri) {
+            file_lock
+                .release()
+                .map_err(|err| DocumentError::UnableToRemoveFile {
+                    path: uri.path().to_string(),
+                    err: err.to_string(),
+                })?;
+        }
+        Ok(())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

sway-lsp/src/handlers/notification.rs

@@ -2,10 +2,7 @@
 //! Protocol. This module specifically handles notification messages sent by the Client.
 
 use crate::{
-    core::{
-        document::{self, Documents},
-        session::Session,
-    },
+    core::{document::Documents, session::Session},
     error::LanguageServerError,
     server_state::{CompilationContext, ServerState, TaskMessage},
 };
@@ -89,7 +86,10 @@ pub async fn handle_did_change_text_document(
     state: &ServerState,
     params: DidChangeTextDocumentParams,
 ) -> Result<(), LanguageServerError> {
-    if let Err(err) = document::mark_file_as_dirty(&params.text_document.uri) {
+    if let Err(err) = state
+        .pid_locked_files
+        .mark_file_as_dirty(&params.text_document.uri)
+    {
         tracing::warn!("Failed to mark file as dirty: {}", err);
     }
 
@@ -138,7 +138,9 @@ pub(crate) async fn handle_did_save_text_document(
     state: &ServerState,
     params: DidSaveTextDocumentParams,
 ) -> Result<(), LanguageServerError> {
-    document::remove_dirty_flag(&params.text_document.uri)?;
+    state
+        .pid_locked_files
+        .remove_dirty_flag(&params.text_document.uri)?;
     let (uri, session) = state
         .uri_and_session_from_workspace(&params.text_document.uri)
         .await?;
@@ -159,7 +161,7 @@ pub(crate) async fn handle_did_change_watched_files(
     for event in params.changes {
         let (uri, _) = state.uri_and_session_from_workspace(&event.uri).await?;
         if let FileChangeType::DELETED = event.typ {
-            document::remove_dirty_flag(&event.uri)?;
+            state.pid_locked_files.remove_dirty_flag(&event.uri)?;
             let _ = state.documents.remove_document(&uri);
         }
     }

sway-lsp/src/server.rs

@@ -2,7 +2,6 @@
 //! It provides an interface between the LSP protocol and the sway-lsp internals.
 
 use crate::{
-    core::document,
     handlers::{notification, request},
     lsp_ext::{MetricsParams, OnEnterParams, ShowAstParams, VisualizeParams},
     server_state::ServerState,
@@ -43,7 +42,10 @@ impl LanguageServer for ServerState {
     }
 
     async fn did_close(&self, params: DidCloseTextDocumentParams) {
-        if let Err(err) = document::remove_dirty_flag(&params.text_document.uri) {
+        if let Err(err) = self
+            .pid_locked_files
+            .remove_dirty_flag(&params.text_document.uri)
+        {
             tracing::error!("{}", err.to_string());
         }
     }

sway-lsp/src/server_state.rs

@@ -3,7 +3,7 @@
 use crate::{
     config::{Config, GarbageCollectionConfig, Warnings},
     core::{
-        document::Documents,
+        document::{Documents, PidLockedFiles},
         session::{self, Session},
     },
     error::{DirectoryError, DocumentError, LanguageServerError},
@@ -49,6 +49,7 @@ pub struct ServerState {
     pub(crate) cb_tx: Sender<TaskMessage>,
     pub(crate) cb_rx: Arc<Receiver<TaskMessage>>,
     pub(crate) finished_compilation: Arc<Notify>,
+    pub(crate) pid_locked_files: PidLockedFiles,
     last_compilation_state: Arc<RwLock<LastCompilationState>>,
 }
 
@@ -66,6 +67,7 @@ impl Default for ServerState {
             cb_tx,
             cb_rx: Arc::new(cb_rx),
             finished_compilation: Arc::new(Notify::new()),
+            pid_locked_files: PidLockedFiles::new(),
             last_compilation_state: Arc::new(RwLock::new(LastCompilationState::Uninitialized)),
         };
         // Spawn a new thread dedicated to handling compilation tasks