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//! `coarse-prof` allows you to hierarchically measure the time that blocks in
//! your program take, enabling you to get an intuition of where most time is
//! spent. This can be useful for game development, where you have a bunch of
//! things that need to run in every frame, such as physics, rendering,
//! networking and so on, and you may wish to identify the hot spots, so that
//! you know whether and what to optimize.
//!
//! `coarse-prof`'s implementation has been inspired by
//! [hprof](https://github.com/cmr/hprof).
//! In contrast to `hprof`, which resets measurements after each frame, this
//! library tracks averages over multiple frames. Also, `coarse-prof` provides
//! the macro [`profile`](macro.profile.html) for profiling a scope, so that
//! users do not have to assign a name to scope guards.
//!
//! # Example
//!
//! ```
//! use std::thread::sleep;
//! use std::time::Duration;
//!
//! use coarse_prof::profile;
//!
//! fn render() {
//! profile!("render");
//!
//! // So slow!
//! sleep(Duration::from_millis(10));
//! }
//!
//! // Our game's main loop
//! let num_frames = 100;
//! for i in 0..num_frames {
//! profile!("frame");
//!
//! // Physics don't run every frame
//! if i % 10 == 0 {
//! profile!("physics");
//! sleep(Duration::from_millis(2));
//!
//! {
//! profile!("collisions");
//! sleep(Duration::from_millis(1));
//! }
//! }
//!
//! render();
//! }
//!
//! // Print the profiling results.
//! coarse_prof::write(&mut std::io::stdout()).unwrap();
//! ```
//!
//! Example output:
//! ```text
//! frame: 100.00%, 10.40ms/call @ 96.17Hz
//! physics: 3.04%, 3.16ms/call @ 9.62Hz
//! collisions: 33.85%, 1.07ms/call @ 9.62Hz
//! render: 96.84%, 10.07ms/call @ 96.17Hz
//! ```
use std::cell::RefCell;
use std::io;
use std::rc::Rc;
use std::time::Duration;
use instant::Instant;
thread_local!(
/// Global thread-local instance of the profiler.
pub static PROFILER: RefCell<Profiler> = RefCell::new(Profiler::new())
);
/// Print profiling scope tree.
///
/// Example output:
/// ```text
/// frame: 100.00%, 10.40ms/call @ 96.17Hz
/// physics: 3.04%, 3.16ms/call @ 9.62Hz
/// collisions: 33.85%, 1.07ms/call @ 9.62Hz
/// render: 96.84%, 10.07ms/call @ 96.17Hz
/// ```
///
/// Percentages represent the amount of time taken relative to the parent node.
///
/// Frequencies are computed with respect to the total amount of time spent in
/// root nodes. Thus, if you have multiple root nodes and they do not cover
/// all code that runs in your program, the printed frequencies will be
/// overestimated.
pub fn write<W: io::Write>(out: &mut W) -> io::Result<()> {
PROFILER.with(|p| p.borrow().write(out))
}
/// Reset profiling information.
pub fn reset() {
PROFILER.with(|p| p.borrow_mut().reset());
}
/// Manually enter a scope.
///
/// The returned instance of [`Guard`](struct.Guard.html) should be dropped
/// when leaving the scope.
///
/// Usually, it is more convenient to use the macro
/// [`profile`](macro.profile.html) for including a scope in profiling, but in
/// some special cases explicit entering/leaving can make sense.
pub fn enter(name: &'static str) -> Guard {
PROFILER.with(|p| p.borrow_mut().enter(name))
}
/// Use this macro to add the current scope to profiling. In effect, the time
/// taken from entering to leaving the scope will be measured.
///
/// Internally, the scope is inserted in the scope tree of the global
/// thread-local [`PROFILER`](constant.PROFILER.html).
///
/// # Example
///
/// The following example will profile the scope `"foo"`, which has the scope
/// `"bar"` as a child.
///
/// ```
/// use coarse_prof::profile;
///
/// {
/// profile!("foo");
///
/// {
/// profile!("bar");
/// // ... do something ...
/// }
///
/// // ... do some more ...
