src/tools/rust-analyzer/crates/profile/src/lib.rs

   1 //! A collection of tools for profiling rust-analyzer.
   2
   3 #![warn(rust_2018_idioms, unused_lifetimes, semicolon_in_expressions_from_macros)]
   4
   5 mod stop_watch;
   6 mod memory_usage;
   7 #[cfg(feature = "cpu_profiler")]
   8 mod google_cpu_profiler;
   9 mod hprof;
  10 mod tree;
  11
  12 use std::cell::RefCell;
  13
  14 pub use crate::{
  15     hprof::{heartbeat, heartbeat_span, init, init_from, span},
  16     memory_usage::{Bytes, MemoryUsage},
  17     stop_watch::{StopWatch, StopWatchSpan},
  18 };
  19
  20 pub use countme;
  21 /// Include `_c: Count<Self>` field in important structs to count them.
  22 ///
  23 /// To view the counts, run with `RA_COUNT=1`. The overhead of disabled count is
  24 /// almost zero.
  25 pub use countme::Count;
  26
  27 thread_local!(static IN_SCOPE: RefCell<bool> = RefCell::new(false));
  28
  29 /// Allows to check if the current code is within some dynamic scope, can be
  30 /// useful during debugging to figure out why a function is called.
  31 pub struct Scope {
  32     prev: bool,
  33 }
  34
  35 impl Scope {
  36     #[must_use]
  37     pub fn enter() -> Scope {
  38         let prev = IN_SCOPE.with(|slot| std::mem::replace(&mut *slot.borrow_mut(), true));
  39         Scope { prev }
  40     }
  41     pub fn is_active() -> bool {
  42         IN_SCOPE.with(|slot| *slot.borrow())
  43     }
  44 }
  45
  46 impl Drop for Scope {
  47     fn drop(&mut self) {
  48         IN_SCOPE.with(|slot| *slot.borrow_mut() = self.prev);
  49     }
  50 }
  51
  52 /// A wrapper around google_cpu_profiler.
  53 ///
  54 /// Usage:
  55 /// 1. Install gpref_tools (<https://github.com/gperftools/gperftools>), probably packaged with your Linux distro.
  56 /// 2. Build with `cpu_profiler` feature.
  57 /// 3. Run the code, the *raw* output would be in the `./out.profile` file.
  58 /// 4. Install pprof for visualization (<https://github.com/google/pprof>).
  59 /// 5. Bump sampling frequency to once per ms: `export CPUPROFILE_FREQUENCY=1000`
  60 /// 6. Use something like `pprof -svg target/release/rust-analyzer ./out.profile` to see the results.
  61 ///
  62 /// For example, here's how I run profiling on NixOS:
  63 ///
  64 /// ```bash
  65 /// $ bat -p shell.nix
  66 /// with import <nixpkgs> {};
  67 /// mkShell {
  68 ///   buildInputs = [ gperftools ];
  69 ///   shellHook = ''
  70 ///     export LD_LIBRARY_PATH="${gperftools}/lib:"
  71 ///   '';
  72 /// }
  73 /// $ set -x CPUPROFILE_FREQUENCY 1000
  74 /// $ nix-shell --run 'cargo test --release --package rust-analyzer --lib -- benchmarks::benchmark_integrated_highlighting --exact --nocapture'
  75 /// $ pprof -svg target/release/deps/rust_analyzer-8739592dc93d63cb crates/rust-analyzer/out.profile > profile.svg
  76 /// ```
  77 ///
  78 /// See this diff for how to profile completions:
  79 ///
  80 /// <https://github.com/rust-lang/rust-analyzer/pull/5306>
  81 #[derive(Debug)]
  82 pub struct CpuSpan {
  83     _private: (),
  84 }
  85
  86 #[must_use]
  87 pub fn cpu_span() -> CpuSpan {
  88     #[cfg(feature = "cpu_profiler")]
  89     {
  90         google_cpu_profiler::start("./out.profile".as_ref())
  91     }
  92
  93     #[cfg(not(feature = "cpu_profiler"))]
  94     {
  95         eprintln!(
  96             r#"cpu profiling is disabled, uncomment `default = [ "cpu_profiler" ]` in Cargo.toml to enable."#
  97         );
  98     }
  99
 100     CpuSpan { _private: () }
 101 }
 102
 103 impl Drop for CpuSpan {
 104     fn drop(&mut self) {
 105         #[cfg(feature = "cpu_profiler")]
 106         {
 107             google_cpu_profiler::stop();
 108             let profile_data = std::env::current_dir().unwrap().join("out.profile");
 109             eprintln!("Profile data saved to:\n\n    {}\n", profile_data.display());
 110             let mut cmd = std::process::Command::new("pprof");
 111             cmd.arg("-svg").arg(std::env::current_exe().unwrap()).arg(&profile_data);
 112             let out = cmd.output();
 113
 114             match out {
 115                 Ok(out) if out.status.success() => {
 116                     let svg = profile_data.with_extension("svg");
 117                     std::fs::write(&svg, out.stdout).unwrap();
 118                     eprintln!("Profile rendered to:\n\n    {}\n", svg.display());
 119                 }
 120                 _ => {
 121                     eprintln!("Failed to run:\n\n   {cmd:?}\n");
 122                 }
 123             }
 124         }
 125     }
 126 }
 127
 128 pub fn memory_usage() -> MemoryUsage {
 129     MemoryUsage::now()
 130 }