feat(lsp): add internal debugging logging (#10438)

Ref: #10368

1 files changed, 92 insertions, 0 deletions

diff --git a/cli/logger.rs b/cli/logger.rs
new file mode 100644
index 000000000..f3a12eec2
--- /dev/null
+++ b/cli/logger.rs
@@ -0,0 +1,92 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+
+use std::io::Write;
+use std::sync::atomic::AtomicBool;
+use std::sync::atomic::Ordering;
+use std::sync::Arc;
+
+lazy_static::lazy_static! {
+  pub static ref LSP_DEBUG_FLAG: Arc<AtomicBool> = Arc::new(AtomicBool::new(false));
+}
+
+struct CliLogger(env_logger::Logger);
+
+impl CliLogger {
+  pub fn new(logger: env_logger::Logger) -> Self {
+    Self(logger)
+  }
+
+  pub fn filter(&self) -> log::LevelFilter {
+    self.0.filter()
+  }
+}
+
+impl log::Log for CliLogger {
+  fn enabled(&self, metadata: &log::Metadata) -> bool {
+    if metadata.target() == "deno::lsp::performance"
+      && metadata.level() == log::Level::Debug
+    {
+      LSP_DEBUG_FLAG.load(Ordering::Relaxed)
+    } else {
+      self.0.enabled(metadata)
+    }
+  }
+
+  fn log(&self, record: &log::Record) {
+    if self.enabled(record.metadata()) {
+      self.0.log(record);
+    }
+  }
+
+  fn flush(&self) {
+    self.0.flush();
+  }
+}
+
+pub(crate) fn init(maybe_level: Option<log::Level>) {
+  let log_level = maybe_level.unwrap_or(log::Level::Info);
+  let logger = env_logger::Builder::from_env(
+    env_logger::Env::default()
+      .default_filter_or(log_level.to_level_filter().to_string()),
+  )
+  // https://github.com/denoland/deno/issues/6641
+  .filter_module("rustyline", log::LevelFilter::Off)
+  // wgpu crates (gfx_backend), have a lot of useless INFO and WARN logs
+  .filter_module("wgpu", log::LevelFilter::Error)
+  .filter_module("gfx", log::LevelFilter::Error)
+  // used to make available the lsp_debug which is then filtered out at runtime
+  // in the cli logger
+  .filter_module("deno::lsp::performance", log::LevelFilter::Debug)
+  .format(|buf, record| {
+    let mut target = record.target().to_string();
+    if let Some(line_no) = record.line() {
+      target.push(':');
+      target.push_str(&line_no.to_string());
+    }
+    if record.level() <= log::Level::Info
+      || (record.target() == "deno::lsp::performance"
+        && record.level() == log::Level::Debug)
+    {
+      // Print ERROR, WARN, INFO and lsp_debug logs as they are
+      writeln!(buf, "{}", record.args())
+    } else {
+      // Add prefix to DEBUG or TRACE logs
+      writeln!(
+        buf,
+        "{} RS - {} - {}",
+        record.level(),
+        target,
+        record.args()
+      )
+    }
+  })
+  .build();
+
+  let cli_logger = CliLogger::new(logger);
+  let max_level = cli_logger.filter();
+  let r = log::set_boxed_logger(Box::new(cli_logger));
+  if r.is_ok() {
+    log::set_max_level(max_level);
+  }
+  r.expect("Could not install logger.");
+}