/// }
/// ```
#[macro_export]
macro_rules! profile {
($name:expr) => {
let _guard = $crate::PROFILER.with(|p| p.borrow_mut().enter($name));
};
}
/// Internal representation of scopes as a tree.
struct Scope {
/// Name of the scope.
name: &'static str,
/// Parent scope in the tree. Root scopes have no parent.
pred: Option<Rc<RefCell<Scope>>>,
/// Child scopes in the tree.
succs: Vec<Rc<RefCell<Scope>>>,
/// How often has this scope been visited?
num_calls: usize,
/// In total, how much time has been spent in this scope?
duration_sum: Duration,
/// Minimal duration spent in this scope.
duration_min: Duration,
/// Maximal duration spent in this scope.
duration_max: Duration,
}
impl Scope {
fn new(name: &'static str, pred: Option<Rc<RefCell<Scope>>>) -> Scope {
Scope {
name,
pred,
succs: Vec::new(),
num_calls: 0,
duration_sum: Duration::new(0, 0),
duration_min: Duration::new(u64::MAX, u32::MIN),
duration_max: Duration::new(0, 0),
}
}
/// Enter this scope. Returns a `Guard` instance that should be dropped
/// when leaving the scope.
fn enter(&mut self) -> Guard {
Guard::enter()
}
/// Leave this scope. Called automatically by the `Guard` instance.
fn leave(&mut self, duration: Duration) {
self.num_calls += 1;
// Even though this is extremely unlikely, let's not panic on overflow.
let duration_sum = self.duration_sum.checked_add(duration);
self.duration_sum = duration_sum.unwrap_or(Duration::from_millis(0));
self.duration_min = self.duration_min.min(duration);
self.duration_max = self.duration_max.max(duration);
}
fn write_recursive<W: io::Write>(
&self,
out: &mut W,
total_duration: Duration,
depth: usize,
) -> io::Result<()> {
let total_duration_secs = total_duration.as_secs_f64();
let duration_sum_secs = self.duration_sum.as_secs_f64();
let pred_sum_secs = self.pred.clone().map_or(total_duration_secs, |pred| {
pred.borrow().duration_sum.as_secs_f64()
});
let percent = duration_sum_secs / pred_sum_secs * 100.0;
// Write self
for _ in 0..depth {
write!(out, " ")?;
}
writeln!(
out,
"{}: {:3.2}%, {:>4.2}ms avg, {:>4.2}ms min, {:>4.2}ms max @ {:.2}Hz",
self.name,
percent,
duration_sum_secs * 1000.0 / (self.num_calls as f64),
self.duration_min.as_secs_f64() * 1000.0,
self.duration_max.as_secs_f64() * 1000.0,
self.num_calls as f64 / total_duration_secs,
)?;
// Write children
for succ in &self.succs {
succ.borrow()
.write_recursive(out, total_duration, depth + 1)?;
}
Ok(())
}
}
/// A guard that is created when entering a scope and dropped when leaving it.
pub struct Guard {
enter_time: Instant,
}
impl Guard {
fn enter() -> Self {
Self {
enter_time: Instant::now(),
}
}
}
impl Drop for Guard {
fn drop(&mut self) {
let duration = self.enter_time.elapsed();
PROFILER.with(|p| p.borrow_mut().leave(duration));
}
}
/// A `Profiler` stores the scope tree and keeps track of the currently active
/// scope.
///
/// Note that there is a global thread-local instance of `Profiler` in
/// [`PROFILER`](constant.PROFILER.html), so it is not possible to manually
/// create an instance of `Profiler`.
pub struct Profiler {
roots: Vec<Rc<RefCell<Scope>>>,
current: Option<Rc<RefCell<Scope>>>,
start_time: Instant,
}
impl Profiler {
fn new() -> Profiler {
Profiler {
roots: Vec::new(),
current: None,
start_time: Instant::now(),
}
}
/// Enter a scope. Returns a [`Guard`](struct.Guard.html) that should be
/// dropped upon leaving the scope.
