add support for a log file

examples/arithmetic.rs

@@ -66,17 +66,25 @@ struct Args {
 
     #[arg(short, long)]
     multiple: bool,
+
+    #[arg(short, long)]
+    log_file: Option<String>,
 }
 
 fn main() {
     let args = Args::parse();
 
-    let bencher = plnk::Bencher::new(args.nb_measurements);
+    let bencher = match args.log_file {
+        Some(path) => plnk::Bencher::new(args.nb_measurements)
+            .with_file(path.into())
+            .overwrite(),
+        None => plnk::Bencher::new(args.nb_measurements),
+    };
 
     if args.multiple {
         arithmetic_multiple(&bencher.with_name("arithmetic"));
     } else {
         arithmetic(&bencher.with_name("arithmetic"));
     }
-    random(&bencher.with_name("random"));
+    random(&bencher.with_name("random").append());
 }

src/lib.rs

 #![doc = include_str!("../README.md")]
 
-use std::time::{Duration, Instant};
+use std::{
+    fs::{create_dir_all, File},
+    io::Write,
+    path::PathBuf,
+    time::{Duration, Instant},
+};
 
 use indicatif::{MultiProgress, ProgressBar, ProgressStyle};
 
@@ -13,6 +18,9 @@ pub struct Bencher {
     name: String,
 
     quiet: bool,
+
+    file: Option<PathBuf>,
+    append: bool,
 }
 
 impl Bencher {
@@ -21,6 +29,8 @@ impl Bencher {
             nb_measurements,
             name: "".to_string(),
             quiet: false,
+            file: None,
+            append: false,
         }
     }
 
@@ -30,6 +40,39 @@ impl Bencher {
             nb_measurements: self.nb_measurements,
             name: name.to_string(),
             quiet: self.quiet,
+            file: self.file.clone(),
+            append: self.append,
+        }
+    }
+
+    /// add a file to a bencher
+    pub fn with_file(&self, path: PathBuf) -> Self {
+        Self {
+            nb_measurements: self.nb_measurements,
+            name: self.name.clone(),
+            quiet: self.quiet,
+            file: Some(path),
+            append: self.append,
+        }
+    }
+    /// append to file
+    pub fn append(&self) -> Self {
+        Self {
+            nb_measurements: self.nb_measurements,
+            name: self.name.clone(),
+            quiet: self.quiet,
+            file: self.file.clone(),
+            append: true,
+        }
+    }
+    /// overwrite file
+    pub fn overwrite(&self) -> Self {
+        Self {
+            nb_measurements: self.nb_measurements,
+            name: self.name.clone(),
+            quiet: self.quiet,
+            file: self.file.clone(),
+            append: false,
         }
     }
 
@@ -82,7 +125,29 @@ where
         pb.inc(1);
     }
 
-    println!("{}", label! { label: label, name: b.name, times: times });
+    let output = format!("{}", label! { label: label, name: b.name, times: times });
+    if let Some(path) = &b.file {
+        create_dir_all(path.parent().unwrap()).expect(&format!(
+            "could not create parent directory of log file '{}'",
+            path.to_str().unwrap()
+        ));
+        let mut f = File::options()
+            .write(true)
+            .append(b.append)
+            .truncate(!b.append)
+            .create(true)
+            .open(path)
+            .expect(&format!(
+                "could not open log file '{}'",
+                path.to_str().unwrap()
+            ));
+        writeln!(&mut f, "{}", output).expect(&format!(
+            "could not write to log file '{}'",
+            path.to_str().unwrap()
+        ));
+    } else {
+        println!("{}", output);
+    }
 }
 
 /// run a given piece of code a bunch of times and output the measurements
@@ -105,6 +170,8 @@ pub fn bench_multiple(b: &Bencher, benches: Vec<(String, Box<dyn Fn() -> Duratio
     let pb_main = mpb.add(ProgressBar::new(benches.len() as u64).with_style(style.clone()));
     pb_main.set_message(b.name.clone());
 
+    let mut append = b.append;
+
     for (label, f) in benches.iter() {
         let pb = mpb.add(ProgressBar::new(b.nb_measurements as u64).with_style(style.clone()));
         pb.set_message(label.to_string());
@@ -118,7 +185,31 @@ pub fn bench_multiple(b: &Bencher, benches: Vec<(String, Box<dyn Fn() -> Duratio
         pb_main.inc(1);
         pb.finish_and_clear();
 
-        println!("{}", label! { label: label, name: b.name, times: times });
+        let output = format!("{}", label! { label: label, name: b.name, times: times });
+        if let Some(path) = &b.file {
+            create_dir_all(path.parent().unwrap()).expect(&format!(
+                "could not create parent directory of log file '{}'",
+                path.to_str().unwrap()
+            ));
+            println!("append: {}", append);
+            let mut f = File::options()
+                .write(true)
+                .append(append)
+                .truncate(!append)
+                .create(true)
+                .open(path)
+                .expect(&format!(
+                    "could not open log file '{}'",
+                    path.to_str().unwrap()
+                ));
+            writeln!(&mut f, "{}", output).expect(&format!(
+                "could not write to log file '{}'",
+                path.to_str().unwrap()
+            ));
+            append = true;
+        } else {
+            println!("{}", output);
+        }
     }
 
     pb_main.finish_with_message(format!("{} done", b.name));