1 files changed, 109 insertions, 0 deletions

diff --git a/crates/profile/src/lib.rs b/crates/profile/src/lib.rs
new file mode 100644
index 000000000..ab19271c7
--- /dev/null
+++ b/crates/profile/src/lib.rs
@@ -0,0 +1,109 @@
+//! A collection of tools for profiling rust-analyzer.
+
+mod stop_watch;
+mod memory_usage;
+#[cfg(feature = "cpu_profiler")]
+mod google_cpu_profiler;
+mod hprof;
+mod tree;
+
+use std::cell::RefCell;
+
+pub use crate::{
+    hprof::{init, init_from, span},
+    memory_usage::{Bytes, MemoryUsage},
+    stop_watch::{StopWatch, StopWatchSpan},
+};
+
+/// Prints backtrace to stderr, useful for debugging.
+#[cfg(feature = "backtrace")]
+pub fn print_backtrace() {
+    let bt = backtrace::Backtrace::new();
+    eprintln!("{:?}", bt);
+}
+#[cfg(not(feature = "backtrace"))]
+pub fn print_backtrace() {
+    eprintln!(
+        r#"enable the backtrace feature:
+    profile = {{ path = "../profile", features = [ "backtrace"] }}
+"#
+    );
+}
+
+thread_local!(static IN_SCOPE: RefCell<bool> = RefCell::new(false));
+
+/// Allows to check if the current code is withing some dynamic scope, can be
+/// useful during debugging to figure out why a function is called.
+pub struct Scope {
+    prev: bool,
+}
+
+impl Scope {
+    #[must_use]
+    pub fn enter() -> Scope {
+        let prev = IN_SCOPE.with(|slot| std::mem::replace(&mut *slot.borrow_mut(), true));
+        Scope { prev }
+    }
+    pub fn is_active() -> bool {
+        IN_SCOPE.with(|slot| *slot.borrow())
+    }
+}
+
+impl Drop for Scope {
+    fn drop(&mut self) {
+        IN_SCOPE.with(|slot| *slot.borrow_mut() = self.prev);
+    }
+}
+
+/// A wrapper around google_cpu_profiler.
+///
+/// Usage:
+/// 1. Install gpref_tools (https://github.com/gperftools/gperftools), probably packaged with your Linux distro.
+/// 2. Build with `cpu_profiler` feature.
+/// 3. Tun the code, the *raw* output would be in the `./out.profile` file.
+/// 4. Install pprof for visualization (https://github.com/google/pprof).
+/// 5. Bump sampling frequency to once per ms: `export CPUPROFILE_FREQUENCY=1000`
+/// 6. Use something like `pprof -svg target/release/rust-analyzer ./out.profile` to see the results.
+///
+/// For example, here's how I run profiling on NixOS:
+///
+/// ```bash
+/// $ nix-shell -p gperftools --run \
+///     'cargo run --release -p rust-analyzer -- parse < ~/projects/rustbench/parser.rs > /dev/null'
+/// ```
+///
+/// See this diff for how to profile completions:
+///
+/// https://github.com/rust-analyzer/rust-analyzer/pull/5306
+#[derive(Debug)]
+pub struct CpuSpan {
+    _private: (),
+}
+
+#[must_use]
+pub fn cpu_span() -> CpuSpan {
+    #[cfg(feature = "cpu_profiler")]
+    {
+        google_cpu_profiler::start("./out.profile".as_ref())
+    }
+
+    #[cfg(not(feature = "cpu_profiler"))]
+    {
+        eprintln!("cpu_profiler feature is disabled")
+    }
+
+    CpuSpan { _private: () }
+}
+
+impl Drop for CpuSpan {
+    fn drop(&mut self) {
+        #[cfg(feature = "cpu_profiler")]
+        {
+            google_cpu_profiler::stop()
+        }
+    }
+}
+
+pub fn memory_usage() -> MemoryUsage {
+    MemoryUsage::current()
+}