///
/// Usually, this method will be called by the
/// [`profile`](macro.profile.html) macro, so it does not need to be used
/// directly.
pub fn enter(&mut self, name: &'static str) -> Guard {
// Check if we have already registered `name` at the current point in
// the tree.
let succ = if let Some(current) = self.current.as_ref() {
// We are currently in some scope.
let existing_succ = current
.borrow()
.succs
.iter()
.find(|succ| succ.borrow().name == name)
.cloned();
existing_succ.unwrap_or_else(|| {
// Add new successor node to the current node.
let new_scope = Scope::new(name, Some(current.clone()));
let succ = Rc::new(RefCell::new(new_scope));
current.borrow_mut().succs.push(succ.clone());
succ
})
} else {
// We are currently not within any scope. Check if `name` already
// is a root.
let existing_root = self
.roots
.iter()
.find(|root| root.borrow().name == name)
.cloned();
existing_root.unwrap_or_else(|| {
// Add a new root node.
let new_scope = Scope::new(name, None);
let succ = Rc::new(RefCell::new(new_scope));
self.roots.push(succ.clone());
succ
})
};
let guard = succ.borrow_mut().enter();
self.current = Some(succ);
guard
}
/// Completely reset profiling data.
fn reset(&mut self) {
self.roots.clear();
self.start_time = Instant::now();
// Note that we could now still be anywhere in the previous profiling
// tree, so we can not simply reset `self.current`. However, as the
// frame comes to an end we will eventually leave a root node, at which
// point `self.current` will be set to `None`.
}
/// Leave the current scope.
fn leave(&mut self, duration: Duration) {
self.current = if let Some(current) = self.current.as_ref() {
current.borrow_mut().leave(duration);
// Set current scope back to the parent node (if any).
current.borrow().pred.as_ref().cloned()
} else {
// This should not happen with proper usage.
log::error!("Called coarse_prof::leave() while not in any scope");
None
};
}
fn write<W: io::Write>(&self, out: &mut W) -> io::Result<()> {
let total_duration = Instant::now().duration_since(self.start_time);
for root in self.roots.iter() {
root.borrow().write_recursive(out, total_duration, 0)?;
}
out.flush()
}
}
#[cfg(test)]
mod tests {
#[test]
fn test_multiple_roots() {
super::reset();
for i in 0..=5 {
if i == 5 {
profile!("a");
}
{
profile!("b");
}
}
super::PROFILER.with(|p| {
let p = p.borrow();
assert_eq!(p.roots.len(), 2);
for root in p.roots.iter() {
assert!(root.borrow().pred.is_none());
assert!(root.borrow().succs.is_empty());
}
assert_eq!(p.roots[0].borrow().name, "b");
assert_eq!(p.roots[1].borrow().name, "a");
assert_eq!(p.roots[0].borrow().num_calls, 6);
assert_eq!(p.roots[1].borrow().num_calls, 1);
});
}
#[test]
fn test_succ_reuse() {
use std::ptr;
super::reset();
for i in 0..=5 {
profile!("a");
if i > 2 {
profile!("b");
}
}
assert_eq!(super::PROFILER.with(|p| p.borrow().roots.len()), 1);
super::PROFILER.with(|p| {
let p = p.borrow();
assert_eq!(p.roots.len(), 1);
let root = p.roots[0].borrow();
assert_eq!(root.name, "a");
assert!(root.pred.is_none());
assert_eq!(root.succs.len(), 1);
assert_eq!(root.num_calls, 6);
let succ = root.succs[0].borrow();
assert_eq!(succ.name, "b");
assert!(ptr::eq(
succ.pred.as_ref().unwrap().as_ref(),
p.roots[0].as_ref()
));
assert!(succ.succs.is_empty());
assert_eq!(succ.num_calls, 3);
});
}
#[test]
fn test_reset_during_frame() {
super::reset();
for i in 0..=5 {
profile!("a");
profile!("b");
{
profile!("c");
if i == 5 {
super::reset();
}
assert!(super::PROFILER.with(|p| p.borrow().current.is_some()));
profile!("d");
}
}
super::PROFILER.with(|p| {
let p = p.borrow();
assert!(p.roots.is_empty());
assert!(p.current.is_none());
});
}
}