parallelize reading of GPX files

This is another pretty CPU bound task (parsing the XML files), so it
makes sense to parallelize. We already have rayon, we already have the
setting to control parallelism, so let's use it and make hittekaart
fast!

1 files changed, 19 insertions, 9 deletions

diff --git a/src/main.rs b/src/main.rs
index 8727003..53a1301 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,14 +5,20 @@ use std::{
 };
 
 use clap::Parser;
-use color_eyre::eyre::{bail, eyre, Context, Result};
+use color_eyre::{
+    eyre::{bail, eyre, Context, Result},
+    Report,
+};
 use hittekaart::{
     gpx::{self, Compression},
     renderer,
 };
 use indicatif::{MultiProgress, ProgressBar, ProgressDrawTarget, ProgressStyle};
 use is_terminal::IsTerminal;
-use rayon::ThreadPoolBuilder;
+use rayon::{
+    iter::{IndexedParallelIterator, IntoParallelRefIterator, ParallelIterator},
+    ThreadPoolBuilder,
+};
 
 #[derive(Parser, Debug, Clone)]
 #[command(author, version, about)]
@@ -69,13 +75,17 @@ fn main() -> Result<()> {
     bar.set_prefix("Reading GPX files");
 
     let mut tracks = Vec::new();
-    for file in &args.files {
-        let compression = Compression::suggest_from_path(file)
-            .ok_or_else(|| eyre!("Could not determine format for {file:?}"))?;
-        let data = gpx::extract_from_file(file, compression)?;
-        tracks.push(data);
-        bar.inc(1);
-    }
+    args.files
+        .par_iter()
+        .map(|file| {
+            let compression = Compression::suggest_from_path(file)
+                .ok_or_else(|| eyre!("Could not determine format for {file:?}"))?;
+            let data = gpx::extract_from_file(file, compression)?;
+            bar.inc(1);
+            Ok::<_, Report>(data)
+        })
+        .collect_into_vec(&mut tracks);
+    let tracks = tracks.into_iter().collect::<Result<Vec<_>>>()?;
     bar.finish();
 
     ensure_output_directory(&args.output_directory)?;