feat(lsp): debug log file (#21500)

4 files changed, 97 insertions, 4 deletions

diff --git a/cli/lsp/config.rs b/cli/lsp/config.rs
index 36d4c95c6..42478b593 100644
--- a/cli/lsp/config.rs
+++ b/cli/lsp/config.rs
@@ -454,6 +454,10 @@ pub struct WorkspaceSettings {
   #[serde(default)]
   pub internal_debug: bool,
 
+  /// Write logs to a file in a project-local directory.
+  #[serde(default)]
+  pub log_file: bool,
+
   /// A flag that indicates if linting is enabled for the workspace.
   #[serde(default = "default_to_true")]
   pub lint: bool,
@@ -502,6 +506,7 @@ impl Default for WorkspaceSettings {
       import_map: None,
       code_lens: Default::default(),
       internal_debug: false,
+      log_file: false,
       lint: true,
       document_preload_limit: default_document_preload_limit(),
       suggest: Default::default(),
@@ -1071,6 +1076,10 @@ impl Config {
     paths
   }
 
+  pub fn log_file(&self) -> bool {
+    self.settings.unscoped.log_file
+  }
+
   pub fn update_capabilities(
     &mut self,
     capabilities: &lsp::ClientCapabilities,
@@ -1321,6 +1330,7 @@ mod tests {
           test: true,
         },
         internal_debug: false,
+        log_file: false,
         lint: true,
         document_preload_limit: 1_000,
         suggest: DenoCompletionSettings {
diff --git a/cli/lsp/language_server.rs b/cli/lsp/language_server.rs
index a893ab3a8..225b46eac 100644
--- a/cli/lsp/language_server.rs
+++ b/cli/lsp/language_server.rs
@@ -102,6 +102,7 @@ use crate::factory::CliFactory;
 use crate::file_fetcher::FileFetcher;
 use crate::graph_util;
 use crate::http_util::HttpClient;
+use crate::lsp::logging::init_log_file;
 use crate::lsp::tsc::file_text_changes_to_workspace_edit;
 use crate::lsp::urls::LspUrlKind;
 use crate::npm::create_cli_npm_resolver_for_lsp;
@@ -3242,6 +3243,7 @@ impl tower_lsp::LanguageServer for LanguageServer {
 
     {
       let mut ls = self.0.write().await;
+      init_log_file(ls.config.log_file());
       if let Err(err) = ls.update_tsconfig().await {
         ls.client.show_message(MessageType::WARNING, err);
       }
diff --git a/cli/lsp/logging.rs b/cli/lsp/logging.rs
index b8c8c99e6..39a53f2b8 100644
--- a/cli/lsp/logging.rs
+++ b/cli/lsp/logging.rs
@@ -1,13 +1,85 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
 
+use chrono::DateTime;
+use chrono::Utc;
+use deno_core::parking_lot::Mutex;
+use std::fs;
+use std::io::prelude::*;
+use std::path::Path;
 use std::sync::atomic::AtomicBool;
 use std::sync::atomic::AtomicUsize;
 use std::sync::atomic::Ordering;
+use std::thread;
+use std::time::SystemTime;
 
 static LSP_DEBUG_FLAG: AtomicBool = AtomicBool::new(false);
 static LSP_LOG_LEVEL: AtomicUsize = AtomicUsize::new(log::Level::Info as usize);
 static LSP_WARN_LEVEL: AtomicUsize =
   AtomicUsize::new(log::Level::Warn as usize);
+static LOG_FILE: LogFile = LogFile {
+  enabled: AtomicBool::new(true),
+  buffer: Mutex::new(String::new()),
+};
+
+pub struct LogFile {
+  enabled: AtomicBool,
+  buffer: Mutex<String>,
+}
+
+impl LogFile {
+  pub fn write_line(&self, s: &str) {
+    if LOG_FILE.enabled.load(Ordering::Relaxed) {
+      let mut buffer = self.buffer.lock();
+      buffer.push_str(s);
+      buffer.push('\n');
+    }
+  }
+
+  fn commit(&self, path: &Path) {
+    let unbuffered = {
+      let mut buffer = self.buffer.lock();
+      if buffer.is_empty() {
+        return;
+      }
+      // We clone here rather than take so the buffer can retain its capacity.
+      let unbuffered = buffer.clone();
+      buffer.clear();
+      unbuffered
+    };
+    if let Ok(file) = fs::OpenOptions::new().append(true).open(path) {
+      write!(&file, "{}", unbuffered).ok();
+    }
+  }
+}
+
+pub fn init_log_file(enabled: bool) {
+  let prepare_path = || {
+    if !enabled {
+      return None;
+    }
+    let cwd = std::env::current_dir().ok()?;
+    let now = SystemTime::now();
+    let now: DateTime<Utc> = now.into();
+    let now = now.to_rfc3339().replace(':', "_");
+    let path = cwd.join(format!(".deno_lsp/log_{}.txt", now));
+    fs::create_dir_all(path.parent()?).ok()?;
+    fs::write(&path, "").ok()?;
+    Some(path)
+  };
+  let Some(path) = prepare_path() else {
+    LOG_FILE.enabled.store(false, Ordering::Relaxed);
+    LOG_FILE.buffer.lock().clear();
+    return;
+  };
+  thread::spawn(move || loop {
+    LOG_FILE.commit(&path);
+    thread::sleep(std::time::Duration::from_secs(1));
+  });
+}
+
+pub fn write_line_to_log_file(s: &str) {
+  LOG_FILE.write_line(s);
+}
 
 pub fn set_lsp_debug_flag(value: bool) {
   LSP_DEBUG_FLAG.store(value, Ordering::SeqCst)
@@ -53,7 +125,9 @@ macro_rules! lsp_log {
     if lsp_log_level == log::Level::Debug {
       $crate::lsp::logging::lsp_debug!($($arg)+)
     } else {
-      log::log!(lsp_log_level, $($arg)+)
+      let s = std::format!($($arg)+);
+      $crate::lsp::logging::write_line_to_log_file(&s);
+      log::log!(lsp_log_level, "{}", s)
     }
   )
 }
@@ -67,7 +141,9 @@ macro_rules! lsp_warn {
       if lsp_log_level == log::Level::Debug {
         $crate::lsp::logging::lsp_debug!($($arg)+)
       } else {
-        log::log!(lsp_log_level, $($arg)+)
+        let s = std::format!($($arg)+);
+        $crate::lsp::logging::write_line_to_log_file(&s);
+        log::log!(lsp_log_level, "{}", s)
       }
     }
   )
@@ -75,8 +151,12 @@ macro_rules! lsp_warn {
 
 macro_rules! lsp_debug {
   ($($arg:tt)+) => (
-    if crate::lsp::logging::lsp_debug_enabled() {
-      log::debug!($($arg)+)
+    {
+      let s = std::format!($($arg)+);
+      $crate::lsp::logging::write_line_to_log_file(&s);
+      if $crate::lsp::logging::lsp_debug_enabled() {
+        log::debug!("{}", s)
+      }
     }
   )
 }
diff --git a/cli/lsp/repl.rs b/cli/lsp/repl.rs
index 2f023197d..04905e3bd 100644
--- a/cli/lsp/repl.rs
+++ b/cli/lsp/repl.rs
@@ -300,6 +300,7 @@ pub fn get_repl_workspace_settings() -> WorkspaceSettings {
     import_map: None,
     code_lens: Default::default(),
     internal_debug: false,
+    log_file: false,
     lint: false,
     document_preload_limit: 0, // don't pre-load any modules as it's expensive and not useful for the repl
     tls_certificate: None,