2 files changed, 170 insertions, 0 deletions

diff --git a/crates/ra_prof/Cargo.toml b/crates/ra_prof/Cargo.toml
new file mode 100644
index 000000000..19ce21783
--- /dev/null
+++ b/crates/ra_prof/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+edition = "2018"
+name = "ra_prof"
+version = "0.1.0"
+authors = ["rust-analyzer developers"]
+publish = false
+
+[dependencies]
+lazy_static = "1.3.0"
\ No newline at end of file
diff --git a/crates/ra_prof/src/lib.rs b/crates/ra_prof/src/lib.rs
new file mode 100644
index 000000000..55ad45fb7
--- /dev/null
+++ b/crates/ra_prof/src/lib.rs
@@ -0,0 +1,161 @@
+extern crate lazy_static;
+
+use std::cell::RefCell;
+use std::time;
+use std::fmt;
+use std::mem;
+use std::io::{stderr, StderrLock, Write};
+use std::iter::repeat;
+use std::collections::{HashSet};
+use std::default::Default;
+use std::iter::FromIterator;
+use std::sync::RwLock;
+
+use lazy_static::lazy_static;
+
+type Message = (usize, u64, String);
+
+pub struct Profiler {
+    desc: String,
+}
+
+pub struct Filter {
+    depth: usize,
+    allowed: Vec<String>,
+}
+
+struct ProfileStack {
+    starts: Vec<time::Instant>,
+    messages: Vec<Message>,
+    filter_data: FilterData,
+}
+
+impl ProfileStack {
+    fn new() -> ProfileStack {
+        ProfileStack { starts: Vec::new(), messages: Vec::new(), filter_data: Default::default() }
+    }
+}
+
+#[derive(Default)]
+struct FilterData {
+    depth: usize,
+    version: usize,
+    allowed: HashSet<String>,
+}
+
+impl Clone for FilterData {
+    fn clone(&self) -> FilterData {
+        let set = HashSet::from_iter(self.allowed.iter().cloned());
+        FilterData { depth: self.depth, allowed: set, version: self.version }
+    }
+}
+
+lazy_static! {
+    static ref FILTER: RwLock<FilterData> = RwLock::new(Default::default());
+}
+
+thread_local!(static PROFILE_STACK: RefCell<ProfileStack> = RefCell::new(ProfileStack::new()));
+
+pub fn set_filter(f: Filter) {
+    let mut old = FILTER.write().unwrap();
+    let set = HashSet::from_iter(f.allowed.iter().cloned());
+    let filter_data = FilterData { depth: f.depth, allowed: set, version: old.version + 1 };
+    *old = filter_data;
+}
+
+pub fn profile<T: fmt::Display>(desc: T) -> Profiler {
+    PROFILE_STACK.with(|stack| {
+        let mut stack = stack.borrow_mut();
+        if stack.starts.len() == 0 {
+            match FILTER.try_read() {
+                Ok(f) => {
+                    if f.version > stack.filter_data.version {
+                        stack.filter_data = f.clone();
+                    }
+                }
+                Err(_) => (),
+            };
+        }
+        let desc_str = desc.to_string();
+        if desc_str.is_empty() {
+            Profiler { desc: desc_str }
+        } else if stack.starts.len() < stack.filter_data.depth
+            && stack.filter_data.allowed.contains(&desc_str)
+        {
+            stack.starts.push(time::Instant::now());
+            Profiler { desc: desc_str }
+        } else {
+            Profiler { desc: String::new() }
+        }
+    })
+}
+
+impl Drop for Profiler {
+    fn drop(&mut self) {
+        if self.desc.is_empty() {
+            return;
+        }
+        PROFILE_STACK.with(|stack| {
+            let mut stack = stack.borrow_mut();
+            let start = stack.starts.pop().unwrap();
+            let duration = start.elapsed();
+            let duration_ms = duration.as_secs() * 1000 + u64::from(duration.subsec_millis());
+            let stack_len = stack.starts.len();
+            let msg = (stack_len, duration_ms, mem::replace(&mut self.desc, String::new()));
+            stack.messages.push(msg);
+            if stack_len == 0 {
+                let stdout = stderr();
+                print(0, &stack.messages, 1, &mut stdout.lock());
+                stack.messages.clear();
+            }
+        });
+    }
+}
+
+fn print(lvl: usize, msgs: &[Message], enabled: usize, stdout: &mut StderrLock<'_>) {
+    if lvl > enabled {
+        return;
+    }
+    let mut last = 0;
+    for (i, &(l, time, ref msg)) in msgs.iter().enumerate() {
+        if l != lvl {
+            continue;
+        }
+        writeln!(
+            stdout,
+            "{} {:6}ms - {}",
+            repeat("    ").take(lvl + 1).collect::<String>(),
+            time,
+            msg
+        )
+        .expect("printing profiling info to stdout");
+
+        print(lvl + 1, &msgs[last..i], enabled, stdout);
+        last = i;
+    }
+}
+
+#[cfg(test)]
+mod tests {
+
+    use super::profile;
+    use super::set_filter;
+    use super::Filter;
+
+    #[test]
+    fn test_basic_profile() {
+        let s = vec!["profile1".to_string(), "profile2".to_string()];
+        let f = Filter { depth: 2, allowed: s };
+        set_filter(f);
+        profiling_function1();
+    }
+
+    fn profiling_function1() {
+        let _p = profile("profile1");
+        profiling_function2();
+    }
+
+    fn profiling_function2() {
+        let _p = profile("profile2");
+    }
+}