1 //! This module provides an extension trait which allows in-process profilers
2 //! to be hooked into the `--profile-time` argument at compile-time. Users of
3 //! out-of-process profilers such as perf don't need to do anything special.
4 
5 use std::path::Path;
6 
7 /// Extension trait for external crates to implement which provides start/stop
8 /// hooks when profiling (but not when benchmarking) functions.
9 pub trait Profiler {
10     /// This function is called when Criterion.rs starts profiling a particular
11     /// benchmark. It provides the stringified benchmark ID and
12     /// a path to a directory where the profiler can store its data.
start_profiling(&mut self, benchmark_id: &str, benchmark_dir: &Path)13     fn start_profiling(&mut self, benchmark_id: &str, benchmark_dir: &Path);
14 
15     /// This function is called after Criterion.rs stops profiling a particular
16     /// benchmark. The benchmark ID and directory are the same as in the call
17     /// to `start`, provided for convenience.
stop_profiling(&mut self, benchmark_id: &str, benchmark_dir: &Path)18     fn stop_profiling(&mut self, benchmark_id: &str, benchmark_dir: &Path);
19 }
20 
21 /// Dummy profiler implementation, representing cases where the profiler is
22 /// an external process (eg. perftools, etc.) which do not require start/stop
23 /// hooks. This implementation does nothing and is used as the default.
24 pub struct ExternalProfiler;
25 impl Profiler for ExternalProfiler {
start_profiling(&mut self, _benchmark_id: &str, _benchmark_dir: &Path)26     fn start_profiling(&mut self, _benchmark_id: &str, _benchmark_dir: &Path) {}
stop_profiling(&mut self, _benchmark_id: &str, _benchmark_dir: &Path)27     fn stop_profiling(&mut self, _benchmark_id: &str, _benchmark_dir: &Path) {}
28 }
29